Re: The UK mostly powered by coal?
@AC - You need to understand the difference between dispatch and dispatch on request.
Steam power has been used for centuries, but in that time no-one has solved the problem of the time it takes to build a head of steam (yes, there have been improvements, but it's still far from instant).
If you know some time in advance that it will be needed then you can prepare for the eventuality. If you need to deliver power on short notice then it is a poor solution. If you need to run the boilers on standby ready for when there is demand then it's a wasteful and inefficient solution.
Your steam train needed hours of work before it set off in order to prepare for a journey. Your coal based power plant throws away vast amounts of heat (have you never wondered what those large towers are next to one?), and it just dumps more heat when it's not generating power rather than converting it to electricity and then dumping it.
The idiocracy does indeed seem to have arrived.