Questioning “Our Renewable Future”

February 14, 2017

This valuable book explains many of the difficulties making the achievement of 100% renewable energy uncertain.  However a much stronger case can be given, indicating that present energy-affluent societies cannot be run on renewables.  We can and must shift to renewables, but there must also be dramatic reduction in energy consumption, rich world “living standards” and GDP.

There is a very strong tendency for green people to take it for granted that we can transition to 100% dependence on renewable energy sources without any significant reduction in “living standards” or the economy, and do it at low cost. Many impressive studies and reports make this claim.  I have examined several of these and written a number of detailed critiques.  All make highly challengeable assumptions and most are of little or no value because they are not based on actual weather data for the regions under discussion.

The book Our Renewable Future by Richard Heinberg and David Fridley (2016) provides a detailed and valuable discussion of the scene and of the uncertainties and difficulties. It stresses that even if these are overcome there must also be major change in rich world systems and lifestyles. But I think they do not make clear the magnitude of the challenge, and I want to argue here that there is a more effective way to show this. Only be trying to estimate the amounts of energy needed and available can we estimate how likely or unlikely it is that everything can be run on renewables. This can only be done if the issue is approached in a numerical or quantitative way, that is attempting to assess how much energy is needed in various forms, the possible sources and limits and costs, and especially what amounts of what forms would be needed to get around the intermittency and storage problems. My detailed attempt to do this is here. It derives the conclusion that even in Australia with its highly favourable renewable energy resources it would be much too costly to have sufficient renewable capacity to run anything like the kind of society we have today.  An indication of the case is given below.

For many years I have argued that the alarming and deteriorating global predicament cannot be solved unless we abandon the commitments to economic growth, the market system and a culture of individualistic competitive acquisitiveness. (For the detail see  However most people do not hold this world view, but believe that adjustments and technical advances such as adopting renewables will be sufficient to sustain societies that are more or less like those we have today.  If my view is correct we have to face up to making the most enormous and radical change imaginable, and quickly.  I am arguing here that there is a much more coercive case for this view than is put in Our Renewable Future.

Two preliminary points; firstly, there is no doubt that we must shift to 100% renewable energy, as quickly as possible. In other words this is not an argument against transition to renewables.  Secondly, my analyses are not confident. They set out the situation that the evidence I have seems to support, but they could be quite wrong.  All assumptions and derivations are clear and easily checked and it is important that these analyses be critically examined. Those who doubt my conclusions are encouraged to try to find why they are invalid and thus help us to work towards a more confident understanding of the field.

The electricity task

There have recently been two impressive studies of the possibility of 100% renewable power supply in Australia, involving complicated modeling based on detailed weather data.  The first was by Elliston, Diesendorf and MacGill (2012, 2013.)  I will however deal with the second study, by Lenzen et al. (2016) which I think is based on more satisfactory assumptions. (I am listed as a co-author but played a very minor role; the significance of the study derives from the modeling carried out by the others.)

The general finding is that given the weather data for 2010,100% renewable electricity supply could have been achieved at a production cost of 20c/kWh, but probably 30.3c/kWh under typical conditions. The amount of generating capacity needed to deal with intermittency would have been 5 to 6 times average demand, and considerable use of biomass would have been needed. Most countries have far less biomass potential than Australia.

I have attempted to estimate what the difference between this production cost and a retail price is likely to be, taking into account a) the many factors left out of the study to simplify the already huge computing task, and b) the factors operating on production cost to result in the retail price. My (easily followed) derivation leads to the probably surprising conclusion that retail price would be around 70+c/kWh, or three times the present Australian retail price.

Such a price might be tolerable but it is likely to be at least quite economically disruptive, especially when added to the significant economic difficulties that lie ahead (e.g., accelerating inequality, falling productivity, skyrocketing debt, peak oil, falling ore grades, the coming robot invasion, and ecological deterioration on all sides…) High retail power prices would multiply and pyramid through the whole of the economy. More importantly a high electricity price would have very serious implications for a 100% renewable supply of total energy, because that supply would have to be heavily, indeed almost entirely based on electricity and inefficient derivatives, such a hydrogen.

100% total energy supply from renewables?

