Edited by B. L. Turner, Arizona State University, Tempe, AZ, and approved February 24, 2017 (received for review June 26, 2016)
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.
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.
↵2Present address: Vibrant Clean Energy, LLC, Erie, CO 80516.
↵3Retired.
↵4Table S1 in ref. 11 shows non-UTES storage of 1,065 GW, UTES electric storage of 1,072 GW, and UTES thermal storage of 467 GW. In ref. 11, there is no description of how LOADMATCH differentiates energy types.
↵5In ref. 12, the authors state that “100% conversions [to WWS energy systems] are technically and economically feasible with little downside … Numerous low-cost solutions are found, suggesting that maintaining grid reliability upon 100% conversion to WWS is economically feasible and not a barrier to the conversion [to a 100% WWS system] … We do not believe a technical or economic barrier exists to ramping up production of WWS technologies. Based on the scientific results presented, current barriers to implementing the [100% WWS] roadmaps are neither technical nor economic.” In January of 2016, Jacobson (16) said that “[o]ur goal is to get to 80% by 2030 and 100% by 2050. It is certainly technically and economically practical.”
↵6Excel spreadsheets from refs. 11 and 12, Tab EIA capacity factors 2011–2075 are at web.stanford.edu/group/efmh/jacobson/Articles/I/USStates.xlsx.
↵7The five sources cited in ref. 12 give construction time estimates of 5–8 y.
↵8In the almost 60 y of civilian nuclear power (two of the assumed war cycles), there have been no nuclear exchanges. The existence of nuclear weapons does not depend on civil power production from uranium.
Author contributions: C.T.M.C. and K.C. designed research; C.T.M.C. and S.A.Q. performed research; C.T.M.C., S.A.Q., and K.C. analyzed data; and C.T.M.C., S.A.Q., J.A., M.B., A.R.B., K.C., S.J.D., V.D., M.A.H., P.D.H.H., P.J., D.M.K., J.C.S.L., M.G.M., A.R., V.S., J.S., G.R.T., D.G.V., J.P.W., and J.F.W. wrote the paper.
Conflict of interest statement: The authors declare no conflict of interest, and with the exception of S.A.Q., none received support from sources other than normal salary from their employers for work on the preparation of this paper. With the exception of M.B. and J.C.S.L., all of the authors have recently received outside support for more general research on energy systems and renewable energy. C.T.M.C. received support in the past from NOAA. S.A.Q. was supported for analysis that supported this paper by the Rodel Foundation of Delaware and has received more general faculty funding from Uppsala University. J.A. and M.G.M. have received support from the National Science Foundation (NSF), EPRI, the Doris Duke Charitable Foundation, and members of the Carnegie Mellon Electricity Industry Center. A.R.B. has received support from the California Air Resources Board, the Carnegie Endowment for International Peace, Argonne National Laboratory, Sandia National Laboratory, NREL, Ford Motor Company, and Saudi Aramco. K.C. has received support from the Carnegie Institution for Science endowment and the Fund for Innovative Climate and Energy Research. S.J.D. has received support from the NSF. V.D. has received support from NREL. M.A.H. has received support from the NSF and DOE. P.D.H.H. has received support from the NSF and DOE. P.J. has received support from the NSF, EPA, and NOAA. D.M.K. has received support from the NSF and the Zaffaroni and Karsten Family Foundations. A.R. has received support from the NSF. V.S. has received support from the Sloan Foundation. J.S. has received funding from Jay Precourt, Bloom Energy, EPA, ExxonMobil Corporation, California Energy Commission, and DOE. G.R.T. has received support from DOE and the University of California, San Diego (UC San Diego) Deep Decarbonization Initiative. D.G.V. has received support from EPRI, the UC San Diego Deep Decarbonization Initiative, and the Brookings Institution. J.P.W. has received support from DOE, EPA, and industry affiliates of the Energy Modeling Forum. J.F.W. has received support from the NSF, DOE, DOD, Toyota, and Aquion Energy.
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