(86f) Techno-Economic and Life Cycle Assessment of Reactive CO2 Capture to Renewable Natural Gas

The global atmospheric concentration of carbon dioxide (CO2) has increased to 400 ppm over the last few years, mainly due to the generation of energy from fossil sources. The alarming increase in CO2 levels has led to a global need to simultaneously reduce CO2 concentration and deploy renewable energy sources. A strategy to achieve this is through a novel process called Reactive CO2 Capture (RCC). RCC refers to a process that integrates the capture and conversion of CO2 into a value-added product via fewer unit operations than separate capture and conversion. In our study, RCC utilizes and integrates two existing and developed processes – direct air capture and the Sabatier reaction. Through RCC, CO2 can be captured and directly converted into methane using renewable hydrogen. Methane, also known as natural gas, is a large source of energy carrier; used in hydrogen, electricity and heat production, and even as a transportation fuel. The natural gas produced via RCC is also considered a renewable source when the hydrogen used in the Sabatier reaction is renewable, and thus, this new form of renewable energy can be deployed and used in existing infrastructure.

To systematically compare this novel technology, a techno-economic analysis (TEA) and life cycle assessment (LCA) was performed. The TEA evaluates the potential energetic and economic savings of this integrated process, while the LCA analyzes the total carbon intensity of the production of renewable natural gas (RNG) via RCC. RCC is also being compared to a separated process and other conventional and existing technologies in producing the same product. Observed in the preliminary TEA and LCA is a 10-15% reduction in the minimum selling price of RNG and the carbon intensity of RNG. This is mainly due to increased energy efficiency, process intensification and heat integration, reduced capital expenditure, and the ability to channel CO2 from the air as feedstock into a product resulting in potentially net-negative emissions. Finally, a sensitivity analysis of an array of experimental parameters and its effect on the TEA and LCA is also being studied to better inform and understand the opportunities and limitations of the technology.