Carbon-negative olefins production from biomass and solar energy via direct chemical looping

A novel carbon-negative olefins and green hydrogen (H2) cogeneration system utilizing biomass and solar energy has been proposed, providing a new solution for the high value-added conversion of biomass and solar energy. The entire system mainly includes two parts: biomass-to-olefins (BTO) and photovoltaic-based H2 production (PVHP). Solar energy was used to produce green H2 to utilize redundant carbon dioxide (CO2) and achieve zero CO2 emissions during production. Three cities in China with a demand for the petrochemical industry and abundant solar energy were selected as the research objects, and five types of biomasses were analyzed. A comprehensive evaluation of the proposed system was conducted through energy, exergy, and techno-economic analyses. The results indicated that the annual production of ethylene and propylene are both between 4550 and 5500 t. The energy and exergy efficiencies of the BTO subsystem are both between 55 % and 65 %. According to the techno-economic results, using rice straw as the biomass feed is the best, and the cost can be recovered within 8.5 years. In the future, with the development of PV technology leading to cost reduction, the system will demonstrate a better economy. •A system for achieving negative carbon emission utilization of biomass was proposed.•Solar energy was utilized to convert all excess CO2 into olefins.•A comprehensive thermodynamic and techno-economic evaluation was conducted on the system.•The investment costs of the system can be recovered within 8.5 years at the earliest.