American City & County – The 2019 Crown Communities Awards
The 91st Avenue Renewable Natural Gas (RNG) Plant in Phoenix is the United States’ largest biogas-to-RNG plant located at a wastewater treatment plant. It is a multi-million dollar project that is expected to reduce the equivalent of 44,671 metric tons of CO2 each year — the equivalent of taking 70,452 cars off the road for one year.
Part of the plant’s innovativeness comes from it harnessing a previously wasted by-product of wastewater treatment: raw biogas. The plant uses anaerobic digesters to generate biogas, which is then processed in a pressure swing adsorption system to become RNG. The RNG is then injected into the country’s natural gas pipeline grid — the plant’s first RNG entered the grid in December 2018.