(March 4, 2020) – NACWA and the California Association of Sanitation Agencies (CASA) met with EPA on February 25 to discuss the Renewable Fuel Standard (RFS) program’s classification of fuel produced through co-digestion of biosolids and food waste.

The RFS program offers incentives to produce renewable transportation fuels, but its current classification of biofuels creates a disincentive for utilities to consider co-digestion of biosolids and food waste. NACWA and CASA asked EPA to consider alternative methods for classifying biofuel feedstocks to better incentivize the beneficial management of food waste through co-digestion. 

Biosolids-derived fuel is classified as a cellulosic biofuel, which carries a D3 Renewable Identification Number (RIN) in the RFS program. However, if food waste is added to anaerobic digesters to increase the production of biogas, all of the fuel produced will receive the D5 RIN for advanced biofuel unless the portion of biogas from food waste can be determined. Since D3 RINs currently have a higher value than D5 RINs, utilities reduce their profits by receiving food waste at the digesters.  

This situation conflicts with EPA’s Winning with Food Waste initiative and the Department of Energy and EPA joint challenge to expand renewable energy production at wastewater treatment plants. EPA has denied previous requests from CASA and NACWA to reconsider its RFS policies related to co-digestion, as explained in August 6, 2019 letter to NACWA.

During the February 25 meeting, NACWA and CASA asked EPA to consider different methods for accounting for the biogas produced from food waste versus biosolids during co-digestion.  EPA requested additional co-digestion data so it can fully evaluate alternative methods. 

NACWA members that have data about biogas produced from co-digestion are encouraged to contact Cynthia Finley, NACWA’s Director of Regulatory Affairs.