The potential and limits to renewable energy are hotly debated, and far from settled. Many people take it for granted that it can meet all our energy needs, and numerous impressive agencies and technical reports say this. However until the last few years when simulations based on detailed weather data have become available nearly all pronouncements have been little more than speculation and most have simply selected bits of evidence to confirm preferred beliefs. I have examined about ten of these and have published various analyses showing how unsatisfactory they are. There are now several analysts and studies casting doubt on the 100% renewable claim (e.g., Moriarty and Honnery, 2010, Clack et al., 2017, Heinberg and Fridley 2016, Heard et al. 2017, Friedmann, 2016.)
Just as you can run your house on torch batteries, it is technically possible to run everything on renewables … but that doesn’t mean you could afford to do it. The crucial question is what would it cost to have enough generating capacity to meet demand at any time despite the intermittency of renewable energy? The simulations we now have generally find that to meet an average electricity demand of one GW you would need renewable generating plant capable of generating four to seven GW, and with plausible assumptions it would be much higher. Whether we could afford that is not known.
What about the claim that wind and PV can produce a kWh more cheaply than coal now? That is true but quite misleading. It doesn’t tell us much about what a kWh would cost if it came from a system with enough redundant renewable capacity to be able to supply it at any time. Again that system might have to contain 4 to 7 times as much wind and/or PV capacity as we would need in the form of coal-fired generators.
Won’t batteries solve the storage problem? Not unless costs fall enormously. Grid level systems that have been built cost around $1000 for the capacity to store 1 kWh. (…see my examination of the storage problem for renewables, Trainer 2017a) If you want to store the output from one power station for one day you would need capacity to store 1 million x 24 kWh = 24 million kWh, and at say $100 per kWh that’s going to cost you $2.4 billion…which as much as it would cost to add another coal-fired power station. A system would need the capacity to store for many days in a row.
Pumped hydro storage? Enthusiasts do not deal with the difficulties satisfactorily, especially the lack of affordable sites. (See Trainer 2017a.)
Claims about renewable potential are of little or no value unless they are derived via complex simulations based on detailed weather data for a region over a long period. Very few such studies have been carried out anywhere in the world. In 2012 Elliston, Diesendorf and Macgill (2012) published what I think was the first analysis of this kind for Australia, based on recently available detailed weather data for about 40 regions across the country. This valuable study concluded that a 100% renewable supply system could meet all electricity demand reliably, at a production cost of about 10-15c/kWh. At that time it was costing about 3-5 cents to produce one kWh by a coal-fired generator. In 2015 Lenzen et al. (2016) published the second Australian simulation concluding that the production cost could be 20c, and possibly 30+c.
These simulation studies inevitably involve many assumptions and in my view those made by Lenzen et al. are more acceptable, (… although I have published a detailed case that the assumptions re solar thermal efficiency in winter are much too favourable, maybe by a factor of four. The findings on getting through difficult periods in winter relied very heavily on solar thermal, so the assumptions I think would be more defensible would significantly raise cost conclusions; see Trainer 2017a.)
Wind is the cheapest renewable and Elliston, Diesendorf and MacGill assume it will be a major contributor, providing up to 58% of electricity, but Lenzen et al. assume that it would/should be limited it to 30% in view of the studies indicating that above this level problems in integrating wind into the supply system become difficult and costly. So differences in conclusions in the renewable field are typically due to differing assumptions, and thus conclusions can differ greatly.
In my attempt to derive a possible retail price from the production cost conclusions Lenzen et al. come to I list 10 factors they didn’t and/or couldn’t consider but which would be likely to increase the production cost. (Trainer, 2017b.) Examples are, the fact that the capital cost assumptions used were for a time when the $A dollar was about 35% higher than it is now, meaning the turbines and panels etc. that would have to be imported would now cost far more, the high probability that the year studied, 2010, was not the most difficult one ever likely to occur, and the fact that construction in remote areas has been estimated to increase construction costs 10%. The four factors I could quantify multiplied the Lenzen et al. production cost from 20 c/kWh to about 46 c/kWh. One important factor I could not include is the energy embodied in the construction of the huge amount of turbines, PV farms, transmission lines etc. that would be required.
The next important question is, given this production cost of electricity, what might the retail price be? For coal-fired power at the time of the study the retail price was about 5 times the production cost; i.e., it added about 22 cents to the maybe 3-5 cent production cost, mostly for distribution of electricity to consumers. So it seemed to me that the retail price from the pattern of renewable supply which Lenzen et al. found to minimise cost would probably be at least 46 + 22 = 68 c/kWh, and more likely around 90 c., i.e., 3 to 4 times the retail price at the time of the study. In my view this might be “affordable” but it would be extremely economically disruptive.
Keep in mind that this has been about Australia which has probably the best renewable energy sources of any rich country. My attempt to assess the prospects for Europeans (Trainer, 2013) concluded that they would be most unlikely to be able to run on renewables. They frequently endure weeks of continually very cold, stable and cloudy conditions, and have little biomass for back up.
But all that is only about providing electricity. Over 80% of our energy use is not electrical; much of it is in the form of liquid fuels. Meeting this demand is far more problematic. Following is an indication of my recent attempt to clarify the task of meeting total Australia’s energy demand via renewables. (Trainer, 2017b.)
I assumed, among other things, all light vehicles converted to electricity, use of the 96 million tonnes/y of biomass Crawford et al. (2012) find could be taken for energy, most of it producing ethanol, use of hydrogen thereby providing for all storage required, and conversion of as many functions as possible to electricity. (All the assumptions, derivations and arithmetic are easily followed in the paper.)
