With domestic robots coming in the near future (with any luck), thinking about labor in this way is going to be grossly misleading. Thinking about land is still

With domestic robots coming in the near future (with any luck), thinking about labor in this way is going to be grossly misleading. Thinking about land is still relevant, however. As for energy, if given enough land for solar energy, it can be accounted for. In short, land availability would be the primary limiting factor for self-sufficiency.