The move is "the latest action in its commitment to become the 'greenest' technology company in the planet," Dell said in a statement.
"We encourage other companies to follow their lead and set similarly aggressive energy efficiency and renewable-power targets," said Steve Howard, CEO of the Climate Group in a statement this week.
Dell obtains 35 percent of its U.S. energy use from green power, including the Oklahoma City campus, it said. The firm will aim to reduce its global facilities' CO2 emissions as much as 40 percent by 2015.