Demonstration of the Entire Production Chain to Renewable Kerosene via Solar Thermochemical Splitting of H2O and CO2

Abstract

The European consortium SOLARJET has experimentally demonstrated the first ever production of jet fuel via a thermochemical H 2 O/CO 2 -splitting cycle using simulated concentrated solar radiation. The key component of the production process of sustainable “solar kerosene” is a high-temperature solar reactor containing a reticulated porous ceramic (RPC) foam structure made of pure CeO 2 undergoing a 2-step redox cyclic process. During the first endothermic reduction step at 1450–1600 °C, the RPC was directly exposed to concentrated thermal radiation with power inputs ranging from 2.8 to 3.8 kW and mean solar flux concentration ratios of up to 3000 suns. In the subsequent exothermic oxidation step at 700–1200 °C, the reduced ceria was stoichiometrically reoxidized with CO 2 and/or H 2 O to generate CO and/or H 2 . The RPC featured dual-scale porosity: millimeter-size pores for volumetric radiation absorption during reduction and micrometer-size pores within its struts for enhanced oxidation rates. For a cycle duration of 25 min, mean reduction rates were 0.17 mL O2 min –1 g –1 CeO2 and mean oxidation rates were 0.60 mL CO min –1 g –1 CeO2 . The solar-to-fuel energy conversion efficiency was 1.72%, without sensible heat recovery. A total of 291 stable redox cycles were performed, yielding 700 standard liters of syngas of composition 33.7% H 2, 19.2% CO, 30.5% CO 2, 0.06% O 2, 0.09% CH 4, and 16.5% Ar, which was compressed to 150 bar and further processed via Fischer–Tropsch synthesis to a mixture of naphtha, gasoil, and kerosene.