Biofuels: A Pathway to Sustainable Development and a Green Economy in Sri Lanka

Abstract

Energy was a mere option for convenience once, but it has evolved into an indispensable necessity for daily activities. The quest for a clean, safe, sustainable, reliable, and economically feasible energy supply is intensifying for the global energy transition. In Sri Lanka, the urgency of achieving carbon neutrality and complete energy transition is being integrated with the current utilization of biofuels, primarily bioethanol, biodiesel, and biogas derived from first- and second-generation biofuels. Being a tropical country with extensive vegetation and biodiversity, Sri Lanka has the ability to reduce dependence on fossil fuels through the additional progress of biofuels. Moreover, the measures of Sustainable Development Goals (SDGs), notably SDG 7, insist on transition for accelerated, sustained, and transformative action to meet their targets on time. In this context,
Sri Lanka is far from achieving its targets and is still running behind due to economic and political challenges, technical and financial constraints, policy and regulatory hurdles, and public awareness. In the current situation, the utilization of third- and fourth-generation biofuels is vital for ensuring the conceptual framework of water-food-energy nexus by exploring the diverse microalgae species and genetic engineering approach for biofuel production. However, aligning Sri Lanka with the bioeconomy can strengthen the energy sector to attain sustainable development while avoiding environmental impacts.

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Young Scientist Forum (YSF)
National Science and Technology Commission Sri Lanka
YSF Thematic Publication- 2025
ISBN: 978-955-8630-38-9
Sustainable bioeconomy approaches to strengthen
economy, society and the environment in Sri Lanka
Editor-In-Chief
Dr. Sumudu Mapa
Editorial board
Dr. R.D.A.A. Rajapaksha
Dr. M.A.P.C. Piyathilaka
Dr. Hasintha Wijesekara
Prof. Nadarajah Kannan

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Biofuels: A Pathway to Sustainable Development and a Green Economy in Sri Lanka
S. Dharshika*, and R. S. Dassanayake*
Abstract
Energy was a mere option for convenience once, but it has evolved into an indispensable necessity
for daily activities. The quest for a clean, safe, sustainable, reliable, and economically feasible
energy supply is intensifying for the global energy transition. In Sri Lanka, the urgency of achieving
carbon neutrality and complete energy transition is being integrated with the current utilization
of biofuels, primarily bioethanol, biodiesel, and biogas derived from first- and second-generation
biofuels. Being a tropical country with extensive vegetation and biodiversity, Sri Lanka has the
ability to reduce dependence on fossil fuels through the additional progress of biofuels. Moreover,
the measures of Sustainable Development Goals (SDGs), notably SDG 7, insist on transition for
accelerated, sustained, and transformative action to meet their targets on time. In this context,
Sri Lanka is far from achieving its targets and is still running behind due to economic and political
challenges, technical and financial constraints, policy and regulatory hurdles, and public
awareness. In the current situation, the utilization of third- and fourth-generation biofuels is vital
for ensuring the conceptual framework of water-food-energy nexus by exploring the diverse
microalgae species and genetic engineering approach for biofuel production. However, aligning
Sri Lanka with the bioeconomy can strengthen the energy sector to attain sustainable
development while avoiding environmental impacts.
Keywords: bioeconomy, bioenergy, biofuels, green energy, sustainable development goals
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Department of Biosystems Technology, Faculty of Technology, University of Sri Jayewardenepura, Homagama 10206,
Sri Lanka
* Corresponding author(s): dharshikasugumaran@gmail.com (DS), rdassanayake@sjp.ac.lk (RSD)

