Google cofounders Sergey Brin and Larry Page. Ralph Orlowski/Getty Images Google forked out over $500 million for a little-known London startup called DeepMind in 2014 without specifying how the company's artificial-intelligence technology would be used to increase Google's revenues, which already run into tens of billions of dollars every year.

That all changed on Wednesday when DeepMind announced that Google had found a use for DeepMind's technology in its enormous data centers.

Since being acquired by Google, DeepMind's AI has been used to beat humans at board games and create free apps with the National Health Service. Neither application has helped Google make — or save — any money.

But now Google is using a DeepMind AI system to control the huge air-conditioning units in its power-hungry data centers, where servers consume enough energy to power entire cities and get very hot in the process.

The AI system does this by predicting how much air conditioning will be needed to deal with an anticipated change in data-center temperature, which fluctuates as demand for services like YouTube, Google Maps, and Gmail rises and falls.

DeepMind says its AI can make the cooling units in Google's data centers 40% more efficient, ultimately cutting the data centers' overall electricity consumption by 15%.

DeepMind's technology has been deployed across only a handful of Google's data centers, but Google is planning to introduce the company's machine-learning software to all 15 of its data centers by the end of the year, potentially resulting in massive energy savings on Google's sizable electricity bill.

DeepMind cofounder Mustafa Suleyman was unable to say how much money Google stood to save on its electricity bill, but the figure could run into tens or even hundreds of millions given the size of Google's data-center operation. In 2011, Google's data centers reportedly used 0.01% of the world's electricity.

But data centers aren't the only place where DeepMind can have an effect on Google's bottom line.

The company has also said in the past couple of months that it intends to sell its products and services to healthcare providers like the NHS at some point, providing Google with an additional revenue stream.

All of this adds up to make DeepMind an interesting acquisition that could create significantly more than the $500 million Google paid for the startup.

"DeepMind looks to be an acquisition of YouTube/Android significance for Google," Chris Lacy, an entrepreneur and software developer, wrote on Twitter, prompting a retweet from one of DeepMind's employees.