This is part 2 of six. Part 1: How Long Is a Dunkelflaute? · Next, part 3: What the Thermal Fleet Actually Does
Figures keep one numbering across the whole series, so a reference to figure 29 means the same chart wherever you meet it.
Figures 8-11 and 20.
Britain's other grid
Britain runs a second energy network, and it is the bigger one. On a January morning it delivers close to three times what the electricity system has ever managed at its own all-time peak — and almost nobody thinks about it, because in a century of operation it has never once asked them to.
That is the network the last part left us standing in front of. This part is about what happens when its job is handed to the wires.
The reason nobody thinks about it is the whole trick, and it is not the network — it is the fuel. Heating has always been the largest thing a British household does with energy and much the most seasonal. What made that manageable is that wood, coal and oil are dense and they sit still. You could put a winter in a cellar in October and take it out in February. Nobody had to build a delivery system sized for the coldest morning, because by the coldest morning the delivery had already happened. Even mains gas keeps a version of this: "linepack", the gas already sitting in the pipes, lets the network balance over days where electricity gets seconds.