Put some kilowatts in your closet

Altair Nanotechnologies, which specializes in lithium ion batteries, said Monday that it will work with investor AES to develop home energy storage systems that can hold more than 500 kilowatts of energy.

AES, a power company, invested $3 million in Altair earlier this year.

Home storage is one of the holy grails of the clean technology field. With a big battery in the closet, the energy harvested from solar panels on the roof could be used by a homeowner at night. Home storage also gives utility owners breathing room. Get enough batteries out there and the risk of a brownout goes down.

It can even help utilities put off erecting additional power plants. PG&E says that plug-in hybrids could serve as home energy storage units.

Start-up GridPoint has emerged as an early leader in the field, but it's still relatively small. More companies will jump in.

Altair is trying to play in lots of markets. It also makes lithium ion batteries for plug-in hybrids and claims its batteries can recharge rapidly, a big sticking point for electric cars. Altair also says the batteries are safer than traditional lithium ion batteries.

So far, however, Altair is not producing massive numbers of batteries. At clean tech conferences, the name comes up a lot. But the question everyone asks is, if the technology is so good, how come the company isn't bigger?