Google has dropped over a billion dollars into a range of renewable energy projects, possibly so that it can trim the power bills from its other big buys.

The tech giant has certainly been spending-up in recent times, matching billions spent on infrastructure, robots and data centres with the latest investment in clean energy.

Google is now aggressively moving to solar, wind and other alternative energies to try and pay back its massive power requirements.

“We've invested over a billion dollars in 15 projects that have the capacity to produce two gigawatts of power around the world, mostly in the U.S., but that's the equivalent of Hoover's Dam worth of power generation,” said Rick Needham Google's director of energy and sustainability.

The renewable spend was signed-off as the company flicked the switch on one of its earlier projects - the world's largest solar thermal project in California.

The forward-thinking project has a total of 347,000 sun-facing mirrors to draw 392 megawatts of energy.

Any large-scale company should see renewable energy not as a cost, but as a saving, Google executives said.

“The fact is that all of these things, procuring power for ourselves, investing in power plants, renewable power plants, they all make business sense, they make sense for us as a company to do. We rely on power for our business,” Needham added.

According to company figures, about 34 per cent of Google's operations are powered by renewable sources.

“That's through a combination of renewable resources that are in the utility areas that we operate, as well as the direct power procurements that we've done,” he said.

“Our goal is to be 100 percent renewable powered. There's lots of challenges in getting there, not the least of which is operating in many jurisdictions that are in different parts of the world.”