As a result, we will remain critically dependent on our nuclear and combined cycle gas generation (CCGT) turbines to deliver power when renewables let us down.

And herein lies the problem — a significant proportion of our reliable generation capacity is due for closure over the next few years. For example, all of our existing nuclear power stations will be retired by 2031. The only replacement in the offing is Hinkley Point C, due for completion in 2027 (although industry rumour has it that 2030 is more likely). There is a plan to build a further 24 GW, but that’s in the distant future.

Meanwhile, CCGT plants are being retired too, as they reach the end of their 25-year lifetimes. There is little enthusiasm among investors build new ones either, even with subsidies available. These machines work best when run flat out, and all those renewables mean that will happen only rarely.

Finally, Britain’s last coal-fired power station is due for closure within months.

The upshot is that by 2025 – the first full year of a Labour government – we may have just 18 GW of nuclear and gas left (Figure 2). By the end of its term of office, the total may have fallen to as low as 12 GW. Extending the lives of nuclear power stations, if safety regulators allow it, might add a bit more, and there is biomass too. However, if, as noted above, demand peaks at 45 GW or more, it is hard to imagine how we will avoid a serious crisis, with unsustainable electricity prices, black- and brown-outs, or both.