Last week brought the unveiling of the Bloom Energy Server, a fuel-cell energy generator that spent many years shrouded in secrecy and hype. Now that it's out, well, the hype remains to be verified or dispelled.

In a nutshell, the Bloom Energy Server takes natural gas, biogas, or other hydrocarbons and converts them to energy. Eventually, Bloom Energy plans to be able to use solar or wind power to provide fuel for the server, but that technology is not in play yet. The innovation in a Bloom box is its use of common, low-cost materials -- a type of silicon -- in its fuel cells. As a result, the Energy Server can generate electricity at the competitive rate of eight to 10 cents per kilowatt-hour.

To date, eight companies -- major players all -- have purchased Bloom boxes, an investment of $700,000 to $800,000 per box. Although Bloom Energy predicts a three- to five-year payback on the boxes, and a lifespan of 10 years with "reasonable maintenance," this is not the kind of acquisition a company makes lightly.

To find out what drove these companies to sign on with Bloom Energy, we spoke to several proud owners.

eBay

eBay's San Jose campus was the location of Wednesday's Bloom box launch party, a press event featuring industry and political stars alike. The company purchased five boxes last year and has been running them all since last fall with no problems. eBay is currently powering the servers with natural gas, but is finalizing a contract to run them on biogas.

"Since day one, we've seen that this can help us with our commitment to reduce our carbon emissions," explained Amy Skoczlas Cole, the head of eBay's Green Team. eBay plans to get the company's carbon footprint 15 percent below 2008 levels by 2015, and the Bloom boxes will help them hit that goal.

Coupled with the massive solar array on the campus -- 3,248 solar panels that take up 65,000 square feet of roof space and generate 650 kilowatts of energy -- eBay is now able to generate 33 percent of the campus's energy on-site and off the grid.

In making the case to senior management for the Bloom purchases, Cole said the solar array figured into the discussion in two ways. "We had gone through the process and understood what it took to make the business case to executives -- we had a little bit of a road map to follow [for the Bloom discussions], because we'd already figured out how the business might think about an investment in renewables."

Secondly, eBay was simply out of roof space for more solar. Each Bloom server takes up the area of a parking space, so installing five of those on the campus grounds was an option where adding more solar panels was not.

Cole cited several arguments used in making the sale to eBay executives: First and foremost was the company's need to achieve their greenhouse gas reductions goal. Secondly, CEO John Donahoe had begun shifting the company to be more visible and aggressive in its environmental commitments, and being the first on the Bloom bandwagon sent a prominent green signal. Thirdly, Cole said, "We are a Silicon Valley firm that shares some common DNA around the concept of disruptive technology -- we understood the power of this kind of disruptive technology."

And finally, for a company with a deep commitment to engaging its employees around environmental initiatives (the employee-led green team was responsible for bringing the solar array to fruition in the first place), Cole said the Bloom boxes are a point of pride for its 15,000 employees that eBay is an early adopter of these kinds of projects.

FedEx

FedEx has long invested in environmental initiatives -- hybrid delivery trucks, the nation's largest solar array, and a high-scoring green paper policy, to name just a few.