۱- Introduction

۲- Feasibility versus viability

۳- Feasibility criteria

۴- Other issues

۵- Conclusions

References

Abstract

A recent article ‘Burden of proof: A comprehensive review of the feasibility of 100% renewable-electricity systems’ claims that many studies of 100% renewable electricity systems do not demonstrate sufficient technical feasibility, according to the criteria of the article’s authors (henceforth ‘the authors’). Here we analyse the authors’ methodology and find it problematic. The feasibility criteria chosen by the authors are important, but are also easily addressed at low economic cost, while not affecting the main conclusions of the reviewed studies and certainly not affecting their technical feasibility. A more thorough review reveals that all of the issues have already been addressed in the engineering and modelling literature. Nuclear power, which the authors have evaluated positively elsewhere, faces other, genuine feasibility problems, such as the finiteness of uranium resources and a reliance on unproven technologies in the medium- to long-term. Energy systems based on renewables, on the other hand, are not only feasible, but already economically viable and decreasing in cost every year.

Introduction

There is a broad scientific consensus that anthropogenic greenhouse gas emissions should be rapidly reduced in the coming decades in order to avoid catastrophic global warming [1]. To reach this goal, many scientific studies ([2–۶۱] are discussed in this article) have examined the potential to replace fossil fuel energy sources with renewable energy. Since wind and solar power dominate the expandable potentials of renewable energy [3], a primary focus for studies with high shares of renewables is the need to balance the variability of these energy sources in time and space against the demand for energy services. The studies that examine scenarios with very high shares of renewable energy have attracted a critical response from some quarters, particularly given that high targets for renewable energy are now part of government policy in many countries [62,63]. Critics have challenged studies for purportedly not taking sufficient account of: the variability of wind and solar [64,65], the scaleability of some storage technologies [66], all aspects of system costs [64,65], resource constraints [67,68], social acceptance constraints [68], energy consumption beyond the electricity sector [68], limits to the rate of change of the energy intensity of the economy [68] and limits on capacity deployment rates [69,68]. Many of these criticisms have been rebutted either directly [70–۷۲] or are addressed elsewhere in the literature, as we shall see in the following sections. In the recent article ‘Burden of proof: A comprehensive review of the feasibility of 100% renewable-electricity systems’ [۷۳] the authors of the article (henceforth ‘the authors’) analysed 24 published studies (including [3–۹,۱۲,۱۳,۱۰,۱۱]) of scenarios for highly renewable electricity systems, some regional and some global in scope. Drawing on the criticisms outlined above, the authors chose feasibility criteria to assess the studies, according to which they concluded that many of the studies do not rate well.