Might as well have this conversation in public:

Solar panel kits

How far down would you think this would have to come before it was feasible?
Also: Combination systems:

Vacuum insulated black water pipes for pre-heating water before heading into the water tank.

Underground piping for creating a temp difference for a compressor.

How can you figure out what it is actually going to return?

I mean come on, if you are going to spend $5000.00 of beer money, you had better be dam sure that your going to get something back.

And one final question: do you think that people have not independently tried alternative energy because we are all basically too lazy and have no imagination for these sort of things?

Out of any one, 2D has the most time on his hands to sit around with a calculator and play with numbers.