According to the Daily Beast, poop is one of the most popular forms of biofuel, with waste powering everything from trucks to street lamps to cooktops and heaters around the globe. How did human fecal matter become the potential solution to powering the world?
Sewage is approaching crisis level in the heartland, and The Atlantic reports that 3 to 10 billion gallons of untreated waste is released from U.S. sewage-treatment plants every year. It’s a renewable biomass made up of carbon that’s already circulating in the atmosphere; the brown, in this instance, is completely green.
Corinne Drennan leads the biofuels research program at the Pacific Northwest National Laboratory. She used to start up conversations in a room full of colleagues in her field by asking “How many of you have played with poop?,” but admits it’s not really a joke anymore.
“I think now we’re realizing there are technologies that are really viable and that are able to convert the sludge into very high-quality fuels.”
At PNNL, sewage slurry is forced through a tube at extremely high pressure (3,000 PSI) and at a high temperature (about 660 degrees Fahrenheit) to create an oil rich phase that can realistically be compared to crude oil, according to Brennan.
According to ars Technica, this hydrothermal liquifaction (HTL) process has been licensed by PNNL to a Salt Lake City-based company called Genifuel, which is building a demonstration plant in Vancouver with an estimated online date of late 2018. Another demonstration facility is in the works in California, in partnership with Contra Costa County.
PNNL estimates that the 34 billion gallons of sewage produced by Americans every day could potentially be converted into two to three gallons per American of unrefined biocrude a year, or 30 million gallons of refined oil annually.
In an interview with the Office of Energy Efficiency and Renewable Energy, Drennan and her colleague, Greg Kunkel, commented on the public perception of turning poop into a power source.
“Turning human waste into fuel isn’t a particularly new concept. Even hydrothermal liquefaction has been around for a few decades. What’s novel and intriguing with the process we’ve developed is how energy efficient it is. As mentioned, in less than 30 minutes we can produce biocrude. And, since we’re using a waste as a feedstock instead of a crop — something that costs money to grow — the ROI of the technology makes a lot of sense.”
The biggest advantage of creating biofuel from human sewage, say proponents, is that it reduces the amount of drilling for oil that is required for the same amount of energy producing fuel.