Ed. note: This article was originally published in Spanish here: https://www.fuhem.es/papeles_articulo/transicion-energetica-y-escenarios-postcrecimiento/
We are living in a context today in which the physical limits, natural resource constraints, and conditions of overshoot associated with the expansion of the dominant system of production and consumption are becoming increasingly clear. An important example is the question of energy. It seems clear that the two-fold energy crisis that we are undergoing places us before a complicated dilemma. From the standpoint of sinks, we are confronted with accelerating climate change brought on by a form of human socio-economic functioning that essentially depends on the burning of fossil fuels. With regard to sources, the arrival of the peak of conventional oil is now recognised as a fact by international organisations and signifies the beginning of a phase of worldwide decline in the extraction of crude oil. This circumstance brings societies face to face with the coming energy shortage and could likely confirm the beginning of the end of an economic era of cheap energy. As is evident, this transition alone already entails socio-economic transformations of considerable magnitude.
According to the sixth report of the IPCC, an increase of between 2.8 and 4.6°C by 2100 (compared to the pre-industrial era) is considered very likely if the current trajectory of greenhouse gas emissions (GHG) continues. It is unlikely that the human species will be able to endure such increases. But what is certain is that the great majority of crops and agricultural systems on which it depends for its food will not withstand them. It is understood, then, that for some time the best-documented scientific works have reached the conclusion that the rate of reduction of GHG emissions should be 6% annually over four decades, beginning in 2013. Hence, even apart from a consideration of future problems of access to fossil fuels, climate change already confronts us harshly with the necessity of a reduction in consumption. The dilemma is clear: If we think that using half of the available hydrocarbons has brought about such global warming as we have now, where will burning the other half take us?
Climate change and energy transition. Do we still have time?
In its 2018 report concerning the conditions for fulfilling the Paris Agreement, the IPCC called attention to the dramatic reductions of GHG emissions which we must undertake in the coming years in order to meet the objective of not increasing the average temperature of the planet by more than 1.5°C.
But the prospects for achieving this are not very promising. If we bear in mind the plans which countries presented in order to contribute to fulfilling the objectives of the Paris Agreement (2015), we arrive at a paradoxical conclusion: As we have shown in a recent study, if all of the countries met the objectives set out in their plans, their emissions in 2030, far from being reduced, would increase by 19.3% compared to average emissions over the period 2005-2015, bringing the increase in temperature to between 3-4°C above pre-industrial levels. Although countries had the opportunity to update their commitments in 2020, only 22 (including the European Union) did so. As a result, assuming that these countries keep their increased commitments, the emissions in 2030 would be 15.9% greater instead of 19.3%, according to the UNFCCC. Apart from the fact that these commitments are generally not kept, this paradoxical result exposes the flawed manner in which the negotiations have been conducted, and the lack of seriousness with which the problem is being addressed. On the one hand, it was about voluntary commitments (that is to say, without penalties in the case of non-compliance). In other cases, objectives were set out for relative reduction (in relation to GDP), but not for an absolute reduction of emissions (which is what is important for climate change). And finally, there was no concern over whether the different plans presented were compatible with the general objective they were trying to reach (as has sadly been demonstrated). Given that the only way to reduce emissions, so that they do not build up and do not increase the average temperature, is by reducing extractive activity, what would we need to do to confront this problem internationally if we really took it seriously?
A very revealing study that was published recently shows that, in order to prevent the rise in temperature from exceeding the hoped-for upper limit of 1.5°C in 2050, 60% of natural gas and oil reserves, and 90% of coal reserves, would have to be left in the ground without extracting them (and therefore without burning or emitting). Part of these reserves are in the hands of states, and another part in the hands of transnational corporations (TNCs), which want to obtain the profits that can be had by exploiting them. This presents a great difficulty for any strategy that seeks to address climate change. If there was a desire to really tackle the problem beyond mere rhetoric and inaction, the negotiations in Paris would surely have to have been two-fold: 1) Discuss with the owners of the reserves (states and TNCs) compensation for leaving those assets underground without exploiting them, and 2) think seriously about the important and urgent changes that we must make in order to continue producing and consuming goods and services that satisfy the needs of the population using declining available resources. This is the great challenge, and everything that does not address the problem with respect to at least these two aspects will likely continue reinforcing the merely “ceremonial” character of the international climate negotiations.
