The Tennessee Renewable Group, LLC. (TRG) partnered with U.S. Gain to revitalize an old landfill in Church Hill, Tennessee by converting it into a renewable energy and natural gas processing plant. Owned by Republic Services, Inc. and developed by The Hunter Group, this facility is one of only a few hybrid projects that use landfill gas (LFG) to produce both renewable natural gas (RNG) for the transportation sector and electricity for the Tennessee Valley Authority (TVA).
LFG is a natural byproduct of the decomposition of organic materials in landfills and is composed mostly of methane, the primary component of natural gas. LFG can be extracted from landfills using a series of wells in combination with a blower, flare or vacuum system.
LFG can be used for electricity generation (leveraging electricity conversion technologies like reciprocating internal combustion engines, turbines and microturbines and fuel cells; additionally, co-generation or combined heat and power systems can use LFG to produce both electricity and thermal energy, usually in the form of steam or hot water), direct offset of another fuel as a medium-Btu gas (replacing coal, natural gas, or fuel oil within a boiler, dryer, kiln, greenhouse or other thermal application) and as an upgrade to natural gas. The U.S. Environmental Protection Agency has compiled a list of these options and associated technologies for reference.
When natural gas is made through the collection and treatment of LFG, it is considered to be a form of RNG. Although RNG can be made from a variety of organic feedstocks (e.g., livestock waste, wastewater treatment, crop residues, etc.), most of Tennessee’s RNG is produced via the collection and treatment of LFG.
“The project takes the landfill methane into the RNG plant where it is stripped of carbon dioxide and other impurities before being processed for injection into the General Gas Pipeline for transportation as renewable natural gas,” David Mauney, president of TRG, said.
In March of 2019, the U.S. Environmental Protection Agency (EPA) recognized the TRG project as a certified renewable fuel producer under the federal Renewable Fuel Standard (RFS) program, which requires a certain volume of renewable fuel to replace or reduce the quantity of petroleum-based transportation fuel, heating oil or jet fuel used in the U.S. each year.
With the support of incentives provided under the RFS program, the TRG project generates enough RNG to fuel more than 80 heavy-duty trucks each day, displacing almost 1.5 million gallons of diesel fuel each year.
In addition to the facility’s RNG production, LFG is processed onsite by a Caterpillar 16-cylinder engine genset to produce electricity up to one megawatt. The generated power is then routed by the local power company, Holston Electric Cooperative, to TVA’s electric transmission grid, which services Tennessee as well as portions of Alabama, Mississippi, Kentucky, Georgia and North Carolina. In total, the project reduces carbon dioxide emissions by over 20,000 tons annually.