IEEE Power & Energy Magazine - Grid Edge 2023 - 54

Type
Energy density (Wh/kg)
Power density (W/kg)
table 1. Main attributes of representative batteries.
Lead-Acid NiMH
60-120
Li-ion
25-50
75-300
Cycle life (100% depth of discharge)
Capital cost (US$/kWh)
Round-trip efficiency (%)
Self discharge
75-200
250-1,000 500-2,000
900-3,500 300-2,500
~65
85-97
Medium
NaS
150-240
150-230
300-500
75-90
VRB
10-30
80-150
200-1,000 180-2,000 1,000-10,000 2,500-4,000 >12,000
100-300
75-85
Low
High
Sources: M. Aneke and M. Wang, 2016; X. Luo, J. Wang, M. Dooner, and J. Clarke, 2015.
A flooded lead-acid battery is the less expensive of the two
but usually requires at least monthly maintenance to check for
and add distilled water. Furthermore, its operation needs to be
performed in vented locations because it produces flammable
gases. As a lower-maintenance solution, the VRLA battery uses
a valve to minimize water loss by allowing hydrogen and oxygen
recombination.
The main advantages of using lead-acid batteries are high
400
350
300
250
200
150
100
50
Existing Capacity in 2012
Installed Capacity in 2013-2014
energy efficiency, low self-discharge rate, and low up-front
cost. Nonetheless, their further promotion for commercial
use suffers from some obvious technical drawbacks, including
low depth of discharge (<20%), low cycle life, low energy
density, and slow charging rate.
Lead-acid batteries are still primarily employed in cases
where cost effectiveness, reliability,
and abuse tolerance are
critical but energy density and
lifetime are not as important.
Such applications include automotive
starting, lighting, and ignition,
uninterrupted power supply
(UPS), and renewable balancing.
According to the Alliance for
Other
Batteries
35,000
30,000
25,000
20,000
15,000
10,000
5,000
NICd RFBs Advanced
Lead-Acid
(a)
Sodium Metal Hydride
NaS
Advanced Lead-Acid
RFB
Li-ion
Revenue
35,000
30,000
25,000
20,000
15,000
10,000
5,000
2016 2017 2018 2019 2020 2021 2022 2023 2024 2025
(b)
figure 1. The (a) estimated installed battery capacity and (b) commissions (MW) in
the worldwide power sector. (Sources: Navigant Research and the U.S. Department
of Energy's global database.)
54
ieee power & energy magazine
Li-ion NaS
Rural Electrification's 2013 report
" Using Batteries to Ensure Clean,
Reliable, and Affordable Universal
Electricity Access, " Morocco
deployed approximately 50,000
solar home systems equipped with
lead-acid battery storage to provide
rural electrification between
1995 and 2009. The same data
sources also reveal that, in Bangladesh,
3.5 million solar home
systems have been installed that
incorporate lead-acid batteries.
NiMH Battery
An NiMH battery consists of
a nickel-oxyhydroxide-based
positive electrode, a metallic
cadmium-based negative electrode,
and an alkaline electrolyte
(usually potassium hydroxide).
As an upgrade to its nickel cadmium
(NiCd) counterpart, the
NiMH battery has higher power/
september/october 2017
-
150-1,000
75-90
Negligible
(MW)
(MW)
(Million US$)
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