Brookfield Asset Management has signed a 20-year deal to sell up to 3,000 megawatts of hydroelectricity to Google Inc., in what the companies are touting as the “world’s largest framework agreement” for a hydropower purchase.

The first contracts under the deal, worth more than US$3 billion in power sales, will cover 670 MW from Brookfield’s Holtwood and Safe Harbor hydro facilities in Pennsylvania, Brookfield said in a release.

The agreement “demonstrates the critical role that hydropower can play in helping hyperscale customers meet their energy goals,” said Brookfield President Connor Teskey. “Delivering power at scale and from a range of sources will be required to meet the growing electricity demands from digitalization and artificial intelligence.”

“Hydropower is a proven, low-cost technology, offering dependable, homegrown, carbon-free electricity that creates jobs and builds a stronger grid for all,” added Amanda Peterson Corio, Google’s head of data center energy.

The release says the framework agreement focuses on hydropower assets “that will be relicenced, overhauled, or upgraded to extend the asset’s useful life and continue adding power to the grid.”

Citing a report on Semafor, Reuters said Google is expected to invest another $25 billion in data centres across Pennsylvania and neighbouring states over the next two years.

“Over roughly the last year, Google has struck several first-of-a-kind power purchase agreements, including for carbon-free geothermal energy and advanced nuclear,” the news agency writes. “The company is also working with the country’s largest electricity grid operator, PJM Interconnection, to use AI to speed up the process of hooking up new power supplies to the grid.”

In his fortnightly Carbon Commentary newsletter, UK climate author and speaker Chris Goodall questioned whether the hydropower deal would deliver actual emission reductions.

“If Google buys all the electricity coming from the dams, existing customers will have to purchase their power from other sources,” Goodall wrote. “In all probability these replacement generators will use fossil fuel, implying that the overall effect of Google’s increasing power needs will be to add to emissions.”

While Google and Brookfield “try to get around this point by claiming that as a result of the contract the dams will be ‘relicenced, overhauled, or upgraded to extend the asset’s useful life’,” he added, “I’m not convinced: if Brookfield could make money from extending the operating period of the dams, it would have done so whether or not Google bought the power. The company needs to build its own solar or wind farms to show its expansion is truly carbon neutral.”

Brookfield media spokesperson Simon Maine did not reply to an emailed request for comment on Goodall’s assessment, or on the possible impact of climate change-induced drought on hydropower output over the life of a 20-year power purchase agreement. We’ll update this story if we hear back.