Transition pathway towards 100% renewable energy across the sectors of power, heat, transport, and desalination for the Philippines

Abstract

Transition towards sustainable energy systems is of utmost importance to avert global consequences of climate change. Within the framework of the Paris Agreement and Marrakech Communique, this study analyses an energy transition pathway utilising renewable resources for the Philippines. The transition study is performed from 2015 to 2050 on a high temporal and spatial resolution data, using a linear optimisation tool. From the results of this study, technically, a 100% fossil free energy system in 2050 is possible, with a cost structure comparable to an energy system in 2015, while having zero greenhouse gas emissions. Solar PV as a generation and batteries a as storage technology form the backbone of the energy system during the transition. Direct and indirect electrification across all sectors would result in an efficiency gain of more than 50% in 2050, while keeping the total annual investment within 20-55 b€. Heat pumps, electrical heating, and solar thermal technologies would supply heat, whereas, direct electricity and synthetic fuels would fuel the energy needs of the transport sector. The results indicate that, indigenous renewable resources in the Philippines could power the demand from all energy sectors, thereby, bringing various socioeconomic benefits.

Full text

Renewable and Sustainable Energy Reviews 144 (2021) 110934
1364-0321/© 2021 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
Transition pathway towards 100% renewable energy across the sectors of
power, heat, transport, and desalination for the Philippines
Ashish Gulagi
a
,
*
, Myron Alcanzare
b
, Dmitrii Bogdanov
a
, Eugene Esparcia Jr.
b
, Joey Ocon
b
,
Christian Breyer
a
a
LUT University, Yliopistonkatu 34, 53850, Lappeenranta, Finland
b
Laboratory of Electrochemical Engineering (LEE), Department of Chemical Engineering, University of the Philippines Diliman, Quezon City, 1101, Philippines
ARTICLE INFO
Keywords:
Energy transition
100% renewables
Solar energy
Battery storage
All sectors
Philippines
ABSTRACT
Transition towards sustainable energy systems is of utmost importance to avert global consequences of climate
change. Within the framework of the Paris Agreement and Marrakech Communique, this study analyses an
energy transition pathway utilising renewable resources for the Philippines. The transition study is performed
from 2015 to 2050 on a high temporal and spatial resolution data, using a linear optimisation tool. From the
results of this study, technically, a 100% fossil free energy system in 2050 is possible, with a cost structure
comparable to an energy system in 2015, while having zero greenhouse gas emissions. Solar PV as a generation
and batteries a as storage technology form the backbone of the energy system during the transition. Direct and
indirect electrication across all sectors would result in an efciency gain of more than 50% in 2050, while
keeping the total annual investment within 20–55 b
€
. Heat pumps, electrical heating, and solar thermal tech-
nologies would supply heat, whereas, direct electricity and synthetic fuels would fuel the energy needs of the
transport sector. The results indicate that, indigenous renewable resources in the Philippines could power the
demand from all energy sectors, thereby, bringing various socio-economic benets.
1. Introduction
There is a consensus among nations to transform the global energy
systems mainly relying on nite fossil fuels towards utilising renewable
and sustainable resources to avert the irreversible effects of anthropo-
genic climate change [1]. While some countries are taking lead in
renewable energy (RE) utilisation, concurrent global efforts are still
missing as seen from increasing greenhouse gas (GHG) emissions [2]
Consequently, a growing number of catastrophic climate change events
are common occurrences in different parts of the world. The Philippines,
a country with 7641 islands, is cited as one of the most susceptible
countries to climate change [3], exposing itself to super typhoons [4],
rising sea levels [5], and droughts [6]. For the Philippines, transforming
its energy system by utilising higher shares of renewable resources
would help decreasing GHG emissions and consequently mitigating
these vulnerabilities.
Transition towards utilising higher share of renewables, however,
requires an overhaul of the current fossil fuel-based energy system.
Besides being highly efcient, the energy system should be a new
combination of several renewable technologies. For example, solar
photovoltaics (PV) is likely to play a major role in the electricity pro-
duction [7,8] on a global scale, followed by wind energy and other
sustainable technologies. Simultaneously, technologies, like heat
pumps, electrical heating, and electric vehicles, would make the heat
and transport sectors more efcient. Furthermore, exibility provided
by bridging and storage solutions, would ensure security of energy
supply of Variable Renewable Rnergy (VRE) technologies. Finally, an
integrated all energy sector transition towards 100% RE is complex,
however studies for the entire planet [9–12] and country-level studies
for Chile [13], Bolivia [14], Ethiopia [15] and Jordan [16] have shown
that it is technically and economically possible.
In this research, a 100% renewable energy transition pathway for the
Philippines was simulated using the LUT Energy System Transition
model [9,12,17]. The energy sectors power, heat, transport and desali-
nation were realised, and their complex interaction was studied.
The paper is structured as follows. Section 1.1 describes the Philip-
pine energy system structure. The energy planning and motivations are
given in Section 1.2, and Section 1.3 tackles the historical context of the
Philippine energy sector. Section 1.4 describes the Philippine energy
* Corresponding author.
E-mail address: Ashish.Gulagi@lut. (A. Gulagi).
Contents lists available at ScienceDirect
Renewable and Sustainable Energy Reviews
journal homepage: http://www.elsevier.com/locate/rser
https://doi.org/10.1016/j.rser.2021.110934
Received 3 July 2020; Received in revised form 25 February 2021; Accepted 3 March 2021

Renewable and Sustainable Energy Reviews 144 (2021) 110934
2
generation and demand sector. Section 1.5 gives an overview of the
current renewable energy scenario in the Philippines. Section 1.6 pro-
vides a review on the main energy transition studies for the Philippines
or where the Philippines is part of a larger study and Section 1.7 gives
the scope and novelty of the article. Section 2 details the methods,
resource potential of the various renewable technologies while also
mentioning the important constraints and assumptions used for the
energy transition modelling. Section 3 contains the parameters for en-
ergy analysis. Section 4 describes detailed nancial and technical results
of the modelling with corresponding discussions drawn in Section 5.
Finally, Section 6 draws conclusion of the research.
1.1. Philippine energy system structure
The Philippine energy system is dominated by the power sector with
49% share of the total primary energy supply. Because of the country’s
archipelagic features, the power grid is essentially divided into on-grid
(main grid) and off-grid areas. On-grid is dened as areas which are
connected to the major islands such as Luzon, Mindanao, Panay, Cebu,
Guimaras, Bohol, Negros, Leyte, and Samar as part of the national power
grid. In contrast, off-grid areas are typically small islands and inland
mountainous areas that are not techno-economically viable to connect
to the main grid.
The power industry in the Philippines is divided into four different
segments: generation, transmission, distribution and retail electricity,
all coming under the umbrella of the Energy Regulatory Commission
(ERC) [18]. The generation segment consists of private companies,
distribution unit-owned companies, and the unsold assets of the Na-
tional Power Corporation (NPC). The transmission sector is handled by
the privately-owned National Grid Corporation of the Philippines
(NGCP). The distribution sector consists of electric cooperatives and
privately or independently-owned utilities with few instances of local
government-owned distribution utilities. The retail electricity sector
consists of electricity aggregators for the contestable end-users. The
energy storage systems are integrated across the electricity supply chain
depending on intended applications. The participants from generation,
distribution, and retail electricity sector can participate either through
wholesale electricity spot market and/or bilateral contracts upon open
competitive bidding.
On the other hand, the off-grid areas have different market structure
with the role of NPC relegated to missionary electrication by providing
power, with the provision to operate transmission and distribution as-
sets, in rural and remote off-grid areas in the Philippines through NPC -
Small Power Utilities Group (NPC-SPUG) [18]. Other entities such as
New Power Providers (NPPs) handle generation in off-grid areas and
require power purchase agreements (PPA) with the distribution unit
while Qualied Third Parties (QTP) essentially handle both generation
and distribution in off-grid areas, which require a waiver from the
electric cooperative originally handling the area. In some cases, the local
government unit handles operation of the micro-grid.
Non-power sectors such as transportation and industry also
contribute in the national energy demand through its usage of fuel and/
or direct electricity. Transportation in the Philippines is dominated by
road vehicles with jeeps for inter-city and buses for regional passenger
transport, and trucks for freight transport. In rural areas, motorcycles
and tricycles are the more prevalent mass transit option. Roll-on/roll-off
ships and ferries are prevalent in marine inter-regional passenger and
freight transport, especially with the promotion of nautical highway
system in mid-2000s, while motorised bangka (double outrigger canoe)
are preferred in small remote islands. Aviation travel has a larger share
than ferries for long-distance travel between islands since the mid-1990s
due to price competition by low-cost airline companies, and availability
of new routes [19].
The industry sector contributes ~30% of the total GDP (at constant
2018 price) behind services sector with ~60% share, with high value
export goods in 2019 focused on electronic products (semiconductors),
agricultural products (fresh bananas and coconut oil), machinery and
transport equipment, ignition wiring sets, and metal components [20].
Economic activity of the industry sector comes at an energy consump-
tion of 7449 kTOE, with direct fuel use constituting ~72% of the total
while the rest from direct electricity use as of 2016 [21].
1.2. Philippine energy planning and motivations
A target in the Philippine Energy Plan (PEP) [22] is to have an
optimal 2030 power energy mix as follows: 70% base generation ca-
pacity dened in PEP as coal, geothermal, large hydropower, natural
gas, nuclear and biomass, 20% mid-merit capacity, utilised from natural
gas, and 10% capacity for peaking, utilised from oil-based plants and
VRE such as solar PV and wind. Another target is to increase the ef-
ciency related to the transport sector, which is the most energy inten-
sive, according to the Department of Energy (DOE) [22]. This is planned
to be addressed through deployment of compressed natural gas (CNG),
LPG, hybrid-electric, and all-electric road vehicles, with conversion of
marine and aviation vehicles being initiated after successful transition of
road vehicles. Additionally, railways are briey mentioned because of
the anticipated increase in electricity consumption brought upon by the
planned line extension and greeneld projects. For the industry sector,
energy conservation and efciency programs will be implemented, with
cement, steel, semiconductor, manufacturing, and sugar industries as
priority [22]. Initiatives for demand response and demand side man-
agement are planned. In summary, the development of the PEP
considered economic growth projection, availability of indigenous nat-
ural resources, long-term energy security and reliability goals [22].
Nomenclature
AC Alternating Current
A-CAES Adiabatic compressed air energy storage
Capex Capital expenditure
CCGT Combined cycle gas turbine
CHP Combined Heat and Power
CSP Concentrating solar thermal power
ERC Energy Regulatory Commission
FLH Full load hours
GHG Greenhouse gases
HVAC High-voltage alternating current
IEA International Energy Agency
IPP Independent Power Producers
KTOE Kilo tons of oil equivalent
LCOC Levelised cost of curtailment
LCOE Levelised cost of electricity
LCOS Levelised cost of storage
LCOT Levelised cost of transmission
LPG Liquied petroleum gas
LUT Lappeenranta – Lahti University of Technology
NGCP National Grid Corporation of the Philippines
OCGT Open cycle gas turbine
Opex Operational expenditures
PEP Philippine Energy Plan
PHES Pumped hydro energy storage
PV Photovoltaics
RE Renewable energy
TES Thermal energy storage
WACC Weighted average cost of capital
A. Gulagi et al.

