After a recent 60 Minutes airing about Bloom Energy, California-based Bloom Energy is receiving a new wave of hype around its flagship SOFC (solid oxide fuel cell). Both Google and Ebay have purchased the "mini power plants in a box" and are banking on the units as a way to ensure a steady stream of greener, cleaner power. But let's be clear, this is not totally "clean" energy.

Fuel cells have been around for decades, but until new the solid oxide technology, which dispenses with toxic acids and precious minerals — has remained out of reach due to the high temperatures (800 degrees or more) required to make the fuel cell work.

But founder K.R. Sridhar discovered a solution while developing a technology to produce oxygen for a NASA mission to Mars. After the mission was abandoned, Sridhar realized that if he inverted his process (consuming rather than producing oxygen) he had the makings of a durable, reliable SOFC.

Bloom Energy was born, and thanks to backer Kleiner Perkins was able to develop an industrial-scale model that is now being used by Walmart, Google and Ebay. Each 100 kilowatt unit costs about $750,000, but the buyers expect to recoup their investments in five years through energy savings.

This is certainly a game changer on the clean energy front. Instead of COMBUSTING fuels like coal and natural gas to drive steam turbines (how most of the world's power generation works) the fuel cells work by OXIDIZING the fuel, which is inherintly more efficient, possibly even two times as efficient.

To be clear, these devices need liquid hydrocarbon fuel (lots of it) like gasoline or propane, though Bloom can also work on biofuels like ethanol and biodiesel. Also, though founder Mr. Sridhar talks about "sand" as the primary material required, that's a wee bit disingenuous. Yes the ceramic disks (printed with annode and cathode minerals on each side) are made from a sand-like material, but that most likely is a scandia stabilized zirconia, based on a reading of Bloom's U.S. patent. Scandium oxide is not an abundantly produced mineral -- less than 2,000 kg per year -- and it costs up to $2000 per kilogram.

So Bloom energy is no global panacea, but if you think about the amount of dirty power that big Fortune 500 companies like Google and Walmart are currently pulling from coal power, Bloom Energy promises a major reduction in CO2 emissions over the long haul.

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