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

Abstract

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. © 2018 Society of Chemical Industry and John Wiley & Sons, Ltd

Experimental investigation and mathematical modelling of batch and semi-continuous anaerobic digestion of cellulose at high concentrations and long residence times

“…(10), were considered to be the sum of the Model SC and of the carbohydrates in the variables X S , X, X I . For X S , the carbohydrates were calculated by dividing X S by the COD conversion factor for cellulose (1.185 gCOD g −1 cellulose), for X and X I the carbohydrates were calculated assuming that the microorganisms dry weight is made of 27% carbohydrates [3]:…”

“…However, AD could also be used in a biorefinery context to produce chemicals such as short-chain organic acids, ethanol, and hydrogen, which are intermediates in the digestion process [1,2]. According to recent studies [3,4], most of the potential of AD for the generation of energy is still undelivered. Indeed, on a global scale AD generates less than 1% of the electricity it could potentially generate based on the available feedstocks and, in the UK, only 19% of the AD potential is being delivered.…”

Multi-criteria decision analysis of agri-food waste as a feedstock for biopolymer production

“…The global agricultural residue production from six key crops (barley, wheat, maize, soybean, rice, and sugar cane) was estimated as 3.7 Gt dry matter (DM) per year for the period 2006-2008 (Bentsen et al, 2014). Other studies reported global generation rates of 4.5-4.7 Gt DM/yr from 13 crops in 2014 (Dionisi et al, 2018) and 5 Gt DM/yr from 26 crops in 2013 (Cherubin et al, 2018). Kim and Dale (2004) estimated that 1.5 Gt of crop residue is available for conversion to bioethanol from seven crops comprising of corn, barley, oat, rice, wheat, sorghum, and sugar cane.…”

Effect of the operating conditions on the anaerobic digestion of wheatgrass for chemicals and energy production

“…According to our recent study [3], on a global scale, the current energy generation by anaerobic digestion is only a minor fraction of the total potential energy that could be generated based on the generation rate of organic waste. One of the limitations in the use of anaerobic digestion for energy or chemicals production is the lignocellulosic nature of many types of organic waste (e.g.…”