Mega, we regularly discuss how this is done in practice, and how it costs consumers. Why don't you contribute to these threads?
There is one just started today the new role for coal in german energy revolution
The problems of backing up renewables with coal are far greater than they are on an island with a diesel which can accelerate instantly. The major problem in my eyes is making conventional power redundant because it doesn't have a guaranteed market as wind/solar do. Once they are mothballed they need a year's notice to power up again, not a couple of minutes.
