The influential climate scientist Jim Hansen, [i] [ii] [iii] among others,[iv] [v] [vi] argues for a global shift towards nuclear power on grounds that associated greenhouse gas emissions reductions offer the best path to mitigate climate disruption [vii] As the International Atomic Energy Agency put it in one of their flagship publications, “nuclear power can make an important contribution to reducing greenhouse gas emissions while delivering energy in the increasingly large quantities needed for global socioeconomic development.” [viii] Similar projections showing large-scale increases in nuclear generation also appear in the OECD International Energy Agency’s Energy Technology Perspectives, where nuclear power is projected (without technology breakthroughs), roughly to triple in aggregate worldwide capacity by 2050.[ix]
Others, however, contend that renewable sources of energy are the best path towards a low-carbon energy system. Armstrong writes that “renewables are essential” to a low-carbon future, but also that many countries will promote nuclear power as a “low-carbon technology that can mitigate climate change.”[x] Morgan et al. argue that “achieving deep decarbonization of the energy system will require a portfolio of every available technology and strategy we can muster.”[xi] Chu and Majumdar likewise note “nuclear power can have an important role in efforts to decarbonize the production of electricity,” but also that “renewable energy is rapidly becoming competitive with other sources of energy.”[xii] Davis et al. concur and argue that a mix of nuclear and dispatchable renewable sources of energy are key to future “net-zero emissions” energy systems.[xiii] Research in Australia argues the electricity grid could accommodate 100% renewable energy generation without a significant cost increase.[xiv] Other studies have noted the same for Ireland,[xv] China,[xvi] Canada,[xvii] Denmark,[xviii] Macedonia,[xix] New Zealand[xx] and Portugal,[xxi] to name a few. Many of these analyses take into account the necessity, in order to achieve carbon emissions reduction, for radical increases in generating capacity driven by electrification of transport infrastructures.
As a way to negotiate these contending positions, a frequent mantra is that energy strategies should seek to “do everything” in order to address the climate disruption challenge.[xxii] But – as a number of commentators have noted – this would actually be a highly irrational course of action.[xxiii] [xxiv] Where “doing everything” involves making investments that are slower or less cost effective than might otherwise be possible, which divert resources away from preferable options, or which in some other way impedes them, then there would result a potentially disastrous slowing and diminishing of the efficacy of carbon emissions mitigation.
From whatever side of the debate they may come from, then, arguments that options should be pursued merely as a way to “do everything” can be generally recognized as irrational special pleading. Amidst many uncertainties, the real questions are about which specific investments offer the most cost-effective and widely strategically beneficial ways forward in different contexts?
Our paper seeks to contribute towards this kind of debate.
Background to the current article
Right at the outset, we should be candid about what is for us, a uniquely awkward feature of the background to this present article. Motivated (as now) by the serious oddity noted above – that systematic scrutiny has been so neglected for the relative efficacy of different options for addressing such a serious global problem – the present pair from among the authors of the current article discussed in this blogpost, did make an earlier attempt to address this gap. Working with a third individual (not among the present authors) as the lead author, we undertook in 2016, a more simple quantitative analysis of relations between national carbon emissions mitigation efficacy and intensity of commitments to nuclear and renewable energy.[xxv]
Unfortunately, two basic errors were made in the processing and analysis of raw data by the first author of that article. Very embarrassingly – neither of the present two authors nor a number of referees (for a different leading climate policy journal) managed to notice this prior to publication. As a result, the finding in that earlier paper that nuclear power represents a less effective means to carbon emissions reduction than renewable energy, was immediately acknowledged by the authors to represent an invalid conclusion based on flawed analysis. It is a matter of abiding regret that (for the only time in our careers as authors of a combined array of more than 500 peer reviewed journal articles), we had to undertake an author retraction of that earlier paper.
In seeking to handle this retraction in the most immediate, open, rigorous and professional way, the present two authors of that earlier flawed analysis immediately and proactively contacted the journal to undertake an author retraction. We also immediately reported the issue to our home university in order to initiate an independent inquiry into the circumstances. A third immediate step was to also proactively contact the specialist public interest organization Retraction Watch, in order to ensure full disclosure and critical scrutiny of this retraction and solicit advice on how to minimize adverse effects on wider debate.
