Drop-In Fuels from Sunlight and Air

> A promising solution [for long-haul carbon-neutral transportation] are drop-in fuels (synthetic alternatives for petroleum-derived liquid hydrocarbon fuels such as kerosene, gasoline or diesel) made from H2O and CO2 by solar-driven processes [...] While individual steps of such a scheme have been implemented, we now demonstrate operation of the entire thermochemical solar fuel production chain, from H2O and CO2 captured directly from ambient air to the synthesis of drop-in transportation fuels (e.g. methanol, kerosene), with a modular 5-kWthermal pilot-scale solar system operated under real field conditions

The research article itself seems to be paywalled. A few divulgative articles have been published, e.g. https://techxplore.com/news/2021-11-technical-feasibility-su... , with an interview with project architect Aldo Steinfeld and study co-author Anthony Patt:

> For the past two years, researchers led by Aldo Steinfeld, Professor of Renewable Energy Carriers at ETH Zurich, have been operating a solar mini-refinery on the roof of the Machine Laboratory in the center of Zurich

> [The produced fuels] are carbon neutral because solar energy is used for their production and because they release only as much CO2 during their combustion as was previously extracted from the air for their production. [...] [T]he solar redox unit ... converts CO2 and H2O into a specific mixture of CO and H2 so-called syngas [to be converted] into liquid hydrocarbons [...] [With] the not-so-optimal solar irradiation of Zurich ... during a representative day run, the amount of syngas produced is about 100 standard liters, which can be processed into about half a decilitre of pure methanol ... Substantial process optimisation is still required.

> 2019 global aviation kerosene consumption was 414 billion liters; the total land footprint of all solar plants required to fully satisfy global demand would be about 45,000 km2, equivalent to 0.5 percent of the area of the Sahara Desert