I found that the total amount of electricity that would needed to meet estimated 2050 total energy demand came to 5,867 PJ, and all available biomass was used. If the retail price of electricity was 50c kWh (and the argument above was that it could well be twice this) the cost of energy would be $814 billion p.a., which is around 54% of 2015 GDP, or 27% of 2050 GDP assuming 2% economic growth. Note that this does not include the cost of the biomass, converting it to ethanol, the transmission lines, the hydrogen production system, or any of the embodied energy costs built into the turbines and PV farms etc.
If this analysis is at all valid then 100% renewable supply to meet all energy demand would be utterly impossible to afford. At present Australia spends about 8% of GDP on energy. For the US it has been found that if the percentage goes above about 6% for any period of time there is recession. (Hall and KIitgaard, 2014.)
I have more recently attempted to estimate the Energy Return on Energy Invested (EROI) for a 100% renewable electricity generating system. (Trainer, 2017d.) As noted above, such a system must have a lot of generating capacity sitting idle much of the time, maybe 5 times as much equipment as would do the job in the form of coal-fired plant. The present system’s EROI is probably around 40, but I estimated that it would be 7.3, and there are reasons for thinking it would be considerably lower. If it is 7.3 then or each unit of energy spent producing electricity we would have 6.3 to use, whereas at present we have 39.
This has been an indication of the kind of detailed analysis one must carry out before one is in a position to make assertions about whether renewables can save us. The fact is that we are a long way from clear and confident conclusions in this area, but there is a strong case that we could not afford the amount of capacity needed to be 100% dependent on renewables.
In an age of serious existential threats where it is extremely important that we work out what to do calmly, rationally and cooperatively it is very depressing that this field exhibits so much prejudice, dogmatism and readiness to assert preferred claims without sound support, and sadly, with hostile personal abuse.
In my view renewable energy is not a very important issue in the quest for sustainability. I think it’s too late to fix the climate problem and at the very least renewable energy will be quite costly and this will add to the mounting and terminal difficulties affluence and growth society is running into. Many other factors will be more powerful determinants of our fate, most obviously oil depletion, financial collapse, and the discontent brewing among the perhaps 80% in rich countries for whom consumer-capitalism is increasingly failing to provide.
What then should we do? The answer is, emphatically, move to 100% renewable energy supply as fast as possible! But we cannot do that unless we undertake an astronomically big De-growth transition to The Simpler Way. That means scrapping capitalism, the obsession with wealth and affluence, individualism and competition, and instead being content to live frugally and cooperatively mostly in highly self-sufficient local communities. The many people living in eco-villages today know that these ways can provide all with a high quality of life on extremely low per capita resource use rates. No other way can defuse the big global problems, because they are basically due to the quest for affluence and growth. We could make this transition easily and quickly…if enough of us wanted to do it. (For the detailed case see thesimplerway.info/.) I think the chances of this path being taken are very poor, but lots of people are working for it, including the Simplicity Institute (2017.)
Ted Trainer is a Conjoint Lecturer in the School of Social Sciences, University of New South Wales and is a Simplicity Institute contributing author. This article and his other writings can be found at http://thesimplerway.info/
Clack, C. et al., (2017), “Evaluation of a proposal for reliable low cost grid power with 100% wind, water and solar”, PNAS, June 27, 114, 26, 6722 – 6727.
Crawford, D., T. Janovic, M. O”Connor, A. Herr, J. Raison and T. Baynes, (2012), Potential for electricity generation in Australia from Biomass in 2010, 2030, and 2050, AEMO 100% Renewable Energy Study, 4 Sept. CSIRO Report EP – 126969.
Elliston B., Diesendorf, M.,and I. MacGill, (2012). “Simulations of scenarios with 100% renewable electricity in the Australian National Electricity Market”, Energy Policy, 45, 606 – 613.
Friedmann, A., (2016), When Trucks Stop Running, Dordrecht, Springer.
Hall, C. A. S and K. A. Klitgaard, (2014), Energy and the Wealth of Nations, Dordrecht, Springer.
Heinberg, R., and D. Fridley, (2016) Our Renewable Future, Santa Rosa, California, Post Carbon Institute.
Hart, E. K., and M. Z. Jacobson, 2011. A Monte Carlo approach to generator portfolio planning and carbon emissions assessments of systems with large penetrations of variable renewable, Renewable Energy, 36, 2278 – 2286.
Heard, B., et al, (2017), “Burdon of proof: A comprehensive review of the feasibility of 100% renewable-electricity systems”, Renewable and Sustainable Energy Reviews, 76, 1122-1133.
Heinberg, R., and D. Fridley, (2016) Our Renewable Future, Santa Rosa, California, Post Carbon Institute.
Lenzen, M., B. McBain, T. Trainer, S. Jutte, O. Rey-Lescure, and J. Huang, (2016), Simulating low-carbon electricity supply for Australia, Applied Energy, 179, Oct., 553 – 564.
Moriarty, P., and D. Honnery, (2010), The Rise and Fall of Carbon Civilization, Springer, Dordrecht.
The Simplicity Institute, 2017. simplicityinstitute.org/
Trainer, T., (2013), "Can Europe run on renewable energy? A negative case", Energy Policy, (63) 845 – 850.
Trainer, T., (2017a), “Some problems in storing renewable energy”. Energy Policy, (in press.) thesimplerway.info/REstorage.htm
Trainer, T., (2017b), “Can renewables meet total Australian energy demand: A “disaggregated” approach.” Energy Policy, (in press.) https://authors.elsevier.com/a/1VRG014YGgTtEE, and at thesimplerway.info/CanRE.htm
Trainer, T., (2017c), “Estimating the retail price for 100% Australian renewable electricity.” (thesimplerway.info/REretailprice.htm
Trainer,T., (2017d), “The overlooked significance of the EROI for renewable energy supply systems.” (In press.) thesimplerway.info/REsystemEROI.htm