Process modelling and life cycle assessment of a carbon capture and conversion technology for methane production in indoor air and bioenergy environments

Abstract

The climate change crisis demands urgent action to prevent crossing tipping points that could jeopardize societal well-being. This research presents the process modelling and life cycle analysis (LCA) of a novel carbon capture and conversion system referred to as the “De-cent concept” (decentralised mitigation technology of CO2 emissions). This innovative system is designed to capture CO2 and convert it into methane suitable for grid injection, also providing high quality air. The technology consists of an absorption/desorption unit for CO2 concentration and a bio-electrochemical system for methane conversion. The potential implementation of this system is first modelled using process simulation software (SuperPro Designer® v11) to obtain the mass and energy balances of methane production, considering two environments: indoor air and apple-based bioethanol production. Next, the environmental impacts of methane production, as well as the integration of the conversion technology into a bioethanol biorefinery, are assessed using the LCA methodology. Additionally, a sensitivity analysis is conducted to enhance the environmental performance of the products (methane and bioethanol) by identifying critical hotspots in these scenarios. The results indicate that methane production in indoor environments could represent a promising approach to low or even negative carbon emissions (in the ‘cradle to gate’ scope) when renewable energy sources such as photovoltaic systems support the technology’s electricity supply. Furthermore, the environmental impact of bioethanol production could be reduced by approximately 55% to 84% by integrating carbon capture and conversion technology, together with renewable energy sources, into the design of the biorefinery. This research highlights the potential for energy generation in indoor environments and highly rich in CO2 industrial streams, and the development of bioenergy models that simultaneously capture carbon and generate methane.