Fuel cell proponents like to talk about how the devices can use biogas to create zero-carbon power, but that actually doesn't happen very often. Typically, natural gas is the fuel that feeds the electrochemical process.
Not so at the Microsoft Data Plant in Cheyenne, Wyoming, however. This data center was built alongside a wastewater treatment plant, where anaerobic digesters break down you-know-what to produce the gas that feeds the fuel cells that keep the electronics humming.
Mind you, this data center is not a key part of Microsoft's global infrastructure. The IT server container demands just 200 kilowatts, and Microsoft said that after 18 months of use, it will "donate the Data Plant infrastructure to the participating Wyoming communities, including the University of Wyoming, for further research." The state put in $1.5 million of the $7.6 million cost of the project.
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That's pricey for a 300-kilowatt power system (the extra power helps run the wastewater treatment plant), but at the official opening in Cheyenne last week, Sean James, senior research program manager for Microsoft's Datacenter Advanced Development team, pointed to the value of taking real steps toward the holy grail of energy generation – clean, closed-loop systems.
"A lot of people talk about what could happen," James said. "Today is about what is actually happening."
Data centers are an appropriate target for such novel ventures because the centers are rapidly growing energy consumers. According to researchers at the Berkeley Lab, "In 2000, U.S. data centers used less than 0.12 percent of the nation's energy; by 2010, that figure had grown to about 2 percent."
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In Utah last year, eBay opened a data center that uses several megawatts of fuel cells from Bloom Energy as its primary energy source, with the grid as backup. At the time, eBay said the fuel cells "will be powered by biogas." What eBay meant was that the fuel cells would use natural gas, but the company would pay to bring more biogas onto the gas grid. This is known as "directed biogas."
But when eBay celebrated the opening of the Utah data center a year later, it didn't mention biogas. Instead, eBay said it was turning to Ormat Technologies to develop a "recovered energy generation" (REG) power plant nearby. Here's how that works: Natural gas is compressed to "push" it through pipelines. Compression stations every 50 or so miles keep the gas moving. The compression process yields hot exhaust. At an REG, that hot exhaust is recovered by using heat exchangers, the heat is used to vaporize a fluid, and the vapor is used to spin an electricity-generating turbine.
Elegant as this solution is – eBay is using natural gas, true, but it's using natural gas as efficiently as possible – it only highlights the challenge of running fuel cells on biogas. Even directed biogas can be hard to come by in the U.S., despite the fact that potential sources are abundant. The National Association of Clean Water Agencies estimates that energy generated at U.S. wastewater treatment plants could meet as much as 12 percent of U.S. energy demand.
Germany is the world's biggest user of biogas, which accounts for around 4.5 percent of the country's electricity, typically generated using combustion motors. That's a solution with modest capital costs, but FuelCell Energy, the fuel cell provider for the Wyoming project, notes that generating electricity by burning biogas isn't as efficient as using biogas in an electrochemical reaction, nor as clean.
Don Collins of the Western Research Institute, a participant in the Wyoming pilot project, highlighted another potential advantage of using fuel cells: Certain types of fuel cells can capture carbon dioxide and deliver a very pure CO2 stream, which could theoretically be utilized to take the whole system from zero to negative carbon emissions.
—Pete Danko, Breaking Energy