I should say I agree that we don't have much experience in building tech that will last a long time and that the expense is definitely high. I don't know that component reliability is as important as being able to replace components efficiently with as little waste as possible. Energy demand is a big concern. Having a fully automated power plant of some kind is a big concern, although maybe solar wouldn't be so bad. I know you'd still desire to store the heat energy, say, as molten saline, to get steady output, and that could cause big difficulties in the long term. Maybe steady output isn't necessary though, just frequent enough and high enough output to keep things repaired before too many break down.