Anaerobic codigestion (AcoD) can address food waste disposal and manure management issues while delivering clean, renewable energy. Quantifying greenhouse gas (GHG) emissions due to implementation of AcoD is important to achieve this goal. A lifecycle analysis was performed on the basis of data from an on-farm AcoD in New York, resulting in a 71% reduction in GHG, or net reduction of 37.5 kg CO2e/t influent relative to conventional treatment of manure and food waste. Displacement of grid electricity provided the largest reduction, followed by avoidance of alternative food waste disposal options and reduced impacts associated with storage of digestate vs undigested manure. These reductions offset digester emissions and the net increase in emissions associated with land application in the AcoD case relative to the reference case. Sensitivity analysis showed that using feedstock diverted from high impact disposal pathways, control of digester emissions, and managing digestate storage emissions were opportunities to improve the AcoD GHG benefits. Regional and parametrized emissions factors for the storage emissions and land application phases would reduce uncertainty.

Anaerobic codigestion of dairy manure and food-based feedstocks reflects a cradle-to-cradle approach to organic waste management. Given both of their abundance throughout New York State, waste-to-energy processes represent promising waste management strategies. The existing waste-to-energy literature has not yet fully realized the environmental impacts associated with displaced grid electricity generation and feedstock-hauling emissions on the net environmental impact of centralized codigestion facilities. The key objective of this study is to provide a comprehensive environmental impact assessment with the purpose of understanding the existing environmental status of centralized codigestion facilities. Real-time data from an operational codigestion facility located in Western New York State was used to conduct this environmental impact statement. A comprehensive inventory of greenhouse gas emissions associated with renewable electricity production at the codigestion facility was developed using the Emissions & Generation Resource Integrated Database (eGRID) (U.S. EPA), while emissions associated with feedstock hauling were quantified using the fuel life-cycle approach developed by the Greenhouse gases, Regulated Emissions, and Energy use in Transportation model (GREET) (U.S. DOE). With each of the emissions models used for this analysis, it was determined that the net environmental impact associated with hauling food-related feedstocks from the many locations throughout the Northeast U.S. region would be acceptably low, and thus could be part of future sustainable development of centralized codigestion facilities.

Anaerobic digestion is a waste-to-energy conversion process that offers potential economic and environmental benefits of organic waste diversion and renewable energy generation. However, these systems are often not feasible for small-to-medium size food processors, due to the significant capital investment involved. The key objective of this study is to identify the volume and composition of dairy manure and liquid-phase food manufacturing waste streams available in New York State (NYS) to make co-digestion of multiple feedstocks in centralized anaerobic digester facilities an economically attractive alternative. Organic waste volume and property data were obtained via Freedom of Information Law (FOIL) requests at the county and municipal levels for each of the 62 counties in NYS. Spatial analyses of dairy confined animal feeding operations (CAFO) locations relative to food manufacturing facility locations were analyzed using Microsoft MapPoint imaging software, which identified concentrations of high strength liquid-phase waste in the upstate corridor extending between Buffalo and Albany. The results show that if anaerobically digested, dairy CAFO manure and food manufacturing waste can contribute significantly to the State’s renewable energy portfolio. A laboratory scale two-phase anaerobic digester (bioDrillTS-AD200©) can help establish the correlation between waste properties (e.g. total solids, etc.) and quantity and quality of biogas produced.