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Can solid-oxide fuel cells like the Bloom box remake the energy landscape?

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The fuel cell has a long history. Various types of fuel cells have been part of the NASA space program, and the basic science of how fuel cells work—an energy carrier comes in, creates a flow of charge in the anode, which migrates to the cathode creating a current, and separated by some form of electrolyte—has been known for more than a century. Yet, Bloom Energy believes the time is finally right for one of the more promising fuel-cell technologies—solid-oxide fuel cells, so-called because the electrolyte is a solid rather than the more common liquids—to produce electricity on a grander scale.


The company, featured in a 60 Minutes segment on February 18, has developed a version of the solid-oxide fuel cell that relies on natural gas to generate 100 kilowatts of electricity, all for $800,000. Even at that price, the company has sold 30 of them to customers such as eBay, Google and Wal-Mart, primarily so that those companies can ensure dependable electricity even in a situation where the supply from the traditional grid is interrupted. The expensive technology would replace the more typical diesel generator often employed by hospitals and the like, which can cost as little as $25,000 not counting costs associated with the petroleum-derived fuel.


In fact, the Bloom box makes no economic sense whatsoever without various government subsidies, particularly a federal tax credit paired with incentives from the state of California. According to Bloom's CEO K. R. Sridhar that means electricity from his box costs as little as nine cents per kilowatt-hour, or three cents less than California's average electricity price.


But solid-oxide fuel cells have run hot and cold over the years, literally. That's because the technology relies on operating temperatures of as much as 1,000 degrees Celsius and, perhaps because of those high temperatures, remains acutely vulnerable to breaking down, particularly all the extra bits required to make the fuel cell run: fans, heaters and devices to process the natural gas fuel. Plus, microscopic defects in the materials that compose the anode, cathode and electrolyte can shut the whole thing down and the cell must warm up to operating temperature before it can produce electricity, making it slow to start.


Bloom claims to have surmounted these problems for its "Energy Server," but they are far from the only ones working on it, as evidenced by research from the recent ARPA-E summit. Physicist Gunter Luepke and physicist-in-training Erik Spahr at the College of William and Mary are developing such a fuel cell that uses infrared light to enable faster start-up and longer lifetimes, potentially suitable even for cars. And materials scientist Eric Wachsman of the University of Maryland has successfully dropped operating temperatures to as low as 400 degrees Celsius.


Of course, since such solid-oxide fuel cells rely on natural gas, they are not exactly the zero-emitting electricity source of tomorrow—producing roughly one-third less CO2 per kilowatt-hour than an internal combustion engine. But plants can be gasified to form the fuel, making the process at least carbon neutral. Whether such solid-oxide fuel cells can live up to the hype is another question. After all, just a few years ago it was Plug Power or Ballard Power Systems and proton exchange membrane fuel cells that were going to be the force for home electricity and car propulsion.

Image: Bloom Energy Server being installed. Courtesy of Bloom Energy

The views expressed are those of the author and are not necessarily those of Scientific American.

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