Photos: Green tech in focus at MIT Energy 2.0 conference

An employee with battery start-up A123 Systems shows off a plug-in hybrid Toyota Prius with the company's battery inside it at the Massachusetts Institute of Technology's Energy 2.0 Conference, which took place March 9 and 10. Combined with the Prius' existing battery, a person can drive about 30 to 35 miles per day and recharge at night.

Photo by Martin LaMonica/CNET News.com