Powering America on Renewable Energy Alone May Be Harder Than Anticipated

A new analysis critiques a 2015 blueprint for achieving 100 percent renewable energy production in the United States by midcentury.

Published on 6/19/2017 at 3:10 PM

Not so fast, argues a new critique of an ambitious blueprint for a carbon-free America. Running the continental United States on renewable energy alone — primarily wind, solar, and hydroelectric power — by 2050 would require “unprecedented rates of technology deployment” and yet-unseen advances in energy storage, hydrogen power, and other systems.

Other low-carbon technologies, including nuclear power and fossil fuels with still-developing carbon capture and storage, will be needed to power the country for some time to come, said Christopher Clack, the new study’s lead author.

“From the modeling I have done with other authors, so far the lowest cost option is one with approximately 80 percent carbon-free and 20 percent carbon-generating [energy],” said Clack, a former mathematician with the National Oceanic and Atmospheric Administration and the University of Colorado. “We can move higher than that, and should, but it becomes harder and harder to squeeze out the last remaining portions of carbon.”

The findings were published in the peer-reviewed scientific journal Proceedings of the National Academy of Sciences. Clack’s co-authors include researchers from a variety of universities and think tanks — and they’re directly challenging a 2015 report that laid out a plan for the Lower 48 to run entirely on renewables by 2050.

The paper drew a sharp rebuttal from the authors of the earlier research, led by Stanford University engineering professor Mark Jacobson. In an accompanying piece in PNAS, Jacobsen and his co-authors called the new study “riddled with errors,” and said it had “no impact” on their conclusions.

Jacobsen defended his estimates of the potential for new technologies and expanded use of existing sources like hydroelectric power and argued that Clack and his colleagues failed to account for the “true costs or risks” of nuclear energy, carbon capture, and fossil fuels.

Renewables just hit a milestone in the United States, hitting 10 percent of monthly power generation, while nuclear energy has foundered economically and carbon-capture technology has yet to achieve widespread commercial success. On a yearly basis, renewables now make up about 7 percent of US electric power, according to federal statistics.

But Clack said it took more than three decades for solar panels and wind turbines to gain the ground they have.

“This great and brilliant achievement has resulted in 7 percent of electricity from these sources,” he said. “Electricity is 39 of energy. So the scale of the problem is gigantic.” Scaling up a newer technology like hydrogen fuel cells would be more difficult, and Jacobsen’s study “woefully miscalculated” the amount and speed that other technologies could be deployed, he said.

“To do all these in parallel, as they suggest, is harder than the current seen trends in wind and solar, because they existed at commercial scale,” Clack said.

Clack said most other studies come to “vastly different” conclusions, and he and his co-authors felt compelled to set things straight.

“We want climate change to be solved,” he said. “It has to be done rapidly, and if we get it wrong, the consequences are catastrophic. We do not get another go at this.” But he added, “We need sound science that helps policy makers choose the right actions to achieve a near-zero emissions economy by mid-century.”

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