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Introduction
In the past few years, the need for new energy sources for day-to-day activities has
significantly increased globally than ever before. Numerous investigations are underway
to find promising and environmentally friendly alternatives for the present and future
energy restrictions on conventional fossil fuel-based energy sources. There are crucial
concerns regarding the energy sources brought on by the exhaustion of conventional
fuels, such as coal, petroleum, and natural gas. These are remnants of past life preserved
in the earth’s crust and defined as fossil fuels [1]. The shrinkage of petroleum reserves,
rising demand and price, energy security, geopolitical instability, especially global
warming, and environmental issues, forcing the reduction of the dependence on fossil
fuel and raising the demand for best substitutes [2], [3], [4]. According to the World
Energy Outlook 2023 of International Energy Agency (IEA) reports, the high fossil fuel
dependency has led to the beginning of the end of the fossil fuel era. Additionally, it has
been speculated that the global demand for fossil fuels will increase drastically and reach
a high point before 2030 [5]. These circumstantial evidences throw light on the foresight
of renewable energy sources, including hydropower, solar, wind, geothermal, and
bioenergy, to combat the limitations and challenges of fossil fuels by shifting energy
reliance globally [4]. In pursuing a future energy source, bioenergy is evidenced as a
potential contributor among the options for economic opportunity.
Bioenergy is produced from renewable sources of natural and biological origins that can
be converted into heat, electricity, and biofuels [6]. More specifically, biofuels have
emerged as a viable solution in this fast-growing energy demand. Biofuels are solid, liquid,
and gaseous fuels derived from biomass and are considered imperishable and
inexhaustible. Biofuels have been gaining increasing global concern due to the
sustainable, eco-friendly, renewable, carbon-neutral, and readily available alternative
energy options to conventional fuels [7], [8]. The hope of biofuels as a substitute was
ignited by Dr. Rudolph Diesel by using vegetable oil in compression engines in the 1900s.
Recently, upgrading and improving the production process of biofuels has inevitably
increased due to their potential to act as a mainstay of energy [9]. Based on the source of
biomass or feedstock, biofuels are divided into primary and secondary biofuels. Primary
biofuels are obtained in their raw form without being processed. In contrast, secondary
biofuels are obtained from processed biomass or feedstock and further divided into first
(edible biomass), second (non-edible biomass), third (substrates like seaweeds, microbes,
and microalgae), and fourth (genetically modified algae, photobiological solar, and
electro-fuels) generations [8], [10]. Moreover, fifth-generation biofuels (in-vitro plant
tissue culture and plant propagation techniques) are the most advanced option and are
not yet widely established for industrial discussion [11], [12].
Further, biofuels are commonly classified into bioethanol, biodiesel, biomethanol, biogas,
and biohydrogen and possess scope around economic viability and efficiency [8], [10]. The
abundant organic sources undergo one or more conversion processes to produce energy
via physical, agrochemical, thermochemical, or biochemical means [3]. To date,
economically feasible production processes utilize biomass and pave the way for biofuel
expansion of its robust advantages [8]. Biofuels have occupied a prominent position that
offers numerous environmental, economic, and social advantages. These multiple
potential benefits of biofuels are leading to the mandate of their use in some countries
like Brazil, the United States, China, India, and Indonesia as a viable sustainable energy

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source [13]. Sri Lanka has been facing numerous issues over the past few years to meet
the energy requirements and hence is looking for long-term energy security, especially
the need for energy for residential, commercial, industrial, transportation, and agriculture
use. For instance, the major energy crisis in the year 2022 impacted the daily livelihood
immensely [14], [15]. The emerging role of biofuels as renewable energy with clean, safe,
sustainable, reliable, and economically feasible options provides hope for clean energy
transitions. Aligning Sri Lanka with affordable, reliable, sustainable, and modern energy
for all concepts in the United Nations (UN) Sustainable Development Goal (SDG) 7,
contributes towards a sustainable green economy and reducing the dependence on fossil
fuels for future goals through biofuels [14], [16].
Generations, Production Processes, and Types of Biofuels
The following section discusses the classification of biofuels based on their generation,
production process, and type. These classifications focus on feasibility, productivity, and
effectiveness and overcome the problems that exist at the time to incorporate biofuels as
our energy source over fossil fuels with optimization.
Biofuel Generations Based on the Biomass Feedstock
Biomass is renewable organic matter generated from plants and animals. The biomass
undergoes different processes of conversation to produce biofuels. Meanwhile, biofuels
are classified into five generations based on using biomass feedstock [17], [18]. Biomass
feedstocks include agricultural crop residues, forestry residues, bacteria, algae, wood
residues, food, animal, industrial, and municipal waste. Out of five generations, the first
four generations are still common. Figure 1 shows the classification of biofuel production
based on their feedstock.
Figure 1: Classification of biofuel production based on feedstock types

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First-Generation Biofuels
First-generation biofuels are denoted as conventional biofuels. They are primarily
produced from edible biomass, such as starch-based (potato, corn, barley, and wheat),
sugar-based (sugarcane and sugar beet), oil-based (sunflower seed oil, cottonseed oil,
palm oil, rapeseed oil, and soybean oil), grains, and animal fats [7]. These feedstocks are
processed through simple conversation processes like fermentation and
transesterification [8]. The availability of crops, simple production processes, and
economic benefits give rise to their wide use. However, the impact on food supply and
price, insecure biomass supply chain, diverting of agricultural land, use of fertilizer and
pesticides for the crops, low yield, and portable water usage hinder their
commercialization in many countries [10], [19].
Second-Generation Biofuels
Second-generation biofuels are emerged as alternatives to first-generation biofuels to
avoid fuel versus food security issues. It is produced from non-edible biomass, such as
dedicated energy crops (jatropha, caster, camelina, and willow), lignocellulosic biomass,
woody crops, agricultural residues (corn stover, straw, and sugarcane bagasse), forest
residues, municipal and industrial wastes, processed wastes, and organic wastes [8], [20].
The feedstocks are processed through thermochemical and biochemical conversation
with temperature control and various mesophilic and thermophilic microorganisms [21],
[22]. Aid food security, no need for agricultural land, no use of fertilizers and pesticides,
eco-friendly and sustainable, less production cost and energy cost, low amount of waste
production, increased fuel recovery, and lower greenhouse gas (GHG) emissions of
feedstocks are offering a viable solution for energy supply by second-generation biofuels.
However, energy-intensive manufacturing and conversion processes, pretreatment of
biomass, potable water usage, and deforestation are considered the main limitations of
second-generation biofuels [8], [10], [23].
Third-Generation Biofuels
The third-generation biofuels are derived from algal biomass (microalgae and
macroalgae), cyanobacteria biomass, animal oils and fat, fish oil, and waste cooking oil as
primary sources [24]. The conversion process of these feedstocks includes
transesterification or hydrotreatment, photo fermentation, and dark fermentation [7],
[25], [26]. The biofuels produced from algal biomass are highlighted for their short
cultivation time, high carbohydrate, protein and lipid content, increased biofuel yield, no
impact on food security, saline water usage and relative abundance, renewable, and non-
arable land usage. Notably, the amount of CO2 taken up by algal biomass is higher than
that of CO2 released for photosynthesis. Major setbacks of third-generation biofuels
include marine eutrophication, the requirement for control conditions and the cost due
to the expensive harvesting, drying, and energy-intensive extraction process [27].
Moreover, the maintenance of cultivation systems such as open ponds, raceway ponds,
and closed photobioreactors is also expensive [20]. The use of oils and fats during
microbial growth also complicates the biofuel process with their chemical composition
and adding impurities. Despite those challenges, progress and advances in third-
generation biofuels have gained attention among stakeholders in large-scale production.