Renewable and Sustainable Energy Reviews 144 (2021) 110934
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The main motivations in crafting the latest PEP are as follows, rstly,
to address the high cost of retail electricity rates in the Philippines,
which is second only to Japan having the most expensive rates in Asia as
of 2018 [23]. The report uses average MERALCO retail electricity rate as
point of comparison, but retail electricity rates are higher in some areas
of the Philippines [24] with Visayan Electric Company Inc. (VECO) in
Metropolitan Cebu being the highest in the Philippines at 11.04
PHP/kWh (0.19
€
/kWh) compared to MERALCO at 8.85 PHP/kWh
(~0.15
€
/kWh) as of 2020 [25]. In addition, electricity rates in the
Philippines are unsubsidised compared to neighbouring countries as a
result of deregulation. Secondly, to address the lack of electricity access
for 2.3 million potential end-users in remote areas [26]. This is chal-
lenging to resolve considering that line extension to the main grid can be
a costly option despite minimal economic activity in these areas to
justify the investment. Government funding is used to address inade-
quate energy access through construction of new micro-grids and pro-
vision of subsidies for equitable electricity rates in off-grid areas.
Subsidies in electricity rates, however, are ballooning over time due to
increased demand. Thirdly, to address the vulnerability of the country
towards geopolitical tensions and highly volatile fossil fuel market since
52% of the total primary energy supply is imported as of 2016 [21], with
approximately 68% of coal in the Philippines is currently imported, 96%
of which is sourced from Indonesia [27]. Additionally, there is an
anticipated vulnerability due to the projected depletion of local natural
gas resource in Malampaya gas eld within the next few years [27].
1.3. History of Philippine energy sector
The energy situation in the Philippines and the current energy
planning motivations can be understood by mentioning the brief his-
torical context of the past 50 years. In 1969, the Philippines then sup-
plied 96% of its total energy demand from petroleum and was severely
affected during the rst oil crisis in 1973 [28]. This crisis prompted
exploration of indigenous resources for power and non-power applica-
tions and inclusion of nuclear energy to the energy mix. However, the
inclusion of nuclear power was halted in 1986 [29].
Insufcient power plants were built during the late 1980s despite
introduction of independent power producers [30]], resulting in a
power supply crisis during the early 1990s with rotating blackouts
throughout the country reaching from 8 to 12 h per day [31]. The
rotating blackouts ended in 1993, when NPC engaged with Independent
Power Producers (IPPs) through contracts to resolve the crisis. During
the same year, the Philippine legislature granted emergency powers to
the Philippine president to engage in negotiated contracts for con-
struction and maintenance of power plants to avoid another supply crisis
[32]. This caused NPC to accumulate debt due to IPP contract obliga-
tions which was exacerbated during the Asian Financial Crisis in 1997
due to decrease in electricity demand and high devaluation of the
Philippine peso. Eventually, the Philippine power industry was liberal-
ised in 2001 with provision to privatize all generation and transmission
assets of NPC, to recover NPC debt, and to allow wider participation of
the private sector [18]. Stranded debts are still being paid by the retail
customers as of 2020 [33], while the high generation cost comes from
Power Purchase Agreements (PPAs) and contracted supply which are
primarily dominated by coal and natural gas red power plants [34]. A
new law was enacted to reduce retail electricity rates using the proceeds
in Malampaya gas eld to pay the NPC debt [35].
The country has made efforts in its energy sector to improve the RE
share. In 2008, the country passed the Renewable Energy Act which
provides non-scal provisions such as feed-in tariff, net-metering,
renewable energy market, green energy option, renewable portfolio
standards and scal incentives such as corporate and import tax breaks
for RE development [36]. However, the full implementation of the
provisions was realised a decade after the enactment of the law and the
energy share of fossil fuel power plants has further increased. In 2017,
the Philippine tax code was amended to include increased coal and
petroleum excise tax rates. In 2019, a framework for energy storage
system integration in the electricity supply chain was implemented [37].
In the same year, a carbon tax feasibility study, generally dened as
taxing CO
2eq
generated, was started by the Department of Finance [38].
The current energy planning for transport and industrial sector was
inuenced by series of events. The country’s oil industry was liberalised
in 1998 [39]. It was done to reduce government subsidies by ending the
oil stabilisation fund, and to encourage competition [40]. However, high
reliance on imported oil makes domestic oil prices follow international
market price behaviour [40]. In 2006, the biofuels law was enacted to
improve air quality, mitigate greenhouse gas emissions, and further
reduce dependence on imported oil by imposing mandatory biodiesel
and bioethanol blends [41]. However, as of 2020, biodiesel and bio-
ethanol blends are still at 2% and 10%, respectively due to insufcient
local production. In 2017, the public transportation modernisation
program was implemented to phase out old mass transport vehicles and
shift into either (battery) electric vehicles or Euro-5 compliant internal
combustion engines vehicles [42]. In mid to late 2010s, there was a
surge in railway project proposals and investments in line extension or
new lines following to resolve the increasing decongestion in urban
areas [43]. With the surging fossil fuel cost and persistent high retail
electricity cost, the energy conservation and efciency measures were
institutionalized in 2019 in order to reduce operating costs and fuel
usage especially for commercial and industrial sector [44].
1.4. Energy demand and generation
The economy of the Philippines is one of the fastest growing in Asia
with an average annual GDP growth rate of 6.3% from 2010 to 2018
[45]. Since economic growth and increasing electricity consumption are
often correlated, it is clearly observed in the case of the Philippines when
electricity consumption increased from 67.7 TWh in 2010 to 99.8 TWh
in 2018 [45].
In 2016, primary energy demand was fullled with an energy mix of
59% from fossil fuels and 41% from renewables. The share of imported
oil in the total energy supply mix was the largest with 32% [46]. Figs. 1
and 2 present the installed capacity and electricity generation by
different sources, respectively, as classied by the Philippine Depart-
ment of Energy. In the early 2000s, the country had more than 30% RE
share due to its geothermal and hydropower plants, however, the
increasing energy demand was supplied by additional coal and natural
gas red power plants [21]. As of 2019, the total installed power ca-
pacity in the on-grid areas is 25.0 GW with a capacity mix as follows:
41.7% coal, 15.1% oil, 13.8% natural gas, 14.9% hydropower, 7.7%
geothermal, 3.7% solar PV, 1.7% wind, 1.4% biomass [47]. The total
installed capacity in the off-grid areas as of December 2019 is 525.7 MW
with 94.2% coming from oil (diesel) and the remaining from hydro-
power and solar PV [47].
There are about 5.7 GW of committed power plant projects and 48.7
GW of indicative power plants projects as of December 2019. Majority of
the committed power plant projects come from coal (72.5%) and natural
gas red power plants (11.4%). Most of the installations are greeneld
while others are increasing the current capacity. For indicative power
plant projects, most of the installations are coming from solar PV
(24.2%), coal (21.5%), natural gas (17.0%), and oil red power plants
(16.5%). The capacity of the indicative battery energy storage systems
projects is about 2 GWh
cap
. The committed and indicative power plant
projects show high preference towards coal and natural gas red power
plants from 2020 onwards [49] which is in line with the PEP target in
2017 regarding energy mix [50].
Road vehicles dominate the nal total transport energy demand
followed by marine and aviation, respectively (Fig. 3) with a large surge
starting in early 2010s. Within the fuel type, diesel and gasoline domi-
nates to supply the energy demand of the sector (Fig. 4). There is an
increase in LPG and biofuels use for vehicles starting in late 2000s due to
government programs on usage of alternative fuels but there is also a
A. Gulagi et al.

Renewable and Sustainable Energy Reviews 144 (2021) 110934
4
surge of diesel fuel use starting in early 2010s. Miniscule demand sup-
plied by direct electricity is attributed to the light rail in Metropolitan
Manila.
Large share of industrial energy demand is coming from non-metallic
mineral processing, food, beverages and tobacco, iron and steel and
machinery (Fig. 5). Direct use of coal, fuel oil, and diesel are prevalent in
the Philippine industrial sector with fuel preference shifting from fuel oil
to coal starting in early 2000s. Use of direct electricity is also prevalent
to satisfy industrial demand as shown in Fig. 6.
1.5. Current status and potential of renewable energy in the Philippines
The Philippines has substantial resources to harness RE, especially
solar PV as seen from Fig. 7 [51]. The installed capacity of
ground-mounted solar PV in the country is at 921 MW as of 2019. Ma-
jority of the ground-mounted installed capacities come from Negros
Occidental, Batangas and Tarlac [48]. Rooftop solar PV was also tapped
albeit in miniscule installed capacity through net-metering program. In
off-grid areas, investments in RE-based micro-grids which are typically
dominated by solar PV, has been the focus in enabling sustainable en-
ergy access for the inhabitants [52].
The Philippines is ranked third globally in terms of geothermal
power plant installed capacity after United States and Indonesia, [53].
Geothermal energy was rst incorporated in the Philippine energy mix
in 1969. After the rst oil crisis in 1973, the country began to ramp up
tapping the geothermal resource, with substantial large-scale
Fig. 1. Installed power capacity in the Philippines from 1990 to 2019 [47].
Fig. 2. Annual electrical energy generated of the Philippines per sources from 1990 to 2019 [48].
Fig. 3. Annual nal transport energy demand per mode of transportation from 1990 to 2016 [37].
A. Gulagi et al.

Renewable and Sustainable Energy Reviews 144 (2021) 110934
5
installations starting in early 1980s. In 2019, the installed capacity of
geothermal power plants in the Philippines is 1.93 GW. Most of the
capacities are in Makiling-Banahaw, Tiwi, Maibarara, Bacon-Manito,
Tongonan, Palinpinon, and Mt. Apo.
Wind energy constitutes about 1.9% of the total installed capacity
mix as of 2019, primarily located in Ilocos Norte, Rizal, Aklan, Mindoro,
Guimaras, and Romblon. The indicative onshore wind installations as of
December 2019 accounts for 427 MW with capacity expansion of
existing sites and possible new onshore wind sites at Laguna, Sorsogon,
Batangas, Negros, Iloilo, Camarines Norte, Camarines Sur, Bohol, Aklan,
Capiz, and Samar [49]. In addition, an in-depth feasibility study to
install 1.2 GW offshore wind sites at Aparri Bay in north Luzon and
Guimaras Strait in western Visayas was given a greenlight by the
Department of Energy [54].
Hydropower in the country has a combined total installed capacity of
3.8 GW in 2019, mainly composed of large dammed hydropower plants.
These plants are mainly located in mountainous regions such as in
Cordillera and Sierra Madre mountain range, Bukidnon, and Lanao area.
Run-of-river installations across the country are also incorporated in the
energy mix.
The Philippine agricultural sector contributed 7.1% to the GDP
(current price) in 2019 [20]. This sector produces agricultural waste that
can be used in various ways, one of which is biomass energy production.
Consequently, majority of biomass power plants in the Philippines are
located near large agricultural lands that produce rice, corn, coconut,
and sugarcane. In 2019, biomass-red power plants had an installed
capacity of 363 MW mostly located in Cagayan Valley, Central Luzon,
Negros, and Central Mindanao [47].
There are also substantial ocean energy resources that can be
potentially harnessed. For instance, part of the Pacic Ocean region with
Fig. 4. Annual nal transport energy demand per fuel use [37].
Fig. 5. Annual nal industry energy demand according to type of industry from 1990 to 2016 [37].
Fig. 6. Annual nal industry energy demand per fuel use from 1990 to 2016 [37].
A. Gulagi et al.

Renewable and Sustainable Energy Reviews 144 (2021) 110934
6
largest temperature difference which can be harnessed by ocean thermal
power plants being located within the exclusive economic zone of the
Philippines. Some of the areas are also potentially viable for ocean tidal
and ocean wave energy [55,56]. There has been a boom and bust in the
hype of installing ocean energy citing uncertainty over a proper feed-in
tariff for ocean energy and technological readiness [57,58].
The lack of priority in deploying VRE in the PEP resulted in limited
energy storage system installations in the Philippines, with only two
utility-scale energy storage systems that are operational in the main grid
as of 2019: a battery energy storage system in Zambales and a pumped
hydro energy storage (PHES) in Laguna.
1.6. Review on energy transition studies for the Philippines
Energy transition studies utilising high shares of renewable and
sustainable energy resources for the Philippines has been gaining mo-
mentum in recent years. While most of these studies focus on the tran-
sition of the power sector with scenarios utilising some share of fossil
fuels as a backup, Gulagi et al. [59,60], Jacobson et al. [10] and Teske
[11] offer scenarios ranging for various sectors towards 100% renewable
Fig. 7. Solar PV generation potential for optimally xed tilted systems for the Philippines [51].
A. Gulagi et al.

