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Comment on Seibert, M.K.; Rees, W.E. Through the Eye of a Needle: An Eco-Heterodox Perspective on the Renewable Energy Transition. Energies 2021, 14, 4508

Faculty of Arts, Design & Architecture, School of Humanities & Languages, UNSW Sydney, Sydney, NSW 2052, Australia
Energies 2022, 15(3), 964;
Original submission received: 16 August 2021 / Revised: 24 September 2021 / Accepted: 24 September 2021 / Published: 28 January 2022
The ‘review’ by Seibert and Rees [1] of the renewable energy (RE) transition poses the following three questions, arguing that the answer to each is ‘no’:
  • Is it possible to build and implement the RE technology without fossil fuel (FF) inputs?
  • Is it affordable?
  • Can it be done on a climate-relevant schedule?
However, there is overwhelming evidence, summarised in the next section, that the answers to Questions 1 and 2 are ‘yes’. Question 3 is the only question that must be taken seriously, and it needs more research and debate. On the basis of their flawed negative answers to the three questions, Seibert and Rees [1] then argue for degrowth in consumption, but better arguments for degrowth are cited in my response to Question 3.

1. Questions 1 and 2: Technical and Economic Feasibility?

Many detailed scenario models demonstrate the technical and economic feasibility of replacing all FF energy consumption entirely with RE and efficient energy use (EE) for the whole world, regions, countries, and states/provinces. Many of these studies are cited in the 100% RE scenario studies by Jacobson et al. [2,3], Bogdanov et al. [4], and Brown et al. [5] and Diesendorf and Elliston [6]. References [1,2,3,4,5,6], the International Energy Agency’s Net Zero Emissions 2050 Scenario [7], and many other studies agree that the vast majority of global energy consumption (which includes transport and heat) in 100% RE scenarios will be supplied, directly or indirectly, by renewable electricity (RElec), and that most RElec will be generated by wind and solar photovoltaics (PVs), which are already much cheaper than FF and nuclear electricity in most of the world [8,9,10] and are still declining in costs. Hydroelectricity will continue to substantially contribute in some regions. Storage for periods of several hours will be provided by batteries; storage for periods of days to months by hydroelectricity (both once-through and pumped) and other technologies [1,2,3,4]. The most common objections to 100% RElec have been refuted by Brown et al. [5] and Diesendorf and Elliston [6].
The results of practical experience support the findings of the models: for example, Scotland already obtains over 60% of its annual electricity generation and 97% of its electricity consumption from renewables, mostly wind [11]; Denmark has 47% of its generation from wind, supplemented by 15% from biofuels derived from agricultural residues and 3% from solar PV [12]; and South Australia has 56% of its generation from wind and solar PV [13]. All are on track to their governments’ targets of 100% RElec generation by 2030–2035.
To go from 100% RElec to 100% RE requires the electrification of transport and nonelectrical heating. The technologies are commercially available for both of these energy uses. The rollout of electric vehicles is already well advanced in Norway, with the majority of new car sales being electric, and is growing in other parts of Europe and China. Battery prices are falling globally as the market expands. Long-distance air and sea transports still require research and development to reduce the cost of producing hydrogen and ammonia by electrolysis using RElec, but these together account for only about 5% of total global greenhouse gas (GHG) emissions. So far, little has been done to electrify heating by FF, but there are no major technical barriers—the main barrier is sunk costs [14].
The response of Seibert and Rees [1] to this overwhelming body of evidence is to fail to cite the positive studies and to demonstrate the following shortcomings in their main criticisms of RE:
  • Citing a rhetorical statement by Clack et al. [15] claiming errors in Jacobson et al. [2] without citing the point-by-point refutation by Jacobson et al. [16].
  • Claiming that ‘solar PV has a low energy return on energy invested (EROEI or EROI)—too low to power modern civilization [52–55]’, without citing the studies that obtain a different result [17,18,19,20,21] or those that find that static EROEIs of FF electricity technologies are similar to those of solar PV and much less than those of wind [20,22]. Different authors obtain different results by the choice of different methods and regions with different insolations.
  • Failing to distinguish between static EROEI, which depends on the properties of the individual energy technology, its pattern of use, and its location, and dynamic system EROEI, which also depends on the rate of implementation of a system of new technologies [21,23]. A rapid implementation, in which new technologies are built before existing technologies have generated the energy needed to build themselves, will inevitably decrease system EROEI temporarily. However, because wind and solar technologies can be manufactured and installed more rapidly than any other energy supply technology, they are likely to have the smallest reduction in dynamic EROEI of any energy supply technology [21].
  • Making, in effect, the unreasonable demand that the whole life cycle of RE technologies be instantaneously switched from FF to RE. That transition is underway in mining, mineral processing, aluminium smelting, battery manufacture, transport, retail, computer hardware, software, and so forth, with over 300 large companies committed to transition to 100% RElec by specified dates [24]. Because of RElec’s favourable economics, there is no major barrier, apart from sunk costs, to accelerating this transition.
  • Claiming that 100% RElec would require a much higher construction rate for the grid in the USA. Since the current construction rate is low, this is not necessarily a problem for Questions 1 and 2, although it is relevant to Question 3. Transmission costs are generally a small fraction of the cost of the generating system.
  • Exaggerating the importance and difficulty of overcoming many other ‘problems’ with RE technologies, most of which are temporary and/or contingent on government policies.
Thus, Seibert and Rees’s claim that their ‘eco-heterodox view of the renewable energy transition flows from our commitment to critical discourse’ is contradicted by the absence of critical analysis of the anti-RE literature they cite and the failure to acknowledge literature that offers solutions to the issues raised.
One criticism of the technical feasibility of global 100% RElec still stands: the materials’ requirement of RElec technologies and battery storage needs more investigation. Demand for some technology-specific materials will increase many times and may exceed known reserves before 2050 [25] unless policies are implemented to reduce demand by design for disassembly, recycling, substitution, and improved efficiency of manufacturing. Furthermore, the environmental and social impacts of supply, especially in countries with little regulation of mining, must be reduced. This is an issue for the whole global economy, not just RE. Changing to a circular economy would be a step in the right direction, but this has limitations [26], and a more radical change to the economy is needed, as discussed in the next section.

