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Several battery technologies exist amongst other available electric energy storage technologies for both large and small-scale energy storage applications. Lead-acid and Li-ion batteries are presently the two most widely used battery storage technologies for small scale applications. Though environmental temperature greatly affects the operation performance of these two battery technologies, each has temperature range which it is more adaptable to. This paper reviews literatures on battery energy storage aspect of electrical energy storage technologies and literatures on world climatic characteristics to deduce that the comparative battery energy storage technology for tropical region is Lithium-ion battery.
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2017 IEEE 3rd International Conference on Electro-Technology for National Development (NIGERCON)
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Review Of Comparative Battery Energy Storage
Systems (Bess) For Energy Storage Applications In
Tropical Enviroments
Agwu Daberechi D., Opara F. K., Chukwuchekwa N, Dike. D. O., Uzoechi L.,..
Department of Electrical and Electronic Engineering,
Federal University of Technology, Owerri. (FUTO), Nigeria.
Abstract Several battery technologies exist amongst other
available electric energy storage technologies for both large and
small-scale energy storage applications. Lead-acid and Li-ion
batteries are presently the two most widely used battery storage
technologies for small scale applications. Though environmental
temperature greatly affects the operation performance of these
two battery technologies, each has temperature range which it is
more adaptable to. This paper reviews literatures on battery
energy storage aspect of electrical energy storage technologies
and literatures on world climatic characteristics to deduce that
the comparative battery energy storage technology for tropical
region is Lithium ion battery.
Keywords battery, lead-acid, lithium-ion, energy storage,
temperature, tropic
I. INTRODUCTION
One of the major challenges of electricity generation and
consumption using renewable energy resources especially,
solar and wind is their periodic generation discontinuity.
Whilst solar availability can be easily predicted, wind energy
is quite stochastic. This periodic availability makes it difficult
to solely rely on solar or wind electric power generation for
constant power needs. According to [1], this same periodic
availability challenge as well as the fact that its energy
generation is not easily controlled by the system operator,
make it more difficult to integrate solar and wind plants in the
generation pool compared to conventional (hydro, gas,
nuclear, etc) power plants. To overcome this challenge, the
use of electrical energy storage devices is being presently
extensively applied. Electrical Energy Storage (EES)
technology as described by [2] and [3] is the process of
converting electrical energy to a storable form and reserving it
in various media; then the stored energy can be converted
back into electrical energy when needed. Based on electrical,
mechanical, chemical and thermal energy storage principles,
[4] and [5] highlighted that a number of storage technologies
are available with quite different technical parameters and
operating characteristics.
Following the importance of electrical energy storage
systems towards achieving reliability in both renewable and
convectional power systems, scholars keep researching and
developing EES for use in both large and small-scale
electricity generation. Battery Energy Storage (BES) system is
an aspect of EES. Ease of use and scalability to achieve
desired energy storage capacity makes BES a global top
choice for small scale solar and wind power applications.
There are many commercially available battery technologies,
but each has advantages and limitations based on specific
application, environmental factors, power and energy scale,
cost, availability, safety issues, etc. For the purpose of
comparing suitable BES technologies for tropical regions, the
sections below critically review scholarly works on EES
technologies; with emphasis on BES systems.
II CLASSIFICATION OF ELECTRICAL ENERGY
STORAGE TECHNOLOGIES
According to [6], [2] and [3], the several methods
suggested for categorization of various EES technologies
include their functions, response times, and suitable storage
durations. Researchers in [7] and [8] classified according to
form of energy stored as shown in Fig. 1 while [9] and [1]
classified according to form of application as shown in Fig. 2.
The classification by [9] reveals that BESS can be applied
in both small and large-scale applications. A battery is a
combination of electrochemical cells connected in series or
parallel which produces electricity at a designed voltage using
electrochemical reactions. As explained by [10], [11] and [3],
a cell basically consists of two electrodes (one anode and one
cathode) with either solid, liquid or gel states electrolyte.
Depending on phase, a cell bi-directionally converts energy
between electrical and chemical energy. In discharging phase,
electrochemical reactions take place simultaneously at a cell’s
anode and cathode to release and drive electrons through the
external circuit from anodes and to cathodes. In the charging
phase, appropriate external voltage is applied across the two
electrodes to cause reverse reactions and make the battery
recharged.
Batteries have relatively low cycling times and high
maintenance costs. These factor as pointed out by [3] makes
batteries to be rarely used for implementing large scale
facilities despite the fact that it has over time proved to be an
excellent electrical energy storage (EES) device.
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Fig. 1. Classification of EES technologies by the form of stored energy [3]
Figure 2: Classification of EES technologies by the form of application [1]
Another factor as highlighted by [7] is dependency of
battery lifespan on its Depth-of-Discharge (DoD) cycle. This
makes complete discharge of battery inadvisable. The
following subsections describes some important battery
technologies.
