The huge sums energy firms get to not provide power
It is 1am on 3 June. A near gale force wind is blasting into Scotland. Great weather for the Moray East and West offshore wind farms, you would have thought.
The two farms are 13 miles off the north-east coast of Scotland and include some of the biggest wind turbines in the UK, at 257m high. With winds like that they should be operating at maximum capacity, generating what the developer, Ocean Winds, claims is enough power to meet the electricity needs of well over a million homes.
Except they are not.
That's because if you thought that once an electricity generator - whether it be a wind farm or a gas-powered plant - was connected to the national grid it could seamlessly send its electricity wherever it was needed in the country, you'd be wrong.
The electricity grid was built to deliver power generated by coal and gas plants near the country's major cities and towns, and doesn't always have sufficient capacity in the wires that carry electricity around the country to get the new renewable electricity generated way out in the wild seas and rural areas.
And this has major consequences.
Ocean Winds was paid to turn down the output of its wind farms in the Moray Firth
The way the system currently works means a company like Ocean Winds gets what are effectively compensation payments if the system can't take the power its wind turbines are generating and it has to turn down its output.
It means Ocean winds was paid £72,000 not to generate power from its wind farms in the Moray Firth during a half-hour period on 3 June because the system was overloaded - one of a number of occasions output was restricted that day.
At the same time, 44 miles (70km) east of London, the Grain gas-fired power station on the Thames Estuary was paid £43,000 to provide more electricity.
Payments like that happen virtually every day. Seagreen, Scotland's largest wind farm, was paid £65 million last year to restrict its output
71% of the time, according to analysis by Octopus Energy.
Balancing the grid in this way has already cost the country more than £500 million this year alone, the company's analysis shows. The total could reach almost £8bn a year by 2030, warns the National Electricity System Operator (NESO), the body in charge of the electricity network.
It's pushing up all our energy bills and calling into question the government's promise that net zero would end up delivering cheaper electricity.
Now, the government is considering a radical solution: instead of one big, national electricity market, there'll be a number of smaller regional markets, with the government gambling that this could make the system more efficient and deliver cheaper bills.
But in reality, it's not guaranteed that anyone will get cheaper bills. And even if some people do, many others elsewhere in the country could end up paying more.
The proposals have sparked such bitter debate that one senior energy industry executive called it "the most vicious policy fight" he has ever known. He has, he says, "lost friends" over it.
Meanwhile, political opponents who claim net zero is an expensive dead end are only too ready to pounce.
It is reported that the Prime Minister has asked to review the details of what some newspapers are calling a "postcode pricing" plan. So is the government really ready to risk the most radical shake-up of the UK electricity market since privatization 35 years ago? And what will it really mean for our bills?