Factsheet to accompany the report “Pathways for energy storage in the UK”
Nickel-based batteries
Brief description of technology
th
First made at the turn of the 20 century, Ni-Cd
(Nickel Cadmium) batteries have been in
development for almost as long as lead-acid
batteries. The 1990s saw the development of the
NiMH (Nickel-metal hydride) battery, bringing
higher capacity and the use of safer materials.
However NiMH batteries do suffer from a higher
self-discharge rate than equivalent Ni-Cd units,
while Ni-Cd batteries are capable of higher
maximum discharge rates than the equivalently
sized NiMH battery. Ni-MH batteries can generally
improve on the capacity of Ni-Cd by 25% to 40%
[1] for a given battery volume, however to date,
both technologies remain in widespread use. More
recently, other chemistries have been developed,
including Nickel-Zinc (Ni-Zn) and Sodium-NickelChloride (Na-NiCl2), with the cycle efficiencies
ranging from around 70% for Ni-Cd to 90% for NaNiCl2 [2].
Technical/economic data
terminal voltage is comparatively stable over deep
charge cycles, and their average lifetimes are
typically longer than those of lead-acid. The
capacity of Ni-Cd batteries is largely impervious to
rate of discharge, but if discharged excessively as
part of a string of cells, a cell can become reverse
polarized, which leads to capacity degradation [4].
Ni-Cd batteries can cost up to ten times more than
lead-acid batteries, but provide a higher energy
density, longer cycle life and exhibit less frequent
maintenance intervals [1].
Current status
The 14,000 cell Ni-Cd BESS installation run by
GVEA in Fairbanks, Alaska, took the world record
as the world’s most powerful battery in 2003 when
it discharged 46 MW for five minutes during a
maximum limit test. The system is nominally rated
at 27 MW for 15 minutes, but also exceeded this
when it produced 27 MW for 24 minutes [5]. The
project has been hailed a success, with 99.2%
availability throughout its guarantee period of 18
months. As of May 2011, the U.S. Electricity
Advisory Committee listed 26 MW of grid
connected Ni-Cd power capacity as part of a
general grid inventory, suggesting that the
technology has not being pursued further than the
Fairbanks installation [6].
A large scale (27 MW, 6.75 MWh) Ni-Cd battery
energy storage system (BESS) built for GVEA 1 in
Alaska has an energy density of 30MWh/acre, or
5.2Wh/kg. This contrasts with the estimates from
a 2008 European study which put the energy
density for Ni-batteries in the range 20-120 Wh/kg
[2], however the developed BESS system includes
the estimates of the housing. A 2010 energy
storage and management study for the Scottish
government put the cost per kW capacity at £500 £750, with a storage rating of 1-10MWh. But
despite these examples, there are few large scale
systems worldwide [3]. See table 1 for more data.
Other Nickel chemistries have not yet reached
large-scale implementation; in 2010 a Japanese
group announced an 80kWh telecoms backup
system using 95Ah Ni-MH batteries, in 20 parallel
circuits of 40 series connected cells [7]. This
system demonstrated a 40% area saving over an
equivalent VRLA (valve regulated lead-acid) based
system, but no other performance figures were
announced.
Application/markets
Time to commercialisation and R&D needs
BESS systems utilising Ni-based cells have a
response time in the seconds to minutes range,
being able to respond rapidly to transient load
conditions. Suitable applications are therefore
buffering of renewable energy generation
penetration, spinning reserve, frequency and
voltage regulation, power quality improvement
and transmission grid stability.
EU legislation effectively means that Ni-MH has
superseded Ni-Cd technology, due to the high
toxicity of cadmium and restrictions on its use [3].
Currently the moves within the automotive market
are towards Lithium based batteries, where most
of the development in cell technology is now
focussed, despite the Honda Insight, Honda Civic
and Toyota Prius hybrid electric vehicles (HEV’s)
employing NiMH based cell chemistries.