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Consequently, technological advancements in upscaling and reduction of production costs
will be addressed in the future [7], [9], [16].
Fourth-Generation Biofuels
The fourth-generation biofuels are the inexhaustible biofuels generated from engineered
crops, genetically modified algae and microorganisms (bacteria and yeast),
photobiological solar, and electro-fuels using an interdisciplinary engineering approach
[20], [28]. These biofuels primarily focus on the sequestration of CO2 towards carbon
negative and increase lipid synthesis and photosynthesis. These biofuels are engineered
to decrease production costs, simplify production, and increase oil content and yield [4],
[29]. Besides that, they also possess numerous limitations, such as the expenses for initial
investment and pilot set up, the threat of genetically modified organisms (GMOs) to the
environment, including horizontal gene transfer and competition with native species [3],
[19].
Fifth-Generation Biofuels
More recently, in-vitro plant tissue culture has been employed to engineer the lignin
content in crops, produce high-quality biofuel, and avoid competition for arable land and
food, which are bringing up concern for the impediments of prior generations with the
integration of advanced plant agriculture and bioenergy [11]. Fifth-generation biofuels
prepared from plant propagation techniques are still in the infant stage, and numerous
studies are being carried out regarding the new feedstocks and production process [12],
[30].
Methods of Biomass Conversion
Several biomass conversion processes are currently used to generate biofuels from raw
materials. Biofuels are mainly produced by mechanical, thermochemical, and biochemical
conversion routes. However, thermochemical and biochemical processes are widely
utilized and explored [8], [20].
Mechanical Conversion Process
Mechanical conversion is the initial stage of biofuel production. In this process, biomass
is densified into solid biofuel through briquetting or palletization methods under high
compression. This process provides proper shape and structure for easy handling and
storage [31]. Additionally, pressing and expelling techniques are employed to extract oil
from seeds and crops [32].
Thermochemical Conversion Process
The thermochemical conversion process is faster than the biochemical process due to the
high temperature, pressure, and presence of catalysts. Here, organic compounds of
feedstocks undergo thermal breakdown and convert into liquid, gas, and vapor. Feedstock
properties, process parameters (temperature, pressure, and heating rate), product type,
and biomass composition influence the selection of conversion techniques among
torrefaction, pyrolysis, liquefaction, gasification, transesterification, and combustion to
process a wide range of biomass [8], [21], [33].
Torrefaction is a clean and slow thermochemical technique that removes moisture and
partially degrades the biomass at a temperature range of 200 – 300 °C under an inert and

