Fuel from Sunlight and Air – Demonstration of the Thermochemical Pathway

Abstract

The aviation and shipping sectors are strongly dependent on liquid hydrocarbon fuels derived from fossil fuels and are contributing approximately 8% of the total anthropogenic CO2 emissions. Based on projected growth, this proportion could progressively become a dominant CO2-emissions source, but the decarbonization of these transportation sectors via battery-driven electric propulsion is unfeasible for long haul commercial travel. Alternatively, drop-in fuels - synthetic and completely interchangeable substitutes for conventional petroleum-derived hydrocarbons (e.g. kerosene, gasoline, diesel, methanol) - can be synthesized from H2O and CO2 using solar energy. The presentation reports on the experimental pilot demonstration of a modular solar dish-reactor system for the solar thermochemical fuel production from ambient air using concentrated solar energy. It describes the complete process chain and its key components, and presents representative on-sun runs with fully-automated consecutive CO2-splitting and H2O-splitting redox cycles. The system integrates three thermochemical units operated in series, namely: 1) the capture of CO2 and H2O directly from ambient air via an adsorption-desorption cyclic process; 2) the co-splitting of CO2 and H2O to generate a specific mixture of CO and H2 (syngas) via a reduction-oxidation cyclic process using concentrated solar energy; and, 3) the gas-to-liquid synthesis of methanol or Fischer-Tropsch fuels.