New York ? Google Inc. said Tuesday it’s earmarking hundreds of millions for renewable-energy projects as the electricity-hungry search giant moves to embrace solar, wind and geothermal energy.

Google also said it expects to spend “tens of millions” during 2008 on research and development, as well as on related investments in renewable energy.

Becoming the latest Fortune 500 company to take to the green movement this year, Google announced that it had set a goal to produce 1 gigawatt – enough to power the city of San Francisco – out of renewable energy cheaper than coal. It said that it’s optimistic this can be achieved “in years, not decades.”

Google’s “Renewable Energy Cheaper Than Coal” initiative would be part of a new research and development program on alternative power, according to the company.

In a conference call with journalists, executives declined to comment on how much electricity it uses. They also were vague about how Google would spend the hundreds of millions but said they’re sifting through possible companies to invest in and moving ahead with plans to boost efficiency.

Google said it’s developing cutting-edge energy efficiencies to power and cool its data centers in the United States and around the world.

It’s also generating electricity for its Mountain View, Calif., campus from a 1.6-megawatt corporate solar-panel installation, one of the largest in the United States. What’s more, Google is supporting the development and adoption of plug-in vehicles through the RechargeIT initiative, including a $10 million request for investment proposals.

Google co-founder Sergey Brin said “it’s not enough” that Google has purchased carbon offsets to reduce its footprint by flying in jets, but he added that it’s unrealistic for people to stop flying and quit using electricity altogether.

Larry Page, Google co-founder and president of products, said in a statement that the company wants to “apply the same creativity and innovation to the challenge of generating renewable electricity at a globally significant scale, and produce it cheaper than from coal.”