Renewable and Sustainable Energy Reviews 144 (2021) 110934
7
energy for the future. Jacobson et al. [10] offer pathways towards 100%
RE for the Philippines utilising the abundant solar, wind and hydro-
power resources. Gulagi et al. [59] did an overnight 100% RE scenario
excluding the heat and transport sectors for the year 2030 for Southeast
Asia and the Pacic Rim based on different levels of interconnection
between the countries. The Philippines was modelled as an individual
node having High Voltage Direct Current (HVDC) connection to
Indonesia. Another research focusing on the synthetic fuel trading in a
100% RE scenario considers the Southeast and Northeast Asian regions,
analysing the potential of Australia as a future goldmine of synthetic
fuels and displays potential interaction for the Philippines. Teske [11]
analyses a transition towards 100% RE for the globe where the
Philippines is part of the non-OECD Asia countries. The common
conclusion of these 100% RE studies is that it is technically feasible and
cost competitive for the Philippines to transition towards 100% RE, as
well as having various socio-economic benets.
Other research such as Mondal et al. [61] offer low-carbon strategies
for the Philippines using the TIMES model up to 2040 examining
different policy scenarios utilising fossil fuels as backup. However, the
conclusion drawn was similar to the above studies, a high share of RE in
the system has various benets. Due to its archipelagic features,
decentralised renewable energy solutions would benet remote islands,
where grid extension is not feasible. The utilisation of renewable energy
as a cost optimal solution in remote islands is given in Bertheau and
Blechinger [62], Lozano et al. [63], Ocon and Bertheau [64], Bertheau
and Cader [65], Meschede et al. [66] and Bertheau [67].
Table 1 provides a review of main energy transition studies and
decentralised systems with large shares of renewable energy for the
Philippines.
1.7. Scope and novelty of the research
According to its Intended Nationally Determined Contribution
(INDC), the Philippines has committed to 70% reduction in greenhouse
gas emissions from year 2000 in a business as usual (BAU) scenario by
2030 [71]. In addition, the Philippines signed the Marrakech Commu-
nique in 2016 [72], pledging to achieve net carbon neutrality and uti-
lisation of 100% RE in the economy. In order to honour the commitment
Table 1
Main energy transition studies for the Philippines.
Author, year Scope Sectors Key results Remarks
100% Renewable Energy scenarios
Gulagi et al.
(2017) [59]
Southeast Asia and the Pacic Rim.
Philippines considered as a single node
connected to Indonesia via HVDC power
line
Power, seawater
desalination and non-
energetic industrial gas
100% RE system is feasible and cost competitive for
the Philippines, while utilising its local renewable
resources.
A 100% RE overnight
scenario for 2030 on hourly
temporal resolution for an
entire year
Gulagi et al.
(2017) [60]
Southeast Asia and the Pacic Rim and
Northeast Asia. Philippines considered as
a single node connected to Indonesia via
HVDC power line
Power, seawater
desalination and non-
energetic industrial gas
Long distance transmission lines do not yield large
scale benets. However, Australia could become a
synthetic fuel exporter.
A 100% RE overnight
scenario for 2030 on hourly
temporal resolution for an
entire year.
Jacobson et al.
(2018) [10]
Global. Philippines as one of the
countries
Power, heat, transport A cost optimal 100% RE system with solar, wind and
hydropower as the generation sources. Other social
benets related to health and climate.
30-s model time step over the
ve-year period 2050–2054
Teske (2019)
[11]
Global. Philippines is part of the Non-
OECD Asia region
Power, heat, transport Zero GHG emissions achieved by 2050 in all the
sectors
Hourly temporal resolution
for power and heat
Bertheau (2020)
[67]
649 islands in the Philippines Power Cost-optimised 100% RE systems utilising solar and
battery capacities supplemented by wind capacities.
Hourly temporal resolution
for electricity in off-grid
islands
Large share renewable energy scenarios
Blakers et al.
(2012) [68]
Southeast Asia and Australia. The
Philippines as one of the countries in
Southeast Asia
Power In 2050, electricity demand in Southeast Asia would
be satised by transmitting and utilising solar PV
generated electricity from Australia. Other locally
produced renewable and conventional sources with
storage would supplement the supply.
Period 2010–2050
Huber et al.
(2015) [69]
ASEAN. The Philippines as one of the
regions
Power In 2050, cheapest sources of electricity generation
within the region are hydropower, biomass and
geothermal energy. Interconnections between the
countries are benecial.
Hourly for a 12 weeks period
for 2050
Mondal et al.
(2018) [61]
The Philippines Power Increase in energy security as imports decrease. Long-
term diversication of energy supply mix and lower
GHG emissions.
TIMES model from 2014 to
2040
Large share renewable energy scenarios for Islands
Bertheau and
Blechinger
(2018) [62]
133 small isolated island grids in the
Philippines
Power Hybrid diesel systems with solar PV and batteries
results in decrease of fuel consumption as well as the
cost of electricity, while providing continuous
electricity supply.
Hourly for one reference year
Lozano et al.
(2019) [63]
Gilutongan island in the Philippines Power Solar-diesel-storage hybrid system reduces cost by up
to 70%.
HOMER model simulating
for one reference day
Ocon and
Bertheau
(2019) [64]
215 off grid systems located in the
Philippines
Power Cleaner and lower cost continuous electricity possible
with hybrid PV-battery-diesel systems
Hourly for one reference year
Bertheau and
Cader (2019)
[65]
132 islands in the Philippines Power Submarine transmission cables are cost optimal for
larger island, however utilising local RE sources with
diesel generators is cost effective for most of the
islands.
Hourly for one reference year
Meschede et al.
(2019) [66]
Cluster analysis by classifying 502 off-
grid islands in the Philippines based on
different factors
Power About 86% of the islands belong to the ve clusters of
small and exceedingly small islands for which PV-
battery systems are favourable.
K-means clustering approach
having results reective of
techno-economic
simulations
Pascasio et al.
(2019) [70]
143 islands in the Philippines mostly
under NPC-SPUG
Power Optimal conguration of most islands is solar PV-wind
hybrid energy systems with 41.1% LCOE reduction
and 61.38% renewable energy mix.
HOMER model simulating
for one reference day
A. Gulagi et al.

