Politicians have found a slogan for the data center boom. Let the servers come, but make them “100% renewable.”
Wisconsin’s Democratic candidate for governor, David Crowley, put it in his platform. Similar language is turning up wherever a campus is proposed.
But which “100% renewable” do they mean?
There are two. In one, the servers physically run on wind and sun every hour. In the other, a data center draws whatever the grid is producing at 2 a.m. and buys enough renewable contracts and credits to match its consumption on paper over a year.
The second is an accounting ledger. The first is physics. They do not cost the same.
Wisconsin is a measuring stick. The Paris Solar-Battery Park in Kenosha County sits near Microsoft’s Mount Pleasant campus: about 500,000 panels on roughly 1,500 acres, 200 megawatts of solar, and the state’s first large battery, 110 megawatts for about four hours, or 440 megawatt-hours. The project ran about $575 million.
Microsoft says phase one of Mount Pleasant needs about 450 megawatts around the clock. That is 3.9 million megawatt-hours a year.
Start with the ledger. In Wisconsin, solar produces about 18 percent of its rated capacity over a year, so Paris generates about 315,000 megawatt-hours annually. Matching one hall on paper takes 12 to 13 Paris-sized projects: roughly 2,500 megawatts, 6.5 million panels, 19,000 acres, about 30 square miles.
Built as complete Paris plants, on the order of $7 billion. That is the cheap version of the promise. The servers still run on the grid at night.