The Oakland wastewater treatment plant in Topeka, Kansas will generate up to 530 SCFM of pipeline-ready renewable natural gas (RNG) each year with SUEZ Methanis* membrane biogas upgrading. The project, which marks the first North American installation of Methanis, will not only offset the operating costs at the plant, but also generate additional revenue from the sale of renewable natural gas. “Biogas capture gives us a way to generate a long-term revenue stream from what would have been a waste product,” said Michelle Neiswender, Project Manager for the City of Topeka. “It’s good for ratepayers, and good for the environment.”
Biogas is the byproduct of the biological decomposition of organic matter through anaerobic digestion (AD). It can be generated from the AD of organic wastes, such as food waste, manure, agricultural residues, and sewage sludge at wastewater treatment plants. Methanistakes the generated biogas and purifies it to pipeline quality RNG. The system will capture more than 99 percent of the methane within the raw biogas, resulting in RNG that can be injected directly into pipelines, offsetting the consumption of fossil fuel natural gas.
“With this technology, the plant will be able to convert approximately 700 cubic feet per minute of biogas into clean, renewable natural gas,” said Kevin Cassidy global business leader for SUEZ – Water Technologies & Solutions. “It’s an impressive project highlighting significant environmental and economic benefit.”
Of the 16,000 wastewater treatment plants in the U.S., about 1,500 have AD. While many of them use the biogas on site, only a small percentage convert it to renewable energy and sell it. If U.S. wastewater treatment plants captured all of the biogas they generated, it would meet 12 percent of national electricity demand.
The market for RNG is driven primarily by carbon-offset natural gas credits. Companies using natural gas can purchase the credits to offset greenhouse gas emissions, providing small and medium-sized users a cost-effective way to reduce their carbon footprint. This arrangement allows RNG producers to sell their product at a premium.