Converting methane gas to energy is not a new concept. However, it is not a widely applied method given the EPA’s Landfill Methane Outreach Program lists only 623 systems in operation throughout the country. Of those systems, very few are publicly owned and most are large-scale operations. These facts did not deter the City of Augusta from pursuing such a system to put the local municipal solid waste disposal site to work.
Hatch Hill Landfill serves the capital city’s population of 19,500 and eight surrounding communities of approximately 21,500 residents. In early years of operation, the methane gas produced by decomposing trash was released into the air. To reduce environmental impact, an underground system of pipes was later installed to collect methane and burn it off by flare, with some gas still released directly into the air through vents. With a localized collection system and flare in place, Woodard & Curran determined the landfill’s decomposing trash produced enough methane gas to fuel a 550-kilowatt generator.
Harnessing the power
Confident the quality and quantity of methane gas was available, new gas wells were installed to collect gas through 1,700 feet of 8-inch underground pipe and transport it to a gas treatment system near the facility’s operations building. Collected gas goes through a dehydration skid to remove moisture and other contaminants. Extracted condensate goes to an on-site leachate holding pond then pumped to the city’s wastewater treatment facility. Once treated methane reaches proper temperature, it is released to fuel the generator.
The generator feeds electricity into the local utility provider’s grid under a net metering agreement with the city. The credit will be used to offset electric bills for landfill operations, as well as nine city properties that cost the most to power, including: City Center, Augusta Civic Center, Cony High School, Capital Area Technical Center, two of the city’s four elementary schools, the police station, Lithgow Public Library, and Buker Community Center. Within 11 years, the $3 million project is expected to recover the investment through the reduction of the City’s energy costs. In 17 years, Augusta anticipates a return on investment of $1 million. Additionally, the methane collection and power generation system has reduced nuisance odors and greenhouse gas emissions.
The project also included construction of a 1,490-square-foot operations building to house critical electrical components required for net metering, including the CT meter, switchboard, and SCADA controls. This facility includes an office and breakroom for staff and provides space for the public to learn about the project.
Happier neighbors, happier environment
Occasionally, the landfill has been a source of neighborhood complaints, mainly due to fugitive odors associated with the hydrogen sulfide component of landfill gas. The new collection system, which employs gas wells, extracts more landfill gas than the previous perforated pipe system alone, collecting and destroying the gas that would otherwise escape the landfill. In 2018, a geomembrane cap placed over a 7-acre portion of the landfill essentially eliminated escaping landfill gas from this area. These measures have already shown positive effects in reducing fugitive odors with neighborhood complaints virtually eliminated.
In addition to reducing the odor pollution, the methane-to-energy system is reducing environmental pollution by limiting the amount of methane escaping the landfill. Methane is a powerful greenhouse gas, 84 times more powerful than carbon dioxide in the first two decades after its release. The generator produces approximately 500-kilowatt of power when operating at full capacity, offsetting other power generation sources. The city will also harness waste heat from the generator to keep the Operation Building safe this winter. A radiant heating system was installed, designed to melt snow and ice on nearby concrete sidewalks and to prevent the truck scale from freezing when winter sets in.
