Manure-to-Energy Plant Launches in San Joaquin Valley

Tulare County, California, recently surpassed nearby Fresno County as the top agriculture-producing county in terms of economic value within the U.S. It's also the country's top dairy producing county. The result has been more investment and economic growth in a rapidly booming area already home to 450,000 people.

But there is also a downside to the local dairy industry’s continued surge: The San Joaquin Valley suffers from some of worst air pollution in the U.S., and cow effluent is a threat to the region’s already troubled watersheds.

The launch yesterday of the Calgren Ethanol Biogester, a manure-to-ethanol plant in Pixley, about 60 miles south of Fresno, is a step toward reducing emissions and dependence on fossil fuels while helping California meet its clean energy goals. According to the companies that worked together on this project, the plant is also the first digester in California to transform agricultural waste into cleaner natural gas to power another renewable energy facility. Instead of relying on the local grid, the otherwise energy-intensive ethanol plant is part of what is close to a closed loop and zero-waste system.

A coalition of several companies, funded in part with a $4.6 million grant from the California Energy Commission, is behind the plant. Designed by DVO of Wisconsin, the anaerobic digester — the core of this plant — was built by Regenis, a Washington state-based contractor. Calgren Renewable Fuels will operate the plant, which will produce up to 58 million gallons of ethanol annually, enough to fuel 145,000 cars a year.

The process starts with a local dairy down the street, Four J Farms, home to about 1,800 dairy-producing cattle. Cow manure from the dairy is piped to the Calgren plant, where it is first stored in the DVO-designed digester that is 16 feet deep and insulated with concrete to prevent any leakage. Bacteria that are naturally occurring in a cow’s digestive system is added to the manure, which is stored and churned there for 22 days — long enough to kill any pathogens including e coli. Moisture extracted from the manure is recycled so local farmers cause use it to water their crops, and the by-product — clean and 99.99 percent bacteria-free — is sent back to Four J Farms so it can be used as animal bedding.

The plant operates akin to a cow’s digestive system, keeping the feedstock at a temperature of 101.5 degrees Fahrenheit (38.5 degrees Celsius) so that the plant can continue to produce these biofuels 24 hours a day, seven days a week. Most importantly from an environmental perspective, the plant turns methane, a potent greenhouse gas that is the bane of the dairy industry, into cleaner burning biogas.

“Electricity (to power cars) and hydrogen are getting a lot of media attention these days as the fuels of the future. But it is the workhouse plants like this Calgren facility that reduce the carbon content of our fuel supply,” said Jim McKinney, a project manager for CEC’s Alternative and Renewable Fuel and Vehicle Technology Program. McKinney noted that the ethanol produced at this plant is the lowest carbon-emitting ethanol currently produced at an industrial scale in California.

More biodigesters such as the one at the Calgren plant could help California solve multiple challenges -- including the increased production of clean transport fuels, achieving reduced agricultural waste and an improvement in the San Joaquin Valley’s air quality. “There is enough organic waste (in California) to power 2 to 3 million homes or to generate 2.5 billion gallons of clean, ultra-low carbon transportation fuels,” said Regenis Vice President Bryan VanLoo. In addition, Steve Dvorak, president of DVO, noted that one cow alone creates about 100 to 130 cubic feet of biogas a day, the equivalent of 65,000 BTUs or 6 kilowatt hours daily.

The Calgren plant at first comes across as a seamless and logical way to augment California’s energy portfolio, boost local waste diversion efforts and create new jobs. But today’s launch was long in the making: The project was first conceptualized in 2009 and took several years to come to fruition. Ensuring a reliable supply of feedstock and gaining the buy-in of local businesses and politicians are among the challenges projects like this one confront. But as long cows produce milk, there will always be waste — and what I saw yesterday is a far cleaner and more productive option than the costly and environmentally risky disposal of cow manure.

Image credits: Leon Kaye

Based in California, Leon Kaye has also been featured in The Guardian, Clean Technica, Sustainable Brands, Earth911, Inhabitat, Architect Magazine and Wired.com. He shares his thoughts on his own site, GreenGoPost.com. Follow him on Twitter and Instagram.