The historical rates of installed electric-generating capacity per capita (watts per year per capita) for China (blue), Germany (gray), and the United States (black) are shown with the estimated values for the US proposals from the works by Jacobson et al. (red) and MacDonald et al. (green). It shows that the 100 percent wind, solar, and hydropower power plan requires installation of new capacity at a rate more than an order of magnitude greater than that previously recorded in China, Germany, or the United States. The rate would have to be continued indefinitely because of replacing generation as it aged. Graphic: Clack, et al., 2017 / PNAS

Washington, DC, 19 June 2017 (Carnegie Institution For Science) – Solving the climate change problem means transitioning to an energy system that emits little or no greenhouse gases into the atmosphere. According to new work from a team of experts including Carnegie's Ken Caldeira, achieving a near-zero-emissions energy system will depend on being able to draw on a diverse portfolio of near-zero-emissions energy technologies.

The study, from a group of 21 top researchers led by Christopher Clack of Vibrant Clean Energy, was published by the Proceedings of the National Academy of Sciences. The group says that solving the climate problem will depend on making use of energy technologies such as bioenergy, nuclear energy, and carbon capture technology, correcting a misleading 2015 research roadmap that indicated the entire United States could be powered by just solar, wind, and hydroelectric energy.

"While wind, solar, and hydroelectric should play a central role in future American energy systems, we concluded that a much broader array of energy technologies is necessary to transition to a zero-emissions future as quickly and seamlessly as possible," said lead author Clack.

The team is particularly concerned about having backup energy sources to deal with variability in solar and wind, because current energy storage technology is not sufficient to cover gaps in production on a national scale.

"Our energy system is leaking waste carbon dioxide into the atmosphere. When you call a plumber to fix a leak, you want her to arrive with a full toolbox and not leave most of her tools at home," Caldeira said. "Having a full toolbox means you are more likely to be able to solve the problem."

Careful evaluations of energy system transitions consistently show that broader portfolios form an important base to ensure success, the team concluded. By contrast, they added that studies that ignore all the options and make questionable assumptions don't do decision-makers and policymakers any favors.

"Unrealistic visions based on a very limited set of technologies have made it more difficult to actually transition to cleaner technology in the real world," Caldeira said. "The more technologies that we can bring to the table, the easier it will be to transition to a safe, affordable, and reliable energy system."

'Full toolbox' needed to solve the climate change problem

Historical and proposed hydroelectric generation per year. The historical data ( show generation averaging 280.9 TWh/yr; generation proposed in ref. 11 is 402.2 TWh, 13 percent higher than the 25-y historical maximum of 356.5 TWh (1997) and 85% higher than the historical minimum of 217 TWh (2001). Graphic: Clack, et al., 2017 / PNAS

ABSTRACT: A number of analyses, meta-analyses, and assessments, including those performed by the Intergovernmental Panel on Climate Change, the National Oceanic and Atmospheric Administration, the National Renewable Energy Laboratory, and the International Energy Agency, have concluded that deployment of a diverse portfolio of clean energy technologies makes a transition to a low-carbon-emission energy system both more feasible and less costly than other pathways. In contrast, Jacobson et al. [Jacobson MZ, Delucchi MA, Cameron MA, Frew BA (2015) Proc Natl Acad Sci USA 112(49):15060–15065] argue that it is feasible to provide “low-cost solutions to the grid reliability problem with 100% penetration of WWS [wind, water and solar power] across all energy sectors in the continental United States between 2050 and 2055”, with only electricity and hydrogen as energy carriers. In this paper, we evaluate that study and find significant shortcomings in the analysis. In particular, we point out that this work used invalid modeling tools, contained modeling errors, and made implausible and inadequately supported assumptions. Policy makers should treat with caution any visions of a rapid, reliable, and low-cost transition to entire energy systems that relies almost exclusively on wind, solar, and hydroelectric power.

SIGNIFICANCE: Previous analyses have found that the most feasible route to a low-carbon energy future is one that adopts a diverse portfolio of technologies. In contrast, Jacobson et al. (2015) consider whether the future primary energy sources for the United States could be narrowed to almost exclusively wind, solar, and hydroelectric power and suggest that this can be done at “low-cost” in a way that supplies all power with a probability of loss of load “that exceeds electric-utility-industry standards for reliability”. We find that their analysis involves errors, inappropriate methods, and implausible assumptions. Their study does not provide credible evidence for rejecting the conclusions of previous analyses that point to the benefits of considering a broad portfolio of energy system options. A policy prescription that overpromises on the benefits of relying on a narrower portfolio of technologies options could be counterproductive, seriously impeding the move to a cost effective decarbonized energy system.

Evaluation of a proposal for reliable low-cost grid power with 100% wind, water, and solar


  1. Dennis Mitchell said...

    The U.S. Could be powered by solar, wind, and hydro. We can live wonderful lives at much, much lower levels of energy. Say five percent. First off we get to walk again. No air conditioning. Misting does wonders at cooling. As does shade. Underground structures would help cooling and heating. No more airplanes.

  2. Anonymous said...

    Human activity and particular energy production cannot be done without leaking carbon into the atmosphere. Multiplied by billions (and then more billions) it is clearly evident that modern civilization will always be a heat engine leaking carbon. We're not even going to be able to make anything, or mine any minerals (or any other resources like crops, trees, fish, etc.) without leaking carbon.

    Negative emissions technology is the only way to recapture what we will inevitably release. Which doesn't yet exist to scale (and we don't want to pay for it either).

    Massive population reduction would help - as long as the manufacturers and global corporations that are the real culprits are also massively reduced.  


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