DC's revolutionary plan to use sewage to generate electricity.

WASHINGTON, DC - MAR 18: - Seth Lehman, Senior Superintendent at Pizzagalli Construction, inside a massive anaerobic digester tank at DC Water at Blue Plains in Washington, DC, March 18, 2014. When completed, it will be the largest thermal hydrolysis plant in the world. Though the practice has been employed in Europe, the water sector in North America has not yet adopted this technology. The process "pressure-cooks" the solids left over after wastewater treatment to produce combined heat and power-generating 13 MW of electricity ($10 million savings annually). These vessels can also ingest scraps, fats and grease to generate power. ($400 million project) (Photo by Evelyn Hockstein/For The Washington Post via Getty Images)