Sunnyvale, Calif.-based Bloom Energy held a press event Wednesday morning detailing the Bloom box fuel cell, which is designed to be stacked into small blocks and housed in a unit about the size of a refrigerator. Luminaries in attendance included California Gov. Arnold Schwarzenegger, former Secretary of State Colin Powell, legendary venture capitalist John Doerr, Google co-founder Larry Page, and top executives from heavyweight companies such as eBay, Wal-Mart, and FedEx.

Bloom box challenges: Reliability, cost