Renewable and Sustainable Energy Reviews 144 (2021) 110934
8
that the Philippines engaged in Paris and Marrakech, this paper show-
cases a concrete cost-optimal pathway towards 100% renewable energy.
The novelty of this work is that it contributes to the constructive
discourse of energy transition towards renewable and sustainable en-
ergy in the Philippines by providing an open, quantitative, and analyt-
ical approach towards creation of a cost-optimal pathway towards 100%
RE. While the research articles support the need for the Philippines to
shift towards a higher share of renewables albeit the energy crises, they
lack the comprehensiveness concerning technology portfolio and high
temporal resolution. This research is the rst of its kind simulating all
energy sectors in an hourly scale for an entire year, while utilising the
various generation, storage and bridging technologies which are
described in Sections 2 and 3.
A 100% RE transition pathway for the Philippines will not only
ensure low vulnerability towards climate change events but also
external threats such as market speculations, stranded assets and the
geopolitics involving imported fossil and nuclear fuels, and at the same
time, reducing GHG emissions and air pollution [73,74]. Additionally, it
would also enable total electrication of the country because of the
modularity and scalability of RE technologies, which can be deployed in
a decentralised and distributed manner, apt for the archipelagic features
of the country. The deployment of modular RE in off-grid areas creates
signicant impact on the inhabitants not just by resolving energy
poverty but also economic poverty [75,76]. Despite being seemingly
counterintuitive due to high investment requirements, a 100% RE
transition pathway provides cheap long-term and stable energy prices
for the Philippines especially with an increasingly favourable global
market conditions in RE and energy storage. This option is in line with
the PEP goal to resolve the problem of high electricity retail cost asso-
ciated with high generation cost. These favourable market conditions
provide an opportunity for the country to decouple GHG emissions in its
industrialisation efforts [77]. The benets of pursuing 100% RE can
cascade to other Sustainable Development Goals such as water access,
food access, health, poverty, gender inequality, and quality education
[17,78].
2. Methods
This study analyses the energy transition towards 100% renewable
energy for the Philippines from 2015 to 2050, using the LUT Energy
System Transition model. A detailed description of the general model
and its inputs are given in Bogdanov et al. [17,79]. A recent review of
long-term energy system transition models ranked the applied model
highest among all the investigated models/tools [80]. A brief summary
of the main constraints is presented here.
Cost minimisation of an integrated energy system is the primary
target function of the transition model. To minimise cost, the model
optimises future RE power production and demand on an hourly scale
for any given year, within the boundaries of the linear constraints and
assumptions given as input. A ve-year time step is utilised, starting
from 2015 and continuing until 2050. However, different time steps can
be utilised as per the requirement. A third party solver, MOSEK ver. 8
[81], is used to optimise the main target function in Eq. (1). The post
processing of the optimisation results and input data for model compi-
lation is done using Matlab [82].
r, reg - all regions, t,tech. – all technologies, CAPEX
t
- capital expen-
ditures; crf
t
- capital recovery factor, OPEXx
t
- operational expendi-
tures xed, OPEXvar
t
- operational expenditures variable, instCap
t,r
-
installed capacity, E
gen,t,r
- electricity generation, rampCost
t
- ramping
cost and totRamp
t,r
- total power ramping annually.
In addition, decentralised generation and consumption (power and
heat) in the form of individual PV systems installed on rooftops and
batteries are also included in the modelling. Based on the power and
heat demand, these individual system owners are divided into three
categories: residential, commercial, and industrial. The prosumer (self-
generation and consumption of energy) model is an independent sub-
model which has the main aim of cost minimisation of consumed elec-
tricity, however, there are slight differences from the main target
function described above. The main difference is that it includes cost of
electricity from the grid and income earned from selling excess elec-
tricity to the grid, which is deducted from the total annual costs. The
target function for prosumer optimisation is given in Eq. (2).
r, reg - all regions, t,tech. – all technologies, CAPEX
t
- capital expen-
ditures; crf
t
- capital recovery factor, OPEXx
t
- operational expendi-
tures xed, OPEXvar
t
- operational expenditures variable, instCap
t,r
-
installed capacity, E
gen,t,r
- electricity generation, rampCost
t
- ramping
cost and totRamp
t,r
- total power ramping annually, instCap
t
- installed
capacity E
gen,t
- annual generation, elCost – electricity retail price;
elFeedIn – electricity feed-in price; Egrid - electricity consumed from grid
annually and Ecurt.- electricity fed-in to the grid annually.
The important constraints and features utilised for the modelling are
given here: First, modelling on an hourly resolution for a year depicts an
energy system much closer to reality showing a clear interaction not
only between generation and demand, but also various other technolo-
gies. Second, a constraint related to growth in RE installed capacity in
each 5 year time step is set to a maximum of 20% of the total installed
capacity. This avoids unrealistic excessive build-up of RE capacities.
Third, a constraint of no new fossil and nuclear capacities are allowed to
be installed after 2015 with an exception of gas power plants, as these
can be used in the future by utilising synthetic natural gas and bio-
methane produced sustainably. Fourth, a constraint on maximum pro-
sumer demand is set to 20% of the total demand, so that the growth in
prosumers is not drastic and depends on the demand of that region.
Additionally, growth in prosumer demand also depends on the cost
competitiveness of the entire prosumer system and the local electricity
prices.
min(∑
tech
t=1
(CAPEXt⋅crft+OPEXfixt)⋅instCapt+OPEXvart⋅Egen,t+elCost ⋅Egrid +elFeedIn ⋅Ecurt)(2)
min(∑
reg
r=1∑
tech
t=1
(CAPEXt⋅crft+OPEXfixt)⋅instCapt,r+OPEXvart⋅Egen,t,r+rampCostt⋅totRampt,r)(1)
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Renewable and Sustainable Energy Reviews 144 (2021) 110934
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The owchart of the model from input data to results is presented in
Fig. 8.
A portfolio of different generation technologies is used for power and
heat. The supply of generated electricity within the regions was assumed
to be done by existing alternating current power lines. As renewables are
variable, balancing and exibility was provided by utilising appropriate
storage technologies. The list of various technologies is given in Fig. 9.
On the left are all the renewable technologies such as rooftop PV [83],
optimally xed tilted PV, single-axis tracking PV [84], onshore wind,
hydropower, geothermal, biomass, waste-to-energy and fossil genera-
tion technologies, including CHP plants. On the right are the heating
only plants. The storage technologies such as batteries, pumped hydro
energy storage, adiabatic compressed air energy storage (A-CAES) [85],
gas storage and thermal energy storage (TES) enable a temporal shift of
the generated electricity and heat.
3. Parameters and assumptions
This study consists of various assumptions related to the input data.
Section 3.1 provides detailed assumptions and methods related to the
input generation proles of the important resources. Section 3.2 and 3.3
present the nancial and technical assumptions, respectively. Section
3.4 provides the assumptions regarding the demand growth of power,
heat and transport sectors during the transition.
3.1. Resource potential and generation proles
Hourly generation proles for an entire year were used for different
generation technologies, such as single-axis tracking and optimally til-
ted PV, solar CSP, wind energy and hydropower which were calculated
using different methodologies. First, feed-in proles for optimally tilted
PV, solar CSP and wind energy were based on irradiation and wind
speed data at a resolution of 0.45 ◦×0.45 ◦for the year 2005 from NASA
databases [87,88] reworked by German Aerospace Center [89]. Detailed
calculations on prole preparation are given in Bogdanov and Breyer
[90], whereas for single-axis tracking PV its given in Afanasyeva et al.
[84]. Second, hydropower proles were calculated from the rainfall data
for the year 2005 as a normalised sum of the rainfall in the entire
country. The biomass potential was gathered from Bunzel et al. [91]
according to three different categories: solid wastes (municipal solid
waste and all other waste), solid residues (agricultural and forest resi-
dues), and biogas. Cost numbers from International Energy Agency [92]
and Intergovernmental Panel on Climate Change [93] were used to
assign costs for these three categories of biomass. A 50
€
/ton gate fee for
2015 increasing to 100
€
/ton for 2050 is assumed for solid fuels used in
waste incineration plants [94]. Finally, the geothermal potential which
is used as an input is calculated according to Aghahosseini et al. [95].
The installed capacities for 2015 for generation technologies were
taken from Farfan and Breyer [96], which are the lower limit of the
capacities. On the other hand, capacity cap or the upper limit were set on
renewable technologies, so that unrealistic installed capacity should not
occur. The potential of solar and wind were calculated based on a cri-
terion that only 6% and 4% of the total available land is utilised,
respectively for each technology. Due to the variability of the renewable
generation prole and demand, the model utilises various storage
technologies.
3.2. Financial assumptions
The Supplementary Material (SM) Table S8 provides the data on
nancial assumptions of the different technologies utilised in the
modelling for the Philippines. Due to the absence of country specic
data on cost projections for all the technologies, a global average
number based on the expected cost decline was assumed [86,97–100].
Due to the expected improvements in technology, production processes,
materials and installations, the costs are expected to fall until 2050. For
example, cost of solar PV [99], wind energy [101] and batteries [97,99,
102] have decreased considerably in the last few years. Consequently,
this has triggered a rapid rise in installed capacities for many countries.
The weighted average cost of capital (WACC) is set at 7% in real terms
for all technologies, while for residential rooftop PV installations, a 4%
WACC was used due to lower nancial return expectations. The increase
or decrease in WACC for residential rooftop PV systems does not
considerably affect the per unit cost of electricity [7]. Additionally,
prosumers can sell excess electricity to the grid at 0.02
€
/kWh after
satisfying their own demand. The fuel prices for the fossil and nuclear
fuels and GHG emission costs are given in the SM Table S10. The elec-
tricity prices for residential, commercial and industrial categories for
2015 are assumed from Gerlach et al. [103] and price projection until
2050 were calculated according to the methodology described in Breyer
and Gerlach [104].
3.3. Technical assumptions
The data on the power plant capacities for 2015 can be found in the
SM (Table S11). The assumptions of the technical lifetimes and ef-
ciencies of the power plants can be found in SM Table S8 and S9. The
current installed capacities are assumed to be utilised until their service
lifetime and then decommissioned. No new fossil and nuclear power
plants will be built except for gas power plants. The upper limits for solar
and wind energy was calculated as mentioned in Section 3.1. It was
assumed that fuels required for biomass and waste-to-energy technolo-
gies are distributed evenly throughout the year.
3.4. Demand projection
The regional electricity demands for 2014 were taken from the
Philippine Statistics Authority [105] and extrapolated until 2050 based
on a growth rate of 3.9% [106]. In addition, heat demand from 2015 to
2050 was taken from Ram et al. [9]. The nal energy demand with
detailed numbers for the Philippines is given in SM Table S2. Since heat
and transport sectors also have an electricity demand, the power de-
mand itself excluded electricity utilised in the heat and transport sectors.
This was done in order to avoid double accounting and the fact that basic
power demand prole would be different from demand proles of other
sectors.
The hourly load prole for electricity is based on synthetic load data
from Toktarova et al. [107]. The heating sector was sub-divided into
four categories: space heating, domestic hot water, biomass for cooking,
and industrial heat required in processes. As the modelling is based on
Fig. 8. Model owchart from the input data to the results [17].
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Renewable and Sustainable Energy Reviews 144 (2021) 110934
10
an hourly resolution, heating proles for these three categories were
created, as described in Ram et al. [9]. Due to its location and tropical
climate, it was assumed that space heating is not required over the entire
year. However, domestic hot water may be required for daily activities.
Currently, there are no district heating networks in the Philippines and
we assume it will remain same until the end of the transition period.
For the transport sector, a demand prole as described in Breyer
et al. [108] and based on Khalili et al. [109] was adopted in the
modelling. The regional demand was based on relative population for
road, rail, marine and aviation transport modes. These individual
transport modes were further sub-divided into passenger (p-km) and
freight (t-km) demands. The transportation demand according to
different fuels and several vehicle types were assumed according to
Khalili et al. [109] as shown in SM Table S4. The shares of different
vehicle and fuel types in satisfying the transportation demand over the
projected transition period is given in the SM Table S4 and S5.
3.5. Description of the Scenario considered for the transition
A scenario considering 100% RE system, GHG emission reduction
and least cost of energy was developed for the Philippines. The following
key assumptions were considered in the optimisation and simulation to
achieve the reduction target.
•The start of the optimisation and simulation is in year 2015, as to t
the ve year time step used in the LUT Energy System Transition
Model. Actual installation of power plants beyond 2015 are not
accounted nor are the under construction, committed, and indicative
power plants from 2020.
•New fossil fuel capacities are not commissioned after 2015, except
gas red power plants, due to this being a Best Policy scenario with a
target of having zero emissions in 2050. Decommissioned fossil ca-
pacities can only be replaced by renewables and storage
technologies.
•A GHG emissions tax of 9
€
in 2015, which increases in 5-year time
steps to 28, 53, 61, 68, 75, 100 and 150
€
per tCO
2eq
until 2050 was
implemented. Implementing GHG emissions tax is still under study
by the country’s Department of Finance. However, it is safe to as-
sume that the country would use the GHG emissions tax which are
implemented globally as a benchmark for the taxes in the
Philippines.
•To have a realistic growth in renewable energy installed capacities, a
20% maximum growth limit in the share of total power generation
capacities is applied. The model is free to utilise a lower growth rate
than the maximum if renewables installation is not economically
viable.
•Prosumers cannot sell more than a maximum of 50% of the generated
electricity, in addition to satisfying their own demand rst. This is
mainly to avoid prosumers from developing a business model for
selling electricity to the grid. This is also prevented by an extremely
low price of selling electricity to the grid.
4. Results
The following sub-sections describe the results for the growth in
primary energy demand and efciency gains, cost structure, installed
capacities for technologies and annual GHG emissions in the transition
years.
4.1. Growth in energy demand
As a result of growing economy and population, the primary energy
demand almost doubles in 2050 in comparison to 2015 as observed from
Fig. 10 (left). However, massive electrication through all the energy
sectors results in an electricity share of about 88% in primary energy
demand, while the remaining sources of primary energy are heat and
bioenergy. As seen from Fig. 10 (right), direct and indirect electrication
results in an efciency gain of more than 40%, comparing it with an
energy system as of today (low electrication). Utilising direct elec-
tricity by replacing fossil fuels within the different energy processes and
technologies results in a highly efcient energy system through the
transition.
Fig. 9. The model for the coupled sectors power and heat [79], transport [9], and desalination [86]. Diagram according to Lopez et al. [14].
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Renewable and Sustainable Energy Reviews 144 (2021) 110934
11
4.2. Key nancial results of the energy transition
The total annual cost of the energy system throughout the transition
increases from 20 to 55 b
€
as shown in Fig. 11. The transport sector has
the largest share, while power and heat sectors have similar shares of the
total cost in 2050. Due to the lower desalination demand in the
Philippines, desalination sector has a minor contribution to the overall
energy system costs. Although, capital expenditures increase throughout
the transition as a result of gradually phasing out fossil fuel powered
technologies, the new investments in renewable generation sources and
storage technologies subsequently decrease the fossil fuel imports and
increase energy security. In addition, decreasing GHG emissions help the
Philippines to deliver its commitment to the Paris Climate Agreement as
scheduled.
Due to burgeoning energy demand, additional generation capacities
are added throughout the transition (Fig. 12). These capacities are
entirely based on renewables, rst, due to them being the least cost
source for energy production and second, due to the strict constraint of
the applied scenario that no new fossil-based capacities can be installed
after 2015. However, even if fossil-based capacities were to be con-
structed, these would remain as stranded assets, as these energy gen-
eration sources cannot compete with low cost and GHG emission free,
renewable energy. On the other hand, levelised cost of energy for a
100% RE system in 2050 would be around 49
€
/MWh even though a
stark increase in the capital expenditures by 2030 is observed. This is
due to the fact that aging oil-related infrastructure is decommissioned
after their technical lifetimes and electricity generation from highly
polluting coal power plants are reduced considerably and replaced by
renewables, which requires substantial capital expenditures. Note that
these are one-time investments, which are more than offset by dramat-
ically reduced costs related to variable operational expenditures, fuel
and GHG emissions often associated with fossil fuels. Due to its location
and regular pattern of availability of sunlight throughout the year, solar
PV as a generation source and batteries as storage technology form a
major part of investments through the transition, while signicantly
reducing GHG emissions and costs.
The outlook of energy costs of the different end-use sectors is given
below:
4.2.1. Power and heat
While LCOE of the power sector decreases by almost 23% in 2050 in
comparison to 2015, the LCOH from the heat sector increases by more
than three times in 2050 in comparison to 2015 as shown in Fig. 13. The
LCOE in the power sector mainly comprises of capital expenditures, as
new investments occur in renewable technologies. The fuel and GHG
emission related cost decreases throughout the transition and is almost
zero even before 2050, as phasing out fossil technologies decreases de-
mand for the associated fuels and thereby decreasing the fuel cost.
Detailed distribution of the LCOE according to the generation, storage,
curtailment and emission costs are given in SM Table S24. Additionally,
the heat sector undergoes major transition, decreasing fuel costs and
new investments mainly in direct heating and heat pumps. Despite
LCOH increase during the initial years of transition, it stabilises after
2040 while satisfying the increasing heat demands. Detailed distribution
of the LCOH according to the generation and storage costs are given in
SM Table S25.
4.2.2. Transport
The total LCOE in the transport sector is around 25
€
/MWh in 2050,
comprised mainly of the primary LCOE, storage costs and other system
components. The utilisation of fossil liquid fuels is reduced and replaced
by Fischer Tropsch (FT) fuels as these together with GHG emission costs
Fig. 10. Source-wise primary energy demand (left) and growth in efciency in primary energy demand (right).
Fig. 11. The total annual system costs for each of the demand sectors (left) and individual cost components (right).
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Renewable and Sustainable Energy Reviews 144 (2021) 110934
12
are in the same cost range as the fossil liquid fuels. Usage of electricity
grows prominently through the transition, while LNG is replaced by
more cost competitive SNG fuel. The CO
2
direct air capture as a feed-
stock for production of synthetic fuels , will cost around 31
€
/tCO
2eq
in
2050, utilising waste heat, as shown in Fig. 14.
The nal transport passenger and freight costs are given in Fig. 15.
The passenger transport costs decrease in all transport modes, while a
considerable decrease is observed for the road transport mode. Major
decrease through the transition years is observed for the road transport,
whereas there is a marginal decrease for rail, marine, and aviation.
Replacing liquid fossil fuels with cheap renewable electricity in the road
transport segment enables for a fast decrease in cost through the
transition.
4.3. Installed capacities and generation
In the previous section, it was shown that for the Philippines, tran-
sitioning towards renewables and investing in solar PV and battery
technologies among others, will reduce fuel costs, variable operational
costs and GHG emissions while promoting a sense of energy security. In
this section, installed capacities and electricity generation among
different demand sectors of power, heat and transport is examined.
4.3.1. Power and heat
The installed capacity in the power sector in 2015 is around 16 GW,
mainly composed of fossil fuel power plants. The share of renewables is
around 30%, with major share coming from hydropower and
geothermal energy, while the share of solar PV and wind energy is
Fig. 12. Capital expenditures for individual technologies in each ve year period (top) and levelised cost of energy with individual cost components (bottom).
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Renewable and Sustainable Energy Reviews 144 (2021) 110934
13
Fig. 13. Levelised cost of electricity (left) and levelised cost of heat (right) with individual cost components.
Fig. 14. Fossil and synthetic fuel costs from 2015 to 2050 (top) and fuel cost in 2050 (bottom) for the transport sector.
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Renewable and Sustainable Energy Reviews 144 (2021) 110934
14
negligible. In electricity generation, coal and gas dominate the genera-
tion mix, while a small share is coming from hydropower and internal
combustion engines. As a result of transitioning towards a RE system,
the fossil dominated capacity mix gradually changes towards a sus-
tainable energy mix, utilising the abundant local potential of solar PV
(Fig. 16). Across the power and heat sector, the total installed capacity to
satisfy the demand is around 455 GW, mainly dominated by solar PV
(68%) and other complementing technologies. Some of the old oil power
plants retire and are decommissioned at the end of their technical life-
times, but new coal-based power plants remain in the system as stranded
assets. Detailed installed capacities during the transition are given in the
SM Table S11.
During the transition, oil and coal-based power plants are replaced
by solar PV, while the gas power plants utilise synthetic fuels to satisfy
peak load during specic times. The sudden increase in installed ca-
pacity in 2030, is due to the lower capacity factors of solar PV as
compared to coal and oil-based generation.
The heating demand is quite limited and mostly caters to industrial
process heating needs with small share from domestic hot water re-
quirements. Fig. 17 shows the development of the heat sector through
the transition. The current capacities and generation are dominated by
coal, gas, and biomass-based heating. However, throughout the transi-
tion, the sources of heat supply shift towards utilising direct electricity
and heat pumps, while other heating technologies such as solar thermal
and biomass are utilised in industries catering specic needs. While most
of the heat requirement is for industrial based heating, the residential
and commercial sector has a small share mostly catered by using
biomass.
The heat generation from biomass remains relatively stable over the
transition period for all the end use sectors. Electricity-based heating
increases from 0.7% in 2015 to 41.9% in 2050. The role of gas-based
heat plants using fossil natural gas is reduced considerably until 2030
and converted into synthetic natural gas for heating purposes. Coal-
based heat plants are completely decommissioned from the heating
system. An increase in installed capacities of electric heating during the
nal ve-year period is observed, as fossil fuels are eliminated from the
system. Detailed electricity generation for the power and heat sectors
during the transition are given in the SM Table S14.
4.3.2. Transport
Due to increasing population and industrialisation, transportation
demand in terms of passenger-km [p-km] and ton-km [t-km] increases at
a steady pace from 2015 to 2050 (SM Table S2). Meanwhile, passenger
transport demand almost grows more than three times, the freight
transport grows by over six times during the transition (Fig. 18). How-
ever, as observed from Fig. 15, the costs in the transport sector decrease
throughout the transition period. This is mainly due to the efciency
gains and the use of low-cost renewable electricity, as electrication
sweeps through the transport sector, particularly for road and rail
transportation. The fossil fuel consumption in the transport sector de-
clines from 98% in 2015 to zero in 2050.
From Fig. 19, an increase is observed in the energy demand for
transport during the transition years. During the initial increase in de-
mand, less efcient fossil fuels are utilised as the share of direct elec-
tricity is low. However, shares of electrication, hydrogen and liquid
fuels start to grow from 2025 to 2035, consequently keeping the nal
energy demand for transport stable in these years. On the other hand, as
more liquid fuels are used mainly in the marine and aviation transport
Fig. 15. Final cost for passenger transport (left) and freight transport (right) during the transition.
Fig. 16. Total cumulative installed capacities and electricity generation according to different technologies.
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Renewable and Sustainable Energy Reviews 144 (2021) 110934
15
modes, total nal energy demand increases during the nal years of the
transition. Liquid fuels produced by renewable electricity contribute to
36%, while hydrogen fuel constitutes about 24% of the nal transport
energy demand in 2050. These sustainably produced fuels are mainly
utilised in the hard to electrify sectors like marine and aviation to ach-
ieve full sustainability in these transport modes. Energy crops could play
a vital role in enabling the transition of the transport sector towards
sustainability; however, care must be taken that the energy crops do not
compete with local food production and land use, and local production
must meet local demand.
The power generation capacities for the transport sector are based on
solar PV and increase to about 325 GW in 2050 as shown in Fig. 20.
Detailed numbers are given in the SM Table S12. Low cost solar PV
dominates the installed capacity throughout the transition, as PV costs
decrease and the need for low cost electricity arises due to massive
electrication and electricity required for producing synthetic fuels and
hydrogen. As a result, solar PV is the main source of electricity gener-
ation to meet the transportation demand in 2050.
Fig. 17. Total cumulative installed capacities and heat generation according to different technologies.
Fig. 18. Final transport passenger demands (left) in p-km and freight demands (right) in t-km for each mode from 2015 to 2050.
Fig. 19. Transport sector nal energy demand by different transport mode type (left) and fuel type (right).
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Renewable and Sustainable Energy Reviews 144 (2021) 110934
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4.4. Storage technologies
As the share of renewables increases through the transition, storage
technologies play a vital role in each of the demand sectors to balance
the variability and satisfy the demands. Different storage technologies
are utilised during the transition; however, batteries are the preferred
storage option in all the demand sectors. Due to the large role of solar PV
in electricity generation during the transition years, batteries balance
the night-time demand on daily basis. The following sub-sections
explain the role of storage technologies for all demand sectors.
4.4.1. Power and heat
As solar PV has a signicant role in power and heat sectors during the
transition, it can be seen from Fig. 16, batteries (prosumer and utility-
scale) play a signicant role to satisfy the electricity demand (Fig. 21)
while, heat demands are satised in the initial years by TES and gas
storage in 2050 (Fig. 22). Detailed information on different storage
output is given in SM Table S15. The energy system does not need
storage capacities in the initial years, as fossil fuels are dispatchable
when the need arises, however, during the later years, due to inux of
variable renewable energy, the model rst invests in cost-effective bat-
teries. Prosumer batteries start appearing rst in the system due to the
low-cost installation of solar PV systems on rooftops. The output from
prosumer batteries in 2050 is around 40 TWh, while utility-scale bat-
teries contribute 189 TWh. According to Solomon et al. [110],
penetration-storage-curtailment nexus denes the order of storage
deployment, which is clearly observed in thus study. Batteries transfer
on a daily basis PV generated electricity to satisfy evening and
night-time energy demand. However, in periods of cloudy weather, gas
peakers (CCGT and OCGT power plants) utilise synthetic gas to satisfy
the power demand. As seen from Fig. 16, increasing share of solar PV in
electricity generation during the transition corresponds to an increasing
installation of battery capacities. The combination of solar PV and bat-
teries provide least cost electricity during the transition. Due to low
seasonal variation, long term storage options such as A-CAES and gas
storage are not required to satisfy electricity demand, however seasonal
storage is required to satisfy the heat demand. The total storage output
to cover electricity demand is about 351 TWh, representing a share of
about 51% in 2050. About 73% of this share is supplied by batteries.
Heat storage capacities increase progressively until 2045 to around
0.7 TWh, but in the last ve years of the transition, a huge increase is
observed (Fig. 22). The huge increase is primarily to provide seasonal
heat storage in absence of fossil fuels. While gas storage is the most
relevant to satisfy heat demands, covering about 14%, TES is also
equally important, as it provides about 12% of heat demand in 2050.
Most of the heat requirement is for industrial process heat, while a
low share is for domestic usage. The industrial heat demand must be
covered by centralised heating systems, so it can be seen from the
installed capacities of district heating storage, in addition to energy
storage for high-temperature heat. Detailed information on heat storage
output can be found in SM Table S17.
4.4.2. Transport
The huge overhaul in the transport sector as explained in Section
4.2.3, requires storage technologies to complement the large-scale
electrication. Therefore, electricity storage output increases to over
Fig. 20. Installed capacities (left) and electricity generation (right) in the transport sector.
Fig. 21. Electricity storage capacity (left) and relative contributions (right) of storage technologies to electricity demands.
A. Gulagi et al.

