The New "Black Gold": Biofuel from Sewage

February 15th, 2009 by Tina Casey

We’re already harvesting methane from sewage and spreading treated sewage solids on farms and open space, so it’s not a stretch to imagine running our cars on biofuel from sewage, too. Specifically, running our cars on sewage grease. An enormous amount of grease enters our sewer systems – about 495 million gallons annually in the U.S. alone. Most of it gets captured and collected at sewage treatment plants. So what’s stopping us – the ick factor aside – from siphoning off this readily available and potentially valuable biofuel feedstock?

The Problem with Sewage Grease

Sewage grease – also known as trap grease – is a mutt. Unlike yellow and brown greases, which come from used cooking oils, trap grease contains a bit of anything and everything you can find in a sewer. That means waste grease and oil from home cooking and DIY projects, restaurants, schools, hospitals and institutions, business, and industry.

Bottom line: The contaminants in trap grease, particularly sulfur, exceed ASTM standards for roadworthy fuel.

Sewage Grease Problem – Solved?

With scores of alternative fuel companies dotting the landscape, it was only a matter of time before someone solved the contaminant conundrum. BioFuelBox Corp. is one company that recently announced a modification in its process for refining waste grease from sewage, to achieve a product that meets ASTM standards – including standards for sulfur.

Beyond Sewage Grease and Biofuel

Recycling sewage grease into biofuel dovetails neatly with at least one fundamental aspect of sustainability, the zero waste society.

On-site waste recovery and recycling is another aspect of the BioFuelBox model that fits into the overall picture. The BioFuelBox refineries are mobile, scaleable units suitable for land-strapped areas and wide open space alike. They can be deployed relatively quickly where needed, providing the kind of site-specific flexibility that large centralized refineries don’t have.

The BioFuelBox model also stands to reduce costs and emissions associated with infrastructure maintenance. By converting waste into a usable or marketable product it provides a direct financial incentive to capture more grease on-site, before it enters the sewer system and clogs up the arteries.

Sewage grease carries none of the carbon footprint baggage related to growing crops for biofuel feedstock. In particular, it skirts the ugly pricing and supply issues that can (and have) arisen when a program of using food crops for biofuel is poorly planned and executed.

With biofuel from sewage grease, let’s chalk up another score for our sewers. Wouldn’t want to live in them, but increasingly, can’t live without them.

Image: bmb at flickr under creative commons









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About the Author Tina Casey specializes in military and corporate sustainability, advanced technology, emerging materials, biofuels, and water and wastewater issues. Tina’s articles are reposted frequently on Reuters, Scientific American, and many other sites. Views expressed are her own. Follow her on Twitter @TinaMCasey and Google+.