Advantages/disadvantages
Ni-Cd cells are able to tolerate a state of deep
discharge for long periods, making them more
robust than many other battery chemistries. Their
1
www.gvea.com/energy/bess
1
Factsheet to accompany the report “Pathways for energy storage in the UK”
Energy Density
Typical Rated
Capacity
(MW)
Nominal
Duration
Cycle
Efficiency
[%]
Energy
Cost
[$/kWh]
Power Capacity
Capital Cost
[$/kW]
Typical
Life
50-75 Wh/kg [8]
150-300 W/kg [8]
20-120 Wh/kg [2]
0-40[8]
Secondshours [8]
60-83 [9]
70-90 [2]
800-1500
[8]
400-2400 [9]
500-1500 [8]
10-20 years [8, 9]
1500-3000 cycles [9]
2000-2500 cycles [8]
Table 1: Technical and economic data for Ni-based batteries
Safety, security, environmental and public
perception issues
Cadmium is a heavy metal, highly toxic to all life
forms, and poses considerable environmental
waste issues for Ni-Cd batteries.
Ni-MH batteries are more environmentally
friendly, with most nickel recovered at end of life
and used in corrosion resistant alloys such as
stainless steel [2]. During charging water in the
cell is split into hydrogen and oxygen, which at low
charge rates can recombine to form into water
again, thus making the batteries maintenance free.
However, if a Ni-MH is charged at too high a rate,
the excess energy splits water in the cell
electrolyte into hydrogen and oxygen at a faster
rate than it can recombine which can cause
internal pressure build up at high charge rates
leading to cell rupture [4].
References
[1] N. Garimella and N.-K. Nair, “Assessment of
battery energy storage systems for small-scale
renewable energy integration,” in TENCON 2009 2009 IEEE Region 10 Conference, jan.2009, pp. 1 –
6.
[2] C. Naish, I. McCubbin, O. Edberg, and
M. Harfoot, “Outlook of energy storage
technologies,” European Parliament’s committee
on Industry, Research and Energy (ITRE), Tech.
Rep., February 2008.
of
operation.
Power
Engineering.[Online].
Available: http://www.power-eng.com/articles/print/volume-110/issue-1/dg-update/worldrsquoslargest-battery-storage-system-marks-secondyear-of-operation.html
[6] B. Roberts and J. Harrison, “Energy storage
activities in the united states electricity grid,”
Electricity Advisory committee, Technical Report,
May 2011.
[7] K. Takahashi, A. Yamashita, A. Miyasaka,
K. Saito, and T. Shodai, “An 80-kwh-class
telecommunications backup system with largescale
nickel
metal
hydride
batteries,”
Telecommunications: The Infrastructure for the
21st Century (WTC), 2010, pp. 1 –3, sept. 2010.
[8] H. Chen, T. N. Cong, W. Yang, C. Tan, Y. Li,
and Y. Ding, “Progress in electrical energy storage
system: A critical review,” Progress in Natural
Science, vol. 19, no. 3, pp. 291 – 312, 2009.
[Online].
Available:
http://www.sciencedirect.com/science/article/pii/S100200710800381X
[9] M. Beaudin,
H. Zareipour,
A. Schellenberglabe, and W. Rosehart, “Energy
storage for mitigating the variability of renewable
electricity sources: An updated review,” Energy for
Sustainable Development, vol. 14, no. 4, pp. 302 –
314,
2010.
[Online].
Available:
http://www.sciencedirect.com/science/article/pii/S0973082610000566
[3] O. Edberg and C. Naish, “Energy storage and
management study,” AEA Group for Scottish
Government, White Paper, September 2010.
[4] S. Vazquez, S. Lukic, E. Galvan, L. Franquelo,
and J. Carrasco, “Energy storage systems for
transport and grid applications,” Industrial
Electronics, IEEE Transactions on, vol. 57, no. 12,
pp. 3881 –3895, Dec. 2010.
[5] S. Blankinship. (2006, January) World’s
largest battery storage system marks second year
2