Could Toxic Sewage Sludge be the Next Clean Energy Source?
More than 2 billion pounds of toxic sewage sludge, a byproduct of wastewater treatment, makes its way into landfills every year in the U.S. alone, polluting waterways as well as the atmosphere. This begs the question of whether this material could be utilized as a new type of bioenergy.
Well, the U.S. Department of Energy (DOE) seems to think so, as it recently issued a 3-year, $2 million grant to a team of scientists and researchers with the objective of developing a viable process to convert the sludge into renewable fuel that can be used to power the wastewater treatment process and perhaps even supplement municipal electricity grids.
How Toxic Sewage Sludge Becomes a Clean Energy Source
The researchers, from Worcester Polytechnic Institute (WPI), are developing a system that combines hydrothermal processes, high temperature and pressure to convert the sludge into natural gas.
The hydrothermal gasification process heats the water in the toxic sewage sludge to convert it into a biofuel. From there, it takes multiple additional steps to finalize the process of converting the biofuel into renewable natural gas, and it is the enhancement of these steps that is the focus of the WPI project.
According to the DOE, there is five times more energy in the wastewater entering a typical wastewater treatment plant than the energy needed to treat it, so the overall objective of the project is to capture and convert this wasted energy so it can be utilized as a supplemental power source for the treatment plant.
The DOE estimates that U.S. municipal wastewater plants consume more than $2 billion worth of electricity annually (30 terawatt hours), encompassing 25-40% of total operating costs, so there is a lot of opportunity to reduce costs.
I don’t know if clean energy derived from toxic sewage sludge will be ready for prime time anytime soon, but I am excited at the prospect. If successful, the project could turn a large energy consumer into an energy producer, recycle a good chunk of societal waste, reduce pollution, and provide cheap supplemental energy on demand. Sounds like a winner to me!
