SOLAR TODAY - May 2010

howzit work? | answered here with pictures
Bloom Box: The reversible
Methane Fuel Cell By SETh MASIA

Seth Masia is deputy editor of Solar Today. Contact him at smasia@solartoday.org.

The Bloom Box made a spectacular entrance to the market in February, with a 10-minute segment on “ 60 Minutes” followed by a press conference covered nationally. The box looks like a conventional fuel cell, with a stack of catalytic plates that oxidize a wide range of fossil or renewable fuels to produce heat, electricity and CO2. To the extent that the fuel is produced through a biological process that locks up CO2, the energy production is carbon-neutral.

What makes the Bloom Box new is the low-cost technology used to manufacture the catalyst plates. They’re simple sand-based ceramic wafers, printed on each side with proprietary anode and cathode inks and separated by cheap alloy conductors. This technology took about eight years and $400 million to develop, but inventor K.R. Sridhar, who once designed oxygen-generating cell stacks for NASA, is confident that, within 10 years, he can push the price down to $3,000 for a backyard box that can power the typical American home.

For now, the company has installed about 30 larger 100-kilowatt boxes providing on-site power to the corporate offices of Google, eBay, Federal Express, Wal-Mart and Staples. These machines run either on natural gas or biogas and provide electricity for less than 10 cents per kilowatt-hour, including amortization of the installed price of $750,000 and all fuel and maintenance costs. At today’s price for natural gas, that implies that the catalysis process is about 50 percent more efficient than a natural gas turbine power plant, or roughly the equivalent of a combined-cycle gas turbine/steam turbine unit.

During the “ 60 Minutes” interview, Sridhar mentioned that the box can run on solar. What he meant is that the process is reversible: If you reverse the electrical flow, the Bloom Box will function as an electrolytic gas generator, splitting water into hydrogen and oxygen. That makes it into an energy-storage unit and opens the possibility that the box could even out the power curve of a wind or solar farm. Sridhar also believes

that utility companies will buy boxes to serve as efficient community power plants. It’s certainly easier to install than a combustion fuel plant: It needs no external cooling system or steam lines. On installation, the box is bolted to a concrete pad and hooked up to the gas and electric lines.

The box looks robust: The Google installation has been running 24/7 for a couple of years now and is designed for a 10-year life cycle. Air- and gas-filter elements need periodic replacement, and if the catalyst stacks turn out to be life-limited, well, they’re pretty cheap to replace. ST