Renewable and Sustainable Energy Reviews 144 (2021) 110934
17
85 TWh
el
by 2050 as shown in Fig. 23. Detailed information on storage
output for the transport sector can be found in SM Table S19. Utility-
scale batteries play a major role in installed capacities and electricity
generation on diurnal basis, through the transition, while a small share
comes from PHES, a technology being currently being used in the
Philippines. The share of electricity from storage output to generated
electricity is around 15% for the transport sector. This low share is due
to the exibility provided by batteries, water electrolysers and hydrogen
buffer storage.
While electricity plays an important role in achieving sustainability
in the transport sector, the complete transition towards 100% RE is
achieved by utilising hydrogen, synthetic fuels and sustainable biofuels.
From Fig. 24, it is seen that utilisation of synthetic fuel producing
technologies increase signicantly from 2040, as does the sustainable
transport fuel demand particularly from marine and aviation transport
modes. Installed capacities are around 180 GW in 2050, dominated by
water electrolysis, as 3 mol of hydrogen are required to produce each
mole of a basic hydrocarbon. As the length of carbon chain increases,
hydrogen moles required double. Heat management is important for
achieving energy efciency, especially in CO
2
direct air capture, where a
large amount of heat is required. Process heat in the range of 75 TWh
th
in
2050, as seen in Fig. 25, is used for the energy efcient direct air capture
of CO
2
.
As CO
2
storage and CO
2
direct air capture are important for synthetic
fuels production, the majority of methane storage installation takes
place in 2050. The installed capacity for CO
2
direct air capture is around
70 MtCO
2
(Fig. 25). The CO
2
direct air capture has a major share, due to
it being on an annual basis as compared to CO
2
storage. However,
Fig. 22. Heat storage capacity (left) and relative contributions (right) of storage technologies to heat demands.
Fig. 23. Installed capacities for different storage technologies (left) and storage output (right) for the transport sector.
Fig. 24. Installed capacities of synthetic fuel production technologies (left) and heat management (right) in the transport sector.
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Renewable and Sustainable Energy Reviews 144 (2021) 110934
18
despite having negligible storage capacity CO
2
storage has a higher
throughput during the transition.
4.5. Annual GHG emissions
For the power, heat, transport and desalination sectors annual GHG
emissions are given in Fig. 26. While this study only considers direct CO
2
emissions released, it can be inferred that proportional reduction in
other GHG emissions and PM is possible during the transition towards
sustainability.
The GHG emissions decrease from over 130 MtCO
2eq
to zero in 2050.
During the initial years, the rate of GHG emission reduction is slow, but
after 2030, emissions fall signicantly. The power sector, which is
considered as one of the easier sectors to decarbonise, can be almost
completely decarbonised in the early 2030s, while other sectors are
slowly transitioning towards 100% RE. The hard-to-abate transportation
sector shifts towards increased electrication, biofuels and synthetic
fuels to eliminate emissions until 2050. The energy transition pathway
for the Philippines is in adherence to the ambitious Paris Agreement
target of 1.5 ◦C.
5. Discussion
The previous section shows a concrete energy transition pathway for
the different energy sectors (power, heat, transportation, and desalina-
tion) towards a 100% renewable and sustainable energy system. The
results provide insights and implications for the energy sector planning
in the Philippines if a 100% RE scenario is pursued. Generally, without a
proper context, pursuit of 100% RE presents an increasing capital
expenditure that are usually passed on to the consumers considering that
the Philippine energy sector is liberalised. However, further discussion
based on the results of this study will show that the transition itself will
not only yield lower electricity cost for the consumers but also lower
GHG emissions, higher energy security and clean water.
The pathway towards a fully renewables-based energy system across
all sectors in the Philippines (Fig. 16) clearly shows divergence from the
PEP and actual installations due to contrasting policies. Among the
policies of the PEP are various tax incentives and subsidies on coal-red
power plants because the Philippine government wanted to hasten
generation capacity building to promote and support growth in the
economy [50]. This motivation was due to occurrences of rotating
blackouts especially during the summer period due to insufcient grid
operating reserve. The Department of Energy originally planned to
award contracts for increased local coal extraction, and supported
removal of coal mining ban in Mindanao in order to add 25.3 GW ca-
pacity by 2040 [50]. This plan has changed due to the suspension on
greeneld coal power plant projects starting in 2020 [111] and large
nancial institutions shunning coal nancing [112]. However, this
study shows that investing in renewables will not only provide unin-
terrupted power to support increasing energy demand but also improve
the air quality in big cities.
From the results, a fully renewables-based energy system for the
Philippines shows that single-axis utility scale PV and rooftop PV pro-
duce more than 50% of the needed energy for the power, heat and
transport sectors, as early as in 2030. The solar PV-dominated energy
mix challenges the fundamental notion emanating in the power industry
and the PEP on having a baseload generation using conventional power
plants to maintain grid stability, and therefore resistance to the idea is
highly expected. The traditional baseload concept becomes increasingly
obsolete as energy storage technologies becomes more economically
viable to support variable renewable energy technologies, fostering the
disruptive concept of baseload renewables [113]. A fully renewables
pathway is made feasible through the current and expected cost decline
of utility-scale solar PV and battery energy storage systems. This result is
corroborated by Jacobson et al. [10], Mondal et al. [61], and Teske [11].
According to Teske [11], VRE has a share of almost 63% with majority
share being solar PV, which is observed in this study. The result is re-
ected with the indicative solar PV power plant projects totalling 10.1
GW compared to that of coal-red power plants of 8.9 GW [48]. The
results are in agreement with Agaton [114] showing a shift towards
renewables is the best choice.
The use of solar PV with energy storage enables electrication of
multiple remote islands without the need for grid extension, utilising the
Fig. 25. Installed storage capacities for gas (left) and CO
2
and CO
2
DAC during the transition from 2015 to 2050.
Fig. 26. Total GHG emissions for the power, heat, transport and desalina-
tion sectors.
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Renewable and Sustainable Energy Reviews 144 (2021) 110934
19
modularity of these technologies. This has been observed by Bertheau
and Blechinger [62], Lozano et al. [63], Ocon and Bertheau [64], Ber-
theau and Cader [65], Meschede et al. [66] and Bertheau [67]. On the
other hand, rooftop solar PV reduces land allocated for ground-mounted
solar PV but the current unfavourable net-metering pricing and capacity
limit hinders their widespread use [115]. Amending the net-metering
rule unlocks large rooftop solar PV potentials as shown by Jara et al.
[116] for the Philippine industrial sector under the MERALCO franchise
area. While most of the above-mentioned results show that solar PV is
expected to play a vital role, other resources such as wind energy, hy-
dropower [10], and geothermal energy [61] complement to satisfy the
energy demand.
To support the large solar PV share, results show that utility-scale
batteries dominate the energy storage market by 2050. The large
share of batteries in the energy storage market implies increased
dependence on lithium-ion batteries. To mitigate insufcient supply of
lithium-ion batteries, other non-lithium-ion based batteries should be
considered for diversication of the energy storage mix, provided they
are techno-economically viable. Further, recycling of lithium-ion bat-
tery components after their useful life enhances sustainability as it re-
duces rate of global extraction of resources and reduces impact of
geopolitical risks involving critical minerals [117]. Even if the PHES and
A-CAES capacities were available for the energy system, the daily
availability of solar PV and the cost competitiveness of PV-battery
hybrid solutions would still form the main backbone of a cost opti-
mised energy system.
The transformation of heat energy source towards following the
100% RE pathway for the Philippine industry sector would face more
resistance due to the specicity and complexity of the processes.
Implementation or transitioning to RE would require GHG costs coupled
with the mandated energy conservation and efciency measures in order
to force industries to shift heating from fossil fuels and/or modify their
operations to become more energy efcient. Efcient technologies like
heat pumps and direct utilisation of electricity as well as, solar thermal
and biomass could provide the domestic and industrial heating demand.
In the transport sector, direct electricity, hydrogen, and liquid fuels
generated from RE are preferred in powering vehicles in 2050, with
direct electricity being the cheapest option. The cost of synthetic natural
gas and especially H
2
as fuel are comparable to the fossil fuels. Even
without GHG emission costs, the cost of fossil fuels is higher than direct
electricity and comparable to synthetic H
2
by 2050. The projections in
preferred fuel corroborates with the public transportation modernisa-
tion plan of the Philippine government [42]. Results of Fig. 19 present
that fuel shift alone is compatible with 100% RE scenario. However,
trafc in the Philippines is a problem considering that in 2019, Metro-
politan Manila was ranked 2nd worst trafc among major cities in the
world considered after Bangalore, India [118]. High road passenger
energy demand in the 2015–2020 (Fig. 19) can be mainly attributed in
urban areas. Therefore, a modal shift is also needed to reduce trafc by
investing in an efcient and integrated mass transport system. Electri-
ed railway and tram systems provide cheaper transportation solutions
than road vehicles as seen from the results in near-term (Fig. 15). Full
electrication of railway or tram system is more energy efcient and will
help reduce battery demand [119]. Some groups preferred bus rapid
transits as these have lower capital cost [120] and are easier to deploy,
but they suffer from lower passenger densities [121] which might not be
enough to meet current and future demand. An electried freight rail
transport system is also desirable not just to provide cheaper trans-
portation options for goods but also to reduce use and ownership of
long-haul freight trucks, and reduced transport time [122].
With the projected reduced demand of fossil fuels in road and rail
vehicles, biofuel demand will shift towards marine and aviation appli-
cations in mid-term to reduce GHG emissions. From the results, for the
marine vehicles, hydrogen-based synthetic fuels will dominate in 2050
with substantial percentage coming from synthetic liquid fuels. For
aviation, synthetic liquid fuels still dominates in 2050, with H
2
fuel
being desirable at mid-term. Direct electricity is expected to be used for
domestic ights in the mid-to-long-term within some limits, but it is no
option for international long-distance ights because current battery
technologies cannot meet required range, weight, and cost [109,123].
Although substituting domestic aviation travel to high-speed railway or
ships for decarbonisation is recommended [122], the archipelagic fea-
tures of the Philippines will make implementation a daunting task.
While the domestic use of RE-based fuels has huge benets, the
Philippines could also import synthetic fuels from other countries, such
as Australia, utilising its abundant renewable resources [60]. However,
according to this study, local RE resources could satisfy all the energy
demand until 2050. Additional synthetic fuels could be traded with large
consumption centres in East Asia, creating an additional revenue stream
and a hub for synthetic fuel trading in Southeast Asia and the Pacic Rim
[124].
The overall desalination demand of the entire country is assumed to
be low. However, there is a large water demand especially at the major
metropolitan cities in the Philippines which is exacerbated with water
supply uncertainty during summer period (April to May). Desalination
has been discussed publicly as a possible solution to the water supply
problem, especially in Metropolitan Manila [125] and Cebu [126]. In
addition, remote islands need desalination since these areas have
insufcient groundwater and rainwater for local water demand, and
freshwater supply can be disrupted due to extreme weather events. The
seawater reverse osmosis (SWRO) technology dominates the installed
capacities for the Philippines during the transition, which for the remote
islands corroborate with the results of Castro et al. [127].
Pursuing a 100% RE transition pathway may require the use of direct
CO
2
capture and utilisation. Despite the uncertainty, the country must
prepare to integrate direct CO
2
capture and utilisation in its planning
towards sustainability. Note that afforestation, reforestation, and uti-
lisation of bioenergy crops are not considered in this work which may
reduce direct CO
2
capture capacity, , however Philippines has been
highly deforested in recent years [128]. It is suggested that industries
that rely on methane for combustion in high temperature processes
capture CO
2
and utilise, and produce their own methane using the
captured CO
2
. Most present applications of methane may be switched to
H
2
during the transition period. The identied CO
2
capture point sources
are mainly waste incinerators, limestone processing in cement mills
[129], and pulp and paper mills, as summarised for sustainable CO
2
point sources by Breyer et al. [130]. All the remaining CO
2
demand for
sustainable hydrocarbons for transportation and chemicals demand is
expected to be mainly covered by CO
2
direct air capture [100].
The study assumes that there are no energy interactions between the
neighbouring countries. The HVDC transmission power grid connection
to Malaysia and Indonesia for integrated ASEAN power grid would seem
benecial considering the vast potential of renewable resources in these
countries, providing the Philippines exibility and reducing the need for
storage technologies [69]. This is partially fullled with the intercon-
nection projects for Mindoro and Palawan Island to the main grid that
are already in the pipeline [50]. These projects were pursued partly
because of the anticipated integration into the ASEAN power grid via
Malaysian Borneo. Other possible inter-country connections such as
Mindanao – Halmahera – West Papua – Australia [131] and Luzon –
Taiwan – Japan HVDC connections [132] were also investigated for
feasibility.
Overall, energy transition towards a fully renewable and sustainable
energy system is possible while having zero GHG emissions, which re-
quires a total annual system cost of 50 b
€
by 2050. The increasing Capex
is highly expected due to increasing energy demand and decom-
missioning of old power plants. The share of the system cost is shifted
from fuel cost to capital expenditure throughout the transition. As dis-
cussed, the capital expenditure costs are rather a one-time investment
and there is less risk of price volatility as compared to fossil fuels. The
power sector is projected to reach zero GHG emissions rst by 2035 or
even as early as in 2030 as reported by Gulagi et al. [59], based on a
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Renewable and Sustainable Energy Reviews 144 (2021) 110934
20
comprehensive study with solar PV and batteries playing an important
role, conrming the analysis of this study. The heat and transport sector
follow next in leading to a complete elimination of GHG emissions from
all the sectors. However, tricky part in the implementation of energy
transition towards fully renewable based energy system is, since direct
command on what technologies to build as shown in Fig. 16 will be hard
to implement due to liberalisation of the energy sector. The liberalisa-
tion and the corresponding market design of the Philippine energy
sector may not be an enabler of a fully renewables energy system [133,
134]. The technology preference by the local energy sector players will
depend on the international and local market conditions. Therefore, it is
up to the Philippine government to intervene by using its regulatory and
economic levers to achieve just energy transition towards fully renew-
able and sustainable energy system. With the current international trend
of cost-competitiveness of renewables against fossil fuels particularly
coal, the Philippine government needs to take immediate and concrete
action to take advantage in the global trend.
The energy security will increase because of an energy transition
towards 100% renewables [135]. A recently published energy security
index based on a comprehensive denition of energy security [135,136],
documents a rank 54 for the Philippines among all countries in the
world. Therefore, planning for 100% RE system would signicantly raise
the Philippines’ performance since it addresses the energy trilemma of
equity, security, and sustainability [27].
6. Limitations and recommendations for future work
The technical feasibility and economic viability of a renewable en-
ergy transition scenario is shown for the case of Philippines. The results
and conclusion of this study show one of the various pathways to ach-
ieve a common goal of zero GHG emissions across the energy sectors.
The other limitation of this study is that the total nal energy demand
was assumed to be concentrated at a single node within the country’s
boundaries, without allocating to specic regions. One of the main as-
sumptions here was that the power transmission lines available within
the country will supply RE to every corner, where there is a demand.
However, with the spatial resolution of solar and wind resources, the
potential available throughout the country was utilised. Further, a high
granular data will describe the regional variability in detail. As a next
step of research, we propose a study dividing the Philippines into
various regions, which will give detailed information about the energy
demand and generation in a particular region, and better insights on
resulting power transmission capacity demand or potential local
renewable resource limitations. Comparing different scenarios will give
new insights regarding the energy transition pathways best suited
considering the local resources and policies. In addition, the next step of
research will account actual laws and regulations emanating in the
Philippine energy sector. Sensitivity analysis of the assumptions and the
input data may alter the results, but no drastic changes are expected.
7. Conclusion
In this study, a Best Policy Scenario for the transition pathway to-
wards adopting high shares of renewable energy in the power, heat,
transport and desalination sectors was analysed for the Philippines.
The results of the study show that a 100% renewable energy system
is achievable for the Philippines by 2050, considering the demand from
all energy sectors, with a cost comparable to an energy system in 2015.
Moreover, the energy system in 2050 will be almost 40% more efcient
than the current energy system. However, investing in new coal-red
power plants and utilising fossil fuels in other sectors will not only in-
crease GHG emissions but also the energy costs considerably during the
future years. Furthermore, depending on imports of fossil fuels will raise
questions regarding energy security of the country. Therefore, strategy
of the government should be to invest in utilising the abundant indig-
enous renewable resources. The renewable energy technologies,
especially solar PV, can produce enough electricity to power all energy
sectors, while batteries emerge as a least cost storage technology
through the transition. Excellent solar resource availability combined
with the decreasing cost of PV systems and Li-ion batteries enable a
transition towards a 100% RE system.
Finally, it may be concluded that the Philippines could lower GHG
emissions and increase energy security in the long term, while having
costs comparable to the current system. Transition to RE could solve the
energy trilemma of energy security, energy reliability and affordable
and clean energy services which has been haunting Philippines for many
decades.
Declaration of competing interest
The authors declare that they have no known competing nancial
interests or personal relationships that could have appeared to inuence
the work reported in this paper.
Acknowledgements
The authors gratefully acknowledge support from Energy Watch
Group based on nancing from Stiftung Mercator GmbH and Deutsche
Bundesstiftung Umwelt, which made parts of this study possible. The
authors would also like to acknowledge Arman Aghahosseini for plotting
the diagrams and Upeksha Caldera for providing desalination data. J. D.
Ocon would like to acknowledge the Energy Research Fund project
ElectriPHI funded through the University of the Philippines Ofce of the
Vice President for Academic Affairs and the Senate Committee on En-
ergy led by Sen. Sherwin T. Gatchalian and the Federico Puno Profes-
sorial Chair for Energy.
Appendix A. Supplementary data
Supplementary data to this article can be found online at https://doi.
org/10.1016/j.rser.2021.110934.
CRediT author statement
Ashish Gulagi: Conceptualization, Investigation, Methodology,
Visualization, Writing – original draft, Writing – review & editing Myron
Alcanzare: Writing – original draft, Writing – review & editing Dmitrii
Bogdanov: Methodology, Software Eugene Esparcia Jr: Writing – orig-
inal draft, Writing – review & editing Joey Ocon: Writing – original
draft, Writing – review & editing Christian Breyer: Methodology, Su-
pervision, Validation, Funding acquisition, Writing – review & editing.
References
[1] Han C. Philippines joins the Paris agreement on climate change. New York:
NRDC-Natural Resource Defense Council; 2017. https://www.nrdc.org/expert
s/han-chen/philippines-joins-paris-agreement-climate-change.
[2] [IEA] - International Energy Agency. Global CO2 emissions. 2019. Paris, https
://www.iea.org/articles/global-co2-emissions-in-2019.
[3] Chestney N. India most vulnerable country to climate change - HSBC report.
London; 2018. https://www.reuters.com/article/us-climatechange-hsbc-idUS
KBN1GV20Z.
[4] Mei W, Xie S-P. Intensication of landfalling typhoons over the northwest Pacic
since the late 1970s. Nat Geosci 2016;9(10):753–7.
[5] Climate Central. Land projected to be below annual ood level in 2050. 2020.
New Jersey, https://coastal.climatecentral.org/map/7/121.8352/13.7346/?
theme=sea_level_rise&map_type=coastal_dem_comparison&elevation_model
=coastal_dem&forecast_year=2050&pathway=rcp45&percentile=p50&return_le
vel=return_level_1&slr_model=kopp_2014.
[6] [ESCAP] - The Economic and Social Comission for Asia and the Pacic. Ready for
the dry years: building resilience to drought in South-east Asia. Bangkok: United
Nations; 2019. https://www.unescap.org/sites/default/les/publications/Ready
for the Dry Years.pdf.
[7] Breyer C, Bogdanov D, Gulagi A, Aghahosseini A, Barbosa LSNS, Koskinen O,
et al. On the role of solar photovoltaics in global energy transition scenarios. Prog
Photovoltaics Res Appl 2017;25(8):727–45.
A. Gulagi et al.