It does not appear, however, that the majority of economic, political, and social discourses have reckoned with this reality that is so evident. Quite to the contrary, instead of highlighting the idea of limits, and promoting strategies of collective self-limitation and emergency contraction of the scale of the economy (especially in the rich countries), which would enable us to reduce ecological degradation and keep the Earth a habitable place, means are sought by which to perpetuate, by other names, the belief that it is possible to continue growing the system of production and consumption that has caused the problem.
Green New Deal and green growth: Is it enough just to substitute fossil fuels with sources of renewable energy?
In this context, since a decade ago, the proposals for confronting the global environmental problems have been framed within the programmes for ecological transition, energy transition, and the decarbonisation of our economies. Under this umbrella the green growth strategy has been proposed, emerging out of various initiatives by international bodies such as the OECD and the World Bank. It promises continued economic growth and expansion of the production of goods and services (GDP), but using renewable sources of energy and, thanks to technological advances, reducing the use of natural resources and pollution. The viability of this model, which we believe underlies the reported transition plans to comply with the Paris Agreement, has recently been strongly contested in several academic works.
Nevertheless, inspired by this narrative, since 2019 various rich countries have been proposing “green deals”. A “decaffeinated” version of American “Green New Deal” proposals has been taken up by the Biden Administration, while the European Union’s “Green Deal” has been approved and is being implemented. A global Green New Deal has also been proposed.
The problem with the green growth strategy is that, in order for it to succeed, an extreme degree of dematerialisation of the production of goods and services must be achieved, increasing production while simultaneously reducing the use of resources and pollution. This, unfortunately, has not been the case due to our economic system’s great dependence on natural resources. We are talking about a model of production and consumption which has tripled, on a global scale, the extraction of natural resources since 1970, and which, according to some estimates, is expected to double its use of energy and materials by 2060. The evidence of the problems of green growth and its failure to achieve significant dematerialisation is becoming ever more overwhelming in the scientific literature. We also know that the digitalisation of production and consumption processes and technological progress do not lessen the dependence or the impacts. Rather, they often exacerbate them, thanks to, among others, factors like the “rebound effect”, as we have seen being confirmed for more than two decades.
However, despite this flurry of proposals, for some years now there has been a growing sensation that we are arriving late. That the recent measures set out within the strategies of ecological and energy transition, which, in many cases, were already proposed four decades ago by various scientists, researchers, and social movements, should have begun to be implemented right then, or even earlier. They were excellent ideas to put into practice in the 70s, 80s or even up till the start of the 90s in the 20th Century. But now, for a growing number of people, it is starting to seem late. The reason is that a socio-economic transformation of such magnitude requires several decades to complete, and this amount of time is precisely what the majority of analysts are saying that we do not have, as the emergency of climate change and global ecological degradation has robbed it from us.
The reason why many of these doubts are raised is not so much because there is anything harmful, in principle, about the strategies of substituting fossil fuels for renewable sources. Quite the opposite is the case, as has been systematically defended since the 1970s. It makes perfect sense to seek to replace the use of oil, coal, and natural gas with solar or wind power. The problem has to do with: 1) the aspiration to maintain the same level of energy consumption (only now provided through renewable sources) without taking into account the physical limits of this strategy; 2) the time at which this transformation is supposed to happen (third decade of the 21st Century) with a very narrow time frame for solving the global ecological crisis; and 3) the environmental costs entailed by the widespread deployment of renewable technologies and the electrification that is based on them.