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oxygen-free ambience in a torrefaction reactor. The method enhances the percentage of
carbon and reduces the oxygen to increase the heating value for torrefied and densified
biomass [34], [35]. Pyrolysis is an irreversible thermochemical decomposition technique
applied in the absence of oxygen to break the long-chain molecules into short-chain at
higher temperatures (300 – 900 °C). Biomass is converted into solid gas and vapors, such
as biochar, bio-oil, and gas through slow (carbonization) by traditional pyrolysis or
microwave-assisted pyrolysis [25], [34].
Liquefaction is operated at low temperatures (240 – 380 °C) and under high hydrogen
pressure (5 – 30 MPa) to produce liquid hydrocarbons called bio-crude oil via hydrolysis,
cleavage, decarboxylation, condensation, and polymerization [36]. Gasification is another
thermochemical conversion method to obtain gaseous products, such as syngas and fuel
gas, at temperatures of 800 – 1200 °C for thermal gasification and 400 – 700 °C for
hydrothermal gasification. Hydrothermal gasification of wet biomass tends to be efficient
due to the utilization of subcritical and supercritical water as reaction media [33].
Transesterification is a chemical conversion process widely used for biodiesel production
from non-edible oils and fats by decreasing viscosity and facilitating the formation of
triglycerides into methyl esters. Triglycerides present in the feedstock react with alcohol
and acid, as well as base or enzyme catalysts, to form biodiesel and glycerol as the main
products and by-products, respectively [29], [37]. Combustion is an exothermic redox
reaction process of direct burning of biomass in the air to convert energy into heat and
electricity for stoves, furnaces, boilers, steam turbines, and turbo-generators [38].
Biochemical Conversion Process
The biochemical conversion process involves using bacteria, fungi, and yeast to produce
liquid and gaseous products such as bioethanol, biogas, and biohydrogen. The most
common biochemical methods are fermentation and anaerobic digestion. Generally, the
biochemical process is preferred to bioethanol production due to the high yield. Recently,
a combination of thermochemical and biochemical methods has been performed and
processed to utilize a wide range of feedstocks and to get high yields [39], [40].
Fermentation is a sustainable and efficient technique to produce bioethanol and
biobutanol through feedstock preparation, saccharification, and fermentation, especially
in anaerobic conditions. The complex macromolecules break down into simple molecules
by yeast and clostridium species. Anaerobic digestion is a well-adopted method to
produce biogas in the presence of bacteria for several days under controlled conditions
without oxygen. Initially, the biomass undergoes the hydrolysis of cellulose in the
feedstock to produce soluble organic compounds, followed by acidogenesis,
acetogenesis, and methanogenesis, which produce biogas and solid digestate [41], [42],
[43].
The advantages and disadvantages of thermochemical and biochemical conversion
methods are summarized in Table 1.

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Table 1: Advantages and disadvantages of thermochemical and biochemical conversion
processes [38], [39], [44]
Biomass Conversion
Methods
Advantages
Disadvantages
Bioenergy
Produced
Thermochemical Conversion Process
Torrefaction
No emission of GHGs, can be
used as pretreatment and
conversion technology, high
energy content, low energy
input, low operating cost
Lower overall efficiency,
volatilization of flue gas
Torrified
biomass
Pyrolysis
Convenient to handle,
transport and store, high
efficiency, simple, acceptable
amount of sulfur, water and
sediment
Significant energy input
and reduce the heat value,
high concentration of CO2,
high cost of apparatus,
pretreatment is required
Biochar, bio-oil,
and syngas
Liquefaction
No need of pre-drying,
suitable for wet biomass,
lower critical point
High-pressure usage, low
flowability, possibility of
corrosion, difficulty to
eluting heavy compounds
Bio crude-oil
Gasification
Low tar formation, cleaning
and recovery of gas is
comparably simple, and
faster reaction
High operating cost and
maintenance cost
Biochar and
syngas
Transesterification
Short reaction time, low cost
of production, reaction
conditions can be regulated,
possible to scale-up, mild
chemical reaction
Impact of reaction
conditions, impact of
catalyst, high
concentration of by-
products, depend on the
catalyst for the efficiency,
reusability and cost
Biodiesel
Combustion
Scaling up is possible
Soot, dust ash, NOx, CO,
and CO2 production
Heat and
electricity
(forms of
bioenergy)
Biochemical Conversion Process
Fermentation
Simple method, versatile
feedstock utilization, easy to
scale up and down
Cost of first-generation
feedstock, pretreatment
for second-generation
feedstock
Bioethanol
Anaerobic digestion
Energy efficient, eco-friendly,
low GHG emissions, energy
efficiency is high, nutrient
recycling is possible
High initial investment,
limited feedstocks,
maintain the optimal
condition, odor issue
Biogas