Renewable and Sustainable Energy Reviews 144 (2021) 110934
21
[8] Breyer C, Bogdanov D, Aghahosseini A, Gulagi A, Child M, Oyewo AS, et al. Solar
photovoltaics demand for the global energy transition in the power sector. Prog
Photovoltaics Res Appl 2018;26(8):505–23.
[9] Ram M, Bogdanov D, Aghahosseini A, Gulagi A, Oyewo SA, Child M, et al. Global
energy system based on 100% renewable energy: power, heat, transport and
desalination sectors. Lappeenranta, Berlin: Energy Watch Group and LUT
University; 2019. http://energywatchgroup.org/wp-content/uploads/
EWG_LUT_100RE_All_Sectors_Global_Report_2019.pdf.
[10] Jacobson MZ, Delucchi MA, Cameron MA, Mathiesen BV. Matching demand with
supply at low cost in 139 countries among 20 world regions with 100%
intermittent wind, water, and sunlight (WWS) for all purposes. Renew Energy
2018;123:236–48.
[11] Teske S. Achieving the Paris Climate Agreement Goals: global and regional 100%
renewable energy scenarios with non-energy GHG pathways for +1.5◦C and +
2◦C. Cham: Springer International Publishing; 2019. http://link.springer.com/10.
1007/978-3-030-05843-2.
[12] Bogdanov D, Ram M, Aghahosseini A, Gulagi A, Oyewo AS, Child M, et al. Low-
cost renewable electricity as the key driver of the global energy transition
towards sustainability. Submitted; 2021. Submitted for publication.
[13] Osorio-Aravena JC, Aghahosseini A, Bogdanov D, Caldera U, Mu˜
noz-Cer´
on E,
Breyer C. Transition toward a fully renewable-based energy system in Chile by
2050 across power, heat, transport and desalination sectors. International Journal
of Sustainable Energy Planning and Management 2020;25:77–94.
[14] Lopez G, Aghahosseini A, Bogdanov D, Mensah T, Ghorbani N, Caldera U, et al.
Pathway to a fully sustainable energy system for Bolivia across power, heat, and
transport sectors by 2050. J Clean Prod 2021;293. Art. no.126195.
[15] Oyewo AS, Solomon AA, Bogdanov D, Aghahosseini A, Mensah T, Breyer C.
Transition towards a defossilised energy system for developing economies: a case
study of Ethiopia. Submitted; 2021. Submitted for publication.
[16] Azzuni A, Aghahosseini A, Ram M, Bogdanov D, Caldera U, Breyer C. Energy
security analysis for a 100% renewable energy transition in Jordan by 2050.
Sustainability 2020;12:12. Art. no.4921.
[17] Bogdanov D, Farfan J, Sadovskaia K, Aghahosseini A, Child M, Gulagi A, et al.
Radical transformation pathway towards sustainable electricity via evolutionary
steps. Nat Commun 2019;10:1. Art. no.1077.
[18] Ra 9136. An act ordaining reforms in the electric power industry, amending for
the purpose certain laws and for other purposes. Manila: Government of the
Philippines; 2001. https://www.ofcialgazette.gov.ph/2001/06/08/republic-act
-no-9136/.
[19] Llanto GM, Cherry M, Rodolfo L. The state of competition in the air transport
industry: a scoping exercise. Philippines competition commission, issue papers.
Quezon City; 2020. https://www.phcc.gov.ph/wp-content/uploads/2020/03/
PCC-Issues-Paper-2020-01-The-State-of-Competition-in-the-Air-Transport-Industr
y-A-Scoping-Exercise_v2.pdf.
[20] Philippine Statistics Authority. National accounts of the Philippines. Quezon City;
2020. https://psa.gov.ph/sites/default/les/Q4 2019 NAP Publication-9ch3.pdf.
[21] [DOE] - Department of Energy. Compendium of philippine energy Statistics and
information. Quezon City: Government of the Philippines; 2018. https://www.
doe.gov.ph/sites/default/les/pdf/energy_statistics/doe_compendium_energy_st
atistics.pdf.
[22] [DOE] - Department of Energy. Philippine energy plan 2016-2030. Quezon City:
Government of the Philippines; 2016. https://www.doe.gov.ph/sites/default/le
s/pdf/pep/2016-2030_pep.pdf.
[23] International Energy Consultants. Regional comparison of retail electricity tariffs:
executive summary. Perth; 2018. https://meralcomain.s3.ap-southeast-1.ama
zonaws.com/images/ckeditor-documents/2018_IEC_Study_Updated.pdf.
[24] Kuryente. Ranking of electricity rates. Quezon City; 2020. http://www.kuryente.
org.ph/ranking.
[25] SunStar EDC. Review expensive visayan electric rate. Cebu; 2020. https://www.
sunstar.com.ph/article/1879338/Cebu/Local-News/EDC-Review-expensive-Visa
yan-Electric-rate.
[26] National Electrication Administration. Status of energization. Quezon City;
2018. https://www.nea.gov.ph/ao39/electric-cooperatives/status-of-energizati
on/category/73-2018-monthly-reports.
[27] La Vi˜
na AG, Tan JM, Guanzon TIM, Caleda MJ, Ang L. Navigating a trilemma:
energy security, equity, and sustainability in the Philippines’ low-carbon
transition. Energy Res Soc Sci 2018;35:37–47.
[28] Gonzalo LP. The philippine energy situation. De Gruyter; 1977. http://bookshop.
iseas.edu.sg/bookmarks/SEAA77/015/index.html.
[29] EO 55. Executive order from the Ofce of the president of the Philippines. Manila:
Government of the Philippines; 1986. https://www.ofcialgazette.gov.ph/1
986/11/04/executive-order-no-55-s-1986/.
[30] EO 215. Executive order from the Ofce of the president of the Philippines.
Manila: Government of the Philippines; 1987. https://www.ofcialgazette.gov.
ph/1987/07/10/executive-order-no-215-s-1987/.
[31] KPMG. Infrastructure in-depth : Philippines, 2015 investment guide. Amstelveen;
2015. https://home.kpmg/content/dam/kpmg/ph/pdf/InvestmentGuide/
2015PHInvestmentGuideInfrastructureIn-depthPhilippines.pdf.
[32] RA 7648. Electric power crisis act of 1993. Manila: Government of the
Philippines; 1993. https://www.ofcialgazette.gov.ph/1993/04/05/republic-act
-no-7648/.
[33] MERALCO. Summary schedule of rates effective march 2020 billing. Manila:
Manila Electric Company; 2020. https://meralcomain.s3.ap-southeast-1.amazona
ws.com/2020-03/03-2020_rate_schedule.pdf?null.
[34] MERALCO. Breakdown of generation charge. Manila: Manila Electric Company;
2020.
[35] RA 11371. Murang kuryente act of 2019. Manila: Government of the Philippines;
2019. https://www.ofcialgazette.gov.ph/downloads/2019/08aug/20190808
-RA-11371-RRD.pdf.
[36] RA 9513. An act promoting the development, utilization and commercialization
of renewable energy resources and for other purposes. Manila: Government of the
Philippines; 2008. https://www.ofcialgazette.gov.ph/2008/12/16/republic-act
-no-9513/.
[37] [DOE] - Department of Energy. Providing a framework for energy storage system
in the electric power industry. Quezon City: Government of the Philippines; 2018.
https://www.doe.gov.ph/sites/default/les/pdf/issuances/dc2019-08-0012.pdf.
[38] De Vera BO. DOF studying carbon tax as IMF urges Asean shift to “green”
economy. Inquirer.NET; Makati City 2019. https://business.inquirer.net/282
664/dof-studying-carbon-tax-as-imf-urges-asean-shift-to-green-economy.
[39] RA 8479. An act deregulating the downstream oil industry and for other
purposes. Manila: Government of the Philippines; 1998. https://www.ofci
algazette.gov.ph/1998/02/10/republic-act-no-8479/.
[40] Mendoza MN. Lessons learned: fossil fuel subsidies and energy sector reform in
the Philippines. Manitoba: IISD and GSI; 2014. www.iisd.org/gsi.
[41] RA 9367. Biofuels act of 2006. Manila: Government of the Philippines; 2006.
https://www.senate.gov.ph/republic_acts/ra 9367.pdf.
[42] Republic of the Philippines Department of Transportation DO No. 2017-011.
Omnibus guidelines on the planning and identication of public road
transportation services and franchise issuance. Quezon City; 2017. https://drive.
google.com/file/d/0Bx283SS6qJi2ZmQ0RTdWYlZqc2M/view.
[43] Tuquero L. 6 new railways to look out for. Manila: Rappler IQ; 2019. https:
//www.rappler.com/newsbreak/iq/new-railways-to-look-out-for.
[44] RA 11285. Energy efciency and conservation act. Government of the
Philippines; Manila: n.d. https://www.ofcialgazette.gov.ph/downloa
ds/2019/04apr/20190412-RA-11285-RRD.pdf.
[45] [WB]- The World Bank. GDP growth (annual %) – Philippines data. Washington
D.C.; 2018. https://data.worldbank.org/indicator/NY.GDP.MKTP.KD.ZG?end=2
018&locations=PH&start=2010.
[46] Philippine Statistics Authority. The 2018 philippine statistical yearbook. Quezon
City: Government of the Philippines; 2018. http://www.psa.gov.ph/tags/phil
ippine-statistical-yearbook.
[47] [DOE] - Department of Energy. List of existing power plants per grid. Quezon
City: Government of the Philippines; 2020. https://www.doe.gov.ph/sites/defaul
t/les/pdf/electric_power/existing_power_plants/electric_power_plants_luzon_de
cember_2019.pdf.
[48] [DOE] - Department of Energy. Power Statistics for Philippines. Quezon City:
Government of the Philippines; 2020. https://www.doe.gov.ph/sites/default/le
s/pdf/energy_statistics/2019_power_statistic_01_summary.pdf.
[49] [DOE] - Department of Energy. Private sector initiated power projects as of
december 2019. Quezon City: Government of the Philippines; 2020.
https://www.doe.gov.ph/sites/default/les/pdf/electric_power/luzon_co
mmitted_2019_jan_december.pdf.
[50] [DOE] - Department of Energy. Philippine energy plan: sectoral plans and
roadmaps. Quezon City: Government of the Philippines; 2017. https://www.doe.
gov.ph/sites/default/les/pdf/pep/pep_volume_2_sectoral_plans_and_roadmaps.
pdf.
[51] Solargis. Solar resource maps of Philippines. Washington D.C.; 2017. https://so
largis.com/maps-and-gis-data/download/philippines.
[52] Matich B. Investors ready US$20 Million for off-grid solar projects in the energy-
stricken Philippines. 2019. Berlin, https://www.pv-magazine-australia.
com/2019/11/08/investors-ready-us20-million-for-off-grid-solar-projects-in-t
he-energy-stricken-philippines/.
[53] Renewables REN21. Global status report. 2019. Paris: 2019, https://www.ren21.
net/wp-content/uploads/2019/05/gsr_2019_full_report_en.pdf.
[54] [IEEFA] - Institute for Energy Economics and Financial Analysis. First offshore
wind project planned for the Philippines. 2020. Ohio, https://ieefa.org/rst
-offshore-wind-project-planned-for-the-philippines/.
[55] Quirapas MAJR, Lin H, Abundo MLS, Brahim S, Santos D. Ocean renewable
energy in Southeast Asia: a review. Renew Sustain Energy Rev 2015;41:799–817.
[56] Quitoras MRD, Abundo MLS, Danao LAM. A techno-economic assessment of wave
energy resources in the Philippines. Renew Sustain Energy Rev 2018;88:68–81.
[57] Icamina P. Tariff issues stall philippine ocean energy project. 2016. London, https
://www.scidev.net/asia-pacic/energy/news/tariff-issues-stall-philippine-ocea
n-energy-project.html.
[58] Magagna D, Margheritini L, Alessi A, Bannon E, Boelman E, Bould D, et al.
Workshop on identication of future emerging technologies in the ocean energy
sector. Ispra; 2018. https://ec.europa.eu/jrc.
[59] Gulagi A, Bogdanov D, Breyer C. A cost optimized fully sustainable power system
for Southeast Asia and the pacic Rim. Energies 2017;10(5). Art. no.583.
[60] Gulagi A, Bogdanov D, Fasihi M, Breyer C. Can Australia power the energy-
hungry Asia with renewable energy? Sustainability 2017;9(2). Art. no.233.
[61] Mondal MAH, Rosegrant M, Ringler C, Pradesha A, Valmonte-Santos R. The
Philippines energy future and low-carbon development strategies. Energy 2018;
147:142–54.
[62] Bertheau P, Blechinger P. Resilient solar energy island supply to support SDG7 on
the Philippines: techno-economic optimized electrication strategy for small
islands. Util Pol 2018;54:55–77.
[63] Lozano L, Querikiol EM, Abundo MLS, Bellotindos LM. Techno-economic analysis
of a cost-effective power generation system for off-grid island communities: a case
study of Gilutongan Island, Cordova, Cebu, Philippines. Renew Energy 2019;140:
905–11.
A. Gulagi et al.

