Are Ev's Fuel Source's "dirty?"

According to the UK National Grid Control Room,
. . . It’s a good thing that we use less electricity at night.
. . . Well, with our current generating infrastructure it’s very complicated.

Turning off a massive coal-fired power station is
. . . . . . hugely complex,
. . . . . . very expensive,
. . . . . . wasteful and
. . . . . . slow.
Turning off gas powered generation?  Same problem.
Turning off a nuclear power station?  Don’t ask; they don’t do turning off.
Turning off wind, however?  
. . . they just adjust the blades and those big turbines stop spinning.
So the Grid always try's to use wind because:
. . . it’s cheaper to use and
. . . it produces zero CO2.

This is obviously the first thing that will change and
. . . the current goal is to more than replace that capacity with wind.
As the demand drops through the evening,
. . . all the big coal burners go offline and
. . . more of our electricity comes from wind and nuclear.
. . . I.e. near zero CO2.
So, if you plug your electric car in at night,
. . . not only is it hugely cheaper
. . . but the proportion of power coming from renewables
. . . is likely to be much higher.

Source: thechargingpoint