In the lead up to Earth Day, environmentalist organization Greenpeace took another step in its campaign to push Facebook to slash the reliance of its data centers on coal power.

Greenpeace created a television ad and has publically challenged Facebook to "pledge to go green" by 22 April, date of the Earth Day.

"With Facebook's two new massive new data centers due to be switched on soon, each of which uses enough power to light up tens of thousands of homes, there’s never been a better time for Facebook to unfriend coal and choose the clean, safe, renewable energy future," a Greenpeace blog post read.

This is the latest step in the campaign Greenpeace started in February 2010 with a statement that objected to Facebook’s choice of the power provider for its new data center in Prineville, Oregon. Much of Pacific Power’s (the utility) fuel portfolio is comprised of coal.

Facebook responded to that statement, saying the utility had a roadmap for adding more renewable sources to its portfolio and pointing out the energy efficient design of the data center.

Ken Patchett, whom Facebook hired to oversee construction of the data center an its operation, told DatacenterDynamics the data center would attract other big businesses to Pacific Power’s coverage area, who would then put more pressure on the utility to make its generation portfolio cleaner.

Since the Prineville project was announced – the first data center Facebook built for itself – the company started another data center build in North Carolina. Facebook planned to invest about US$450m into the project in Rutherford County.