Renewable and Sustainable Energy Reviews 144 (2021) 110934
22
[64] Ocon JD, Bertheau P. Energy transition from diesel-based to solar photovoltaics-
battery-diesel hybrid system-based island grids in the Philippines – techno-
economic potential and policy implication on missionary electrication. J Sustain
Dev Energy, Water and Environ Syst 2019;7(1):139–54.
[65] Bertheau P, Cader C. Electricity sector planning for the Philippine islands:
considering centralized and decentralized supply options. Appl Energy 2019;251.
Art. no.113393.
[66] Meschede H, Esparcia EA, Holzapfel P, Bertheau P, Ang RC, Blanco AC, et al. On
the transferability of smart energy systems on off-grid islands using cluster
analysis – a case study for the Philippine archipelago. Appl Energy 2019;251. Art.
no.113290.
[67] Bertheau P. Supplying not electried islands with 100% renewable energy based
micro grids: a geospatial and techno-economic analysis for the Philippines.
Energy 2020;202. Art. no.117670.
[68] Blakers AW, Luther J, Nadolny A. Asia pacic super grid – solar electricity
generation, storage and distribution. Greenpeace 2012;2(4):189–202.
[69] Huber M, Roger A, Hamacher T. Optimizing long-term investments for a
sustainable development of the ASEAN power system. Energy 2015;88:180–93.
[70] Pascasio JDA, Esparcia EA, Odulio CMF, Ocon JD. High renewable energy (solar
photovoltaics and wind) penetration hybrid energy systems for deep
decarbonization in philippine off-grid areas. Chem Eng Trans 2019;76:1135–40.
[71] Republic of the Philippines. Manila: Intended Nationally Determined
Contributions of the Republic of The Philippines; 2015. https://www4.unfccc.
int/sites/submissions/INDC/Published Documents/Philippines/1/Philippines - Fi
nal INDC submission.pdf.
[72] Climate Vulnerable Forum. The Marrakech Communique. Marrakech; 2016.
https://thecvf.org/marrakech-communique/.
[73] Bos K, Gupta J. Stranded assets and stranded resources: implications for climate
change mitigation and global sustainable development. Energy Res Soc Sci 2019;
56. Art. no.101215.
[74] Cox S, Hotchkiss E, Bilello D, Watson A, Holm A. Bridging climate change
resilience and mitigation in the electricity sector through renewable energy and
energy efciency: emerging climate change and development topics for energy
sector transformation. Doe OstiGov; 2017. p. 1–30.
[75] Roxas F, Santiago A. Alternative framework for renewable energy planning in the
Philippines. Renew Sustain Energy Rev 2016;59:1396–404.
[76] Weinand JM, Scheller F, McKenna R. Reviewing energy system modelling of
decentralized energy autonomy. Energy 2020;203. Art. no.117817.
[77] Fankhauser S, Jotzo F. Economic growth and development with low-carbon
energy. Wiley Interdiscipl Rev: Clim Chang 2018;9:1. Art. no.e495.
[78] Fuso Nerini F, Tomei J, To LS, Bisaga I, Parikh P, Black M, et al. Mapping
synergies and trade-offs between energy and the sustainable development goals.
Nat Energy 2018;3(1):10–5.
[79] Bogdanov D, Toktarova A, Breyer C. Transition towards 100% renewable power
and heat supply for energy intensive economies and severe continental climate
conditions: case for Kazakhstan. Appl Energy 2019;253. Art. no.113606.
[80] Prina MG, Manzolini G, Moser D, Nastasi B, Sparber W. Classication and
challenges of bottom-up energy system models - a review. Renew Sustain Energy
Rev 2020;129. Art. no.109917.
[81] MOSEK. Optimization tool. 2020. Copenhagen, https://www.mosek.com/.
[82] Matlab. Programming language. 2020. https://se.mathworks.com/products.html
?s_tid=gn_ps.
[83] Keiner D, Ram M, Barbosa LDSNS, Bogdanov D, Breyer C. Cost optimal self-
consumption of PV prosumers with stationary batteries, heat pumps, thermal
energy storage and electric vehicles across the world up to 2050. Sol Energy
2019;185:406–23.
[84] Afanasyeva S, Bogdanov D, Breyer C. Relevance of PV with single-axis tracking
for energy scenarios. Sol Energy 2018;173:173–91.
[85] Aghahosseini A, Breyer C. Assessment of geological resource potential for
compressed air energy storage in global electricity supply. Energy Convers Manag
2018;169:161–73.
[86] Caldera U, Breyer C. Strengthening the global water supply through a
decarbonised global desalination sector and improved irrigation systems. Energy
2020;200. Art. no.117507.
[87] Stackhouse P, Whitlock C. Surface meteorology and solar energy (SSE) release 6.0
methodology. Langley, VA, USA: National Aeronautic and Space Administration
(NASA); 2008.
[88] Stackhouse P, Whitlock C. Surface meteorology and solar energy (SSE) release 6.0
methodology. Langley, VA, USA: National Aeronautic and Space Administration
(NASA); 2009.
[89] Stetter D. Enhancement of the REMix energy system model: global renewable
energy potentials optimized power plant siting and scenario validation. Stuttgart:
University of Stuttgart; 2012. https://elib.uni-stuttgart.de/handle/11682/6872.
[90] Bogdanov D, Breyer C. North-East Asian Super Grid for 100% renewable energy
supply: optimal mix of energy technologies for electricity, gas and heat supply
options. Energy Convers Manag 2016;112:176–90.
[91] Bunzel K, Zeller V, Buchhorn M, Griem F, Thr¨
an D. Regionale und globale
r¨
aumliche Verteilung von Biomassepotenzialen. Leipzig: German Biomass
Research Center; 2009.
[92] [IEA] - International Energy Agency. Technology roadmap – bioenergy for heat
and power. 2012. Paris, http://www.iea.org/publications/freepublications/publi
cation/2012_Bioenergy_Roadmap_2nd_Edition_WEB.pdf.
[93] [IPCC] - Intergovernmental Panel on Climate Change. Special report on
renewable energy sources and climate change mitigation. 2011. Geneva, https
://archive.ipcc.ch/pdf/special-reports/srren/SRREN_FD_SPM_nal.pdf.
[94] Sadiqa A, Gulagi A, Breyer C. Energy transition roadmap towards 100%
renewable energy and role of storage technologies for Pakistan by 2050. Energy
2018;147:518–33.
[95] Aghahosseini A, Bogdanov D, Breyer C. A techno-economic study of an entirely
renewable energy-based power supply for north America for 2030 conditions.
Energies 2017;10:8. Art. no.1171.
[96] Farfan J, Breyer C. Structural changes of global power generation capacity
towards sustainability and the risk of stranded investments supported by a
sustainability indicator. J Clean Prod 2017;141:370–84.
[97] Schmidt O, Hawkes A, Gambhir A, Staffell I. The future cost of electrical energy
storage based on experience rates. Nat Energy 2017;2:8. Art. no.17110.
[98] Vartiainen E, Gaetan M, Breyer C. The True competitiveness of Solar PV - a
European case study. Munich: European Technology & Innovation Platform;
2017. https://isainfopedia.org/true-competitiveness-solar-pv-european-case-s
tudy.
[99] Vartiainen E, Masson G, Breyer C, Moser D, Rom´
an Medina E. Impact of weighted
average cost of capital, capital expenditure, and other parameters on future
utility-scale PV levelised cost of electricity. Prog Photovoltaics Res Appl 2020;28
(6):439–53.
[100] Fasihi M, Emova O, Breyer C. Techno-economic assessment of CO2 direct air
capture plants. J Clean Prod 2019;224:957–80.
[101] Gernaat DEHJ, Van Vuuren DP, Van Vliet J, Sullivan P, Arent DJ. Global long-
term cost dynamics of offshore wind electricity generation. Energy 2014;76:
663–72.
[102] Nykvist B, Nilsson M. Rapidly falling costs of battery packs for electric vehicles.
Nat Clim Change 2015;5(4):329–32.
[103] Gerlach A, Werner C, Breyer C. Impact of nancing cost on global grid-parity
dynamics till 2030. 29th EU PVSEC 2014;21(1):121–36.
[104] Breyer C, Gerlach A. Global overview on grid-parity. Prog Photovoltaics Res Appl
2013;21(1):121–36.
[105] Philippine Statistics Authority. The 2015 philippine statistical yearbook. Quezon
City: Government of Philippines; 2015.
[106] [IEA] - International Energy Agency. Southeast Asia energy outlook. 2017. Paris.
[107] Toktarova A, Gruber L, Hlusiak M, Bogdanov D, Breyer C. Long term load
projection in high resolution for all countries globally. Int J Electr Power Energy
Syst 2019;111:160–81.
[108] Breyer C, Khalili S, Bogdanov D. Solar photovoltaic capacity demand for a
sustainable transport sector to full the Paris Agreement by 2050. Prog
Photovoltaics Res Appl 2019;27(11):978–89.
[109] Khalili S, Rantanen E, Bogdanov D, Breyer C. Global transportation demand
development with impacts on the energy demand and greenhouse gas emissions
in a climate-constrained world. Energies 2019;12:20. Art. no.3870.
[110] Solomon AA, Bogdanov D, Breyer C. Curtailment-storage-penetration nexus in the
energy transition. Appl Energy 2019;235:1351–68.
[111] [DOE] - Department of Energy. DOE SEC. CUSI declares moratorium ON
endorsements for greeneld coal power plants. Quezon City: Government of the
Philippines; 2020. https://www.doe.gov.ph/press-releases/doe-sec-cusi-declares-
moratorium-endorsements-greeneld-coal-power-plants?ckattempt=2.
[112] Buckley T. Over 100 Global nancial institutions are exiting coal, with more to
come. Ohio: Institute for Energy Economics and Financial Analysis; 2019. http://
ieefa.org/wp-content/uploads/2019/02/IEEFA-Report_100-and-counting_Coal-E
xit_Feb-2019.pdf.
[113] Matek B, Gawell K. The benets of baseload renewables: a misunderstood energy
technology. Electr J 2015;28(2):101–12.
[114] Agaton CB. Use coal or invest in renewables: a real options analysis of energy
investments in the Philippines. Renew: Wind, Water, and Solar 2018;5:1. Art.
no.1.
[115] Ahmed SJ. Unlocking rooftop solar in the Philippines. 2018. Ohio, https://ieefa.
org/wp-content/uploads/2018/08/IEEFA_Unlocking-Rooftop-Solar-in-the-Phi
lippines_August-2018.pdf.
[116] Jara PGB, Castro MT, Esparcia EA, Ocon JD. Quantifying the techno-economic
potential of grid-tied rooftop solar photovoltaics in the philippine industrial
sector. Energies 2020;13:19. Art. no.5070.
[117] Greim P, Solomon AA, Breyer C. Assessment of lithium criticality in the global
energy transition and addressing policy gaps in transportation. Nat Commun
2020;11:1. Art. no.4570.
[118] TomTom. Trafc index. 2019. Amsterdam, https://www.tomtom.com/en_gb/tra
fc-index/ranking/.
[119] García-Olivares A, Sol´
e J, Osychenko O. Transportation in a 100% renewable
energy system. Energy Convers Manag 2018;158:266–85.
[120] Boquet Y. BRT in the Philippines: a solution to Manila and Cebu trafc problems?
IOP Conf Ser Earth Environ Sci 2019;338.
[121] Wright L, Hook W. Bus rapid transit planning guide. Institute for Transportation
and Development Policy; 2007. https://www.itdp.org/2017/11/16/the-brt-p
lanning-guide/.
[122] [IPCC] - Intergovernmental Panel on Climate Change. AR5 climate change 2014:
mitigation of climate change, [Chapter 8]. Geneva: 204AD. https://www.ipcc.ch
/site/assets/uploads/2018/02/ipcc_wg3_ar5_chapter8.pdf.
[123] Sch¨
afer AW, Barrett SRH, Doyme K, Dray LM, Gnadt AR, Self R, et al.
Technological, economic and environmental prospects of all-electric aircraft. Nat
Energy 2019;4(2):160–6.
[124] Ram M, Galimova T, Bogdanov D, Fasihi M, Gulagi A, Breyer C, et al.
POWERFUELS in a renewable energy world. Berlin: Lappeenranta; 2020. https
://www.powerfuels.org/fileadmin/powerfuels.org/Dokumente/Global_Alliance_
Powerfuels_Study_Powerfuels_in_a_Renewable_Energy_World.pdf.
A. Gulagi et al.

