Block’s Indicator of Sustainable Growth

by Ray Block

For some months, I’ve been reading about the exceptional growth potential in the  grid energy storage market.  A current  market of US$326 million growing to an expected US$8.3 billion by 2016, according to NanoMarkets. Now that’s explosive growth.

I was impressed with the Seeking Alpha blog by John Petersen particularly in posts of  August 9 and 16 2009, and various posts of  Greentech Media, particularly Jeff St John ( July 31 2009) and John Kluza  (August 17 2009)

I first came across grid energy storage when researching  wind energy, and saw a report on Tokyo Electric’s use of large sodium sulphur high temperature batteries for use in their power plants.  The batteries are about the size of a double decker bus.

The Japanese utility (TEPCO) is a partner with NGK Insulators of  the NaS  large batteries for storage of electricity, to enhance reliability, provide support for weak sub-transmission systems, avoid equipment overload, and offset intermittent supply of wind and solar energy.

A key advantage  of electrical energy storage is for load levelling, and power quality systems to protect commercial and industrial users from outage interruptions, which is a major cost factor for large consumers.

There is also the advantage of  peak  shaving systems to help commercial and industrial users manage their electricity costs more efficiently. The new emphasis on energy efficiency  allows for transmission and distribution support systems  to help utilities reduce grid congestion, defer upgrades, and minimise waste. And in wind and solar energy, the critical need is to better match peak wind and solar output with peak demand.

The Japanese utility first installed two 6 megawatt NaS  storage systems in 2002. According to John Baker of EA Technology in the UK, the installed capacity of these battery systems is now  in excess of 300 MW  across some 150 sites, principally in Japan, with a growing market in United States.

The success of sodium sulphur batteries is that 80 per cent of  the electricity stored in the battery can be recovered. The downside is the cost of maintaining a high temperature of 300 degree Celsius.

The largest energy storage battery in the world is currently a 8 megawatt/58 MWh NaS  system installed at a Hitachi plant in Japan.  

American Electric Power, which had a demonstration system since 2002,  installed a 1.2 MW  NaS storage system in 2006. The next step was a 6 megawatt NaS system  for its Ohio and West Virginia service, particularly to support its wind operations. The aim is to install 25 megawatts of NaS batteries over coming years. 

AEP has gone one stage further with the installation of a distributed energy system at its Citizens Substation in Bluffton, Ohio. There are three major components involved- NaS energy storage;  a smart grid storage management system to move from  dc-to-ac energy conversion; and a step-up transformer, which converts the ac system output to line voltage.

Xcel Energy, which operates more than 15 GW of  generating capacity including  3 GW of wind energy,making it No 1 in American wind energy       operates  in  10 Western and Midwestern states.  Xcel has installed a 1 MW   NaS battery for direct wind energy storage at the 11 MW wind farm in Luverne, Minnesota. The utility, which also has 28 hydropower plants, 2 biomass generators and some solar PV has a need  to  manage excess energy more flexibly.

There will shortly be a competitor to the Japanese NaS battery with General Electric targeting the sodium sulphur battery market. 

The problem with this  battery is the high price -$3000-4000 per kilowatt hour, compared to compressed air energy storage at prices approaching pumped hydro power of $250 to $500 per kilowatt hour.

Compressed air technology is to be used by PG&E supplying energy to Northern and Central California. Wind power and other energy supplies is to be pumped into an underground reservoir when electricity is cheap. The compressed air can then be released to boost a gas turbine, helping to generate up to 300 MW of stored energy for up to 10 hours. 

There are a number of other batteries seeking to gain favour in the energy storage market. One of these is the vanadium redox battery made under license to the University of NSW in Sydney. These batteries are  manufactured by Sumitomo Electric in Japan and VRB Power Systems in Vancouver, Canada.  There is a 2MW VRB storage battery installed at the 32 MW wind farm at Some Hill, Ireland.

Ulltracapacitors made by Maxwell Technologies, APowerCap Technologies. EnerG2 Inc and EEstor are finding market opportunities in regenerative braking,which captures kinetic energy from brakes. The advantage of the ultracapacitors is the abilityto charge and discharge faster, and over more life cycles, than batteries.

The South Korean government is testing Maxwell ultracapacitors for subway regenerative braking systems, and the company has sold units for bus companies in China and Europe, and to provide backup power for wind  turbine blade pitch control systems produced by LTi REEnergy.

Another technology is the flow battery,  which is also seen as a potential for large scale stationary storage, including the growing field of electricity grid storage. Its advantage is the relatively low price compared to other types of batteries.    

But there is a downside with their relatively low efficiency, tending to lose a higher portion of the energy put into them than rival batteries. ZBB Energy Corp is the leader in this market space, with its zinc bromide batteries. Two other firms-the Swiss, ReVolt Technology, and Power Air, spunout from the Lawrence Berkeley Naational Laboratory are making zinc air batteries. 

Finally, Socal Edison, the energy supplier in Southern California  is to install a 32 megawatt hour lithium-ion battery for grid energy storage, to be built by A123, which recently had a highly successful public float.