The UK has figured out a nice mix of wind and PV. Their coal use is down to 5% and NG is next.
Below I graph April 2019. I'd like to show the full year but I was too lazy to download 12 files
Coal is ~ 1 Kg/kWh carbon emissions
NG is ~ 600 mg/kWh carbon emissions
Cheapest retail electricity is at night at ~ 4p/kWh ... when the carbon intensity is **lowest**
4 hour battery storage or imports from hydro rich countries will let them pretty much flatten their emission curve and continue to eliminate fossils in the next 5 years or so.
Data source: https://carbonintensity.org.uk/