I think that burning methane from human and animal waste bioreactors and biodiesel from algae and waste biomass could serve as top op power to smooth out short term energy demands. While they still pollute the air they are at least renewable and can be locally sourced. This means they are more sustainable and have somewhat less environmental impact than fossil fuels. Capturing and burning methane that was already being released can reduce climate change impact because carbon dioxide has far less heating effect in the atmosphere compared to methane.<br><br>For prime power we should use mostly next generation nuclear power with inherent passive safety and a thorium fuel cycle. Wind, solar, and other renewables can supply a significant amount and much of this should be local microgeneration and storage that can feed back to the grid. Microgeneration has smoother and more gradual production profiles in aggregate over time than large scale projects and also reduces transmission loss over distance. I think that plug in hybrid and electric vehicles and other devices could assist slightly but are not practical without combining with some time of local microgeneration due to the potentially shared infrastructure at the source. If we invest solely in large scale renewables the power fluctuations and accompanying distribution issues will be insurmountable and market forces will drive us straight back to fossil fuels for large scale top up energy.