The municipal wastewater generated across Nashville homes and businesses could soon become a lucrative source of recurring clean energy revenue for local government under a proposed infrastructure initiative currently moving through the Metro Nashville Council.
City leaders are evaluating a dual-agreement contract between Metro Water Services and a private energy development company that aims to establish a specialized renewable natural gas plant. According to municipal officials, the venture promises to capture gas emissions from sewage treatment and transform them into a reliable energy supply while delivering millions of dollars into the city’s coffers.
The proposed legislation cleared its second reading before the council on September 15. However, the legal measures governing the property lease and gas rights still require a third and final legislative approval before the municipal partnership can officially take effect.
Under the pending arrangement, the Metro government would partner with Burnham, an Arlington, Virginia-based infrastructure firm known for collaborating with public utilities to upgrade sewage treatment infrastructure, curb utility operating costs, and generate renewable power.
The structure of the agreement assigns full operational and financial responsibility to the private contractor. Burnham would oversee the financing, engineering design, construction, ownership, and day-to-day management of the new renewable natural gas conversion facility throughout the lifespan of the project.
In return for obtaining raw biogas produced by the municipal treatment system, Burnham would share the proceeds derived from the refined gas once it is injected into a regional transmission pipeline and begins accumulating clean energy market credits.
According to fiscal documentation provided to the council, the contractual framework guarantees quarterly royalty payments to the city amounting to at least $1 million per calendar year. This financial return is established at 70 percent of the net revenue collected from commercial sales of the processed renewable fuel.
To accommodate the footprint of the plant, a companion lease pact would grant Burnham use of approximately 1.2 acres situated at 1815 Cement Plant Road. In exchange for utilizing the city-owned real estate, the developer would pay Metro Water Services a nominal annual rent of $1 over the initial 20-year agreement term, which includes provisions for two optional five-year extensions if both parties concur.
Should the gas rights legislation receive final approval, the developer will be bound by a strict development timetable. Burnham must commence construction within 18 months of the agreement's effective date and achieve full commercial operations within six months following groundbreaking, meaning the plant could be fully operational in approximately two years.
The facility will utilize byproducts originating at the nearby Metro Water Services biosolids treatment complex located at 1810 Cement Plant Road in the Germantown area. That municipal installation currently generates an average volume of 1.5 million cubic feet of raw biogas every day as a consequence of standard wastewater management.
Biogas generation occurs naturally through anaerobic digestion, a biological process in which specialized bacteria decompose organic waste compounds in enclosed environments completely devoid of oxygen.
At present, the majority of the biogas produced during local sewage processing is simply burned off through on-site waste gas flares to prevent unmitigated atmospheric release. The proposed facility would fundamentally alter this practice, allowing Metro Nashville to achieve 100 percent beneficial reuse of all biogas created at the biosolids complex.
The production of renewable fuel from wastewater sludge also intersects with national clean energy markets. The Environmental Protection Agency explains that renewable energy credits are established whenever one megawatt-hour of electricity is generated from renewable sources and fed into the utility grid, distinguishing clean power from fossil fuel-based generation and allowing consumers to purchase credits to match their power usage.
Wastewater arriving at treatment plants carries a mixture of used water, organic human waste, food remnants, greases, and discarded household chemicals. During the treatment cycle, liquid effluents are separated from the remaining solids, which undergo stabilization to become nutrient-rich material known as biosolids.
As defined under Environmental Protection Agency regulations, biosolids refer specifically to treated sewage sludge that satisfies rigorous safety and environmental thresholds, enabling the material to be recycled as agricultural soil conditioners or fertilizer.
By converting the gaseous breakdown products of these biosolids into pipeline-quality renewable natural gas, Nashville aims to eliminate waste flaring and secure a reliable financial return, turning everyday municipal wastewater into a sustainable asset for years to come.
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