Summary Box: Fuel-cell startup is promising but skimpy on details

Summary Box: Fuel-cell startup skimpy on details

KEEPING QUIET: Bloom Energy, a richly funded Silicon Valley startup, is keeping critical parts of its business plan secret as its first product launch draws international attention.

THE PROMISE: Bloom Energy’s fuel cells promise to allow homes and businesses to generate their own power, but it’s not clear how the company will get prices down.

WHAT BLOOM IS SAYING: For the first time the company offered details about the price its customers pay for power, but experts said it wasn’t enough to gauge whether they’re saving money only because of generous federal and state subsidies.