Studies from recent years are putting in doubt the possibilities of maintaining the current level of energy consumption using renewable sources. On the one hand, it is often overlooked that renewable technologies are mainly focused on electricity, which is generally 20% of final energy use. This means that the remaining 80% is provided by liquid fuels derived mainly from fossil fuels for energy and non-energy uses for which there are no simple alternatives.
Part of this consumption has to do with transport, and, concerning that category, particularly high hopes have been placed in the growing use of the private electric car. However, the electric car continues to be a product that is highly dependent on fossil fuels and non-renewable resources: Most of the electricity generated is still made using fossil and non-renewable (nuclear) fuels (in Spain, almost two thirds of the total, and on a world scale, almost three quarters), which makes the CO2 emissions savings of an electric car relative. Electric cars also require using six times more material and mineral inputs than a conventional car, which partly accounts for why, considering life cycle analysis from mining through production, 67% more energy is used in the manufacture of an electric car than in the manufacture of a conventional car. And all this without taking into account the demands that switching to electric cars would make on the electric system in terms of recharging the same number of vehicles that we have now. This explains why, far from furthering decarbonisation processes, a full substitution of the fleet of conventional vehicles with electric ones, on a world scale, is so slow and does not resolve the problems of climate change. Rather, as a consequence of the rebound effect, it tends to aggravate them.
If the mass electrification of private transport, without changing the number of vehicles and trips, is problematic, what has no electric alternative is the heavy transport of goods by road (lorries) or by ship (which represents the greater part of international goods commerce). For reasons to do with thermodynamics it is not possible to put batteries in these types of vehicle, as their dimensions would make them non-viable. Moreover, as Vaclav Smil reminds us, “the best lithium batteries are 260 Wh per kilogram. This may be enough for a car but for sea and road transport we need 12,600 Wh per kilogram. And even more for an aeroplane’s kerosene”. In other words, there is no easy electric (or renewable) alternative for the heavy transport of many goods that are essential for the economic system’s functioning. An alternative solution put forward in this regard is the use of hydrogen, as an energy vector, which would share the virtue, with the oil it aims to replace, of being easy to accumulate and transport. This technology promises to support a large industry in the coming decades, but raises numerous questions about its sustainability (origin of the primary sources for the electrolysis, consumption of water, etc.) and energy return (the amount of energy obtained per unit of energy invested in the process, likely quite meagre in this case).
On the other hand, the construction of renewable technologies (solar and wind) depends on the burning of fossil fuels. Among the industrial processes of heat production used in the manufacturing of solar panels, turbines, and batteries, Megan Siebert and William Rees  (using data from the US Environmental Agency) emphasize the high temperatures involved in these processes (between 1,480 and 1,980°C for photovoltaic panels, and between 980 and 1,700°C for cement and steel in wind turbines). Currently, these processes heavily rely on high-density fossil fuels. Given that most renewable sources (e.g biofuels) for generating heat in industrial processes are in the low-temperature range (less than 400ºC), using renewable sources to generate heat is highly problematic. On the other hand, a massive renewable electrification of these processes (apart from the reduction in EROI that it would bring about) would also require replacing large amounts of industrial equipment and machinery used for these heating processes (ovens, etc.), which are now largely powered by coal and fossil fuels. As the U.S. Environmental Agency report concludes: “Often, the most valuable role that renewable heating technologies can play in industrial applications is to provide “pre-heating” before an existing conventional energy source is used”. https://www.epa.gov/rhc/
If we bear this dependence in mind, and that, moreover, we are in a peak-oil context in which the future availability of fossil fuels will be diminishing, then our current civilisation is facing what has been termed the “energy trap”. This is: the expansion of renewable sources and infrastructure requires the massive use of fossil fuels (and more of it the faster we want to implement the transition process) and, at the same time, this will entail, during the first years, higher GHG emissions which will aggravate the climate change problem. And this, in circumstances where time is also short, and where, moreover, given the installations’ useful life of 20-30 years, within three decades we would end up needing similar amounts of energy to replace them (for which it would be difficult to find available fossil resources).