A. Leadacid batteries
In practical implementation of battery technologies, [12]
and [2] presented the LeadAcid (LA) battery as the most
widely used rechargeable battery. LA batteries are widely used
in stationary devices as back-up power supplies for computing
devices, telecommunication systems and energy management
in utility facilities; as well as hybrid or full electric vehicles.
The cathode of LeadAcid (LA) battery is made of PbO2
while its anode is made of Pb, and the electrolyte is sulphuric
(H2SO4) acid. Authors in [13], [14] and [2] all described
attribute of LA battery to include fast response time, small
daily self-discharge rates (<0.3%), relatively high cycle
efficiencies (63-90%) and low capital costs. Other attributes
include energy density (5090Wh/L) and specific energy (25
50 Wh/kg). Just as [3] and [8] mentioned, [15] and [16]
respectively pointed out that the application of Lead Acid
battery for large utility applications is still limited because LA
battery have relatively low cycling time (up to about 2000).
Besides, Leadacid battery performance is temperature
dependent. Thus for optimal performance, a thermal
management system is normally required which of course
increases cost of the entire system.
Currently, researches for development of better LA
batteries seems to be focusing on:
(a) Materials research for performance improvement in
areas such as extending cycling times and enhancing the deep
discharge capability.
(b) Implementation strategies for enhanced performance in
the wind, photovoltaic power integration and automotive
sectors applications.
B. Lithium-ion (Li-ion) batteries
The cathode of Li-ion battery as explained by [17] and [3]
is made of a lithium metal oxide such as LiCoO2 and LiMO2
while the anode is made of graphitic carbon. The electrolyte is
non-aqueous organic liquid containing dissolved lithium salts,
such as LiClO4. According to [6], [14] and [2], Li-ion battery
have their response time, energy and power density in the
order of milliseconds, 75200Wh/kg and 1502000W/kg
respectively. They further stated in their publications that Li-
ion batteries have high cycle efficiencies, up to 97%.
Reference [3] highlighted that the main drawbacks of Li-ion
BES system are that Depth of Discharge (DoD) cycle could
affect the Li-ion battery’s lifetime and that the battery pack
usually requires electronic controllers to manage its operation.
This of course increases its overall cost. The performance also
depends on operating temperature just like LA battery. Current
researches on Li-ion battery as pointed out by [3] focuses on:
(1) Increasing battery power capability with the use of
nano-scale materials
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(2) Enhancing battery specific energy by developing
advanced electrode materials and electrolyte solutions.
(3) Implementation strategies/management systems for
enhanced performance
C. Sodiumsulphur (NaS) batteries
In their publication, [18] explained that a Sodiumsulphur
(NaS) battery uses molten sodium and molten sulphur as its
two electrodes and uses solid electrolyte referred to as “beta
alumina”. They further explained that the reactions normally
require a temperature of 574624 K to ensure that the NaS
battery electrodes remain in molten state in order to maintain a
high reactivity.
The advantages of Sodiumsulphur (NaS) battery as
highlighted by [6] and [17] include relatively high energy
densities (150300Wh/L), almost zero daily self-discharge,
higher rated capacity than other types of batteries (up to
244.8MWh) and high pulse power capability. It was further
revealed in [17] and [2] that NaS battery uses inexpensive,
non-toxic materials leading to 99% recyclability. Sodium
sulphur (NaS) is not commercially available in very small
scale because it has very high annual operating cost. Besides,
extra heating system is required to guaranty its operating
temperature. According to [3], NaS battery is considered as
one of the most promising candidates for large scale, high
power EES applications.
D. Nickelcadmium (NiCd) batteries
Authors in [3] explained that a NiCd battery uses nickel
hydroxide and metallic cadmium as the two electrodes and an
aqueous alkali solution as the electrolyte. NiCd battery has
relatively high robust reliabilities and low maintenance
requirements. However, the weaknesses of NiCd batteries as
pointed out by [19] include: environmental hazards and
pollution because cadmium and nickel are toxic heavy metals,
the battery capacity can be dramatically decreased if the
battery is repeatedly recharged after being partially
discharged. Till date there have been very few commercial
successes using NiCd batteries for large scale EES
applications. Thus [3] is of the opinion that NiCd batteries will
unlikely be heavily used for future large-scale EES projects.