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Types of Biofuels
Biofuels are the only renewable source proven to be the best substitute for fossil fuels.
Pure and blended biofuel products are appearing on today’s market and gaining
significant interest due to their desirable properties to fulfill the energy and
environmental demand. Biofuels can be in solid (such as charcoal, fuelwood, wood pellets,
wood residue, and animal waste), liquid (bioalcohol and biodiesel), and gaseous (biogas,
biohydrogen, and biosyngas) forms [38], [39].
Bioalcohols
Typically, bioethanol, biomethanol, and biobutanol are categorized under bioalcohols and
produced mainly through the fermentation of biomass. Among these bioalcohols,
bioethanol is the most common and frequently produced liquid fuel. Bioethanol is
produced by the yeast and bacteria fermentation of cellulose, glucose, starches,
carbohydrates, and sugars in feedstocks, especially from edible sugarcane, corn, and rice
[8], [18]. Dedicated energy crops like switchgrass, miscanthus, and poplar, as well as
forestry and agricultural residues, are also utilized for bioethanol production. However,
the utilization of microalgae, such as Chlamydomonas reinhardtii, Chlorella vulgaris, and
Spirulina spp., for bioethanol production has been developed and used more than first-
and second-generation biomass [45]. Bioethanol has high energy content, lower
evaporation, and low flammability and can be stored in pure fuel. In addition, higher
octane numbers and compatibility with motor combustion engines and flex-fuel vehicles
without further modification have drawn more attention recently. The United States and
Brazil are at the forefront of bioethanol users in transportation, industrial, and household
applications. The blend of bioethanol under the European Union (EU) quality standard
with gasoline or other fossil fuels helps to enhance fuel properties, reduce the
dependence on fossil fuels, and GHG emissions. Common blends with gasoline include a
fuel mixture of 10% anhydrous ethanol and 90% gasoline (E10), E15, E20, E30, and E85.
E10 is the most common for gasoline engines, while E20 and E30 are less used. E15 offers
more environmental benefits, and E85 is used to avoid the lower vapor pressure of
bioethanol in colder conditions for proper engine function [46], [47].
Biodiesel
Biodiesel is a fatty acid methyl ester (FAME) produced through transesterification from
edible, non-edible oils or fats and algal-based oils. Dedicated energy crops like Jatropha
curcas (jatropha), Mahuna spp. (mahuna), Millettia pinnata (karanja), and Azadirachta
indica (neem) are also highly recognized for biodiesel production [4], [18]. Green diesel is
also a renewable diesel produced by hydrotreating vegetable oil through
hydrodeoxygenation, decarbonylation, and decarboxylation processes. Biodiesels are
non-toxic compared to fossil diesel, have a lesser influence on climate, decrease GHG
emissions, best local fuel for rural communities, largely biodegradable input and output,
and can be directly used in vehicles without engine modification. Biodiesels are used in
their pure form (B100) or blended with petroleum diesel as B20 (20% biodiesel and 80%
fossil diesel) or B5 (5% biodiesel and 95% fossil diesel) [37], [48], [49].
Biogas
Biogas is produced through the anaerobic digestion of organic matter, especially
lignocellulosic substrate in the presence of microbial consortium using a dry model or wet
model anaerobic digestor. The breakdown of organic matter in the absence of oxygen
(anaerobic digestion) primarily generates CH4 and CO2 with traces of H2S, O2, and N2.

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Biogas majorly helps mitigate GHGs by capturing methane from organic wastes for
industrial energy, cooking, heat, and power production in urban and rural areas. Biogas
from microalgae is a promising method that aligns with unique benefits with compelling
opportunities for sustainable energy strategy at the current energy need [18], [50].
Biohydrogen
Biohydrogen is hydrogen gas produced through the biological process with
photosynthetic bacteria, cyanobacteria, and green algae as a renewable and
environmentally favored production method. Dark fermentation, photofermentation,
water biophotolysis, and microbial electrolysis cells are the key hydrogen production
methods used in various industrial processes. Even if low yield and low efficiency,
inhibition of hydrogenases by molecular oxygen, production cost, purification, and
storage are the main drawbacks and need for research and technological developments
[40], [51], [52].
Biosyngas
The biological synthesis gas is a mixture of H2, CO2, CO, and CH4 produced through
gasification, pyrolysis, and biological processes. It can be used as fuel for electricity
generation, heating, and aerospace and maritime industries. The use of biosyngas in those
sectors is at the experimental stage with pilot projects. Specifically, the Fischer-Tropsch
reaction converts biosyngas into liquid hydrocarbons for versatile applications [53].
Synergy between Biofuels and Sustainable Bioeconomy
In 1987, the UN established the definition of sustainability development, which is the
“development that meets the needs of the present without compromising the ability of
future generations to meet their own needs” [54], [55]. Sustainability development
focuses on environmental protection, economic and social development, and the welfare
of present and future generations. First and foremost, the Millennium Development Goals
(MDGs) were signed in 2000 to target 8 goals, subsequently paving the way for SDGs by
UN Member States in 2015. SDGs cover 17 areas and 169 targets that are expected to be
achieved by 2030. It is part of almost all sectors to make a more sustainable environment
for everyone [56]. In this context, sustainable bioeconomy addresses the production,
utilization, conversion, and transformation of biological resources, including energy
through digital technologies for smart and sustainable transition [57], [58]. In the search
for energy transition, sustainable bioeconomy has been substantially pursued with SDG 7
to focus on affordable, reliable, sustainable, and modern energy for all, particularly
bringing significant attention to clean energy for developing countries. However, fossil
fuels cannot be a solution to meet the world's energy demand and need a replacement in
advance. The exploration of alternative renewable energy sources come up with the topic
“biofuel” under discussion for over a decade. The relationship between biofuels and
sustainability development is not only in line with SDG 7 but also with SDG 8, 12, 13, 15,
and 17 [13], [56], [59] as depicted in Figure 2.

