> It's higher than prevailing prices. And it gets higher the more autarkic and decentralised the system needs to be.

I don't actually think that that is true. If I look at the cost / KWh + the network costs + various subsidies you can probably supply a house for a lifetime if you the energy consumption costs for that same lifetime and spent them up front on decentralized generation + storage.

It's all about the density, not so much about the cost and as the density goes up so do the complications and the costs. But if you have enough ground (which really isn't all that much) it is perfectly doable today, and probably you'll be in the black in a surprisingly low number of years. The higher the cost of oil the higher the cost of gas, and the higher the cost of gas the higher the cost per KWh (this may vary depending on where you live).

> How much extra are your citizens willing to pay every year to reduce supply disruptions?

That's a very good question. Probably not much until it starts to happen regularly, so I would expect that problem to solve itself over time. Energy has been a hot topic for the last decade and with every price shock it is getting easier to convince people that if they had more autonomy they would be less affected. Solar + heatpumps have exploded in Europe in the last decade and that trend has not stopped, in spite of a reduction in net metering. Ironically, the biggest stumbling blocks are the governments that want to tax energy but see no way of doing this if it is generated and consumed on the spot.