A group of scientists from Newcastle University have published findings showing that the energy potential of waste water is almost 20% higher than existing estimates.

The research suggested that, instead of incurring the costs of processing waste water (estimated as over 1% of energy consumption), it could be worthwhile to extract methane, hydrogen and other fuels from it. Globally, based on population numbers and the average waste generated by each person every day, research indicated that waste water could represent a continuous energy source of 70GW-140GW-equivalent to burning 52mnt-104mnt of oil in a power station or up to 24,000 wind turbines working continuously.

Source - Newcastle University