An interesting little report from the US. Looking at the full integrated costs (yes, including carbon emissions not made) of the various options for energy capture and or generation. And it looks like wind and solar really just don't cut it:
[A]ssuming reductions in carbon emissions are valued at $50 per metric ton and the price of natural gas is $16 per million Btu or less—nuclear, hydro, and natural gas combined cycle have far more net benefits than either wind or solar. This is the case because solar and wind facilities suffer from a very high capacity cost per megawatt, very low capacity factors and low reliability, which result in low avoided emissions and low avoided energy cost per dollar invested.
It's worth noting that that $16 gas price is well above the current gas price in the UK (around 40p per therm, while $16 equates to perhaps 100p a therm).
So, the really interesting question is how has the UK government managed to do the calculations showing that natural gas isn't the answer? To which the correct response is that they've assumed that natural gas prices are going to rise very strongly in the future. Yea, even if we frack the entire country, for all of that would just be exported anyway. This is, to say the least, an unsupportable assumption.
In the long run the answer is undoubtedly going to include a lot of solar. Prices are still falling at 20% a year and it really doesn't take all that many years for that to have a significant effect. As Bjorn Lomborg pointed out by 2025 we'll all be installing solar purely on price grounds anyway. In the interim gas is still the best answer: so we really should get fracking.