If that wasn’t enough, the mass deployment of renewables has some important consequences in terms of extraction and the use of non-renewable minerals which it is essential to assess and take into account. Just as the International Energy Agency has pointed out, in a scenario in which the Paris Agreement objectives were met, the demand for minerals for renewable technologies would increase world consumption of them over two decades by 40% for copper and rare earths, 60-70% for nickel and cobalt, and almost 90% for lithium, leaving barely enough room for other current uses of them. As previously mentioned, the electric car would require six times more minerals than a conventional car, which demonstrates how the general electrification of private transport would generate such a high demand that it would lead, according to estimates for various scenarios, to the exhaustion of available reserves of aluminum, copper, cobalt, lithium, manganese, and nickel, leaving no available resources for other industrial uses.
Nevertheless, to all of these obstacles we must add, perhaps, one that is of greater relevance. The majority of the strategies for energy transition usually disregard the limited potential (for thermodynamic reasons) which renewable technologies really possess and which makes it impossible to use renewables to provide for 100% of the energy consumption levels which are now provided for by fossil fuels. This is what De Castro, Mediavilla, Miguel, and Frechoso discovered in the case of wind energy, when they saw that the renewable potential of wind energy would be approximately 1 TW, which would mean only the equivalent of 6% of total world primary energy consumption. And the same is the case with solar energy, given that the majority of estimates made do not usually take into account the limits of photovoltaic energy density and the competition which its expanded use implies for other uses of land and minerals. In this case, the envisioned sustainable deployment of solar energy on a world scale would only allow us to supply up to 25% of current primary energy consumption, which is a significant percentage, but is far from the notion of 100% renewable that is usually proposed.
All of this to a large extent demands that any successful energy source meet two other criteria which are reasonable to expect in the current situation: sustainability and viability. Even if they are renewable, it is hard to see how their production on a large enough scale to satisfy the current levels of energy consumption could be sustainable, given the environmental costs which they generate and because they depend on fossil fuels. This limits their viability as energy sources for society, given that they are not capable of reproducing themselves with the same source and, at the same time, given their low rates of energy return, they have difficulty in generating an ample energy surplus with which to power the rest of society’s activities.
The point of the previous considerations is not to undervalue renewable sources of energy or the advantages of using these types of technologies in the production and consumption of goods and services compared to the massive use of fossil fuels. Not at all. Important achievements have been reached which it is good to keep in mind. The aim is rather to caution against placing exaggerated hopes in their mass deployment as a means of confronting an energy crisis and climate emergency in the third decade of the 21st Century, and to show the limitations of adopting them on a large scale in order to substitute the energy consumption which is now supplied by oil, gas, and coal. It does not seem possible (or desirable) to continue fostering the illusion of a painless transition with regard to energy consumption, when the data and scientific evidence suggest that we should put all means and efforts into reducing our production and consumption, adjusting them to the real possibilities which these renewable energy sources offer.
In short, if it is not possible to adjust the means to meet the objectives (growth), then we must substantially reduce the objectives to fit the available means. So we need to conceive and implement scenarios to urgently reduce the scale of our social and economic activity, in ways that reduce natural resource use, emissions, and pollution and combat social inequality.
Reducing scale and implementing post-growth scenarios
These questions and challenges are among the concerns which we in the Grupo de Energía, Economía y Dinámica de Sistemas (GEEDS) [Energy, Economy, and System Dynamics Group] of the University of Valladolid have studied as we consider the consequences for the economy of various future scenarios of energy transition. Toward that end we have developed the MEDEAS model (“Modelling Energy Development under Environmental and Socio-economic Constraints”), which is an integrated assessment model (IAM) of energy, economy, and climate change. It takes an ecological macroeconomics approach focusing on the world and European economies. As part of this, an extension of this model to the case of the Spanish economy is also being developed.
