Facebook Policy Communications director Barry Schnitt has left a lengthy response on a ZDNet chat area, including a scathing look at Greenpeace's own IT infrastructure, in response to criticism about is use of coal for its US data center.

This week it was announced that more than 500,000 Facebook users, spurred on Greenpeace which kicked off a campaign on the social networking site, had signed a petition against Facebook's decision to bypass renewable energy in favour of coal for its planned Oregan data center.

Schnitt wrote in response to a chat area opened up on ZDNet to discuss the issue, saying Facebook had little choice over the power source offered to it by the state and that its data center should be praised for the high efficiency he said would come from within.

"There is no such thing as a coal-powered data center, Schnitt argued. "Similarly there is no such thing as a hydroelectric-power data center. Every data center plugs into the grid offered by their utility or power provider . . . Even when a facility is in close proximity to an individual source of energy, such a dam or coal plant, there is no guarantee that the electricity produced by that source are flowing to the facility," he said.

He also highlighted what he said were Greenpeace's own data center failings in the area of energy efficiency.

"Greenpeace's own infrastructure illustrates many of the challenges we face. As recently as March of this year, they indicated that they had a number of servers in a rented data center in northern Virginia. There representative commented that these servers are using whatever the grid mix is in Virginia. The reporter on the story estimates that mix to be 46% from coal, 41% from nuclear, 8% from natural gas, and just 4% of its power from renewable generation," Schnitt wrote.

"The point is, if an organization focused on environmental responsibility like Greenpeace can't do better than the mix above for just a few servers, what options are available to Facebook?"

Schnitt said Facebook was looking  long term at its site selection, and that Oregon's plans for future renewable sources would mean the site would eventually be more energy friendly.

"In addition, in selecting Oregon, we chose a region that offers a uniquely dry and temperate climate. This climate enable us to go beyond just customization in design, but also to think innovatively about what else we can do to use less energy. For example, almost all data centers use mechanical chillers or large air conditioners for part, if not all, of the year to cool the computers within the facility. These mechanical chillers use a lot of energy and are only exceeded in their energy use by the thousands of computers inside the data center. Because of the climate around Prineville and our unique design, we won't use any mechanical chillers. None. We won't even build any. Instead, the data center will use an innovative evaporative cooling system.

"All of these investments in efficiency design, planning and technology will result in one of, if not the most, energy efficient data centers in the world. Data center energy efficiency is measured by Power Usage Effectiveness (PUE). The industry average for PUE ranges from 1.6 to over 2. Our Prineville data center will have a PUE of 1.15." 

Greenpeace has criticised Facebook for choosing Pacific Power as its energy provider ÔÇô Pacific uses more coal for power than the national average (about 58 percent, as opposed to 50 percent.

"If we located the data center most other places, we would need mechanical chillers, use more energy, and be responsible for an overall larger environmental impact even if that location was fuelled by more renewable energy," Schnitt argued.

He said that despite using mostly coal for now, the state of Oregon has aggressive plans for renewable energy in future, and this swayed Facebook towards building a data center there.

"Their most recent plan calls for having more than 2,000 megawatts of renewable resources by 2013. Thus, our data center is only going to get greener over time as these resources come on line and contribute to even greater proportions of the facility's energy," Schnitt wrote.