One issue that should be considered, apart from the fact that the problem is population growth, rather than generation, is the method of supply. A lot of people are talking big complex systems here and they wont solve the problem. One way to make a real dent is to change the rationale. Instead of massive concentrated systems, why not go the other way and build small integrated systems for MOST power supply, like a distributed network similar to the internet. More robust, less complex, lots of efficiencies etc etc...
