Farmland and mines (or the minerals in them) seem to be limited world-wide and maybe good investments (though we may improve artificial ways to produce food tha

Farmland and mines (or the minerals in them) seem to be limited world-wide and maybe good investments (though we may improve artificial ways to produce food that are less dependent on land). Water is a regional thing (for some places it's less of a problem). Not really sure how one effectively "invests" in water. Solar is entirely different. I think solar has a great future, but as an investment, I'm not so sure. It seems highly likely that we will needs lots more power in the future and it does seem that much of it would come from solar. Current solar technologies are still relatively young, inefficient and (relative to future technologies) expensive. Investing in solar at this point would be like investing in an car manufacturer in the early 1900s.