Sterling engines can do heavy work but here is the catch, I have not found anyone manufacturing them today other than toy models, or engines out of our price range.
Here is one that was made in the 1895 solid, true machine that still works today.
The down side is exactly as he said, it takes 8 -10 min to start. It is hard to justify making one when you can buy a $100.00 generator ( cheap 2 cycle gen ) , and a sump pump to pump water much quicker and cheaper than if you were to pay yourself per hour to chop wood, and put in the system. ( in my estimation ) This is why there is not a demand for these as I see it.
This guy has been working HARD on making one that is usable. It is still in experimental stage.
This one works on sunshine making 10KW but out of our price range.