A private developer of renewable energy projects hired RETTEW to conduct a due diligence evaluation of a 400-ton-per-day food waste anaerobic digestion facility in Charlotte, North Carolina. The facility receives organic feedstocks from poultry and other food processing operations, pre- and post-consumer food waste from grocery chains, and manure from local farms. The feedstocks are received, depackaged, and decontaminated prior to being fed into the anaerobic digestion process. The facility was designed to receive liquid, slurry, solid, and packaged waste streams.

The resultant biogas is scrubbed and burned in a combined heat and power (CHP) system rated at 5.2 MW total electrical, and the electricity is then sold to the local grid under a long-term contract. Waste heat from the CHP system is used to heat the digestion process to thermophilic and mesophilic temperatures. Digestate from the facility is dewatered using a centrifuge and the centrate is treated on site with an activated sludge treatment system.

RETTEW’s evaluation included reviewing the facility’s operations to determine if it could operate at nameplate capacity and developing a cost estimate to achieve or exceed nameplate capacity and ensure reliable operation for the next 20 years.