By Dave Elliott
It’s hard to keep up with the spate of studies suggesting that it would be technically possible to get to near 100% of electricity, or even of all energy, met from renewables by around 2050 at reasonable costs. With the broad options and potentials now quite well mapped out by academic and NGO studies covering many countries and regions, and also the world as a whole, the latest batch of studies focuses on the issues that would be raised on the way to that.
In ‘Smart Energy Europe: The technical and economic impact of one potential 100% renewable energy scenario for the European Union’, published in Renewable & Sustainable Energy Reviews, three Danish academics, D. Connolly, H. Lund, and B.V. Mathiesen, present a scenario for a 100% renewable energy system in Europe by the year 2050, looking at the changes needed and their implications.
The transition from a business-as-usual situation to a 100% renewable energy Europe is analysed in a series of steps, each of them reflecting a major technological change. In each step the impact is presented in terms of energy (primary energy supply), environment (CO2 emissions), and economy (total annual socio-economic cost). The steps involve progressively technically larger and politically harder changes: decommissioning nuclear power, implementing a large amount of heat saving, converting the private car fleet to electricity, providing heat in rural areas with heat pumps, providing heat in urban areas with district heating, converting fuel in heavy-duty vehicles to a renewable electrofuel, and replacing natural gas with methane.
The results indicate that by using the Smart Energy System approach, a 100% renewable energy system in Europe is technically possible without consuming an unsustainable amount of bioenergy. This is due to the additional flexibility that is created by connecting the electricity, heating, cooling, and transport sectors together, which enables an intermittent renewable penetration of over 80% in the electricity sector. The cost of the Smart Energy Europe scenario is approximately 10–15% higher than a business-as-usual scenario, but since the final scenario is based on local investments instead of imported fuels, it will create approximately 10 million additional direct jobs within the EU.
Looking more globally, in ‘Towards 100% renewable energy systems: Uncapping power system flexibility’ published in Energy Policy, Papaefthymiou and Dragoon similarly outline the necessary steps in creating power systems with the flexibility needed to maintain stability and reliability while relying primarily on variable energy resources. These steps are provided in the form of a comprehensive overview of policies, technical changes, and institutional systems, organized in three development phases: an initial phase (penetration up to about 10%) characterized by relatively mild changes to conventional power system operations and structures; a dynamic middle phase (up to ~50% penetration) characterized by phasing out conventional generation and a concerted effort to wring flexibility from existing infrastructure; and the high penetration phase that addresses how power systems operate over longer periods of weeks or months when variable generation will be in either short supply, or in over-abundance. Although this transition is likely a decades-long and incremental process and depends on the specifics of each system, the paper says policies, research, demonstration projects and institutional changes need to start now precisely because of the complexity of the transformation.
Looking more specifically at a key region, in ‘North-East Asian Super Grid for 100% renewables: Optimal mix of energy technologies for electricity, gas and heat supply options’, published in Energy Conversion and Management, Dmitrii Bogdanov and Christian Breyer spell out their vision of a NE Asian HVDC supergrid linking up renewables across China, Korea and Japan. Using an hourly resolved model, based on linear optimization of energy system parameters under given constraints, five scenarios are explored for 100% renewable energy power systems in North-East Asia with different high voltage direct current transmission grid development levels, and varying industrial gas demands and energy security levels.
It was found that renewables can supply enough energy to cover the estimated electricity and gas demands of the area in the year 2030 and deliver more than 2000 TWh (t) of heat on a cost competitive level of 84 €/MWh (e) for electricity. Further, it is claimed that this can be accomplished for a synthetic natural gas price at the 2013 Japanese liquefied natural gas import price level and at no additional generation costs for heat. The total area system cost could reach 69.4 €/MWh (e), if only the electricity sector is taken into account. In this system about 20% of the energy is exchanged between the 13 regions, reflecting a rather decentralized distribution pattern, with 27% supplied by stored energy. The major storage technologies are batteries for daily storage and power-to-gas for seasonal storage. ‘Prosumers’ are seen as likely to play a significant role due to favourable economics.
A highly resilient energy system with very high energy security standards would increase the electricity cost by 23% to 85.6 €/MWh, but overall, the results clearly show that a 100% renewable energy based system is feasible and lower in cost than nuclear energy and fossil carbon capture and storage alternatives.
Unsurprisingly, studies like this are widely promoted by those seeking to phase out nuclear and fossil fuels in preference for renewables. For a useful listing of many of the studies, initiatives and commentaries from around the world, see: www.mng.org.uk/gh/scenarios.htm
In my last three posts I looked at some examples of UK studies along those lines, and also at Labour’s new ambitious proposal to get to 65% renewables by 2030 and then possibly 80%. That was based in part on a 2011 Poyry high renewable UK study, which included one scenario with renewables supplying 95% of UK power by 2050: https://www.theccc.org.uk/archive/aws/Renewables%20Review/232_Report_Analysing%20the%20technical%20constraints%20on%20renewable%20generation_v8_0.pdf
There have been many more since then, including the 2013 study by the British Pugwash group of three UK energy pathways to 2050 (High Nuclear, High Renewables and Intermediate), using the DECC 2050 Pathways Calculator to test them – although it said there were problems with DECC’s model. In its High Renewables scenario renewables supplied 80% of all energy by 2050, including some imported green power for balancing. Pugwash has now looked at the global model extension that DECC made subsequently, and at some of the pathways DECC and others have produced using it. Pugwash still has problems with parts of DECC’s approach, but concludes from its review of three examples that getting below 2 degrees is possible though it will be tough and require significant technical and social changes. http://britishpugwash.org/wp/wp-content/uploads/2016/02/Climate-change-and-the-DECC-Global-Calculator_FINAL1.pdf
However, Pugwash is rather timid in its global High Renewables example. It uses DECC’s ‘Climact’ pathway, which only has renewables supplying 38% of global energy by 2050. That’s hardy high renewables. They are at ~20% now (and 25% of electricity) globally. 38% is at the bottom of the range of major 2050 predictions, many of which see ~50% as more likely, while, as noted above, some look to near 100%, at least for electricity. And as I reported in an earlier post, the team at Stanford University has been working on a global package – looking at near 100% renewable energy scenarios for 139 countries.
It is good to see the newer studies moving beyond just electricity to look also at heat and gas, and supergrid regional integration and grid balancing. In my next few posts I will be looking at those issues some more, covering some new studies of grid integration in the EU and elsewhere.