Two years ago, a paper came out arguing that America could cheaply power itself on wind, water, and solar energy alone. It was a big deal. Policy makers began relying on the study. A nonprofit launched to make the vision a reality. Celebrities got on board. We named the lead author of the study, Stanford University professor Mark Jacobson, one of our Grist 50.

Now that research is under scrutiny. On Monday, 21 scientists published a paper that pointed out unrealistic assumptions in Jacobson’s analysis. For instance, Jacobson’s analysis relies on the country’s dams releasing water “equivalent to about 100 times the flow of the Mississippi River” to meet electricity demand as solar power ramps down in the evening, one of the critique’s lead authors, Ken Caldeira of the Carnegie Institution for Science, told the New York Times.

Jacobson immediately fired back, calling his critics “nuclear and fossil fuel supporters” and implying the authors had sold out to industry. This is just wrong. These guys aren’t shills.

It’s essentially a family feud, a conflict between people who otherwise share the same goals. Jacobson’s team thinks we can make a clean break from fossil fuels with renewables alone. Those critiquing his study think we need to be weaned off, with the help of nuclear, biofuels, and carbon capture.

Grist intends to take a deeper look at this subject in the coming weeks, so stay tuned.

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