The 38.5% figure you're using is a mean over the course of a year so you're double counting, and the 40% you've chosen to discount by is an arbitrary fiction, the question is about the value of a "stockpile" and so arbitrarily assuming we can just buy more gas as we please to fill some of it back up begs the question.
Point to a specific calculation where 38.5% double counting.
That 40% was a ridiculous over the top doomsday estimate as the UK procedures a lot of natural gas and only ~7% of their imports came from Russia in 2021. https://www.statista.com/statistics/1324377/uk-natural-gas-i... The only reason to use 40% is to simulate the EU is reducing global supply and it’s impact wasn’t even close to that severe.
As to just buying more natural gas, that’s what actually happened so I don’t need to assume anything. The entire EU was able to successfully replace all Russian natural gas from the global market.
> Point to a specific calculation where 38.5% double counting.
The calculation you did. It uses this figure, but the figure itself is already accounted for in what you were trying to model, that is what double counting is.
The annual 38.5% includes both very windy days, and very sunny days, in which consequently PV input and wind power input were very high, as well as the dark and cold but still days in which neither produces very much power.
But the problem scenario we care about is long dark cold days of winter. You can't use a figure which averages in a bright but gusty June morning and use that as representative of a miserable January, you need to look at what it's like on such days, and it's much higher than 38.5%.
Remember, your original thesis is that somehow not using gas in June will save you needing gas in January and I've shown why that's nonsense, the "stockpile" involved is just far too small for this to make any sense.
For what you wanted to do to actually make sense the UK would need to buy at least ten times as much storage as it has now, ie enough to last out a nasty winter. But it shows no sign of wanting to do that, if anything exactly the opposite, preferring to "leave it to the market" and then acting confused when the market does what you'd expect, ie gouge them for every penny it can.
So in 2020 the UK produced 312 TWh * 35.7% = 111.384 TWh (Natural gas) / 365 = 305 GWh per day from Natural Gas.
Ignoring domestic production when the war started they where going to need to make up ~7% of that or 21 GWh per day or ~7.7 TWh across the entire year from missing Russian natural gas supply.
Now you've gone on a weird tangent where instead of talking about the topic on which I pointed out the numbers don't work (stockpiling gas in June so as to not need it in January), you've decided that for some reason the UK's goal needs to be making exactly the same ratio of extra electricity as as the fraction of Russian gas they used to import.
But those aren't comparable numbers, which will be why you've got this ludicrously small result. Even with the weird choice to replace specifically Russian gas in the UK (What about elsewhere? What about the huge price increases? What about global supply concerns?) you need to replace the gas not some portion of electricity. So that means you need to stockpile... drum roll... 5.6 billion cubic meters of gas.
But gas is a physical material, you need to keep it somewhere and the UK doesn't own storage for 5.6 billion cubic meters of gas.
It might seem like they must have more than that, but imagine what it would look like, imagine a 20km by 20km box, 14 metres high, that's the internal dimensions of the storage you're imagining.
The UK did own a noticeable fraction of 5.6 billion cubic meters, not enough but a fair start, the Rough storage site. Rough is actually gas wells which are dry, re-purposed as storage. However, the UK government didn't want to pay for this, so after it was sold into the private sector the owner decided they weren't bothered and it was moth-balled. Once emergency payments were forthcoming, a fraction of Rough that was in least bad condition was re-opened for this winter. Again though, even the whole site if magically restored to 100% service would not store 5.6 billion cubic meters, that's just a lot of gas.
Also, this may be shocking for you but people don’t store gas at standard pressure and temperature in big above ground tanks. So no 5.6 billion cubic meters of gas isn’t a 20km by 20km box. The UK has plenty of geologic features to store gas namely the same places it was extracting it from for decades.