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Figure 2: Sustainable Development Goals (SDGs) in the context of biofuels (Source: Sustainable
Development Goals - sdgs.un.org/goals)
SDG 7 aims for affordable, reliable, sustainable, and modern energy for all. As of now,
biofuels play a crucial role in SDG 7 by facilitating the adoption of clean energy for rural
and off-grid areas, reducing reliance on fossil fuels, and accessing renewable energy
sources by upgrading generations for universal access. SDG 8 targets sustained, inclusive,
and sustainable growth, full and productive employment, and decent work for all. The
quest is contributed through biofuel production by creating new market opportunities
and boosting investment, promoting decent work by creating employment, especially
rural economic development, and adopting advanced agriculture for resource efficiency.
SDG 12 focuses on sustainable consumption and production patterns. Biofuel production
and consumption positively impact their targets as second-, third- and fourth-generation
biofuels, reducing waste generations by turning waste into energy or utilizing agricultural
residues and byproducts, coupling with the circular economy. In contrast, first-generation
biofuels lead to food insecurity and water scarcity. Addressing this issue and moving
towards second-generation biofuels significantly adhere to SDG 12 criteria. There has
been significant relationship between biofuels and SDG 13. SDG 13 concentrates on
climate action and combating its impact. The use of biofuels plays a crucial role in climate
action by reducing greenhouse gas emissions with a lower carbon footprint, whereas
some biofuel crops can contribute to carbon sequestration. Notably, the utilization of
agricultural and forestry residues in second-generation biofuel production reduces
methane emissions to the environment. Biofuel production offers an enormous
opportunity to overcome global warming and anthropogenic CO2 emissions. SDG 15 aims
to protect, restore, and promote sustainable use of terrestrial ecosystems, sustainably
manage forests, combat desertification, and halt and reverse land degradation, and
biodiversity loss. Biofuel production in the second-, third- and fourth-generations
significantly contributes to SDG 15 compared to the first-generation by utilizing waste
residues for production, rehabilitating marginal or degraded lands, and enhancing
biodiversity with a co-culturing system. Algal biomass utilization for biofuel production
ensures forest losses, land degradation, and species extinction to achieve SDG 15. Biofuel
production supports and strengthens SDG 17 and its targets and the other way around.
SDGs aim to strengthen implementation and revitalize the global partnership for

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sustainable development through economic growth. At present, developing countries
need help fulfilling their requirements to meet the energy demand. Assistance of
developed countries for technology transfer, effective partnership, global public-private
ties, and shared goals towards sustainability development can ensure achievable global
energy requirements and mitigate fast climate changes [56], [59], [60], [61].
With the current rate of progress in SDGs in energy transition, the water-energy-food
nexus has been given attention to secure the sustainable provision of water, energy, and
food for global demand. The water-energy-food (WEF) nexus is interdependent with each
other and encourages sustainable development of natural resources [62]. Notably, the
interconnections between “food and energy” and “water and energy” demonstrate the
importance of biofuels and sustainable development synergies, as shown in Figure 3 [8],
[63]. In view of this, energy is imperative for agricultural processes to produce food;
meanwhile, food crops and crop residues are required for biofuel production. Energy is
currently required for water supply and vice versa. The interrelationship between these
three commodities is pivotal and primarily plays a crucial role in biofuel generations to
make biofuel production adequate or barely adequate in scattered communities [64]. The
first-generation biofuels negatively impact the ecosystem and directly affect the nexus by
using food crops, inland resources, and massive amounts of water for biofuel production.
Further governance towards second-, third- and fourth-generations reduces the threat to
the WEF nexus by utilizing non-food crops, reducing water usage, and increasing the share
of biofuels in the energy mix in developing countries [65]. Typically, water, energy, and
food are critical to our life. Still, to date, they are limited by the impacts of disruptive
climate-related changes, population growth, lifestyle change, resource depletion, political
consensus, etc. However, the integration of sustainable development goals and WEF
nexus with renewable energy, especially biofuels, is essential to nurture the adaptation in
society over fossil fuels as an alternative [64], [65], [66].
Figure 3: Biofuel implication and interconnections with water-energy-food nexus [8], [62]
The Role of Biofuels in Sustainable Development in Sri Lanka
The national energy grid of Sri Lanka is under the control of the Ministry of Power, Energy,
and Business Development, which strides towards sustainable development with national

