But why don't they have electricity for power tools? They've been in the prison for what, a year? It only takes a few hours (maybe a couple days for a first-timer) to cobble together a basic wind power generator. There are certainly enough abandoned cars around to supply a large battery bank for power storage.
I'd choose a diesel. The reasons should be obvious.
They send people out to get stuff pretty frequently. If they were smart enough to pick up the right things, they could be much more self-sufficient. These people have their priorities all messed up. The first things they should be perfecting are defense, reliable water, and a renewable food source. They seem to treat all those things as hobbies.
well, they did say on the show that they had looted every pharmacy, doctor's office, etc in a 50 mile radius for drugs and supplies. The farther out they go, the more greater the chance of them running into trouble.
They had wind power at Hershel's Farm - it just wasn't a secure location.