EPA approves RFS fuel pathway for Agresti Energy

The U.S. EPA on March 15 approved a fuel pathway under the Renewable Fuel Standard filed by Agresti Energy for the generation of D3 cellulosic biofuel renewable identification numbers (RINs) for compressed renewable natural gas (RNG) produced via a proprietary process that uses hydrolysis and anaerobic digestion.

A document published by the EPA indicates that the pathway approval applies specifically to Agresti Energy’s proposed facilities in Stevens County, Minnesota; Swift County, Minnesota; and Jasper County, Indiana.

In the pathway approval document explains that Agresti Energy’s process utilizes agricultural digestate as a feedstock, which is digestate resulting from anaerobic digestion of crop residue, separated yard waste, and/or animal manure. The digestate feedstock is subjected to pressure hydrolysis, which uses wet oxidation and weak acid hydrolysis under high temperature and pressure to break down lignin and convert hemicellulose and cellulose into sugar, according to the EPA. The resulting cellulosic sugar solution is injected into an anaerobic digester, where the sugar is converted into biogas. The biogas is then purified and compressed.

The EPA’s analysis determined that compressed RNG produced through the Agresti Energy AD pathway achieves a 60.2 percent greenhouse gas (GHG) reduction when compared to a 2005 diesel baseline.

A copy of the pathway approval document can be downloaded form the EPA website.