Enhancing biogas efficiency: environmental impact of various feedstock pretreatment technologies

Abstract

<p>The impact of biomass pretreatment on environmental aspects and the enhancement of biogas or biomethane yield is a significant area of research. The pretreatment methods, designed to break down the complex structures of various biomass types, have direct implications on both the environmental footprint of the process and the efficiency of biogas production. Pretreatment techniques, especially for manures and lignocellulosic biomass, play a pivotal role in reducing the emissions of biogas production. By breaking down the complex structure of lignin and enhancing the accessibility of cellulose and hemicellulose, these methods reduce the energy input required for biomass breakdown during anaerobic digestion. These pretreatment methods may significantly increase the yield of biogas and biomethane. By improving the breakdown of organic material in the biomass, these methods enhance the efficiency of the anaerobic digestion process. For instance, certain pretreatment methods can increase the surface area of the biomass, making it more accessible to microbial action, which directly translates to higher biogas. <p>Methodology: The study used Life Cycle Assessment (LCA) technique to evaluate the environmental impacts associated with the utilization of various feedstocks in biogas production, focusing specifically on the effects of biological using rumen fluid, chemical – using carbon dioxide injection, and biological products additives (BPa) pretreatments. The environmental impact analysis was executed using the SimaPro 9.1 process modelling software. Information related to the necessary technological equipment was extracted from the Ecoinvent v3 database. The impacts of these processes were quantified using the CML-I calculation method. The study's unique aspect involved comparing the global warming emissions resulting from different pretreatment processes, thereby determining their respective Global Warming Potential (GWP) impacts. <p>Results: The manure energy value obtained from manures after CO2 pretreatment increased by 21.6–31.2%. After microbial pretreatment with rumen fluid the biogas yield from the same feedstock indicated a notable pretreatment efficiency of 12% on alfalfa leaves biomass. The addition of biological product during pretreatment resulted in a substantial 20.8% increase in biogas yield compared to untreated straw. Biogas production processes are more efficient and environmentally sustainable when biomass is pretreated before being combusted. The utilization of renewable energy sources can be significantly improved through further research and development in this area.