Two Fortune 500 firms announced significant commitments to renewable energy Tuesday: Dell has partnered with a local utility to supply its Oklahoma City campus with 100 percent wind power. Meanwhile, PG&E announced plans to develop 500 megawatts of solar power over the next five years.

Dell also revealed on Tuesday a new goal of reducing absolute greenhouse gas emissions produced in its facilities 40 percent by 2015.

About 35 percent of the energy used at the company's worldwide facilities now comes from renewable sources. Dell's Round Rock, Texas, headquarters and Twin Falls, Idaho, campus also use 100 percent green power; up to 17 percent of energy used in its Austin Parmer Campus is derived from renewable sources.

One of the biggest sources of greenhouse gas emissions comes from its energy use, according to Spokesman Sean Donahue. Investing the money in green power, either directly or through renewable energy certificates, he said, sends a signal to the market.  

"The other thing is it provides price certainty for our operations at a time when energy markets are volatile," Donahue said.

To dramatically cut emissions to meet its 2015 goal, Dell also plans to focus on optimizing energy efficiency, such as HVAC and lighting retrofits or power management technologies.

"We're implementing the latest and greatest energy smart technologies that we're manufacturing and selling to our customers," Donahue said.

PG&E Makes First Direct Investment in Renewable Energy in a Decade

In other renewable energy news, California utility Pacific Gas and Electric said Tuesday it will develop 500 megawatts of solar power over the next five years.

The company will invest directly in utility-owned photovoltaic generation of 250 MW, as well as partner with independent solar developers for mid-sized projects that will produce another 250 MW. The projects, to be located in northern and central California, could produce enough solar energy to power 150,000 homes.

"According to nationwide data collected by the Solar Electric Power Association (SEPA), as of the end of 2007, more than 50 percent of all photovoltaic systems in the country were located in PG&E's service territory," SEPA Executive Director Julia Hamm said in a statement.

PG&E hasn't invested directly in green power in more than a decade, choosing instead to source it from third-party generators. But utilities have shown increasing interest in owning solar projects due to the 30 percent investment tax credit, Hamm said.  

"A number of utilities have announced programs for utility-owned solar projects in the past six to eight months, including Southern California Edison, San Diego Gas & Electric, Duke Energy, and most recently, PSE&G in New Jersey," Hamm said. "We expect many other similar programs to emerge in the coming months."

California's renewable portfolio standard requires a third of the state's electricity come from renewable sources by 2020.