On Monday, a team of prominent researchers sharply critiqued an influential paper arguing that wind, solar, and hydroelectric power could affordably meet most of the nation’s energy needs by 2055, saying it contained modeling errors and implausible assumptions that could distort public policy and spending decisions (see “Fifty-States Plan Charts a Path Away from Fossil Fuels”).
The rebuttal appeared in the Proceedings of the National Academy of Sciences, the same journal that ran the original 2015 paper. Several of the nearly two dozen researchers say they were driven to act because the original authors declined to publish what they viewed as necessary corrections, and the findings were influencing state and federal policy proposals.
The fear is that legislation will mandate goals that can’t be achieved with available technologies at reasonable prices, leading to “wildly unrealistic expectations” and “massive misallocation of resources,” says David Victor, an energy policy researcher at the University of California, San Diego, and coauthor of the critique. “That is both harmful to the economy, and creates the seeds of a backlash.”
The authors of the earlier paper published an accompanying response that disputed the piece point by point. In an interview with MIT Technology Review, lead author Mark Jacobson, a professor of civil and environmental engineering at Stanford, said the rebuttal doesn’t accurately portray their research. He says the authors were motivated by allegiance to energy technologies that the 2015 paper excluded.
“They’re either nuclear advocates or carbon sequestration advocates or fossil-fuels advocates,” Jacobson says. “They don’t like the fact that we’re getting a lot of attention, so they’re trying to diminish our work.”
In the original paper, Jacobson and his coauthors heralded a “low-cost solution to the grid reliability problem.” It concluded that U.S. energy systems could convert almost entirely to wind, solar, and hydroelectric sources by, among other things, tightly integrating regional electricity grids and relying heavily on storage sources like hydrogen and underground thermal systems. Moreover, the paper argued, the system could be achieved without the use of natural gas, nuclear power, biofuels, and stationary batteries.
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But among other criticisms, the rebuttal released Monday argues that Jacobson and his coauthors dramatically miscalculated the amount of hydroelectric power available and seriously underestimated the cost of installing and integrating large-scale underground thermal energy storage systems.
“They do bizarre things,” says Daniel Kammen, director of the Renewable and Appropriate Energy Laboratory at the University of California, Berkeley, and coauthor of the rebuttal. “They treat U.S. hydropower as an entirely fungible resource. Like the amount [of power] coming from a river in Washington state is available in Georgia, instantaneously.”
In an e-mail, Jacobson stood firm on every conclusion in the original article: “There is not a single error in our paper.”
Other models, including Kammen’s, do show that the U.S. can transition to nearly 100 percent zero-emissions energy technologies. But the established view among energy researchers is that it would require making use of nearly every major technology available and that the transition, particularly getting the last 20 percent or so of the way there, would be prohibitively expensive using existing technologies. One of the key missing pieces is affordable grid-scale storage that can efficiently power vast areas for extended periods when wind and solar sources aren’t available (see “Why Bad Things Happen to Clean-Energy Startups”).
Various political and advocacy figures have embraced Jacobson’s ideas. Prior to the 2015 paper, he published a 50-state plan for moving to 100 percent renewables by midcentury, which he says contributed to decisions by both New York and California to enact laws requiring 50 percent renewable energy sources by 2030.
He also cofounded a clean-energy advocacy group, the Solutions Project, whose board members include actor and activist Mark Ruffalo and commentator Van Jones. In late April, Senator Bernie Sanders co-wrote an op-ed with Jacobson in the Guardian, highlighting the 50-state research and trumpeting a bill proposed that week that would move the United States to 100 percent clean energy by 2050.
The authors of Monday’s rebuttal were quick to stress that cutting emissions as quickly as possible is a crucial goal. The concern is that paths for getting there will be wrong if they’re based on incorrect assumptions or miscalculations. Among other things, it can skew the public debate by suggesting it’s merely a question of marshaling political will, rather than achieving difficult technological breakthroughs and substantial cost reductions.
That could lead to spending public resources on the wrong technologies, underestimating the research and development still required, or abandoning sources that might ultimately be necessary to reach the stated goals.
Notably, there is growing fear that accelerating retirement schedules for the U.S. fleet of nuclear plants will make it increasingly difficult to make the transition to clean energy. While some interest groups remain opposed to the technology, many researchers believe it should be a crucial part of the energy mix, since it’s the only major zero-emissions source that doesn’t suffer from the intermittency issues plaguing solar and wind.
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“Energy issues are complex and hard to understand, and Mark’s simple solution attracts many who really have no way to understand the complexity,” Jane Long, another coauthor and former associate director at Lawrence Livermore National Laboratory, said in an e-mail. “It’s consequently important to call him out.”
Lead author Christopher Clack, chief executive of Vibrant Clean Energy and a former NOAA researcher, described Jacobson’s accusation that the authors were acting out of allegiance to fossil fuels or nuclear power as “bizarre.” The 21 authors of the rebuttal, which features a conflict-of-interest statement, include energy, policy, storage, and climate researchers affiliated with prominent institutions like Carnegie Mellon, the Carnegie Institution for Science, the Brookings Institution, and Jacobson’s own Stanford.
Clack says he was motivated to oversee the additional peer-review process because he believed the earlier conclusions were wrong, and the authors refused to correct them. He added that the process took more than a year and went through two reviews by the journal’s editorial board.
“We stayed the course because we believe it, and want the truth out there,” he says.