Tech companies drove a surge in corporate purchases of clean energy last year, according to a new analysis by BloombergNEF.

Overall, corporations bought a record 31.1 GW of clean energy in 2021, equivalent to more than 10 percent of all new renewable energy capacity added worldwide that year. Over half of the power purchase agreements for clean energy made by corporations were signed by tech giants, including Amazon, Microsoft, Meta, and Google.

Agreements with utilities or developers to purchase enough clean power to match annual electricity use are one strategy that companies use to claim they are running their operations on 100 percent clean energy. In reality, that clean energy usually isn’t flowing directly into corporate offices and factories 24/7 because the grids they’re hooked up to might not have enough renewables online yet. In other words, most power purchase agreements that American companies sign are considered “virtual.”

“Companies like Google and Apple and Microsoft and Meta, they’re the pioneers of the virtual power purchase agreement as we know it today,” Kyle Harrison, head of sustainability research at BloombergNEF, tells The Verge. Still, there’s more progress tech companies need to make to clean up their operations.

Data on Google’s power purchase agreements last year highlights an emerging trend that could help companies reduce their pollution while potentially getting more carbon-free energy onto power grids. Google used to be the top corporate purchaser of clean energy but has fallen behind Amazon, Microsoft, Meta, and a couple other companies outside of tech. That’s because Google is pioneering a new strategy for meeting its environmental goals that involves matching its electricity needs with clean energy on a round-the-clock basis, according to the BloombergNEF report. To do so, it’s seeking different kinds of renewable energy investments and contracts other than traditional power purchase agreements.

Google first announced plans to procure clean energy for its data centers and campuses on a 24/7 basis by the end of the decade in 2020. Doing so involves investing in new technologies, pushing for “smart policy,” and bringing new sources of clean energy online. For example, in May, Google signed a deal with startup Fervo to develop a new geothermal project in Nevada that should eventually feed power to the local grid that serves Google’s data centers. While solar and wind are still the sources of clean electricity most sought after by corporations, the shift toward 24/7 clean energy goals is likely to increase demand for other kinds of carbon-free energy that don’t vary so much depending on the weather — like geothermal, hydropower, and nuclear energy.

Last year, Microsoft announced a similar goal of matching its electricity use with renewable energy on a 24/7 basis. It still relies heavily on power purchase agreements, although Microsoft told The Verge last year that it was starting to change its agreements in an effort to bring more clean energy to local grids where it operates. The company was the second-biggest corporate purchaser of clean energy in 2021.

Amazon, which has yet to make a 24/7 clean energy matching commitment, narrowly beat out Microsoft to hold onto the top corporate clean energy purchaser spot for the second year in a row. Amazon’s clean energy portfolio is now the 12th largest among all kinds of companies globally, according to BloombergNEF.

Companies outside of tech haven’t been transitioning to clean energy with as much enthusiasm. While the total renewable energy purchased by corporations in 2021 was almost 24 percent higher than the previous year, the overall number of companies making clean energy purchases actually shrank.

“This dominance by tech, it’s kind of also a testament to the fact that this market hasn’t expanded into other sectors as fast as you would have hoped,” Harrison says.