Technological watch

A large number of CO2 emissions caused a serious greenhouse effect, aggravating global warming and climate change. Therefore, CO2 utilization has been a research hotspot, especially after the Paris Agreement, and among the various CO2 utilization technologies, the power-to-gas (PTG) and power-to-liquid (PTL) processes have recently attracted significant attention because they can transform CO2 into fuels and/or chemicals. Considering the lack of detailed information in the literature with regard to process design and economic analysis, we have critically and comprehensively summarized the recent research progresses concerning the PTG and PTL processes. Herein, we mainly focus on the power-to-methane in the case of PTG and the power-to-syncrude, power-to-methanol, and power-to-ethers in the case of PTL. From the technical point of view, the bottleneck problem of PTG and PTL processes is the low system efficiency, which can be improved by heat integration and/or process integration. Meanwhile, from the economic point of view, the production cost of PTG and PTL processes needs to be further reduced by the following measures, such as by increasing the carbon tax, lowering the electricity price, improving the electrolysis efficiency, reducing the capital expenditure of the electrolytic cell, and formulating sustainable incentive policies. The main purpose of the paper is to present a comprehensive updated review of CO2 utilization in PTG and PTL processes from process system integration, the techno-economic aspects, such as, state-of-the-art synthesis technologies, process system integration and the production cost, and provide useful information and reliable suggestions for the future development trends of the PTG and PTL processes.