So what's the problem with sustainable/green energy?

Cost

Part of the problem is that many times libs want to use green energy in place of fossil fuels not in conjunction with fossil fuels. Some green energy sources are not consistently reliable such as wind power and others such as wind farms kill large amounts of birds. Note too that when wind farms were proposed off the coast of Cape Cod the libs went nuts-it was the old not in my back yard syndrome.

Relatively recently, we thought "Oh crap! We should turn to alternative energy" so the stuff isn't up to par yet. All the systems have there downs but we are working to figure them out.

There are huge tax breaks and subsidies for wind generation and solar panels. Wind turbines are an absolute nightmare for bird but they are even worse for bats. I have seen bats killed by wind turbines even though they didn't get hit - the vortex close to the blade is such it can burst their lungs. Wind, Wave, and Solar power in the UK are not in any way shape or form predictable or consistent. You cant wait for it to get windy or sunny for everyone to put their kettle on. As yet the UK has very limited energy storage capabilities. For these green sources to be used the UK would probably have to be able to store enough power for the equivalent of 3 whole days. That's a colossal amount of power. Also Wind / Wave / Solar does not work well in conjunction with current generation methods. EG when the wind drops conventional generating has to take over. If the wind drops fast this can cause a problem as conventional power stations cannot ramp up just like flicking a switch. Wedefinitely need more storage like the hollowed out mountain in wales that pumps water in to store electricity and then runs as a hydroelectric plant to get it back again. However we would need several thousand of them at least (I'd estimate possibly 20,000 such plants) to cover for overcast days with no wind in winter.