E. Other battery energy storage technologies
In [20], the Nickelmetal Hydride (NiMH) battery was
extensively discussed. NiMH is similar to NiCd battery except
that a hydrogen-absorbing alloy is used as the electrode
instead of cadmium. NiMH battery has moderate specific
energy (70100Wh/kg) and relatively high energy density
(170 - 420Wh/L) that is significantly better than those of the
NiCd battery. Compared to NiCd, NiMH batteries are more
environmental friendly and has longer life cycle compared
with Li-ion batteries. However, [3] and [20] did point out that
NiMH has very high rate of self-discharge, losing 520% of
its capacity within the first 24hrs after full charging. They also
highlighted that NiMH is sensitive to deep cycling the
performance decreases after a few hundred full cycles.
Sodium Nickel Chloride (NaNiCl2) battery commonly
referred to as ZEBRA battery is described to have similar
properties to that of NaS battery by [21], [22] and [2]. The
specific energy of NaNiCl2 battery which is about 94
120Wh/kg is moderate. NaNiCl2 has energy density of
150Wh/L, specific power (150170 W/kg), and a high
operating temperature that ranges from 523K to
623K.Researchers in [3] presented NaNiCl2 battery as having
the advantages of good pulse power capability, cell
maintenance free, very little self-discharge and relatively high
cycle life.
The drawback of NaNiCl2 battery as indicated in [3] is that if
the electrodes solidifies, it takes 1215 h to heat up the
electrodes of the battery back to molten. Only few companies
have been involved in the development of this technology and
have produced this type of battery, thus limiting its
commercial availability. Table 1 is an excerpt of battery
energy storage systems summarized alongside other Electrical
Energy Storage (EES) systems by [3].
TABLE I. SUMMARY OF DIFFERENT BES TECHNOLOGIES
Attributes
Lead-
Acid
Li-ion
NaS
NiCd
Life time
(Years)
5 15
5 - 15
10 - 15
10 -
15
Cycling
Times
500
1000
1000 -
10000
2500
2000 -
2500
Discharge
Efficiency
85
85
85
85
Cycle
Efficiency
70 80
90 - 97
75 - 90
60 -70
Self-
Discharge
0.1 - 0.3
0.1 - 0.3
~ 0
0.2 -
0.6
Response
Time
Ms
ms
Tens of
ms
ms
Energy
Density
(Wh/L)
50 80
200 -
500
150 -
250
60
150
Power
Density
(W/L)
10 400
1500 -
10000
140 -
180
80 -
600
III OPTIMAL OPERATING TEMPERATURES OF LI-ION,
LEAD ACID BATTERY AND TROPICAL EFFECTS
The performance of Lead acid battery and Li-ion battery
are affected by environmental temperature. Upon critical
review of the characteristics of the various battery energy
technologies, one may wonder why Lead acid batteries are
the most widely used despite their relatively low cycle time,
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cycle efficiency, energy and power densities. This puzzle was
answered indirectly by [3] in the maturity status indicated as
status of the technology. Presently, Lead acid battery
technology is said to be technically matured, meaning it has
been developed to the extent that it is very acceptable.
The optimal operating temperature range for lead acid
battery is 20 to 25° C. In their tips for maximizing battery life
in solar application, [23] stated that for every 10° C (1F)
rise above room temperature (25 °C or 77 °F), battery life
decreases by 50%. Hence, [23] advises users to store and
operate batteries in a cool, dry place. Authors in [24] in their
technical report revealed that the life of a battery at 25°C is
71%, at 30°C it is 50% and at 40°C the life is only 25%. The
implication is that if a battery which originally has a 10years
lifespan is kept at 40°C, the effective ‘design life’ would be
2.5 years and performance would drop below 100% before 2
years.
According to [25], Lithium-ion performs well at elevated
temperatures but prolonged exposure to heat reduces
longevity. Manufacturers of Li-ion battery usually gives the
operating temperature of lithium ion battery to range from 0
to 45°C for charging operations and 20 to 60°C for
discharging operations. However, in their report [26] claims
that the optimal temperature range for lithium ion battery
operation is between 15 to 35°C. Fig. 3 is a graphical
summary of [26] analysis.
Fig 3: Optimal operating temperature of Li ion battery [26]
The rate of chemical reactions to produce electric power in
Li-ion batteries reduces as temperature decreases. According
to [27], [28] and [29], decrease in temperature causes
contraction of the electrode materials; which slows down ion
movements in the intercalation spaces. As this continues, the
electrodes will stop accommodating current flow thereby
resulting in reduced power output as well as irreversible
capacity loss due to Lithium plating of the anode. On the other
hand, operating Li-ion battery at high temperatures gives rise
to a different set of problems which can result in the
destruction of the cell. First, the magnitude of available power
and capacity start decreasing after 35°C according to [26].
However, [30] has it that operating Li-ion battery slightly
above 50 ºC also reduces cycle life and at above 70 ºC the
threat of thermal runaway arises. Fig. 4 is a graphical
summary of temperature Storage capacity relationship
analysis as presented by [30].
