Calculation of the potential production of methane and chemicals using anaerobic digestion

The aim of this paper is to calculate the amount of energy or chemicals that can be produced using anaerobic digestion (AD). Five feedstocks were considered: the organic fraction of municipal solid waste (OFMSW); cattle, pig and poultry manure; energy crops; agricultural residues, and sewage sludge. Carbohydrates, proteins, and lipids were assumed to be the biodegradable components of the feedstocks. Chemical oxygen demand (COD) was assumed as a basis for the calculations of the production of methane and other chemicals. Methane production was calculated assuming that AD converts the biodegradable COD to methane with a yield of 80% COD/COD. The potential production of chemicals, i.e. acetic, propionic, butyric, and lactic acids, ethanol, and hydrogen, was calculated assuming conversion yields of carbohydrates, proteins, and lipids from the literature. Globally, with the assumptions made in this study, the AD of the feedstocks considered here can potentially satisfy 17-20% of the total energy consumption and 33-39% of the electrical energy requirements. Potentially, AD can generate organic acids at rates that are hundreds or thousands of times their current production rates. Ethanol and hydrogen can be produced by AD at rates that are up to 2-3 times their current production rate. This paper also discusses the main challenges that must be overcome to achieve the potential of AD. (c) 2018 Society of Chemical Industry and John Wiley & Sons, Ltd