The Scoop on Poop: Turning Sewage Sludge into Energy and Dollars

UpStart [uhp-stahrt] n. 1. A company or organization with innovative approaches to energy use, carbon pollution, resource consumption, and/or social equity, 2. A company or organization overcoming market barriers to build the new clean energy economy.

Newton Creek Wastewater Treatment Plant in Brooklyn New York, Photographs by Lisbeth Kaufman

by Lisbeth Kaufman

Waste water treatment is an expensive, energy-intensive process. But it’s also a potentially rich renewable energy source. A few fearless UpStarts are developing technologies and services that can convert dirty sewage sludge into clean energy, cutting pollution and costs while making a profit.

Companies like BlackGold Biofuels, XEBEC, Quasar, and EnerTech are taking the most vile waste products that clog sewers and erode critical infrastructure, and are turning that waste into a valuable resource of renewable energy.  Likewise, cities and regions such as San Francisco CA, Rialto CA, and Quebec, Canada are harvesting sewage to power the processing plants and generate a new stream of income.

The Problem
Sewage treatment and water access is a massive problem in developing countries like Kenya, where 72% of local government authorities lack sewerage systems.  According to the World Health Organization, 39% of the world’s population lacks access to basic sanitation and waste treatment.  And here in the U.S., sewage and waste sludge presents a major problem for water utilities across the country.

The U.S. produces 7 million dry tons of waste per year.  Managing this massive amount of waste is a heavy burden that occupies about 20% of the EPA’s entire budget and 4% of the nation’s electricity use.  According to the EPA, America is having difficulty keeping up with the growing amount of sludge (i.e poop) that Americans produce, as waste water investment needs have been rising at $11 billion per year.  According to a Clean Watersheds Needs Survey report to Congress from 2008, waste-water utilities will need to invest $298 billion over the next two decades to keep up services.

There’s also a heavy emissions cost to waste water treatment. Energy-related emissions in the U.S. resulting from POTW (Publicly Owned Treatment Works) operations – not including organic sludge degradation – led to 15.5 million tons of CO2-equivalents, with an acidification potential of 145 gigagrams [145,000 tons] (Gg) SO2 equivalents.

The fats, oils, and greases (FOGs) in sewage waste is particularly problematic. High in free fatty acid content, FOGs are too toxic for biodiesel feedstock, and are usually transferred to a landfill or incinerators.  In the process FOGs clog pipes, add to pollution, and cost water utilities many millions a year in infrastructure repair. The National Renewable Energy Laboratory (NREL) estimates that the U.S. produces $500 million gallons of FOGs a year, costing billions of dollars to treat, haul, and dispose.  The city of San Francisco estimates that it produces 2.5 million gallons of brown grease, costing it $47 million dollars in annual damage to the system.

The Solution
Companies like BlackGold Biofuels, XEBEC, Quasar, and EnerTech have developed technologies that reduce waste, cut disposal costs, and harvest a valuable energy resource to create new revenue streams.

The Canadian company XEBEC, for instance, has developed a suite of technologies that digest waste and purify biogas for high quality pipeline natural gas and transportation fuel.

The company has partnered with the city of Quebec and built an energy-self-sufficient system of anaerobic digesters to treat waste.  Saving the city more than $1 million a year in cut waste-treatment costs, the facility will pay for itself in five years.  Quebec is using the plan to reach its goal of banning organic material in landfills by 2020, and the city expects that it will soon be able to sell 4 to 5 million cubic meters of biomethane per year.  At a price of about 25-30 cents per cubic meter, that’s a $1.5 million bonus for the city generated by a formerly toxic and costly nuisance.

Another company, EnerTech of Atlanta, GA, has developed an alternative waste digestion process that uses less energy than the classic anaerobic digesters.  EnerTech’s SlurryCarb Process avoids the high-energy intensive process of evaporation that most waste processors employ, and processes waste in liquid or slurry form. This requires much less energy and produces about twice as much energy as it consumes.

The SlurryCarb Process creates a dried solid fuel and has a heating value of 6,500 to 7,000 Btu/lb.  EnerTech calls this product eFuel, which can be used in the place of pulverized coal or distillate fuel, but produces essentially zero net greenhouse gas emissions.

EnerTech has partnered with the city of Rialto in California to create the first SlurryCarb facility. The plant has the capability of processing 270,000 tons of waste per year, providing a long-term waste recycling plan for five municipalities in the Los Angeles region. The facility will produce about 60,000 tons of eFuel per year, which local industries can use in place of dirty fuels like coal.  It will prevent the emission of over 80,000 tons of fossil-based carbon dioxide.

The Philadelphia-based BlackGold Biofuels is a bit more picky when it comes to the sewage it processes.  It seeks out the very worst in waste. “Anything that smells really, really bad, that nobody else wants – that’s our sweet spot,” Emily Landsburg, CEO of BlackGold Biofuels told ClimateProgress reporter Stephen Lacey in 2010.  She went on to explain that:

The beauty of Black Gold’s product is that we are taking this environmental pollutant, this cost liability that’s also an environmental liability and providing our customers with the technology and the equipment to convert that into a renewable energy asset, something that actually offsets their costs and that they can sell for direct revenue stream.

BlackGold is currently partnering with the City of San Francisco to build the first commercial scale brown-grease to biodiesel facility in the U.S.  The plant will produce 100,000 gallons of biodiesel a year, turning a waste stream into a revenue stream and saving the city $24 million a year in infrastructure lifespan determination costs.

Like in the electricity sector, technology adoption is slow in the water-treatment sector. But these Upstarts are hoping to prove that turning “brown” to “green” is both scaleable and cost-effective.

— Lisbeth Kaufman, Center for American Progress

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