The Town of New Paltz is aiming to become a little greener through the use of brown.
Since May of 2018, the Town of New Paltz board has been consulting with energy companies like General Electric, Fair Banks Morse, Caterpillar (CAT) and Carollo Engineers, Inc. to try to convert sewage waste into energy for the municipality. According to town board member Don Kerr, a CAT representative has been consulted on the project.
“It’s common practice in a lot of places to take the methane gas that waste water generates and turn it into electricity through a heat exchanger,” Kerr said.
Kerr discloses that this environmental project wasn’t his idea, and that the credit truly goes to Shweta Sagun Sawant— a master of science student in the department of electrical engineering at SUNY New Paltz and an intern for the town’s Environmental Policy Board.
A 12-page report made by Sawant “establishes the merits and benefits of Anaerobic Digester technology and Combined Heat and Power technology (Cogeneration), the existing conditions at state wastewater treatment plants (WWTPs) and the potential for a renewable energy strategy that focuses on WWTPs as resource recovery centers.”
Cogeneration is the use of a heat engine or a power station to simultaneously generate electricity and useful heat.
“Methane is an extremely powerful greenhouse gas. One pound of methane traps 25 times more heat in the atmosphere than a pound of carbon dioxide. Because methane can be extracted from wastewater treatment plants, it can be burned to produce electricity, heat buildings or power vehicles,” Sawant wrote.
A main ingredient in natural gas, capturing methane before it gets into the atmosphere helps reduce the effects of climate change.
The Wastewater Treatment Plant (WWTP) of New Paltz currently uses anaerobic digestion—a biological process that produces a gas principally composed of methane and carbon dioxide, otherwise known as biogas.
“Currently the methane produced is flared (which means burned) to the atmosphere,” Sawant claimed. “This is currently a lost opportunity to recoup the energy and reduce air pollution.”
Waste water plants have a capacity of 1.5 million gallons per day (MGD). The amount of sewage water produced per day in New Paltz is about 1.1 MGD. After the sewage water is processed at WWTP, 99.5 percent of the cleaned water is released to the Wallkill River.
If a cogeneration facility is introduced in WWTP, then the current gas can be converted into electrical energy for the town.
Converting sewage waste into electrical energy yields financial, environmental and efficiency benefits.
The financial benefits of implementing cogeneration are reducing energy costs—which can offer energy savings up to 40 percent—zero costs outlay options—allowing to finance the system cost effectively—enhanced capital allowance—allowing to claim tax back on procurement of large and small-scale cogeneration systems—a renewable obligation certificate—providing an income from the cogeneration system—and renewable heat incentives.
The environmental benefits are clear.
“CHP systems reduce methane and CO2 emissions with biomass, and biogas CHP being essentially carbon neutral,” Sawant said.
For efficiency purposes, CHP systems can supplement larger energy demands, providing exceptional energy security. Additionally, CHP systems can work on a wide variety of fuels, including biomass pellets, biogas, natural gas and other fuel types.
“The unit we are looking at is Caterpillar Package Generator Set, and it takes biogas and turns it into electricity,” Kerr said. Through this technology, biogas can be efficiently converted into electricity and heat.
With all of these benefits, it seems like a no-brainer for New Paltz to implement a CHP system. Yet, with all the pros comes the cons.
“There are times when during rain events—when the plant is near to the 1.5 MGD and the 1.1 MGD range—where there isn’t much gas produced because the plant is full of water. In those times, to keep the equipment running, you need to use natural gas or propane in place of methane and that is additional cost and additional complication,” Kerr said.
According to Sawant, the initial costs for a CHP system can be high without funding, which can make it prohibitive for smaller scale installations, like the town of New Paltz.
While Mayor Tim Rogers and the Town Board are excited and interested in this environmental project, at the end of the day, it’s a question of whether it’s economically possible. Kerr is currently waiting on a price quote for the project, which he predicts will be available by Thursday or Friday.
“We’re trying to not to raise taxes on people,” Kerr said. “We’ve kept, I think, three years in a row of no tax increases which is rather unprecedented in the village. So it really comes down to the cash value of the electricity versus the upfront cost of the equipment and that is a number that we don’t know yet.”
