NGK Insulators has recently announced that it will sell a 50MW/300MWh sodium sulfur (NAS) battery system to Mitsubishi Electric Corporation. When this battery storage system becomes operational in 2016 it will be the largest in the world eclipsing NGK insulator’s previous record of a 34MW/238MWh battery storage system for a Japanese wind farm. I have written about NAS batteries previously here.
Installed costs are about $400/kwh with an expected cycle life of 4500 at 80% depth of discharge. By contrast the much ballyhooed 10kwh Tesla Powerwall will set you back $7140 dollars or $714/khw, and I believe the cycle life is significantly less than that of NAS batteries.
NGK batteries have more capacity deployed on he grid than any other battery type. The sales of this technology suffered a blow in 2011 when a battery fire broke out at one installation site. NGK shut down manufacturing operations as well as existing installations until they had analyzed the cause of the fire and developed a technical fix. Although they resumed manufacturing operations in 2012 and have rebuilt a number of existing sites with with enhanced safety features, I had the impression that sales of their batteries had slowed down. This latest sale indicates that this technology still has life left in it. NGK’s batteries are probably too expensive to truly revolutionize grid operations, but the the current generation of lithium ion batteries are even more expensive and therefore even less likely to bring about a revolution in grid operations.