I did a back-of the-napkin calculation for geothermal power, which goes as follows:
1MW * 24H * 365 D = 8760 MWH per year. I expect this power to pay 10c/KWH in the future, so the Revenue per MW is ~$876k/yr. After a five year payoff on the physical plant, I would expect to see ~$0.5M/yr earnings per MW.
Given a simple P/E of ten, which is very low right now, each MW of resource should translate eventually to $5M of market cap.
If we were looking at an even longer term, eventually I would expect a 3% dividend to be paid (30% of net revenue), based on projected earnings and market cap. Of course this would be after all projects were build out, which I currently expect to take ten to fifteen years.