Summary Box: Secretive fuel-cell startup unwrapping first product, stirring hopes, skepticism

Summary Box: Fuel-cell startup unwrapping product

BLOOM BOX: Bloom Energy is a secretive Silicon Valley startup that is working on a new way to produce cleaner energy. Its first product is a huge box of fuel cells that it hopes will allow homes and businesses to generate their own electricity.

THE PROMISE: The fuel cells promise to produce more power — with less environmental damage — than others on the market.

POTENTIAL PITFALLS: Analysts warn that the technology has yet to be widely proven, and that little is still publicly known about the long-term costs of owning a Bloom Box.