There is a secondary marketplace of "green energy futures". edit: Going from memory... The fine print on your electric bill in Texas says something like: "If w

There is a secondary marketplace of "green energy futures". edit: Going from memory... The fine print on your electric bill in Texas says something like: "If we, the electricity provider, don't have enough renewable energy to meet your current need, we promise to offset the amount of non-renewable energy we provide to you now with a future purchase of the same amount of renewable energy from an electricity generator." In other words, you get the electricity today, they get the money today, but they have to buy more renewable energy in the future.