SAN FRANCISCO (MarketWatch) -- Google Inc. on Wednesday unveiled a $4.4 trillion energy plan to greatly reduce U.S. use of fossil fuels by 2030 by tapping alternative sources, including wind and solar power.

Google GOOG, +0.32% has explored a number of alternative-energy initiatives through its nonprofit organization Google.org, including investments in startups developing related technology. As justification for its interest and investments in alternative energy, the Internet giant has cited a need for more efficient ways to power its data centers around the globe.

In an online posting, Jeffery Greenblatt, Google.org's climate and energy-technology manager, wrote that while the cost of Google's plan would be significant, exceeding $4 trillion, it could result in net savings of $1 trillion over its 22-year span. Visit Google's blog.

The plan is the result of an analysis by Google, which said its goal is to "stimulate debate." The company said its own related initiatives have included making $5 million in "building efficiency" investments, which it aims to recoup in two and a half years.

In addition, Google last month announced that it would begin partnering with General Electric Co. GE, -1.29% to lobby Washington lawmakers and promote the use of alternative energy. See related story.

Greenblatt wrote that the "Clean Energy 2030" plan would involve heavy investments in transmission capacity for wind and solar power in the "Great Plains and desert Southwest" to help cut 88% of fossil fuel use and 95% of carbon-dioxide emissions by 2030.

In addition, Greenblatt wrote that geothermal energy, or natural energy that can be harnessed beneath the Earth's surface, is the "sleeping giant" of alternative energy. Geothermal-energy systems promise "extremely rapid growth if key technologies can be proven in the next few years," he said.

Through Google.org, Google has invested in geothermal-energy company Potter Drilling, which is developing technology to pierce hard rock and has provided a grant to Southern Methodist University's Geothermal Lab.

Google Chief Executive Eric Schmidt is scheduled to speak publicly in San Francisco Wednesday evening about geothermal energy and other related topics.