Solar-Powered Tower Produces Carbon-Neutral Jet Fuel from Just CO2, Water, and Sunlight

Long-time Slashdot reader Bodhammer shared this story of a remarkable solar-powered tower that produces carbon-neutral, sustainable versions of diesel and jet fuel - using only water and carbon dioxide (plus sunlight) as its inputs.One hundred and sixty-nine sun-tracking reflector panels, each presenting three square meters (~32 sq ft) of surface area, redirect sunlight into a 16-cm (6.3-in) hole in the solar reactor at the top of the 15-m-tall (49-ft) central tower. This reactor receives an average of about 2,500 suns' worth of energy - about 50 kW of solar thermal power. This heat is used to drive a two-step thermochemical redox cycle. Water and pure carbon dioxide are fed in to a ceria-based redox reaction, which converts them simultaneously into hydrogen and carbon monoxide, or syngas. Because this is all being done in a single chamber, it's possible to tweak the rates of water and CO2 to live-manage the exact composition of the syngas. This syngas is fed to a Gas-to-Liquid (GtL) unit at the bottom of the tower, which produced a liquid phase containing 16% kerosene and 40% diesel, as well as a wax phase with 7% kerosene and 40% diesel - proving that the ceria-based ceramic solar reactor definitely produced syngas pure enough for conversion into synthetic fuels.... The team says the system's overall efficiency (measured by the energy content of the syngas as a percentage of the total solar energy input) was only around 4% in this implementation, but it sees pathways to getting that up over 20% by recovering and recycling more heat, and altering the structure of the ceria structure. "We are the first to demonstrate the entire thermochemical process chain from water and CO2 to kerosene in a fully-integrated solar tower system," said ETH Professor Aldo Steinfeld, the corresponding author of the research paper. "This solar tower fuel plant was operated with a setup relevant to industrial implementation, setting a technological milestone towards the production of sustainable aviation fuels." "The solar tower fuel plant described here represents a viable pathway to global-scale implementation of solar fuel production," reads the study.

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