New research shows that the sun’s energy could be used to turn carbon dioxide and water into synthetic fuel. A team from the Paul Scherrer Institute and ETH Zurich, Switzerland, have collaborated to develop a new procedure and material to achieve this.
The procedure allows solar energy to be stored as chemical bonds, rather than electricity, by using heat to trigger certain chemical processes. This takes place at very high temperatures above 10000C. Cerium oxide loses and reacquires oxygen when heated and cooled, allowing anything passed over it to release oxygen atoms to be absorbed by the cerium oxide. Once it is re-oxidised, the cycle begins again. This means that water becomes hydrogen, and carbon dioxide becomes carbon monoxide – from which fuel can be produced. The team also developed a material that allows the direct production of fuel with one process. Small amounts of rhodium were added to cerium oxide – rhodium’s catalytic nature permits reactions with hydrogen, carbon monoxide and carbon dioxide.
The researchers claim that this material is key to the reaction, as it is essential to the anticipated catalytic process. Following the reaction, the fuels are either used or stored and the cyclical process begins again, following the reactivation of the cerium oxide.
Tests were performed in a high performance oven, and showed that the catalyst has long-term stability. The researchers carried out 59 cycles in quick succession, with the catalyst surviving comfortably. The next step is to optimise the procedure in the hope that this study will lead towards the chemical storage of solar energy.
Their study, First demonstration of direct hydrocarbon fuel production from water and carbon dioxide by solar-driven thermochemical cycles using rhodium–ceria, is published in Energy and Environmental Science.
