MIT Technology Review indicates plasma burning of garbage generates 6 times the energy consumed. There's enough energy in U.S. municipal and other waste to replace as much as a quarter of the gasoline the country uses, says Daniel Cohn, cofounder of IET and senior research scientist at the MIT center.
Previously this site covered microbial fuel cells. Waste water fuel cells can produce 18 watts per 260 gallons of water and achieved a charge efficiency of more than 70 percent.
Lesser developed countries discharge approximately (the equivalent of) 100 trillion gallons (380×10**9 m³) of untreated sewage per annum. This could potentially generate 7 Terawatts of power for them and clean up their waste water.
These kinds of approaches plus a lot more nuclear power and shifting to more electrical transportation (hybrids and all electric.)can be used to blunt peak oil.