2. Question 3: A Climate-Relevant Schedule?

This is a much more difficult issue. In this case, I would agree with Seibert and Rees’ qualitative statement that ‘the only viable response to overshoot is a managed contraction of the human enterprise until we arrive within the safely stable territory defined by ecological limits’, provided that the word ‘only’ was omitted. The earth’s environment needs both a radical technological change (i.e., transition to an energy system based on RE and EE) and a reduction in consumption (i.e., degrowth to an ecologically sustainable steady-state economy with a reduced use of energy, materials, and land and a population that is not growing). This has been the conclusion of researchers for several decades [27,28,29,30,31,32,33,34], but surprisingly, Seibert and Rees cite none of them, creating the incorrect impression that they are discovering degrowth for the first time. The case for degrowth is robust and does not have to depend on flawed arguments that 100% RE is technically infeasible and unaffordable.
How much reduction in consumption is really needed? Because Seibert and Rees (2021) lack quantitative analysis, they offer no basis for making their rhetorical statement ‘Truly renewable energy sources will be largely based on biomass (especially wood), simple mechanical wind and water generation, passive solar, and animal and human labor’. To the contrary, a simple calculation suggests that there is no need to sacrifice electricity or motor cars to achieve the necessary degrowth, provided that these energy end-uses are provided, directly or indirectly, by RElec. Let us assume that the world’s total primary energy supply (TPES) and the RE (excluding biofuels and waste) contribution to TPES in 2021 are approximately the same as in 2018, due to COVID-19 i.e., 598 EJ (14,280 Mtoe) and 27 EJ (649 Mtoe), respectively) [35]. If TPES were reduced exponentially so that it is halved by 2050, and if RE grew exponentially, then RE could replace all fossil energy by 2050, provided that it doubled every 8.4 years. RElec from noncombustible sources doubled in Denmark and Australia in the 8 years between 2011 and 2019. In Germany and China, it doubled in the 7 years from 2012 to 2019 [36]. Much faster growth is possible provided that the transmission system can keep pace. Most GHG emissions come from primary energy consumption. TPES and hence GHG emissions will be halved automatically by the huge gains in energy conversion efficiency obtained from transitioning to 100% RE + EE [2,3,4,5]. Substituting for one unit of FF electricity saves typically three units (range, 2–4 units) of primary energy. Substituting electric heat pumps for low-temperature heating by FF gives similar savings. Electric vehicles with 80%–85% energy conversion efficiencies can replace most internal combustion engine vehicles with 15%–30% efficiencies. The 2050 target would return global TPES to the 1978 level, while maintaining the energy services of 2018. This would be very different from returning to human and animal muscle.
However, having RE (excluding biofuels and waste) replace all fossil energy by 2040 would be more challenging: even if TPES is halved by 2040, the necessary doubling time of RE becomes 5.5 years.

3. Conclusions

The review by Seibert and Rees [1] is one-sided and does not accurately reflect the literature or the facts. If we were to believe their claim that 100% RE is impossible without FF inputs, we would have to either keep polluting with FF or avoid using electricity and cars and we would have to heat our homes with polluting firewood. Both of these options would be disastrous for the environment, our health, the economy, and social justice. Fortunately, a global energy system that is entirely renewable, with little or no use of bioenergy, is technically feasible and affordable and is evolving towards independence from FF.
However, time is of the essence. To achieve a high probability of bringing the escalating climate crisis under control, both technological and socioeconomic changes are needed. We need both an energy system of 100% RE with greatly improved end-use EE and degrowth to a steady-state economic system. Seibert and Rees [1] do a disservice to climate mitigation and environmental protection in general by publishing a one-sided ‘review’ that exaggerates the challenges faced by RE and presents an unnecessarily severe picture of degrowth.


This research received no external funding.

Informed Consent Statement

Not applicable.

Conflicts of Interest

The authors declare no conflict of interest.


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Diesendorf, M. Comment on Seibert, M.K.; Rees, W.E. Through the Eye of a Needle: An Eco-Heterodox Perspective on the Renewable Energy Transition. Energies 2021, 14, 4508. Energies 2022, 15, 964.

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Diesendorf M. Comment on Seibert, M.K.; Rees, W.E. Through the Eye of a Needle: An Eco-Heterodox Perspective on the Renewable Energy Transition. Energies 2021, 14, 4508. Energies. 2022; 15(3):964.

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Diesendorf, Mark. 2022. "Comment on Seibert, M.K.; Rees, W.E. Through the Eye of a Needle: An Eco-Heterodox Perspective on the Renewable Energy Transition. Energies 2021, 14, 4508" Energies 15, no. 3: 964.

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