Meeting total energy demand from renewable sources is a quite different task to just meeting electricity demand.  At present electricity makes up less than 20% of total energy demand in a rich country, and it is the form most easily provided by renewables. Biomass is the only renewable form that does not directly produce electricity, and it is limited. Providing all forms of energy needed from renewables involves much more than simply scaling up the power supply system by a factor of 5. This is mainly because most of the remaining 80% of energy used and not presently in the form of electricity sets problems to do with a) the nature and number of these other forms, and b) costs and losses in switching them to electricity, c) the amount that cannot conveniently be switched, and d) the energy and dollar costs of converting electricity or biomass into these more difficult forms.

To analyse the situation well we would need a complete list of the different kinds of energy in the present total energy budget, such as how much liquid fuel is needed for what purposes, and we would need to ask about the extent to which electricity might be able to replace each of these. How might we run trucks, ships, aircraft, remote mines etc.? What might be the conversion losses and efficiencies, and what might be the ultimate total renewable system cost? Unfortunately there is little information on these issues. Therefore the following exploration must be regarded as uncertain and indicative only.  However it does illustrate the kind of analysis that is needed, and it provides a strong case that if a 100% renewable energy supply is achievable it will at best be very difficult and costly to do.

Estimating a 2050 Australian total energy budget

The approach detailed in is to begin with an attempt to work out the quantities of energy in what forms might be needed in Australia by 2050, given the goal of converting all demand to renewable forms. Following is a summary of the main elements in the case; all assumptions and derivations are spelled out clearly in the full account.

My apologies for all the numbers and arithmetic following, but meaningful discussion of this issue cannot be undertaken without these. The issue is a quantitative one. My main aim here is to indicate the form or approach that a convincing case must take.

Main assumptions: Present (2015) final energy consumption 4,130 PJ, electricity 810 PJ, 20% of final, transport 1603 PJ, 39% of final, population will multiply x 1.82, 2050 BAU (“business as usual”) demand is very difficult to estimate but is assumed here to continue the 1974-2017 growth rate which was proportional to population, and thus be 7,520 PJ by 2050 (this is quite debatable, and reconsidered later.)

Thus 2050 final energy demand is taken as, Electricity, 1,472 PJ, Transport,   2,917 PJ, Remainder  3,131 PJ, Total 7,520 PJ. How night these quantities be provided?

  • Electricity energy provision: Assume 94% of electricity provided by wind, solar, and hydro, plus 6% from biomass used for back up (from Elliston, Diesendorf and MacGill, 2012, 2013), requiring 340 PJ/y biomass assuming the Australian Energy Market Operator estimate of 26% generation efficiency. (Crawford, et al., 2013.)
  • Transport energy provision: Assume all passenger vehicles can be electric vehicles, doubling energy efficiency (not trebling, in view of the high embodied energy cost of EVs), one third of light trucks each run on electricity, ethanol and hydrogen, half heavy trucks run on ethanol and half on hydrogen (transfer of freight to rail not accounted, but that would greatly increase light truck use for distribution from rail heads), air transport fuelled by ethanol, shipping energy use not included.
  • Remaining energy provision: This is quite large, 3,131 PJ and 43% of total demand.  It is difficult to find information on its composition, or to work out how much of it could be provided via non-electrical paths, and therefore how much additional electricity this category would require to be generated.

Let us take out of the electricity task all low temperature space heating on the (unrealistic) assumption that it can be provided without electricity, e.g. from simple solar thermal panels. The two most relevant figures available are, firstly residential heating and cooling makes up about 5.6% of total Australian energy use, and industrial plus commercial energy use add to about 32% of the total. If one quarter of this second quantity is low temperature heat that need not be provided via electricity, then residential + industrial + commercial low temperature heating might add to 12% of total energy. This would mean that 12% of the BAU target 7,530 EJ, i.e., 904 PJ, can come from solar thermal panels, reducing the remaining category to 2,227 PJ. (In the real world much heating and cooling will be carried out by heat pumps, using electricity, but the above assumption is that all is provided by solar thermal panels, unrealistically reducing the total electricity demand to be met.)

Let us now make the simplifying (but also incorrect) assumption that all of the remainder category can be provided by electricity. The resulting quantities to be supplied would be,

                                                    Electricity                Biomass                  Hydrogen

Electricity demand              1,384 PJ             340 PJ biomass

Transport  demand                 765 PJ            977 PJ as ethanol,        977 PJ                                                                                = 2,443 PJ biomass

Remaining 45%                    2,227 PJ


Totals                                     4,376 PJ                2,783 PJ biomass       977 PJ



The biomass figures above are for ethanol derived from biomass.  If it is assumed that the energy efficiency of this process is 40% it would require 2,783 PJ of biomass to produce. But when the amount assumed for back up of electricity generation (above) is taken into account, along with the estimate by Crawford et al., (2013) of the total possible Australian biomass energy harvest, there is a shortfall of 1,395 PJ. This would have produced 558 PJ of ethanol, so it will be assumed that this will now have to met by hydrogen, bringing that total to 1,535 PJ.