It is a model of simulation and assessment which, methodologically, integrates two powerful techniques, system dynamics and input-output analysis, in an original way, and takes into account, among other things, the international and European context regarding the physical constraints of the availability of non-renewable energy sources (peak oil), the need to limit GHG emissions, the technical and sustainable potential of renewable energies, and the demand for energy by the various sectors. The model is structured in different modules (economy, energy, climate, land uses, minerals, etc.), each one interrelated with the others and together forming an integrated system. Crucial to the method is to take into account not only direct and indirect energy consumption in the economic module, but also the feedbacks which are produced with other spheres and modules, and which also drive consumption and emissions.
With these conceptual tools, we have assessed, for example, different transition scenarios towards a world and European low-carbon economy in the time horizon 2030-2050, with very revealing results. The three scenarios we have considered are: 1) continuation of the current tendencies (business as usual, or BAU); 2) green growth, which bets heavily on technology, energy efficiency, and the transition to renewables (electrification, wind, photovoltaic, bioenergy, etc.), with high growth of middle and low incomes and medium growth for high incomes; and 3) post-growth, which combines policies of energy efficiency and renewables, a modest annual reduction in GDP per capita, measures to reduce inequality, such as a policy to increase employment while reducing each worker’s work week, by sharing workloads more equitably among the working-age population, and, finally, an economic policy that strongly favours public services over economic sectors which use natural resources intensively.
We examine each of these scenarios using two alternative sets of assumptions, simulating what would happen with the existence of energy limits, and also simulating what would occur without these limits, in order to see the consequences of the different strategies concerning GHG emissions, GDP, employment, etc. The aim is to determine, for example, which of the scenarios would guarantee not going above a 2°C temperature increase by 2050. (Taking the average emissions from the period 2005-2015 as a base, this would mean reductions of more than 40% in 2050 relative to the 2005-2015 average.)
What we find from the simulation of the three scenarios is the following:
In the case of BAU, the world emissions increase in 2030 and 2050 between 25% (2030) and 8% (2050) (assuming energy limits), or between 57% (2030) and 210% (2050) (assuming the absence of energy limits). In the green growth scenario, and without energy limits, the emissions increase between 51% (2030) and 14% (2050). With energy limits, the increase in 2030 would be 14% and in 2050 there would be a reduction of 16% of GHG emissions (as the spread of renewables would have begun to show effects, though still far from achieving the climate objective). And finally, in the post-growth scenario, due to its very nature, the results are barely affected by the absence or presence of energy limits. It would produce a reduction in emissions of 13% in 2030 and of 57% in 2050, which would allow us to keep the temperature increase below 2°C and achieve the Paris Agreement objective.
It bears mentioning that the results of the simulation carried out for the case of the EU-28 (taking into account the various perspectives of energy consumption proposed by the same European Commission in its Energy Roadmap 2050) also show that the post-growth scenario is the only one capable of achieving conversion to renewables while simultaneously achieving a substantial reduction of energy consumption and emissions (by 70%), which would allow the EU to fulfill its climate commitments. At the same time, the employment policies of reduction and sharing of working hours associated with the post-growth scenario would serve to maintain levels of employment.
With their limitations, these results clearly show that when we incorporate the biophysical constraints and the narrow time frame within which we must act, in the BAU and green growth scenarios the conflict between economic growth, policies to fight climate change, and environmental sustainability is undeniable. On the other hand, the scenarios also suggest that it is better to do something than do nothing at all, although it clearly shows that general economic growth is not an achievable model in the context of climate and energy constraints. Macroeconomic models therefore should not ignore this result and should incorporate biophysical constraints into their analyses.
