[dalke]

The original premise was already unrealistic. I made it even more unrealistic. If there is a "Mr. Fusion" device which can produce 1.21 GW, on-demand, safely, and it small and light enough to fit in your car, then there's no need for a grid. You would just have several of those devices in your house.

My hypothetical was to show that there could be cases where it does not make sense to use a Mr. Fusion type device to produce hydrocarbon fuel which is then used as the energy source. Everything I said takes place in the original fantasy world. Under the original premise -- "some grad student gets fusion going at a very low price" -- then it must be using some principle we haven't yet thought of. And with that premise in place, almost anything goes.

Once I put realism into place, then the original hypothetical is not sustainable. The long term solutions for real life are decreased energy use, fission, hypothetical fusion, and renewable. None of the last three can exist without a grid, at least for most people. The only way to be without a grid is greatly reduced power use, a less concentrated population, and switch to local renewable resources. That isn't going to happen.