I have just finished reading the book “Sustainable Energy without the Hot Air” by David MacKay who is a professor of physics at Cambridge University. It is a breath of fresh air which cuts through all the politics to analyse our real options for a future without fossil fuels. The news for Britain and most of Europe is not good unless we expand Nuclear Power. The problem is that the energy density of renewable energy is way too small. The most promising renewable for Britain is wind energy, although it is still currently 3 times more expensive than nuclear. The key problem is that the area of land needed to make a big impact is vast. If one covered 10% of the surface of Britain (all the windy parts) in wind farms one could power about 20 light bulbs per person. This is a huge area of land, would have a massive impact on the countryside and represents roughly twice the total number of wind turbines in existence today (US + Europe combined). However even then it only produces about half the energy currently consumed by car transport per person. A future transport system without fossil fuels would most likely have to be electrically generated by these same wind turbines or something else !
Solar energy for Britain will not make a large contribution and is best used for water heating. However it can produce large power if allowed to cover vast areas in deserts using optical concentrators (mirrors and lenses) plus photovoltaic farms. This means that the US could conceivably replace most of its fossil fuel requirements with a solar energy farm covering most of Utah. Europe would have to import energy from Libya or Tunisa where huge solar energy farms the size of Yorkshire would need to be placed in the Sahara desert. Again though we would be dependent for energy security on foreign supplies.
Wave power is too ineffective compared to wind. Tidal power however is fairly economic for a smallish contribution at specific sites like the Severn estuary and tidal pools like the Wash, and has the advantage that it is reliable (unlike wind speed). Biofuels and Biomass burning is just a non-starter. Britain could only sustain < 1 million stone age men burning wood and living on the borderline from the available land. Applying science to exploit non-nuclear renewable energy based in Britain could perhaps sustain a population of 10 million with a moderate standard of living. The current population is 60 million.
The only possible way for Britain (and northern Europe) to be sustainable in the medium term without fossil fuels is a 10 fold expansion in Nuclear (Fission) energy. Renewables can provide a significant contribution but a core energy supply which is 100% guaranteed is essential. Eventually nuclear fusion might provide a long term stable energy “nirvana” with endless supply – but this is still a distant dream and despite ITER is still not a certainty. I believe that it is achievable within 50 years given the willpower and the commitment.
It is very attractive and fashionable to take an emotional political/ideological/religious stance on energy and climate change but the numbers have to add up, and quite frankly they don’t without nuclear. To pretend that a future built just on green renewable energy can sustain a world population of 9 billion is simply daft.