[pi3832]

I think the fact that you'd need a natural gas pipeline, or a propane tank out back, kind of negates the "disconnected from the grid" thingy.

Also, where does one get the energy to heat the magic box to 1800 F?

[cracki]

from the box itself, i'd guess... electric heating elements?

[pedalpete]

electric heating elements to get 1800F? Wouldn't that take more power than this thing would create? I missed the part about heating to 1800.

[ncarlson]

The chemical reaction heats up the box. However, large amounts of insulation is needed to retain the heat.