An energy client was looking to develop multiple renewable natural gas (RNG) projects to meet their corporate sustainability goal of reducing the carbon footprint of the natural gas grid through RNG. These projects will generate biogas that can be upgraded to RNG on site. The feedstocks for this program are agricultural wastes such as dairy and swine manures.

RETTEW provided project development services for these anaerobic digestion facilities. The anaerobic digestion process will be mesophilic and/or thermophilic and involves receiving liquid and slurry wastes at the facility and removing sand and inert matter. The digestate is then disposed of and used as a source of nutrients for land application at farms. The facilities range in size from a few hundred to several hundred thousand animals.

Biogas generated through the anaerobic digestion process will be upgraded on site to remove hydrogen sulfide, carbon dioxide, and other contaminants. This upgraded biogas or RNG will be injected into the local natural gas grid, qualifying the client to qualify to sell RIN D3 renewable energy credits. These facilities will be designed to generate 50,000 to 500,000 dekatherms per year of RNG.

The ultimate goal is to develop more than 50 projects across the United States.