This year, Charlotte Water completed construction on a system at McAlpine Wastewater Treatment Plant that captures and converts methane gas (a byproduct of wastewater treatment) into a fuel for electricity production and useful heat.

Typically the bacteria used to break down organic materials during wastewater treatment creates their own waste in the form of methane. Up to 900 pounds of this waste is produced per day at McAlpine and is normally used for heating in boilers or burned off. The new facility to convert methane gas into something useful is called a Combined Heat and Power (CHP) facility – and Charlotte Water is the first water/wastewater utility in the state to utilize this system.

The CHP facility produces 762,480 kWh in a given month, which is enough energy to run about 846 homes.

The electricity will be added to the electric grid through a partnership with the local electric provider, Duke Energy. The excess heat will be returned to the wastewater treatment process, offsetting some of the electricity it needs to operate.

A 20-year, zero-interest loan from the state’s Clean Water State Revolving Fund (a federal Clean Water Act program that’s been in operation since the late 1980’s) financed the project. The state allowed for no-interest financing because of the project’s positive environmental impact and renewable energy generation, which made it financially feasible for the utility. The partnership means Charlotte Water won’t have to divert any of its operations budget reserved for routine system upgrades, there will be no additional costs to water customers, and the project will pay for itself in about a decade.