Sludge Not So Dirty After All: Clean Energy from Wastewater On the Rise

Producing biofuel from wastewater seems like a natural equation: take a resource that is produced incessantly, and is an environmental pollutant, and turn it into energy—and, in turn, reduce fossil fuel consumption.

Doing this on a large scale is much easier said than done, so it isn't necessarily a widespread practice—but it might be getting there. Here's a look at a few projects or companies that are transforming human waste into usable energy.

1. Biodiesel from sewage sludge is not only possible, but can cost just cents more than regular, petroleum-based diesel.

2. A town in England just started using sewage to heat about 200 homes, and similar projects will only expand throughout the country over the next year.

3. Sewage grease: a company called BlackGold Biofuels makes FOG-to-Fuel, a system that converts fats, oils, and greases (FOG), which tend to clog sewers, into biodiesel. The company says that the system "contributes to reductions in sewer overflows, utility cost-savings, reduced carbon footprint, and increased energy security and independence."

4. Another technology currently in development would transform the scum in wastewater into electricity: microbial fuel cells (MFCs), "which utilize electrothermically-active bacteria grown on an electrode, are able to directly produce electricity from biomass in residential and industrial wastewater streams," Renewable Energy World reports.

These are just a few of the ideas trying to take advantage of what is, fortunately or unfortunately, an endless resource.