In that process, the first author of that earlier paper did personally acknowledge their own responsibility for committing the errors in good faith in a rush to meet deadlines. The present two authors accepted full responsibility for our own failures as second and third authors to check sufficiently thoroughly, the part of the analysis and data transcription undertaken by the first author. Independent in-depth examination of the handling of this author retraction found (in the case of the university investigation), that the mistake was an honest error that had been handled appropriately. The Retraction Watch review concluded that this case was an example of a well-managed author retraction. Commentators in this highly-charged field who had previously rightly criticized that flawed paper, also commended the present authors for being so open and proactive in this retraction.[xxvi]
Noting that broadly similar conclusions to those initially drawn erroneously in that earlier paper are now confirmed with far more detail and greater rigor in this present paper (now, we trust, correctly), we hope (especially given the proactive acknowledgement of this issue in this present blogpost – and whatever broader views might be taken on issues at stake) that we will be recognized to have done what we can to acknowledge and correct our earlier errors. Either way, this blogpost does at least allow us to continue our practice of full disclosure.
Reflexivity and rigor in “independent” policy research
A problem with this kind of real-world background – of uncertainties and errors, divergent interpretations and clashing interests – is that it makes it difficult in practice to achieve the sorts of comprehensive prioritizing analysis called for at the beginning of this blogpost. In the idealized world of “evidence based policy”, by contrast, energy and climate policy would only proceed after comprehensive research concerning every relevant positive or negative aspect of all possible energy resources. The resulting self-evident “facts” would be examined by objective analysts and any uncertainties that exist cumulatively eliminated, until a point where a singular unambiguous ‘truth’ is determined – with grateful policy makers then proceeding to adopt the emerging prescribed optimal energy pathway or portfolio.
Expedient as this storyline is to the justification of policy, this is not like the real world. Across various areas of energy debates – and not restricted to any particular political constituency – crucial roles are often played by deliberate mis-representation of information, by manipulation of discourse in expedient ways, by co-option of leading opposing voices, by direct subversion of opponents and by stifling of meaningful public debate.
Under conditions like this, the line between advocacy and scholarship (porous at the best of times) can become especially loose when analysts become passionate about their topic. Reasons for such passion can be as trivial and proximate as disciplinary identities or sectoral interests, or as deep and expansive as wider political ideologies. Either way, “theorizing” can on all sides thereby be reduced merely to a search for validation and “investigation” to the selective collection of data.
Energy debates in particular currently suffer gravely from these syndromes. “Energy evangelists”[xxvii] on all sides, are convinced they have found “the solution” to societies’ energy problems—whether this be solar energy, hydrogen fuel cells, or nuclear reactors. The intensity of this advocacy (and the scale of the interests often behind it) can lead to rhetorics in which everyone else’s solutions are treated as if sacrilegious. So, exchanges of ideas can become hostile battlefields where proponents are unable to reconcile their underlying differences.
Open about the ways in which our own analysis over many years has informed a generally critical perspective on nuclear power (when compared with alternative low carbon options), each of us have experienced bruising consequences from the resulting polarization. There seems to be an especially pernicious asymmetry in this field, where those whom comparative analysis leads to be generally critical of nuclear power are labelled “anti-nuclear”, whilst no such generally-established terminology exists to the same degree for those who are (entirely legitimately – if debatably) critical of particular features of renewable energy. The situation is aggravated by so much research in this field being (unlike our own) funded (directly or indirectly) by organizations with prior entrenched interests on one side or another.
Despite this asymmetry and polarization, however, the present two authors have each also often found valued opportunities to bridge the divide with those analysts who hold “opposing” views on particular aspects, but with similar open mindedness and good faith.
It is in this spirit that the present analysis is offered. We are open about the background and limitations to this present work. We acknowledge that our evidence does not compel only one supposedly definitive interpretation. We are clear about the particular conditions attached to our own interpretations. By publishing our full dataset and the detailed procedures undertaken in our regression analyses, we offer a firm basis for others to falsify our findings.
Yet we nonetheless remain accountable by advancing an interpretive argument that may itself be criticized in relation to this complex context. If this analysis is successful in stimulating reactions in the same vein, then the cause of scientific scrutiny is reinforced. If on the other hand, an intervention is greeted by less qualified assertions and ad hominen labelling, then the chance of bridging the polarized divides is sadly diminished.
Findings about nuclear power and renewable energy
To turn on this basis, then to the details of our analysis, we can summarize the following. Our paper focuses specifically on situations in which real-world constraints mean that strategic choices have to be made between resource allocations towards prioritizing either nuclear or renewables-based electricity supply investments. Exploring this dilemma retrospectively, by reference to past patterns in relative attachments of different countries to nuclear or renewable strategies, our paper addresses three hypotheses:
First, a “nuclear climate mitigation” hypothesis: that the relative scale of nuclear attachments in electricity supply will tend to vary negatively with overall national carbon emissions.
Second, a “renewables climate mitigation” hypothesis: that the relative scale of attachments to renewables in electricity supply will tend to vary negatively with overall national carbon emissions.