621
energy policy and strategies. Despite fossil fuel usage, Sri Lanka fulfills its energy demand
through low-carbon sources, such as hydro, solar, wind, and biomass. Hydropower has
been the main contributor to the energy sector, while solar, wind power, and biomass
utilization also play essential roles as renewable energy sources. Figure 4 demonstrates
the gradual upward trend in the initial phase of energy consumption in Sri Lanka towards
other renewable energy and some fluctuations along the way. In the 2019 Ministry of
Power, Energy and Business Development National Energy Policy Gazette, Sri Lanka
committed to achieving carbon neutrality and a complete transition of all the energy value
chains by 2050, ensuring convenient and affordable energy services having clean, safe,
sustainable, reliable, and economically feasible energy supply [67], [68]. Specifically, the
Sri Lanka Sustainable Energy Authority (SLSEA) highlights the focus on the direction of
large-scale renewable energy projects, strategic investments in the energy sector, and
research and development. Even though SLSEA underscores the inability to implement
the National Energy Policy and Strategies in Sri Lanka as expected in the 2019 gazette on
account of the COVID-19 pandemic, travel restrictions, the unprecedented economic crisis
in 2022-2023, and many other local and global issues [14], [15].
Figure 4: Renewable and non-renewable energy consumption of Sri Lanka (Source:
ourworldindata.org/energy/country/sri-lanka)
The Statistical Review of World Energy 2024 reports that the per capita energy
consumption of Sri Lanka in the year 2023 was 4,536 kWh for electricity, transportation,
and heating [69]. Fossil fuels alone are insufficient to meet the energy demand;
subsequently, a shift towards renewable and sustainable energy is a necessity for energy
security and economic stability. In particular, using biofuels is an evolving aspect of Sri
Lanka’s energy mix, which aligns with the development of sustainable and modern
bioenergy technologies. Especially, Sri Lanka claimed that it is ranked high among the
countries with a large share of renewable energy. Within this framework, biofuels provide
hope for the way forward for energy security while enhancing energy access. In Sri Lanka,
bioethanol, biodiesel, and biogas are currently being used; meanwhile, substantial

622
attention is paid to biohydrogen, biomethanol, and algal biofuels. In the early 2000s, the
Sri Lankan government started to support the development of bioethanol and provided
investments for production facilities. To reduce the environmental impact and promote
the renewable energy transition, Sri Lanka mandated a certain percentage of bioethanol
and gasoline blending by the mid-2010s [70], [71]. Sugarcane and cassava were primarily
focused on liquid bioethanol production for transportation. Biodiesel is at the primitive
stage regarding knowledge and its application. In 2005, the Coconut Development
Authority promoted biodiesel production using coconut oil and established a 40%
biodiesel blend with fossil diesel for pilot projects and small-scale initiatives. Biogas
technology was initiated in 1973 since the onset of the energy crisis [72], [73], [74].
Initially, biogas projects focused on animal manure and crop residues to produce biogas
for cooking and lighting. Currently, biogas production has been primarily adopted by rural
areas and small industries with government support towards clean energy sources,
reducing dependence on LPG. The bioethanol, biodiesel, and biogas production in Sri
Lanka is in a nascent stage with small-scale operations. Both government and private
sectors are involved in producing bioethanol, biodiesel, and biogas. For instance, Pelwatte
Sugar Industries, Sevanagala Sugar Industries, Lanka Bio Fuels (Pvt) Ltd., and Cargills
(Ceylon) PLC are under the Ministry of Power and Energy and Sri Lanka Sustainable Energy
Authority (SLSEA) as a regulatory or advisory body. Although the need for energy has
grown, the utilization of biofuels as an alternative has not yet evenly increased. Sustained
global comeback has yet to emerge and remains open in the energy mix of Sri Lanka [70],
[75], [76].
The promising advancements and modifications in biofuel production are gaining
attention and contributing to its development as a permanent solution. Policymakers,
business representatives, academics, and researchers view biofuel production as a
strategic concept, offering both economic development opportunities and a promising
market for investment. At the current rate of publications related to biofuel production,
research interest in biodiesel has increased since the early 2010s in Sri Lanka compared
to other biofuels due to more practical and immediate solutions for fossil diesel in the
transport sector. Fernando and Kapilan [77] reported the optimization and efficiency of
brown macroalgae, sargassum spp., as a natural raw material for biodiesel production and
highlighted the increased biodiesel yield that satisfied international standards.
Madusanka and Pathmalal [78] stated the potential of cyanobacteria, especially
Microcystis bloom collected from Beira Lake, Sri Lanka, for biodiesel production. The
authors claimed that the B6 biodiesel blend exhibited high heating value, favorable
density, optimum viscosity, and lubricity of produced biodiesel.
Similarly, Hossain et al. [79] mentioned the potential of different cyanobacteria isolated
from freshwater bodies of Sri Lanka for biodiesel production. At the same time, bioethanol
and biogas are also gaining focus among stakeholders for the energy mix in Sri Lanka.
Kularathne et al. [80] utilized the overripened fruits in Sri Lanka for ethanol production.
The authors obtained maximum ethanol yield using banana (embul kesel variety) with
Pseudomonas mendocina as inoculum by optimizing substrate concentration, pH, and
temperature. Christy et al. [43] reported the efficient bioethanol production from
palmyrah fruit pulp and molasses by yeast fermentation under optimum conditions.
Meanwhile, Munas et al. [42] indicated that domestic biogas from kitchen wastes for
cooking energy requirements through aerobic digestion. Research and development, and

