After dabbling in fuel cells, eBay has decided to run a full data center on Bloom Energy fuel cells and use the grid only for backup power.

The ecommerce company today said it will install six megawatts worth of Bloom Energy fuel cells to power new portions of its main data center in Utah. eBay said it will seek to run the 30 fuel cells on biogas, which consists of methane and other gases generated by organic waste at landfills or farms.

The project is significant for its size and its architecture. Once installed in mid 2013, it will be the largest non-utility fuel cell installation and larger than Apple’s planned 4.8 megawatt fuel cell array at its North Carolina data center now under construction.

The fuel cells will also be the primary power and energy source, rather than supply power when the grid fails. Fuel cells convert a fuel, such as natural gas or hydrogen, into electricity in a chemical reaction rather than burning the fuel. Bloom Energy’s fuel cells, which each take up about a parking space, are solid oxide fuel cells which use the heat generated by the fuel-to-electricity conversion to improve the efficiency.

eBay president and CEO John Donahoe said the Bloom “energy servers, which will generate 1.75 megawatt-hours per year, are part of the company’s goal to lower its environmental footprint. Greenpeace has been leading a campaign to raise awareness of the heavy energy use from giant data centers companies like eBay, Google, and Apple run.

“We are embracing disruptive energy technology and designing it into our core data center energy architecture. Running our data centers primarily on reliable, renewable energy, we intend to shape a future for commerce that is more environmentally sustainable at its core,” Donahoe said in a statement.

 Although the company declined to detail costs, economic factors also played into the decision. The fuel cells will replace back-up generators, which usually run on diesel, and uninterruptible power supplies which are rarely used.

“Does it have risk? Sure. Did it require investment? Sure. But it’s an investment and a risk that is worth taking,” Donahoe told the New York Times. 

From a technical stand point, the project will test the reliability of fuel cells for a very demanding use, as data center operators cannot tolerate down times. Stationary fuel cells are already used to power (and sometimes partially heat) office buildings or retail outlets, but if the eBay project goes well, it could demonstrate stationary fuel cells’ ability to be a primary on-site energy source for data centers.

The cost of power from Bloom Energy fuel cells is roughly the same as grid power in places in some areas and the payback on purchasing the equipment can be three to five years, company executives have said. Natural gas prices are very low right now, which makes fuel cells more attractive economically as well.

At eBay’s Utah data center, however, the price of electricity, generated mostly from coal, is relatively low. A company representative said eBay’s Bloom installation at company headquarters in San Jose, California, where electricity prices are high, is on track to meet its three year return on investment.

There is a limited amount of biogas available in the U.S., which means the Bloom fuel cells in Utah will likely operate on natural gas. But the company is working with Bloom to identify a source of biogas, the representative said.