I have believed...literally for years....that in addition to any change in ways to make and store energy, we need to reduce the total number of people using it. If we do not come to some sort of equilibrium with the environment, WE will lose.

Every bit of land has its "carrying capacity"; the total amount of some specified activity it can sustain indefinitely....and this means the Earth as a whole, too. We cannot catch ALL the fish, we cannot grow an unlimited number of crops, we cannot put an unlimited amount of pollution into the air...etc..etc.
   It is not always clear what those limits are, but I dread being around when we push one of them too far....and I worry that we already have in some areas.