Fortunately, there is now increasing recognition of the need to incorporate these scenarios of economic scale reduction into analyses and projections. Other researchers who have proposed similar approaches view the matter in the same way in relevant works that have also been published recently in important international scientific journals. It is therefore vital to complement technological solutions (efficiency, renewables, etc.) with important socio-economic changes which involve taking measures to reduce consumption and motorised mobility, with policies for the redistribution of income, wealth, and working time, strong economic policies of demand management, promotion of collective consumption, strong public services, ecological agriculture, etc. As hard as the realities may be to face, it does no good to continue deceiving ourselves. To a large degree, some of the policies associated with this post-growth scenario, and others related to the finance and fiscal system which we have explained in other works, clearly go against the tide. They challenge some very powerful interests and affect several policy areas (international, European, national, and even local). For this reason, it will be important to fine-tune their application at every level.
Climate change is a clear example that limits exist to the expansion of economic activity, and that we have gone beyond the biosphere’s capacity to absorb GHG without increasing the average temperature of the planet. We also know that the greater the scale of the economic system, the greater the demands on energy and materials will also be, and, consequently, the waste produced. We must urgently consider scenarios which go in the opposite direction concerning natural resource demands, pollution, and material consumption and production. An economy which rapidly shrinks its energy consumption – as ours must do very rapidly – will find it hard to manage this descent relying mostly on just efficiency alone (especially if it disregards the rebound effect). We need material and social resources which will enable us to move forward in the design of these scenarios and in the serious pursuit of economic policies and social practices which can bring them about.
The authors are grateful to Steven Johnson, Amelia Burke, Translators 4 Transition, and Instituto Resiliencia for their support in the translation of this article. The authors would also like to show their gratitude for the help received from the research project “Modelización y simulación de escenarios de transición energética hacia una economía baja en carbono: el caso español (ECO2017-85110-R)” [Modelling and simulation of scenarios toward a low-carbon economy: The Spanish case], financed by the Ministerio de Economía y Competitividad [Ministry of Economy and Competitiveness. In Spain].
Óscar Carpintero Redondo and Jaime Nieto Vega form part of the Grupo de Energía, Economía y Dinámica de Sistemas (GEEDS) (Energy, Economy and Systems Dynamics Group) and the Department of Applied Economy of the University of Valladolid
 See, for example, Donella Meadows, Dennis Meadows, Jorgen Randers, Limits to Growth: The 30-Year Update, Chelsea Green Publishing, 2004. Also, WWF, Living Planet Report, Gland, Switzerland, 2020.
 IPCC, Climate Change 2021: The Physical Science Basis, Cambridge University Press, 2021. Also, IPCC, Global warming of 1.5°, Geneva, 2018.
 Roberto Bermejo, Un futuro sin petróleo [A Future Without Oil], Los Libros de la Catarata, Fuhem-Ecosocial, Madrid, 2007. And more recently, Antonio Turiel, Petrocalipsis, Alfabeto, Madrid, 2020.
 IEA, World Energy Outlook, Paris.
 IPCC, Climate Change 2021: The Physical Science Basis, Cambridge University Press, 2021.
 James Hansen, Pushker Kharecha, Makiko Sato, Valerie Masson-Delmotte, Frank Ackerman, et al., “Assessing ‘dangerous climate change’: Required reduction of carbon emissions to protect young people, future generations and nature”, PLoS ONE, 8, e81648, 2013.
 IPCC, 2018, op. cit.
 Jaime Nieto, Óscar Carpintero, Luis Javier Miguel, “Less than 2°: An Economic-Environmental Evaluation of the Paris Agreement”, Ecological Economics, 146, pp. 69-84, 2018.
 NDC Synthesis Report, Convenio Marco sobre el Cambio Climático, Naciones Unidas, 2021. Available at: https://unfccc.int/process-and-meetings/the-paris-agreement/nationally-determined-contributions-ndcs/nationally-determined-contributions-ndcs/ndc-synthesis-report#eq-5
 Daniel Welsby, James Price, Steve Pye, Paul Ekins, “Unextractable fossil fuels in a 1.5 °C world”, Nature 597, 230–234, 2021.
