Why the world can't rely on renewable energy if we want to remain affluent

Lenzen’s review of renewable concludes that it is not possible for wind to contribute more than 20 to 25 per cent of electricity demand because problems caused by variability increase steeply after that point, setting integration difficulties. He suggests that a slightly higher figure for PV. But this is debateable. This means that wind and PV can at best supply 55 per cent of the 20 per cent of energy that takes the form of electricity. Where are we going to get the other 89 per cent?

Lets briefly consider the options.

Biomass In an era when land is being lost and a food crisis is developing, the world is very unlikely to find as much as a 1 billion hectare on which to plant biomass energy crops. The loss of habitat is the cause of the holocaust of extinctions we are now causing so we should be returning vast areas nature, not thinking about taking more. If that area was put into producing ethanol we would probably get 50 EJ which is around 5 per cent of the world energy demand figure we are heading for by 2050.

Geothermal Even the renewables-optimistic WWF Energy Report (2010) and the claims of Jacobson and Delucci (2011) assume geothermal can contribute about 4 per cent of world energy. Australia has much better hot dry rock heat resources than the rest of the world but it is anything but clear how effectively they can be tapped, if at all. How much energy will it take to bore holes 5 km deep through rock, fracture rock down there, pump water down and force it 500 metres across to the nearest rising hole? What will be the temperature and rate of flow of the water that comes up, and what generation efficiency will that enable? And what will be the dollar and energy costs of constructing very long transmission lines from the deserts where the hot rock is? The answers are not known yet. The only operating plant in Australia (not at the most promising location) achieves 6 per cent efficiency, one-sixth the value for a coal-fired power station. Early in 2010 the much-publicised Geodynamics venture abandoned its efforts, writing off $350 million. 

Solar thermal Here’s the back-of-envelope calculation. The world is heading towards needing 700 EJ/y of final (not primary) energy by 2050 (Moriarty and Honnery, What energy levels can the earth sustain, 2009). Let us assume a 33 per cent reduction in demand due to energy efficiency effort. My review of solar thermal systems found that in mid-winter both central receivers and Big Dishes could probably deliver at distance a continual flow of about 25W/m2 of collection area. Probably the best strategy. Big Dishes using ammonia for heat storage, might cost $600 per square metre in future. This means we’d need 1,980 million of them, the total cost would be $475 trillion, i.e., $19 trillion p.a. assuming a 25-year lifetime. If we assume world GDP will treble by 2050 this sum would be 13 times the present ratio of energy investment to GDP in developed countries. Note that other costs such as the transmission lines, thousands of kilometres from the deserts, have not been included. And we would still have a problem of intermittency; i.e., what to do when there is little or no sun on the solar thermal fields for days at a time...pay for huge excess heat tank storage capacity

Hydrogen How about using huge numbers of windmills, the cheapest renewable source, to produce and store hydrogen. The energy efficiencies of a) producing hydrogen from electricity, b) compressing, pumping and distributing it, and c) re-generating electricity via (very expensive) fuel cells are optimistic, meaning that for each kWh your windmills generate you end up with .22 kWh to use via this path. So a crude estimate is that to supply 89 per cent of that 700 EJ/y this way we would have to produce 2,8232 EJ/y, and we would need 179 million windmills each of 1.5 MW peak capacity (each producing on average .5 MW or 15.8 TJ/y and costing $3 million), at a total cost of $534 trillion, i.e., about the same cost as the solar thermal option. We would have to add the cost of the hydrogen production compression/liquifaction, distribution and huge storage capacity.

Whatever option you choose, you might have to multiply the total by 1.75 to pay the interest on the capital borrowed to build all that renewable plant. Finally, the cost of energy and materials are now rising fast and will be much higher than is assumed in the above exercise. All this has been a long-winded way of saying that we couldn’t possibly afford it.

By the way, if your goal was to provide to all people, probably 9+ billion by 2050 the energy per capita Australians are heading for, your target would be 5 times as great as the 700 EJ/y assumed in the above exercises. Do you still think the world can all live affluently on renewables?

What is the answer then?

The point is, there isn’t one. If the question is how can we provide the energy to keep going the energy-intensive, growth and market driven societies we have in rich countries today, let alone to enable the continuous and limitless pursuit of ever-increasingaffluent living standards, then the answer is that it cannot be done. For decades many of us have been trying to get the mainstream to grasp that this quest is suicidal. 

We Australians now have a productive land footprint that is ten times as big as would be possible for all people in 2050. It is precisely the mania for affluence and ever-greater levels of production, consumption and GDP that is causing all the big global problems, most obviously resource depletion, Third World deprivation, the greenhouse problem, the destruction of the environment, and international conflict.  Such a society cannot be fixed. For instance you cannot reform a growth-based society so that it can have a zero growth economy, let alone one producing at a small fraction of present levels. Sustainability is not achievable without scrapping and replacing several of the fundamental structures of this society.

For fifty years mainstream society has refused to face up to this case, and their delusion has been strongly reinforced by the unexamined faith that renewable energy can be substituted for carbon fuels and enable us all to go on pursuing affluence and growth. 

This has not been an argument against transition to renewable energy sources. It is an argument that they can’t run energy intensive societies. We must move to full dependence on renewable energy sources as soon as possible. We can all live well on them...but not in consumer-capitalist societies. For detail on the radically different path that must be taken, see The Simpler Way website http://ssis.arts.unsw.edu.au/tsw/ .