But to have 1 unit in the form of hydrogen about 1.7 units must be generated in the form of electricity (… even ignoring the large energy cost embodied in hydrogen production, storage, and pumping equipment and leakage losses.) Thus generating the hydrogen would require 2,610 PJ of electricity.   The electricity total would then become 4,376 + 2,610 = 6,986 PJ, or c. 6,940 PJ after taking the small (c. 50 PJ) hydro contribution into account. This is about 9 times the present amount of electricity generated in Australia.

At this point the detailed account considers the effects of more optimistic assumptions, including a 30% saving due to conservation effort, but they do not seem to make a huge difference.

On the other hand it is likely that in 2050 many functions will require greatly increased energy inputs, such as mining and processing poorer ores, water desalination, denser settlements involving much high rise construction and living, and recycling higher proportions of waste. It has recently been realized that productivity growth is significantly due to adoption of more energy intensive ways, so the quest for it will tend to raise use. Global freight and especially tourism and air traffic are expected to increase faster than population. Energy will be needed to cope with challenges to agriculture. Increasing effort will be needed to deal with generally accelerating ecological deterioration. Above all dealing with the many effects of climate change will add very large energy costs that do not exist at resent, including defensive works such as sea walls, settlement relocation, salt water incursions into agricultural land, remedying storm damage, dealing with refugees, adapting to altered rainfall patterns (which for instance can make existing dams redundant), dealing with pest surges and algal blooms, and developing new crops for altered conditions. Probably the greatest problem will be set by the fact that the IPCC greenhouse targets assume that very large amounts of carbon will have to be taken out of the atmosphere after 2050, which would require use of enormous amounts of energy.


But let us ignore all those factors likely to increase the amount needing to be supplied; what might be the minimum cost of energy?  My detailed discussion of the Lenzen et al. study indicates that the retail price of electricity would have to be at a minimum somewhere above 46c/kWh. To provide 6,940 PJ/y, i.e., 1,927 billion kWh, at 46 c/kWh could cost $887 billion p.a., which is around 55% of the 2015 Australian GDP, or 28% of 2050 GDP assuming 2% economic growth. But the present rich country total expenditure on energy is usually well under 10%, and this includes taxes added on after all production and distribution costs have been totaled. (For example 40% of the price paid for petrol in Australia today is a tax added by government to the retail supply price.) If we could take out taxes we would probably find that the retail cost paid for energy in Australia today was closer to 6% of GDP.

It would obviously be impossible to pay out anything like 29% of GDP for energy. Hall and Klitgaard (2014) find that when energy expenditure remains above about 5.5% of US GDP for some time recession occurs. In other words far lower assumptions than have been made in this exercise would have to be true before the costs arrived at could be affordable. And all this is for Australia, which has possibly the most favourable renewable energy conditions in the inhabited world

The belief that energy supply can be 100% renewable is probably the main element in the tech-fix faith held by most people, including green and left people. They think there is no need to shift from something like present energy and resource intensive lifestyles and systems, or from an economy driven by growth and market forces. If the position arrived at in this reassessment is sound then the big global problems cannot be solved unless there is dramatic reduction in rich world per capita levels of consumption, the present economy is abandoned, there is immense cultural change away from individualistic, competitive acquisitiveness, and transition to some kind of radically Simpler Way. (That this would be workable and attractive is argued at

So I believe a much stronger case for such a transition can be made than is found in Our Renewable Future.


Crawford, D., T. Janovic, M. O”Connor, A. Herr, J. Raison and T. Baynes, (2013), Potential for electricity generation in Australia from Biomass in 2010, 2030, and 2050,  AEMO 100% Renewable Energy Study, 4 Sept. CSIRO Report EP – 126969.

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.


Teaser photo credit: Pumped hydro station image via shutterstock. Reproduced on with permission.

Ted Trainer

Dr. Ted Trainer is a Conjoint Lecturer in the School of Social Sciences, University of New South Wales. He has taught and written about sustainability and justice issues for many years. He is also developing Pigface Point, an alternative lifestyle educational site near Sydney. Many of his writings are available free at his website The Simpler Way.

Tags: Our Renewable Future, Renewable Energy, renewable energy transition, The Simpler Way