Municipal wastewater flowing through the drains of Nashville may soon be transformed from a basic utility byproduct into a lucrative economic and environmental asset. The Metro Nashville Council is formally weighing a pair of long-term commercial agreements that would allow the city to capture renewable natural gas from sewage treatment, creating a multi-million-dollar revenue stream while simultaneously bolstering the region's clean energy output.
The proposed municipal project centers on an infrastructure agreement between Metro Water Services and Burnham, an Arlington, Virginia-based clean energy development firm that specializes in collaborating with public utility providers. Burnham works with municipal entities to upgrade public wastewater operations, lower operating expenses, and develop clean energy infrastructure.
Under the prospective deal, the developer would take biogas generated at the Metro Water Services biosolids plant located at 1810 Cement Plant Road and convert it into high-quality renewable natural gas. This refined fuel would then be directly injected into a nearby utility pipeline network to serve regional heating and energy needs.
The legislative package authorizing the required gas rights and ground leases achieved approval on its second reading during a Metro Council meeting on Sept. 15. However, the measure must still clear an additional round of voting before becoming binding policy, after which full commercial deployment would take roughly two years to reach completion.
Financially, the public-private partnership is structured to shift the project's capital risks onto the private developer. Burnham would bear full responsibility to finance, engineer, build, own, and manage the renewable natural gas facility on municipal property, relieving Nashville taxpayers of the upfront capital costs associated with the new industrial construction.
In exchange for utilizing the biological gas supplied by Metro Water Services, Burnham will disburse recurring royalty payments to the local government once the fuel enters the distribution network. A financial analysis included with the council's legislative agenda confirms that the city will receive quarterly royalty payouts calculated at 70% of net gas sales revenues, anchored by a legally required minimum guarantee of $1 million per calendar year.
The revenue model is further augmented by the generation of renewable energy credits as clean fuel is delivered into the commercial market. According to definitions established by the U.S. Environmental Protection Agency, these market-based credits represent proof that one megawatt-hour of power has been produced from a certified renewable source and fed into the shared energy grid. These certificates help separate clean power generation from conventional fossil fuels and allow sustainability-focused end-users to purchase credits that offset their daily energy footprint.
A companion lease agreement is also under legislative review to provide the physical ground space necessary to house the conversion machinery. The proposed lease grants Burnham control over roughly 1.2 acres of municipal real estate situated at 1815 Cement Plant Road in exchange for a nominal rental fee of $1 per year across the duration of the operational agreement.
The operational timeline for the venture dictates that Burnham must break ground on the facility within 18 months of the agreement's formal execution. Once construction starts, the developer has six months to achieve commercial operations, establishing a total timeline of about 24 months before the system is operational and injecting gas.
Both the primary gas rights contract and the associated land lease are designed with an initial 20-year duration. The contract terms also incorporate options for two subsequent five-year renewals, potentially extending the full collaboration between Nashville and Burnham to three full decades if both entities mutually agree to the extensions.
The scientific framework behind the conversion process relies on the complex chemical transformation of municipal wastewater into usable biomaterials. Raw wastewater entering treatment facilities contains an assortment of liquid runoff, human waste, household food scraps, discarded oils, and miscellaneous household chemicals, all of which require rigorous industrial separation and sanitization.
Once the liquid effluent is separated from solid waste, the remaining materials are processed into treated, nutrient-rich compounds known as biosolids. The U.S. Environmental Protection Agency classifies biosolids as treated sewage sludge that meets strict federal quality criteria, permitting its repurposing as agricultural fertilizer or commercial soil conditioner.
In tandem with biosolids production, the treatment cycle produces biogas through anaerobic digestion—a biological phenomenon in which microorganisms consume and break down organic matter in an airtight environment devoid of oxygen. Metro Water Services' facility in Germantown generates an estimated average of 1.5 million cubic feet of this biogas every single day.
Under existing plant operations, the overwhelming majority of this biogas cannot be stored or utilized and is instead incinerated through on-site waste gas flare burners. If the pending legislation is ratified and Burnham constructs the specialized processing facility, council records confirm that the city will achieve 100% beneficial reuse of all biogas created at the Cement Plant Road facility.
By transforming an ignored and burned-off industrial byproduct into a marketable energy commodity, Metro Nashville stands to eliminate a substantial source of municipal waste while locking in a guaranteed, multi-million-dollar financial return for the local utility system.
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