Nine hours below zero.
Minus £25 a megawatt hour.
An Atlantic storm rolled in on Friday night. By Saturday the turbines were spinning flat out, the sun was doing its bit wherever the clouds broke, and the country did not need any of it. Prices fell below zero for nine straight hours and bottomed out at minus £25. Britain spent Saturday being paid to consume its own electricity.
🌪️ A storm is a fuel delivery
We are trained to think of a storm as a problem. For a grid with a lot of wind on it, a storm is a delivery of free fuel, arriving all at once, whether or not anyone ordered it.
Friday night's Atlantic system drove enormous output from offshore and onshore turbines straight through Saturday.
Saturday is also when factories are shut, offices are dark, and national demand is at its laziest. Maximum supply, minimum demand. The price had nowhere to go but down, and then through the floor.
💷 What minus £25 actually means
A megawatt hour is roughly what a typical home uses in three or four months. At minus £25, a generator was paying £25 to get rid of that.
Nobody knocked on your door to offer you the £25. The people who captured it were the ones with something that could soak up power on command: grid batteries, a few thousand smart-charged EVs, industrial sites with automated load.
Everyone else paid their normal flat rate all Saturday, blissfully unaware that the underlying commodity had briefly become a liability.
🚗 Nine hours is a very long time
This is worth sitting with. Not nine minutes. Nine hours.
That is not a freak half-hour that only a trading algorithm could catch. That is most of a working day. A car plugged in on a Saturday morning could have charged through the entire negative window without anyone lifting a finger.
The technology to do this is a piece of software and a plug. That is the whole shopping list.
On Saturday the wind blew, the grid filled up, and Britain paid people to take electricity away. Most households responded by paying full price for it. The storm was on the news. The nine hours were not.