South Platte Renew (SPR) completed construction on the Renewable Natural Gas (RNG) System in October 2019, the first of its kind in Colorado. The system converts biogas from the water renewal process into pipeline-quality RNG that is injected into Xcel Energy’s natural gas pipeline. Since becoming operational, it has generated approximately $11 million in total revenue.
In July, five and a half years after startup, the system fully recovered the initial capital investment of $7.8 million. This investment was jointly financed by the Cities of Englewood and Littleton Sewer Funds. Beginning in August 2025, SPR will generate positive revenue that will help offset sewer treatment rates for customers in Englewood, Littleton, and 19 other sanitary sewer districts in the southwest metro area. The milestone was reached within the original four-to-seven-year payback estimate.
Biogas is a natural byproduct of wastewater treatment, made up of methane and carbon dioxide. Before 2019, nearly all of it was flared, contributing to greenhouse gas emissions. To improve sustainability and reduce emissions, SPR constructed the RNG System as an innovative solution. By converting biogas into renewable fuel, SPR has reduced emissions by about 3,700 metric tons of carbon dioxide per year. That is similar to eliminating nearly nine million car miles each year. Since 2019, SPR has offset nearly 54 million miles in vehicle emissions.
As the system enters its next phase, SPR will continue generating about $2 million in annual revenue. It will also focus on lowering operating costs, improving efficiency, and minimizing energy use to maximize value for customers.
The RNG System's success reflects the vision and support of the Cities of Englewood and Littleton. It has earned recognition at local, national, and international levels and serves as a model for sustainability and innovation. We would like to thank our partners at Xcel Energy, Carollo Engineers, Filanc, and Anew Climate for their contribution and support on this project.