Tropical regions are simply geographical areas within the
farthest points around the equator where the sun can be
directly overhead. Tropical regions are bounded by the two
23˚ 27’ parallel latitudes in north and south of the equator
commonly referred to as tropic of Cancer and Capricorn,
respectively. A tropical climate has warm temperatures
throughout the year
Fig. 4: Temperature Storage capacity relationship [30]
and a significant amount of precipitation. Nigeria has tropical
climate. According to a report by [31], the maximum
temperatures during the hot season (February and March) in
the south and (March and April) in the north ranges between
30.1 40.0°C. Reference [31] further stated that the southeast
coastal areas had mean maximum temperatures of 30.0
33.0°C, while the coast of the southwest and the inland cities
of the south recorded maximum temperatures between 33.0
36.0°C. Maximum temperatures over the central areas and the
north central parts ranged between 36.0° -38.0°C during hot
period except for Jos and its environs which had mean
maximum temperature ranging between 30° -36°C. Jos
recorded the lowest maximum temperature of 30.1°C.
Elsewhere in the north, maximum temperatures were between
38.0° - 40.0°C.
The minimum temperature recorded at extreme northern
parts of Nigeria happened to be below 18˚C which is a general
benchmark for tropical regions. Table 2 is a summary of
maximum northern daily temperatures for the year 2012.
2017 IEEE 3rd International Conference on Electro-Technology for National Development (NIGERCON)
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Station
Value
(oC )
Period
Frequency
(Days)
Maiduguri
44.7
February - May
53
Nguru
43.6
March - May
57
Sokoto
43.6
February - May
51
Yelwa
43.5
February - May
41
Potiskum
42.4
March - May
48
Gusau
42.2
February - May
30
Kano
42.1
March - May
38
Yola
42.1
February - May
60
Katsina
42.0
April - May
34
Ibi
41.2
March
10
Bauchi
41.0
March - May
29
Gombe
41.0
April
9
Lafia
40.8
March
16
Minna
40.8
March
7
Makurdi
40.3
March
4
Bida
40.0
March
10
IV CONCLUSION
Tthe battery energy storage systems (BESS) have their
merits and demerits, the literatures reviewed in this work
reveal that Lithium ion battery is at the moment the best
energy storage technology for tropical environments. This is
due to the facts that their optimal operating temperature range
is just about the same with the average daily environmental
temperature of the tropics.
For instance, the minimum optimal operating temperature
of lithium-ion battery as given by [26] is 15.0°C while the
average minimum temperature of tropical region is 18.0°C.
Thus Lithium-ion batteries will not have cause to face its
extreme low temperature challenges as pointed out earlier
whilst operating in tropical areas. Likewise, the maximum
optimal temperature by [26] is 35.0°C which is above the
maximum temperature of many tropical region especially the
rainforest. Moreover, the temperature 60.0°C at which [30]
and [26] indicated that Li-ion battery will experience thermal
runaway and drastically drop its capacity is well above the
maximum recorded temperature of 43.7°C in Nigeria as a
tropical region.
Though Li-ion battery requires thermal management just
like lead-acid battery and other battery energy storage
systems, making Li-ion battery a choice for tropical regions
like Nigeria will reduce the efforts and resources channeled
towards battery thermal management. For instance, there will
be no need to heat up its immediate environment during cold
times and also less need to cool the immediate environment
during hot times as compared with lead-acid battery.
The two most widely used battery technology (Lead-acid
and Li-ion) for small scale energy storage applications have
temperature challenge in common. Whilst lead-acid battery
adapts better to lower temperatures suiting temperate climate,
Li-ion battery adapts more to higher environmental
temperature relative to that of tropical climates. If the concept
of comparative advantage will be borrowed in this subject; it
is hereby deduced in accordance with the reviewed literatures
that the comparative battery energy storage technology for
tropical region is Lithium ion battery.
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Electrical power generation is changing dramatically across the world because of the need to reduce greenhouse gas emissions and to introduce mixed energy sources. The power network faces great challenges in transmission and distribution to meet demand with unpredictable daily and seasonal variations. Electrical Energy Storage (EES) is recognized as underpinning technologies to have great potential in meeting these challenges, whereby energy is stored in a certain state, according to the technology used, and is converted to electrical energy when needed. However, the wide variety of options and complex characteristic matrices make it difficult to appraise a specific EES technology for a particular application. This paper intends to mitigate this problem by providing a comprehensive and clear picture of the state-of-the-art technologies available, and where they would be suited for integration into a power generation and distribution system. The paper starts with an overview of the operation principles, technical and economic performance features and the current research and development of important EES technologies, sorted into six main categories based on the types of energy stored. Following this, a comprehensive comparison and an application potential analysis of the reviewed technologies are presented.
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