Huge digestor takes shape in Covington


Huge digestor takes shape in Covington

10/01/11 By Tom Rivers for The Daily News

COVINGTON — When it’s operational in about two months, a facility that heats 1.9 million gallons of manure and organic food waste will use methane gas from that mixture to create enough electricity to power 1,000 homes.

The digester at Synergy on Lemley Road is touted as the largest co-digester in the state. It represents a new generation of technology, extracting more methane gas and producing more power than its counterparts, said John Noble, president of Synergy, a dairy with 2,500 cows.

“It’s another step up in size and technology,” Noble said. “Is this the future? We’ll see.”

Synergy is teaming with CH4 Biogas, a Florida-based company, with the project. Noble is co-owner of Noblehurst Farms, a 1,700-cow dairy in Linwood. It had one of the first digesters in the state about 10 years ago. That facility was destroyed in a fire in April.

The Noblehurst digester produced 135 kilowatts of electricity. The new digester at Synergy will produce 1.4 megawatts and hour, more than 10 times the Noblehurst output.

The Synergy project includes a 1.9-million gallon, insulated steel tank that peaks at 82 feet in height. Inside, the manure will be heated to 140 degrees. Three massive mixer blades will stir the mixture that will be 60 percent manure and 40 percent organic food waste.

CH4 will collect tipping fees from food companies, with sugar-rich products from bakeries a coveted commodity. The sugary food waste will add to the energy value of the manure mix, emitting more methane gas — in turn creating more electricity, said Randy Mastin, project manager for CH4 Biogas.

With the former Noblehurst digester, the manure was only heated to 102 degrees. It wasn’t stirred. The new system at Synergy also includes a secondary tank that holds about 800,000 gallons. After being heated to 140 degrees in the first tank, the manure-food waste mix is “de-sulfurized” or scrubbed so a cleaner-burning methane can be captured in the 800,000-gallon secondary tank.

The new system also differs in that CH4 owns it, and will operate it. Noblehurst ran its system for a decade. Noble said the farm prefers to have a power company handle the digester.

“Our thought process is we milk cows,” he said. “We’re not electric service providers.”

CH4 is expected to hire to employees to manage the co-digester. The company hired SJF of Darien Center for site work and construction.

Mastin, a Pavilion resident, expects the project will be operational in late November or early December. The electricity from the project will go back on the grid and will be sold as green power. Synergy will be able to buy its electricity at a discounted rate as part of the project. Synergy will use about 25 percent of the total electricity produced at the digester.

The farm also will receive bedding from the manure once it spends 21 days in the digester. That bedding will provide a soft surface for cows. The liquefied manure also will be less smelly when it is spread on fields. That will be good for neighbor relations, Noble said.

The digester process also will eliminate phosphorus, creating a batter balanced product when the farm spreads the manure on fields, Noble said.

Noblehurst is talking with CH4 about building a new digester at the Linwood farm. Mastin said the company is talking with other farms about projects as well. The company needs large farms to make the projects work because of their manure. The Synergy digester will take in up to 450 tons of manure and food waste each day.

“We believe in the concept of utilizing the waste stream for additional benefits,” Noble said. “It benefits the community.