Bloom Energy, the fairly stealthy maker of bio and hydrogen fuel cells, says it has raised $16.8 million of what it hopes will be a $200 million private equity offering, reports VentureWire. This is an ambitious goal in the current economy, but I suppose being Kleiner Perkins’ first green investment has afforded the Sunnyvale, Calif. company a certain amount of swagger.

It announced its intention to raise $150 million back in late February, saying that it intends to use the money to commercialize its lead product — a cell that can convert natural gas and feedstocks into hydrogen fuel. The company claims that just one of these cells is enough to power a whole home or small business. For this reason, it appears to be less appropriate for the standard U.S. grid than it is for disconnected villages in developing countries where standalone power systems could make a huge difference.

Formerly dubbed Ion America, Bloom was most recently valued at $1.45 billion. Notably, Bloom said it had booked most of its new round of funding through Advanced Equities Financial, but the newest regulatory filings list Wilson Sonsini Goodrich & Rosati as its primary rep. It’s unclear what prompted the swap.

Bloom’s technology is largely based the solid-oxide fuel cell developed by scientists at NASA. Made out of cheaper materials than average fuel cells, this model is said to be more efficient because it is able to run at higher temperatures and store much of the energy it produces (making it ideal for a shuttle, for example). All told, homes that use a Bloom cell could expect to pay less than they do for electricity today, and slice their carbon footprints by somewhere between 50 and 100 percent (depending on what they feed it — switchgrass, corn husks, natural gas, etc.), the company says. Not much more is known about it, yet it’s been talked up in political, environmental and entrepreneurial cricles for a while now.

While it expects to raise enough capital to transform itself into a multi-billion-dollar business within the next five years, Bloom will depend heavily on equipment sales and leases in the meantime. It has also discussed brokering power-purchase agreements through a subsidiary — but that has yet to take shape.

Right now, the company has about $133.8 million on hand.