Third, a “crowding out” hypothesis: that the relative scale of nuclear attachments will tend to vary negatively with the scale of renewables attachments, and vice versa.
What we find in this study in relation to international patterns as a whole, is that the ”nuclear climate mitigation” hypothesis is not sustained by the evidence at an appropriate level of statistical significance. The renewable climate mitigation hypothesis is confirmed with substantial significance. And the crowding out hypothesis is also significantly sustained.
What might explain these patterns? Technologically, nuclear systems have been prone over the past few decades to greater construction cost overruns, delays, and longer lead times than similarly sized renewable energy projects (see Figure 1). Thus, per dollar invested, the modularity of renewables projects offers quicker emissions reductions than large-scale, delay-prone, nuclear projects.[xxviii]
Figure 1: Construction lead times and opportunity costs for nuclear and renewable power plants
Source: Authors, modified from [xxix] [xxx]
Furthermore, renewables tend to display higher rates of “positive learning” where increased deployment results in lower costs and improved performance[xxxi], especially for wind farms[xxxii] and solar energy parks.[xxxiii] This contrasts with the experience of nuclear power in France which has been prone to “negative learning,”[xxxiv] rising costs or reduced performance with the next generation of technology. In terms of policy, after each of the serious incidents or accidents at Three Mile Island (1979), Chernobyl (1986), and Fukushima (2011), regulatory requirements were significantly tightened for nuclear reactors both operational and under construction. Finally, wider social factors may also work against nuclear energy, and for renewable energy, facilitating faster acceptance, permitting and deployment.[xxxv]
Of course, these are just informed speculations, beyond the scope of the paper itself. Others will favor contrasting interpretations. But here, perhaps the most important issue – especially given the prominence of the topic and the scale of what is at stakes – is that this kind of analysis has been so remarkably neglected over recent years. Given how highly charged and hotly contested is the associated policy controversy, it is rather strange that there does not exist a large body of work on these questions. Either way, the many open questions and issues of detail acknowledged in the present paper show that much work remains to be done.
Nevertheless, the implications for now of this present work are that renewable-based strategies may reasonably be deemed to be significantly more effective than nuclear strategies at addressing pressing global challenges of climate disruption – and that worldwide pursuit of nuclear strategies actually risks not only consuming resources that might otherwise be more effective, but may also have an actively suppressive effect on the uptake of renewable energy.
Returning to the issues raised in the introduction of this blogpost, one message is clear despite the necessity for further research. With the stakes so high and the complexities so stark, currently common “do everything” rhetoric is revealed not only to be simplistic, but also potentially dangerous. In a world where the averting of catastrophic climate disruption is so imperative, such clumsy simplifications are no longer credible. Energy diversity can play many crucial roles in achieving carbon emissions mitigation, but diversity comes in many forms and modes.[xxxvi] [xxxvii]
The “truth” of our study is in this sense not something arrived at by particular analysts claiming individually-transcendent authority, but by contrastingly-oriented analysts contending with each other in an open and pluralistic way, such as to arrive at collectively more robust understandings. This is the organized skepticism of independent science.
The dilemma for society more widely, is not about whether or not to pursue any single loudly-advocated option, but about diversifying in relation to the relative viabilities and collective compatibilities of a diversity of different options. Otherwise, significant opportunity costs will be incurred, delaying carbon emissions reductions (as well as other benefits). Therefore, the challenge is not one of “doing everything” in directions conditioned by any entrenched interest, but about societies rigorously, democratically, and deliberately “choosing what to do”. In light of this analysis, the implication for electricity planning is that diverse renewables are generally proving in the real world to be significantly more effective than nuclear power at reducing climate disruption.
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Renewables are now way cheaper per MWh than new nuclear and much faster to build. So while nuclear is "OK" as regards CO2 emissions per MWh (between solar PV above and wind below), renewables make more sense in most cases.
Thanks for commenting! Although this was not the subject of our study, it does seem to make sense. IRENA publishes a comprehensive global look at the costs of renewables, and it does show continued improvements in performance and declines in cost: https://www.irena.org/publications/2020/Jun/Renewable-Power-Costs-in-2019. The best independent international market overview is often considered Lazard’s. Again, wind and solar scale PV are far, far cheaper than nuclear using today’s technology: https://www.lazard.com/perspective/lcoe2019. (They don’t look at hydro). So this would further support that renewables are more cost effective than nuclear power. And even taking the official view in one of the world’s currently most intensely pro-nuclear policy environments, that of the UK, it is also acknowledged that (even when an unfavourable view is taken of integration and storage costs) renewables off a significant overall cost advantage over nuclear power: https://www.gov.uk/government/publications/beis-electricity-generation-costs-2020