The challenge for green energy: how to store excess electricity

EEStor claims that its device, which is one-quarter the weight of a similar lithium ion battery, can hold a large charge for days. Its patent describes a 281-pound device that would hold almost the same charge as a half-ton lithium ion battery pack installed on the Tesla Roadster. The company’s ultracapacitors have yet to prove themselves in commercial products. But industrial giant Lockheed Martin has already signed up with EEStor to use future ultra capacitors in defence applications, and Toronto-based Zenn Motors, which has also taken an ownership stake in EEStor, says it will have electric cars on the road using the technology in 2010.

If advanced batteries or ultracapacitors aren’t the ultimate answer, maybe using excess electricity to make hydrogen that can be stored will do the trick. Hydrogen can be produced through simple electrolysis, but technical and cost hurdles have made electrolysis impractical. Today, industrial-scale hydrogen is produced using natural gas as a not-so-clean feedstock.

But that may have begun to change last summer when MIT announced that a team led by chemist Daniel Nocera had made a “major discovery” that employs a new kind of catalyst using cobalt and phosphate - abundant and non-toxic materials - to kick-start electrolysis.

Outside observers say the process could be revolutionary: opening up the possibility that electricity made at any time by the sun or wind could be stored by simply splitting (and later recombining) abundant water molecules, perhaps even undrinkable sea water. The breakthrough has been hailed by scientist British scientist James Barber of Imperial College London as having “enormous implications for the future prosperity of humankind”. The website Xconomy reported in April that Nocera had quietly formed a startup company called Sun Catalytix. Efforts to reach Nocera for comment were unsuccessful.

And there is progress being made on an entirely different front - using excess electricity to pump compressed air into caverns, salt domes, and old natural gas wells, and then releasing the air to help state-of-the-art natural gas power plants spin turbines, lowering the amount of fuel consumed by as much as 70 per cent. A consortium of utilities in Iowa, Minnesota, and the Dakotas is already working with the US’s Sandia National Laboratories to develop a giant, 268-megawatt compressed air system. Called the Iowa Stored Energy Park, it would store excess energy from the region’s burgeoning wind industry.