Renewable and Sustainable Energy Reviews 144 (2021) 110934
23
[125] Lee H, Son J, Joo D, Ha J, Yun S, Lim C-H, et al. Sustainable water security based
on the sdg framework: a case study of the 2019 metro Manila water crisis.
Sustainability 2020;12:17. Art. no.6860.
[126] SunStar. MCWD to resort to desalination, to establish facilities in 5 LGUs. Cebu;
2020. https://www.sunstar.com.ph/article/1873053/Cebu/Local-News/MCWD-
to-resort-to-desalination-to-establish-facilities-in-5-LGUs.
[127] Castro M, Alcanzare M, Esparcia E, Ocon J. A comparative techno-economic
analysis of different desalination technologies in off-grid islands. Energies 2020;
13(9). Art. no.2261.
[128] Carandang AP, Bugayong LA, Dolom PC, Garcia LN, Villanueva MMB,
Espiritu NO. Analysis of key drivers of deforestation and forest degradation in the
Philippines. Eschborn; 2013. https://forestry.denr.gov.ph/redd-plus-philipp
ines/publications/Analysis of key drivers of deforestation and forest degradation
in the Philippines.pdf.
[129] Farfan J, Fasihi M, Breyer C. Trends in the global cement industry and
opportunities for long-term sustainable CCU potential for Power-to-X. J Clean
Prod 2019;217:821–35.
[130] Breyer C, Fasihi M, Bajamundi C, Creutzig F. Direct air capture of CO2: a key
technology for ambitious climate change mitigation. Joule 2019;3(9):2053–7.
[131] Mella S, James G, Chalmers K. Evaluating the potential to export pilbara solar
resources to the proposed ASEAN grid via a subsea high voltage direct current
interconnector. Pilbara; 2017. https://www.pdc.wa.gov.au/application/les
/2315/0405/7606/Prefeasibility_Study_Final_Version_030817.pdf.
[132] Itiki R, Manjrekar M, Di Santo SG, Machado LFM. Technical feasibility of Japan-
taiwan-Philippines HVDC interconnector to the Asia pacic super grid. Renew
Sustain Energy Rev 2020;133. Art. no.110161.
[133] Kraan O, Kramer GJ, Nikolic I, Chappin E, Koning V. Why fully liberalised
electricity markets will fail to meet deep decarbonisation targets even with strong
carbon pricing. Energy Pol 2019;131:99–110.
[134] Blazquez J, Fuentes-Bracamontes R, Manzano B. A road map to navigate the
energy transition. Oxford: The Oxford Institute for Energy Studies; 2019. https://
www.oxfordenergy.org/wpcms/wp-content/uploads/2019/10/A-road-map-to-na
vigate-the-energy-transition-Insight-59.pdf.
[135] Azzuni A, Breyer C. Global energy security index and its application on national
level. Energies 2020;13:10. Art. no.2502.
[136] Azzuni A, Breyer C. Denitions and dimensions of energy security: a literature
review. Wiley Interdiscipl Rev: Energy Environ 2018;7:1. Art. no.e268.
A. Gulagi et al.