Is it cheaper per MW of generated power? I thought that the main reason use of gas has increased so much (for power generation) over the past 20-30 years is that gas became cheaper.
It depends on the region. The US has shale gas which is genuinely cheaper than coal. Europe doesn't want to use coal for political reasons. China and India barely use gas since it can't compete with coal.
Gas prices vary across the world, mostly depending on if it's only LNG imports (high prices) or local sources (much cheaper, e. g. the US) or a mix (e. g. Europe but since 2022 it's heavy reliant on LNG which pushes prices up). Coal prices also vary. Guess we cannot compare gas and coal prices globally, only withing a specific region.