623
commercial strategies are progressing towards clean energy for future pathways. All these
studies revealed the priority of second- and third-generation biofuels over first-
generation biofuels for better support in achieving the SDGs.
The major research and technology transfer findings showed that biofuels as the best
substitute and promising alternative to strengthen the economy, society, and
environment. In this scenario, clean energy development with resource efficiency, waste
recycling, adaptability with current engine designs, smaller carbon footprint, non-toxic,
biodegradable nature, lower GHG emissions as well as reduced fuel dependency, the
transition towards circular economy, job creation, rural development, and benefiting
public health than fossil fuel accelerate the sustainability development and boost scale up
investment in clean energy system in Sri Lanka [81], [82], [83]. Early efforts with SDGs
further strengthen the energy security and energy independence of local communities,
government, and private entities [68], [84].
Challenges and Barriers in Biofuel Production
Biofuels in Sri Lanka are suitable for strategic energy initiatives. Given this, biofuels have
the potential to ease and overcome the challenges of fulfilling current and future energy
demands. Despite the potential benefits, many challenges and barriers to biofuel
production must be addressed and concealed. Infrastructure, technological,
environmental, economic barriers, and social challenges are associated with the
production that restricts achieving sustainability and resilience, see Figure 5.
Figure 5: Barriers and challenges in biofuels production and implementation in Sri Lanka
Infrastructure and Technological Challenges
The existing fuel distribution infrastructure is primarily designed for fossil fuels. In
Sri Lanka, the development or modification of physical and institutional infrastructure is
complex and solely depends on government incentives and fiscal support. The feedstock
availability is a major challenge, especially the utilization of first-generation biofuel
feedstocks in Sri Lanka for bioethanol and biodiesel production, which affects the food
supply, while second-generation biofuels are comparably complex and expensive to
process [39]. Further, third- and fourth-generation feedstocks aid in advanced
technologies and research and development investment. So far, Sri Lanka is engaged with
first- and second-generation biofuels, while algal biomass utilization has been explored.
Meanwhile, the process efficiency is lower due to the greater land or feedstock

624
requirements and the need to modify engines and machinery for high biofuel blends in
existing vehicles and industrial applications. Beyond this, other technological constraints
make it challenging to practice and mandate [14], [85].
Environmental Impacts
Expanding biofuel from first-generation biofuels can lead to deforestation and loss of
biodiversity, whereas excessive water usage for edible biomass like sugarcane and corn
triggers water scarcity and food demand. Second-, third- and fourth-generation biofuels
also impact the environment, with no exception. More than the aforementioned barriers,
soil degradation, eutrophication, and the risk of genetically engineered species without
sustainable management and regulatory frameworks give rise to environmental issues
[27], [44]. Biofuels are chemically similar to hydrocarbons and emit fewer GHGs than fossil
fuels, making them acceptable with the principles of carbon neutral process. However,
the additional emissions of GHGs during production, processing, and combustion, such as
CO2, CH4, NOx, and CO can indirectly contribute to global warming at some point [39].
Economic, Policy and Regulatory Hurdles
Energy is a vital input for economic growth, and the widespread adoption and
development of biofuels is an urgent need as a suitable alternative. However, the volatility
of the market in Sri Lanka directly impacts the adoption of biofuels among stakeholders
[68]. Admittedly, the uncertainty of incentives in private sector investments for biofuel
projects is a considerable barrier, as varying regulations and policy frameworks make it
challenging to integrate biofuels into the energy grid. Sri Lanka’s energy policy is still in its
early developmental stages, and there is a notable gap in the absence of a dedicated
biofuel framework. The lack of direct government subsidies or grants for extensive
research due to budget constraints further aggravates the situation [4], [81].
Social and Ethical Issues
Sri Lanka continues to utilize first- and second-generation feedstocks, such as sugarcane
and vegetable oil, for bioethanol and biodiesel production. Still, the reliance on first-
generation biofuels has led to food scarcity or insecurity and increased prices. Notably,
the lack of public awareness about biofuels with inconsistent policies is the major barrier
to the ease of adoption [85]. Other than that, the food vs fuel controversy about
prioritizing biofuels, displacement of local and indigenous people, destruction of habitats,
and social inequality of energy distribution raise ethical concerns in Sri Lanka eventually
with the utilization of biofuels [39], [86].
Conclusion
We are at a moment of truth and reckoning with the need for energy transition to fulfill our energy
demand. Meanwhile, the population surge in Sri Lanka sounds the alarm for an urgent shift
towards renewable, affordable, and clean energy for current and future generations. The SDGs
consistently highlight the broader economic, environmental, and social objectives for sustainable
development. In view of the energy shift, a jump-start on SDG 7 is required to reduce the pressure
on the energy crisis. Biodiesel, bioethanol, and biogas have gained more attention as renewable
alternatives to petroleum fuels in Sri Lanka. However, there is a need to explore other forms of
biofuels with practical applicability. Notably, third-generation biofuels remain primarily confined
to academic research and have yet to be fully realized in practice without being overlooked.
Therefore, the government and private sector need to be reoriented through incentives,
subsidies, and awareness.

625
Acknowledgement
The authors would like to thank the Department of Biosystems Technology, Faculty of
Technology, University of Sri Jayewardenepura.
Conflict of Interest
The authors declare no conflict of interest.
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