In 2015, Mark Z. Jacobson released a report claiming via modeling that 100% of the energy – not just the electricity – needed by the U.S. could be reliably provided at a reasonably low cost by a mixture of wind, water and solar energy. Jacobson’s paper, Low-Cost Solution to the Grid Reliability Problem with 100% Penetration of Intermittent Wind, Water, and Solar for All Purposes, was recently challenged when the Proceedings of the National Academy of Sciences published a paper titled Evaluation of A Proposal for Reliable Low-Cost Grid Power with 100% Wind, Water, and Solar. The new paper, developed by Christopher Clack and a team of 20 co-authors, discovered “errors, inappropriate methods, and implausible assumptions” in the modeling and findings of the Jacobson paper, contradicting the conclusions of the “100% renewables” paper.

One example of the implausible assumptions from Jacobson’s model is the claim that their hypothetical system does not require any new reservoir or dam construction for hydropower. Clack and his co-authors found that there are times in which Jacobson’s modeled system shows a total hydroelectric contribution of 1,300 GW. According to the Energy Information Administration, the total hydroelectric capacity in the U.S. is 80 GW.

Jacobson’s proposal also opposes any contributions by nuclear energy, even that which is already being cleanly produced by existing facilities. Nuclear energy remains the only emission free power source that has proven it can power a country and other energy-intensive, off-grid loads. Clack confirmed that it would not be “theoretically possible” to build a reliable energy system without nuclear energy.

Though Jacobson’s work has received numerous challenges, he has defended his findings, pointing to the fact that his work was published in a “peer-reviewed journal” while that of many challengers has not always been subjected to that process. Without a formal, peer-reviewed challenge from a source with equivalent credentials, Jacobson’s work has been allowed to stand as a reasonably valid alternative approach to addressing future energy supply needs. That is why it is newsworthy to note that there is now a difficult-to-dismiss evaluation of Jacobson’s work showing that his “100% renewables” solution isn’t credible. It cannot be claimed as an achievable goal, no matter how much “will” there is to accomplish it.