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Safety: The Missing Third Leg in the Energy Storage Stool

02.11.2011
Electrons don't like to sit still. That's why the electricity grid has developed over the last 150 years without the benefit of energy storage. Energy storage is--in whatever form it might take--an elaborate attempt at getting electrons to behave while in a passive state. It's been clear for thousands of years that energy storage is physically possible. What has held it back from widespread adoption (outside of fossil fuels and consumer electronics batteries) has been safety. Safety can be achieved, but the cost of engineering danger-mitigation solutions makes most energy storage systems too costly. A recent string of safety incidents at new energy storage facilities around the world have underlined the fact.

While batteries in consumer electronics present a threat (just take a look at pictures of a or the resulting from a cell phone battery explosion), the damage that can be done is limited by their small size. Grid energy storage, on the other hand, requires massive volumes of whatever energy storage medium is chosen (water, pressurized air, batteries, rotating masses, etc.). The bigger these systems get, the greater the danger they pose in case of an emergency. When I recently visited the new 32 MW AES system at Laurel Mountain, West Virginia, I saw safety done right: The more than 1 million individual A123 cells were spaced far apart (as shown in the attached picture) from each other with elaborate water and air cooling systems, surrounded by gargantuan fire retardant systems and all handled by workers who are under such a strict safety regime that they're required to take an onerous training course just to know how to open a trailer door.

Not everyone in the emerging grid energy storage space is approaching the safety challenges inherent in storing electrons with the same level of caution and preparation. I've visited another large battery system that filled a trailer with cells that were--literally--duct-taped together. And now the industry has suffered a series of serious safety events in the last six months:

*On April 22nd, the control room of the Kahuku Wind project (which includes a 15 MW battery system) filled with smoke and the local fire department responded. Although it appears that the fire involved an electrical short in the building wiring and not the Xtreme Power battery cells, it's clear that something went very wrong that day.

*In June, 4 sodium sulfur cells caught fire at an installation in Ibaraki prefecture, causing the entire 2 MW array to shut down. NGK Insulators, which manufactures the batteries, has been very open about the fire and proactive about calling all existing customers to put their batteries into cold storage until the cause of the fire is determined. Nevertheless, they will take an enormous hit on future sales thanks to the fire and the anxiety it has caused.

*Twice, individual flywheels have exploded at the 20 MW Beacon Power frequency regulation plant in Stephentown, NY. Although it wasn't expressly stated, the explosions probably had something to do with the company's decision to declare bankruptcy on October 31.