It is 7pm on a cold, still night in the city which boasts “100% Green Energy”.

Thousands of electric cars are plugged into chargers; electric lights, heaters and TVs are running; electric stoves are cooking dinner, electric trains and lifts are moving late commuters and early revellers, and the pubs and clubs are busy.

The hills bristle with turbines, but there is no wind and not one is turning. Every roof is covered with solar panels, but there is no sunshine and the panels are fast asleep. The green city is facing peak electricity demand . . . on batteries.

But for several days, clouds have shaded the solar panels and there has been no wind to turn the turbines – the battalions of batteries are running out of juice. One by one they drop out. The street lights fade and the city goes dark.

In this green energy utopia all the wicked coal-powered generators have been demolished, exploration for gas is forbidden, no one dares to mention nuclear, hydro schemes have gone (replaced by “Wild Rivers”), new hydro developments are stalled by green lawyers, and diesel generators are banned.

There is only one problem with this green perfection.

When the city wakes to another cloudy windless day, where will its electricity come from?