Date: Jun 7, 2018

How have lithium batteries managed to dominate new grid-scale energy storage?

Thomas Edison successfully started “The Edison Storage Battery Company” more than 100 years ago, offering a large range of lithium batteries for cars, buses, trucks, and other uses, but this lithium battery business faded out with the success of the combustion engine and the availability of fossil fuels. Batteries for electric vehicles are now a key market driver for grid-scale batteries. Modern research and manufacturing methods have greatly improved lithium battery performance and costs. Various lithium battery configurations (NMC, Cobalt Oxide, LMO, LFP, and NCA) are disrupting the transportation and electric power industries by combining with renewable energy generation, to displace fossil and nuclear power.

The deployment of lithium for grid-scale batteries in the US prior to 2009 was exactly “zero”. There were no lithium battery projects before 2009 according to a 2016 Department of Energy report. So how did lithium batteries come to be the preferred type of chemistry by 2018? By 2001 the DOE report identified a handful of small lead-acid battery projects. In 2003 there was the 27MW GVEA (Golden Valley Electric Association), battery energy storage system based on nickel chemistry. GVEA is a cooperative which serves about 100,000 customers in central Alaska, and the battery improved grid reliability, which is a priority in cold winter conditions. Between 2004 and 2008 DOE logged many much smaller sodium-sulfur (NGK) battery projects totaling about 8.2MW. The cost performance of these sulfur-based battery projects was never demonstrated and the cost of these batteries did not decline over the 4-year period. Lithium-ion batteries in 2007 were no better as they were unproven and cost more than $1000/kWh.

Figure 1 from Electropaedia web site at www.mpoweruk.com

The Move to Lithium

In the period from 2010 to 2014, the US saw many new high-risk battery projects driven by the 2009 American Recovery and Reinvestment Act (ARRA) which provided public financing of about $97 million in grid-scale battery storage demonstrations. It was the independent grid operator PJM that saw an early and successful move to lithium batteries. With steady cost and performance improvements in lithium batteries, in 2015 PJM responded to the FERC (Federal Energy Regulatory Commission) 2011 order to “pay for performance” for grid services by encouraging deployment of lithium batteries for the very important frequency regulation market. PJM recognized that new lithium batteries made for the car market could charge and discharge quickly and this is exactly what was needed for frequency control. Modern electric grids use a technique called AGC or automatic grid control to balance generation and loads. In this scheme when a large load is added to a grid the frequency initially falls and synchronous motors, including those in common wall clocks all slow down slightly. This drop in frequency is the control signal used by all generators on the grid to quickly increase power to meet that load and restore grid frequency, while never noticing your wall clock was not keeping steady time.

Because the load response needs a lot of power very quickly, but only a duration long enough to bring new generation on-line, the lithium battery proved successful for this application, and in fact today, lithium batteries have filled the need and saturated the market for frequency control in the PJM service area. Other ISO and RSO (Regional System Operators) are following the lead of PJM and the new FERC 841 rule opens new market opportunities for batteries to compete in wholesale markets.  Owners and operators of renewable energy assets have found the addition of batteries can easily form micro-grids and even nano-grids when coupled with solar PV or wind generation.

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