Renewable energy won’t save us.
A two page summary.
Most people seem to take it for granted that renewable energy can replace fossil fuels and thereby solve the greenhouse and energy problems. Following is a summary indication of the reasons for thinking that this belief is mistaken. (For a 20 page detailed numerical analysis see Trainer, 2010.)
The reviews of renewable energy conclude that wind could only provide about 20% of electricity needed, due to the problems set by integrating such an intermittent source into the supply system. Similarly, even on a very sunny day photovoltaic panels can deliver no energy for about 16 hours in that day and this probably limits it to a slightly bigger contribution than wind. So together wind and PV might contribute about half of the electricity needed, or only about 13% of all energy. There are only three other major possibilities for finding the other 87%. These are biomass, geothermal and solar thermal.
It can be argued that we should not try to develop large scale biomass energy plantations. We are now racing into a major holocaust of species loss, because we are taking so much of nature, especially the habitats plants and animals need. Instead of taking more land from nature to plant trees to harvest we should be returning large areas to natural vegetation.
But let us assume that we take 750 million ha for biomass production, which is three times the area assumed by the recent optimistic World Wildlife Fund Energy Report. (WWF, 2009.) This would produce annually ethanol equivalent to about 15% of world energy consumption. So after wind, PV and biomass we would still have to find 72% of energy via renewable sources.
Most of the world is not likely to get more than about 4% of its energy from hot rock geothermal sources. Australia might get more, but it is not clear whether we can.
That leaves solar thermal. It will be a major contributor, but it only produces electricity and 75% of the energy we need is not electricity.
Here’s probably your best strategy. Let’s assume that in the long term future we will have converted 85% of the economy to run on electricity, with biomass providing that remaining 15%. We will divide the generation task 25%, 30% and 45% to wind, PV and solar thermal respectively.
Let’s also make the common assumption that world energy demand is heading for about twice the present amount by 2050, but that energy-conservation effort will reduce this by one-third. When we take estimated future output and cost figures for renewable technologies (See the detail in Trainer 2011a and 2011b), a little arithmetic leads to an impossible conclusion. The ratio of world energy investment to GDP would be much greater than 20 times the present ratio.
In other words, we could not possibly afford the quantity of renewable plant required.
The longer discussion in Trainer 2011b includes the possibility of storing energy as hydrogen and in the heat tanks of solar thermal plant.
Note also that that if the goal assumed is to provide all the world’s people with the per capita amount of energy Australians use now, the supply target would have to be three times as high as was taken in this analysis.
This extremely energy-intensive consumer-capitalist society cannot be run on renewables. There are several other reasons why it is not an acceptable society, most obviously because it is based on an extremely unjust economy which delivers to the rich countries far more than their fair share of the (dwindling) resources. We can only achieve a satisfactory society if we move to The Simpler Way, i.e., lifestyles and systems that enable us to live well on a small fraction of present resource use and GDP. We need to build small, highly self-sufficient, co-operative and self-governing local economies which we run to meet needs and provide all with a high quality of life...with no economic growth at all and far lower levels of affluence. (For the detail see Trainer 2010, 2011c.)
This has not been an argument against transition to renewable energy. We must make that transition as soon as possible, and we could live well on renewable in The Simpler Way…but not in anything like the present energy-intensive society.
Trainer, 2010, The Transition to a Sustainable and Just World, Sydney, Envirobook.
Trainer, T., 2011a, “Can the world run on renewable energy? A revised negative case.” This is an improved version of the argument published as Trainer, T., (2010), “Can renewables etc. solve the greenhouse problem? The negative case”, Energy Policy, 38, 8, August, 4107 - 4114. http://dx.doi.org/10.1016/j.enpol.2010.03.037
Trainer, T., 2011b,”Renewable energy – cannot sustain an energy intensive society,”, http://ssis.arts.unsw.edu.au/tsw/RE.html
Trainer 2011c, “The Simpler Way, the alternative society”, http://ssis.arts.unsw.edu.au/tsw/TheAltSoc.lng.html