 There are understandable objections to negotiating compensation for precisely those economic actors which have been at the root of the problem and, in many cases, have histories of aggression and ecological destruction of very important common wealth. However, given that the greater good achieved would be worth more than the costs incurred, it would definitely be worth the effort to get the result.
 OECD, Towards Green Growth, OECD, Paris, 2011.
 World Bank, Inclusive Green Growth: The Pathway to Sustainable Development, World Bank, Washington, DC, 2012.
 Iñigo Capellán-Pérez, Ignacio de Blas, Jaime Nieto, Carlos de Castro, Luis Javier Miguel, Óscar Carpintero, Margarita Mediavilla, Luis Francisco Lobejón et al., “MEDEAS: A New Modeling Framework Integrating Global Biophysical and Socioeconomic Constraints”, Energy Environmental Science, No. 13, pp. 986–1017, 2020. Also, the work of Simone D’Alessandro, André Cieplinski, Tiziano Distefano, Kristofer Dittmer, “Feasible Alternatives to Green Growth”, Nature Sustainability No. 3, pp. 329–335, 2020.
 Jeremy Rifkin, The Green New Deal, St. Martin’s Press, New York, 2019.
 Helmut Haberl, Dominik Wiedenhofer, Doris Virág, Gerald Kalt, et al., “A Systematic Review of the Evidence on Decoupling of GDP, Resource Use and GHG Emissions, Part II: Synthesizing the Insights”, Environmental Research Letters, doi: 10.1088/1748-9326/ab842a, 2020.
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 Jason Hickel, y Giorgos Kallis, “Is Green Growth Possible?”, New Political Economy 25 (4), pp. 469–486, 2020. Also: Helmut Haberl, et al., 2020, op.cit.
 Óscar Carpintero, “Los costes ambientales del sector servicios y la nueva economía: Entre la ‘desmaterialización’ y el ‘efecto rebote’ [Environmental costs of the services sector and the new economy: Between “dematerialisation” and the “rebound effect”], Economía Industrial, No. 352, pp. 59-76, 2003.
 Jorge Riechmann, Otro fin del mundo es posible, decían los compañeros [A different end of the world is possible, so the comrades said], mra ediciones, Madrid, 2019.
 Nuclear included. If nuclear power is excluded, the figures are: 36% (Spain) and 60% (World). References: Ministerio para la Transición Ecológica y el Reto Demográfico, Estadísticas y balances energéticos. https://energia.gob.es/es-es/Paginas/index.aspx IEA, Energy statistics. https://www.iea.org/
 IEA, The Role of Critical Minerals in Clean Energy Transitions, IEA, París, 2021.
 Pedro Prieto, “Consideraciones sobre la electrificación de los vehículos privados en España” [Considerations regarding the electrification of private vehicles in Spain], 15/15/15, 2020. Available at: https://www.15-15-15.org.
 A simple example provided by Antonio Turiel (op.cit., p. 145) may help us: “Millions of cars spend the night in the streets in our country [Spain]. In order to recharge those cars overnight you would need to put an electric post approximately every five meters of pavement. If they were 22 KW posts, like those the government wants to install in gas stations, you would have to install wiring and posts for every 125 meters of street in order to supply more than one megawatt (MW) of power. A city like Madrid, with more than a thousand kilometers of streets, would need cabling, electric substations, and control systems providing around 8 GW of power (in other words, as much as all the nuclear power stations in Spain). If we extrapolate these figures for the rest of Spain, we are talking about more than 100 GW (the same as the maximum electrical capacity of Spain)”.
 Ignacio de Blas, Margarita Mediavilla, Iñigo Capellán-Pérez, Carmen Duce, “The limits of transport decarbonisation under the current growth paradigm”, Energy Strategy Reviews, 32, 100543, 2020.
 Vaclav Smil, “Vivimos en un sistema irracional y la Tierra no puede soportarlo. Entrevista” [We live in an irrational system and the Earth cannot tolerate it], El Correo, 27 de agosto de 2021. Disponible en: https://www.elcorreo.com/
 Megan K. Siebert y William E. Rees, “Through the Eye of a Needle: An Eco-Heterodox Perspective on the Renewable Energy Transition”, Energies, 14(15):4508, 2021.
