LEWISTON — A $330,000 Efficiency Maine grant will let the Twin Cities’ water treatment plant build a methane-burning generator, officials announced Tuesday.
Mac Richardson, superintendent for the Lewiston Auburn Water Pollution Control Authority, said electricity from the generator will eventually power the facility.
“This makes us truly a green project in so many ways,” Richardson said. “Not only will we be reducing greenhouse gases and producing our own electricity, we’ll be saving money long term by reducing the amount of solids.”
The authority began work last fall on a solid waste digester that uses anaerobic micro-organisms and heat to digest the solid materials left behind by sewage treatment, reducing that solid waste volume by 40 percent. Right now, those materials are composted, used to fertilize farms and sent to landfills.
The process creates methane gas as a byproduct. That methane can be burned to generate up to 150 kilowatts of electricity per month, enough to save LAWPCA about $15,000 to $20,000 per month.
The project is being paid with a 1 percent loan from a state Revolving Loan Fund. That translates into a $900,000 savings for the project on the financing alone.
The authority’s Board of Directors awarded the bid to Methuen Construction of Salem, N.H., in August for $11.96 million.
Richardson said the contractors have completed the first floor of the digester’s equipment building and are nearly finished pouring concrete for one of two tanks. Work is scheduled to be finished in the fall of 2013.
“We’ve managed to get a bit more work done than we thought because of the mild winter,” Richardson said. “But, it’s a still a bit too early to say we’re ahead of schedule.”
The board had decided to delay work building the electrical generators, saving $817,000.
“Without the generators, it would have meant we would have had to have a flare to burn off the excess methane,” Richardson said.
The state’s efficiency grant, combined with savings from the loan, mean the generators are back in the project.
“Between the savings on electricity, our reduced operating costs when this comes on line and low interest rate we’ve been able to get, we can project significant savings as far forward as I can see, way more than 20 years into the future,” Richardson said.