In the last three decades considerable concern has emerged regarding limits to the future availability of energy in the quantities required by industrial-affluent societies. More recently Colin Campbell and others have argued that the energy source on which industrial societies are most dependent, petroleum, is more scarce than had previously been thought, and that supply will probably peak between 2005 and 2015. Some of these people argue that the world discovery rate is currently about 25% of the world use rate, and that non-conventional sources such as tar sands and shale oil will not make a significant difference to the situation. The USGS (2000) has recently arrived at a much higher estimate for ultimately recoverable petroleum, but this would only delay the peak by some 10 years.
If the discussion is expanded to take into account the energy likely to be required by the Third World, the situation becomes much more problematic. If the present world population were to consume energy at the rich-world per capita rate, world supply would have to be five times its present volume. World population is likely to reach 9.4 billion by 2070. If all these people were to consume fossil fuels at present rich-world per capita consumption rates, all probably recoverable conventional oil, gas, shale oil, uranium (through burner reactors), and coal (2000 billion tonnes assumed as potentially recoverable), would be totally exhausted in about 20 years.
What is not well understood is the magnitude of the overshoot, the extent to which our present consumer society has exceeded sustainable levels of resource use and environmental impact. This is made clear by a glance at the greenhouse problem. The Intergovernmental Panel on Climate Change has given a range of emission rates and the associated levels that the carbon dioxide concentration in the atmosphere would rise to.
Perhaps the most quoted graph shows that if the concentration is to be stabilized at 550 ppm, twice the pre-industrial level, emissions must be cut to 2.5 gigatonnes per year (Gt/y) by 2040 and to 0.2 Gt/y by about 2200. The present level from fossil fuel burning (i.e., not including land clearing) is over 6 GT/y.
To keep the concentration below 450 ppm, emissions must be cut to about 1 + Gt/y by 2100, and to about 0.3 Gt/y by 2200. This target is much too high because the atmospheric concentration is now at about 380 ppm and many disturbing climatic effects are becoming apparent.
If world population reaches 9+ billion, a global carbon use budget of one Gt would provide us all with about 150 kg of fossil fuel per year, which is around 2-3% of our present rich-world per capita use of fossil fuels (in GHGe terms). Alternatively only about 170 million people, 2.5% of the world's present population, could live on the present rich-world per capita fossil fuel use of over 6 tonnes of fossil fuel per year.
These figures define the enormous magnitude of the sustainability problem we confront. Consumer-capitalist society has overshot viable levels of production and consumption by a huge amount. In effect we have to give up fossil fuels altogether. That is, we have to live almost entirely on renewables. This book argues that these very high levels of production and consumption and therefore of energy use that we have in today's consumer-capitalist society cannot be sustained by renewable sources of energy.
However, the foregoing numbers only define the magnitude of the present problem. This is nothing like the magnitude of the problem set when our commitment to growth is also taken into account. If 9.4 billion people are to have the "living standards" we in rich countries will have by 2070 given 3% economic growth, total world economic output every year would then be 60 times as great as it is now.
The question of whether we can run our society on renewable energy is therefore...