 Eric Zencey, “Energy as Master Resource”, in Worldwatch Institute, Is Sustainability Still Possible?: State of the World 2013, pp. 73-83, Island Press, 2013. Available at: doi:10.5822/978-1-61091-458-1_7.
 Alicia Valero, Antonio Valero, and Giomar Calvo. Thanatia. Límites materiales de la transición energética, Prensas de la Universidad de Zaragoza, Zaragoza, 2021.
 The same Agency points out that the construction of a wind farm demands nine times more mineral resources than a gas plant. IEA, op.cit, 2021, p. 5.
 Daniel Pulido Sánchez, Iñigo Capellán-Pérez, Margarita Mediavilla, Carlos de Castro, Fernando Frechoso, “Analysis of the material requirements of global electrical mobility”, DYNA, Vol. 96, pp. 207 – 213, 2021.
 Carlos de Castro, Margarita Mediavilla, Luis Javier Miguel, Fernando Frechoso, “Global wind power potential: Physical and technological limits”, Energy Policy, No. 39, pp. 6677–6682, 2011.
 Carlos de Castro, Margarita Mediavilla, Luis Javier Miguel, Fernando Frechoso, “Global solar electric potential: A review of their technical and sustainable limits”, Renewable and Sustainable Energy Reviews, No. 28, pp. 824–835, 2013.
 Nicholas Georgescu-Roegen, Ensayos bioeconómicos. Los libros de la Catarata (2a edición), Madrid, 2021. Pedro Prieto, y Charles Hall, Spain’s Photovoltaic Revolution. The Energy Return on Investment. Springer Verlag, Nueva York, 2013. Megan K. Siebert y William E. Rees, op.cit.
 We have chosen the label of post-growth since, legitimate controversies aside, it could encompass diverse strategies which seek to get past the growth scenarios (be they green or conventional). These would include strategies which fall under the category of degrowth; the low-growth proposals; those whose advocates consider it essential to distinguish, depending on the particular country that we are talking about, whether or not it needs to increase the production of goods and services; or those whose advocates think that in the future there will be activities that need to be increased and others that will need to be radically reduced, so that the results of these strategies in terms of growth or degrowth of GDP would not be the crucial consideration.
 Iñigo Capellán-Pérez et al., op. cit., 2020.
 The initial provisional results obtained for the case of the Spanish economy with the MODESLOW model (application of MEDEAS to Spain) point in the same direction.
 Jaime Nieto, Óscar Carpintero, Luis Fernando Lobejón, Luis Javier Miguel, “An ecological macroeconomics model: The energy transition in the EU”, Energy Policy, 145, 111726, 2020. Jaime Nieto, Óscar Carpintero, Luis Javier Miguel, Ignacio de Blas, “Macroeconomic modelling under energy constraints: Global low carbon transition scenarios”, Energy Policy, 137, 11090, 2020.
 Jaime Nieto et al., op. cit., 2020.
 Jaime Nieto, Óscar Carpintero, Luis Fernando Lobejón, Luis Javier Miguel, “An ecological macroeconomics model: The energy transition in the EU”, Energy Policy, 145, 111726, 2020.
 Simone D’Alessandro et al., op. cit. See also: Lorenz Keyβer y Manfred Lenzen, “1.5 °C Degrowth Scenarios Suggest the Need for New Mitigation Pathways”, Nature Communications, 12: 2676, 2021.
 Óscar Carpintero y Jorge Riechmann, “Pensar la transición: enseñanzas y estrategias económico-ecológicas” [Thoughts on transition: lessons and economic-ecological strategies], Revista de Economía Crítica, No. 16, pp. 45-107, 2013.
Teaser photo credit: Vauban, Freiburg, a sustainable model district. By Claire7373Andrewglaser – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=2637411