EnerTech Environmental said Tuesday it had snagged $42 million in a second round of funding to turn human and industrial wastes into energy.
Citigroup's Sustainable Development Investments unit and the Masdar Clean Tech Fund led the round, and Nimes Capital and CNM contributed. The funding brings EnerTech's total venture capital to about $57 million.
The company said it will use the money to develop five plants that will convert not-so-pleasant wastes, such as sewage sludge, into renewable energy. Specifically, the funding will go toward engineering, permitting and other steps needed for the company to then go after project financing to build the plants, CEO Kevin Bolin said.
The plants will use a technology EnerTech calls SlurryCarb, which Bolin said duplicates the natural process that creates fossil fuel from organic material. Here's how it works: The company applies heat and pressure to high-moisture biosolids, such as sewage sludge, which ruptures the cellular structure and splits off carbon dioxide in a reaction called "carbonization." The company removes the water that was once trapped inside the cell walls and is left with what EnerTech calls "E-Fuel," a solid material that can replace coal or other fossil fuels to supply energy.
Bolin claims the process to make E-Fuel uses less energy than it contains.
The concept of using waste for energy isn't new. Companies and municipalities have been burning garbage and tapping into landfills to create energy for decades.
But turning watery human and industrial waste into energy poses a unique problem.
"Garbage will burn by itself, sludge will not," said Bolin, adding that efforts to turn wet sludge into energy have failed in the past. For example, Los Angeles dumped $500 million into two such plants in the 1980s and 90s, according to the Los Angeles Times, only to pull the projects after the sludge corroded valves and erupted into flames.
EnerTech thinks its projects will succeed where those two failed.
The company already has a pilot plant in Japan, and in April started construction on what it considers its first commercial-scale plant in Rialto, Calif.
The company raised $160 million in project financing for the plant, which is expected to convert 683 tons of sewage sludge, from five municipalities, into fuel daily when it begins operating in December.
Also on Tuesday, BlueFire Ethanol Fuels announced it had closed $15 million from Quercus Trust to turn waste into ethanol. The company plans to use cellulosic waste that would have otherwise ended up in a Southern California landfill.
In February, the Irvine, Calif.-based company said it had grabbed $40 million from the U.S. Department of Energy to build a plant capable of producing about 17 million gallons of ethanol per year from green waste, wood waste and other cellulosic urban wastes.