气候变化领域集成服务门户

In order to reduce CO2 emissions, the main driver of global warming, Carbon Capture Storage (CCS) and Carbon Capture Utilization (CCU) have become subject to much study. CCU covers a large number of processes and chemical reactions that use CO2 as an alternative carbon feedstock. CO2 can arise from a wide range of sources, including industrial ones, such as power, cement, steel and chemicals industries. The diversity of CO2 conversion routes is usually classified under three main categories: chemical CO2 conversion, mineralization, and biological processes, following routes such as thermochemical, electrochemical and photocatalytic conversion. As a multitude of pathways exist, both in terms of the chemical reactions involved and the processes used, and these pathways have different levels of maturity and performance, a key challenge is to identify those that are the most advanced, mainly in terms of technology availability for the short- to mid-term deployment in industries. An original multistep method is proposed to first reduce the panel of CO2 conversion alternatives, and then to select the best emerging options to be implemented short- to mid-term via a multi-criteria assessment, which includes technical, economic, energetic, environmental and market considerations. An original double-weighted matrix is developed, comprising nine indicators grouped into the 3E performance criteria (Engineering-Economic Environmental). The Analytical Hierarchy Process (AHP) method is used to determine two sets of weights by using pairwise comparison judgments. Finally, both qualitative uncertainty assessment and sensitivity analysis are performed to enhance the robustness of the results and limit the interpretation of biases. A ranking of the emerging CO2 utilization products for short- to mid-term deployment is then discussed. The routes that appear to be viable, with a high level of maturity, and suitable for near-term implementation, involve the production of compounds that have a low unit price, but significant market volume, including methanol, methane, calcium carbonates, microalgae, sodium carbonates, urea, syngas and ethanol, and compounds that have a high unit price but low market volume, such as dimethyl carbonates, polycarbonates, formic acid and salicylic acid.