A Simple Methodology for Estimating the Potential Biomethane Production in a Region: Application in a Case Study

Biomethane is an example of a biofuel that is currently gaining interest due to its possible use as a substitute for natural gas and due to its generation in a “power to gas” production scheme. It can be injected into the gas network under certain purity requirements. It can also act as a source for the production of “green hydrogen”. This paper proposes a simple methodology to estimate the potential to obtain biomethane through the anaerobic digestion of biowaste in a delimited region. The mentioned methodology consists of the following main steps: (i) estimation of the potential biowaste from different sources in the region; (ii) characterization of each type of biowaste production; (iii) estimation of biogas production for each type of biowaste according to the selected anaerobic digestion process; and (iv) estimation of potential biomethane production through the purification of the biogas produced. The different types of biowaste that this methodology considers are the organic fraction of municipal solid waste, agroindustrial solid biowaste (biowaste from the food industry and livestock), and sewage sludge (urban and industrial). Energy crops are not considered because they are not treated as biowaste. After defining the proposed methodology, it is applied to a Spanish case study, in which the potential to obtain biomethane in Spain in 2019 is estimated. The results show that in Spain, around 4499 ktoe could be obtained if all biowaste was destined to produce biomethane, which would allow 31.6% of the final demand for natural gas to be satisfied in a sustainable way. In that sense, a double effect on climate change mitigation can be obtained, reducing use of fossil fuels and minimizing the final biowaste disposal into landfills.