Power-to-X technology using renewable electricity and carbon dioxide from ambient air: SOLETAIR proof-of-concept and improved process concept

This work demonstrates hydrocarbon production directly from water, solar energy, and air-called SOLETAIR. The plant includes direct air capture (DAC) of carbon dioxide, hydrogen production by water electrolysis, and two-step synthesis bench-scale units that operate using grid-connected solar photovoltaic (PV) electricity. In addition, co-feeding of hydrogen and carbon monoxide from gas bundles are utilized to enable scaling between units. This pilot plant achieved a total operating time of approx. 300 h with a combined production of oil and wax of 6.2 kg per day. The mass and energy balances in integration of the units are studied. According to the experiments and studies, potential and bottlenecks to improve the individual units and their integration are found. Finally, a conceptual Power-to-X plant is presented, which can achieve energy and carbon efficiencies of 47% and 94%, respectively, considering liquid and solid hydrocarbons as products.