By The Financial District
Nov 5, 20212 min
Engineers at ETH Zurich have demonstrated a pilot system that can produce fuels from sunlight and air. The device captures carbon dioxide and water from the atmosphere and uses solar energy to convert it into syngas, which is then converted into liquid fuel that’s essentially carbon neutral, Michael Irving reported for New Atlas.
Photo Insert: The solar fuel reactor harnessing heat from concentrated sunlight to convert carbon dioxide and water into syngas
Synthetic fuels could be a decent solution. These are made to mimic current liquid hydrocarbon fuels but are produced from renewable sources, such as biomass, waste products, or carbon already in the atmosphere.
And because they replace or complement fossil fuels, they can be “dropped into” existing engines and infrastructure. In the new study, researchers at ETH Zurich developed and tested a new system that can produce these drop-in fuels using just sunlight and air.
The resulting fuel is carbon neutral, releasing only as much carbon dioxide when burned as its production removed from the air originally. The system is comprised of three units – a direct air capture unit, a solar redox unit, and a gas-to-liquid unit.
The first section sucks in ambient air and uses adsorption to pull carbon dioxide and water out of it. These are then piped into the second unit, where solar energy is harnessed to trigger chemical reactions. A parabolic concentrator focuses sunlight by a factor of 3,000 onto the solar reactor, creating temperatures of 1,500 °C (2,732 °F).
Inside the reactor is a ceramic structure made of cerium oxide, which absorbs oxygen from the incoming carbon dioxide and water, producing hydrogen and carbon monoxide – syngas.
The syngas itself could be collected for use, or it can be funneled to the third unit, where it’s converted into liquid hydrocarbon fuels like kerosene or methanol. To test the concept, the researchers set up a small 5-kW pilot system on the roof of a building.
Running for seven hours a day in intermittent sunlight, the device was able to produce 32 ml (1.1 oz) of methanol each day. That’s not a whole lot, but the team says it shows that the concept works and could be scaled up to commercial production. The research was published recently in the journal Nature.