AMSTERDAM (AP) – Greenpeace said about 500,000 Facebook users have urged the world’s largest social network to abandon plans to buy electricity from a coal-based energy company for its new data center in the U.S.

Greenpeace Executive Director Kumi Naidoo sent a letter Wednesday to Facebook founder Mark Zuckerberg warning that the company risked its reputation and financial health if it ignored the environmental impacts of its actions.

“Facebook is really out of step with the trend” among information technology companies, Naidoo told The Associated Press by phone.

The Amsterdam-based environmental group started a Facebook group in February after the company announced plans to build a center in Oregon, asking it not to use dirty energy. Last week, the group passed 500,000 members, according to Greenpeace’s Web site.

Greenpeace sees such the information industry as the vanguard of companies capable of influencing young people to be aware of concerns over climate change and emissions of carbon dioxide blamed for global warming. Burning coal for power is one of the largest sources of carbon accumulating in the atmosphere.

Google has invested tens of millions of dollars this year in wind farms to power its data centers.

When Facebook broke ground on its center in Prineville, Oregon, in January, it said it would use energy efficient technology to minimize its impact and reduce its power needs, including reusing heat generated by its servers.

But Greenpeace said Facebook signed a deal to source its energy from PacificCorp, which it said uses 83 percent coal in its energy mix.

Facebook “had a choice as to where they located it,” Naidoo said of the data center. “They had a chance to think through this piece of that decision. Clearly they made an active choice to lean in the direction of dirty coal.”

Naidoo said his organization singled out Facebook because of its reach across the globe, especially among the young. Facebook says it now has 500 million users.

He acknowledged Facebook’s policy of neutrality that prevents it from advocating causes on its network, but said climate change should be an exception, since “the future of the planet is at stake,”

Information companies, including titans like Microsoft, contribute an estimated 2 percent of manmade carbon emissions, about the same as the aviation industry. But the IT sector is growing fast. Greenpeace cite studies saying the industry has the capability to reduce its emissions 15 percent by 2020.

Copyright 2010 The Associated Press.