I know this is an old thread, but interesting none the less. I really think in a shtf situation a AP system would create some challenges to keep running, as would anything that relied on electricity. Yes, generators would work fine made from homemade fuel. I think the bigger problem as mentioned already would be security. A person would have a hard time convincing their neighbors they are doing without also, while they could hear the generator chugging away in the background. Just like any survival situation though, the best solution to a problem is not one solution, but many different solutions. I would not rely on only AP to provide all my food. Just as I would not rely on only on weapon to provide my security.