Aviation and shipping currently contribute approximately 8% of total anthropogenic CO2 emissions, with growth in tourism and global trade projected to increase this contribution further.
Carbon-neutral transportation is feasible with electric motors powered by rechargeable batteries, though challenging if not impossible for long-haul commercial travel, particularly air travel.
A promising solution 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.
Among the many possible approaches, the thermochemical path using concentrated solar radiation as the source of high-temperature process heat offers potentially high production rates and efficiencies and can deliver truly carbon-neutral fuels if the required CO2 is obtained directly from atmospheric air.
If H2O is also co-extracted from air, feedstock sourcing and fuel production can be co-located in desert regions with high solar irradiation and limited access to water resources.
While individual steps of such a scheme have been implemented, it can now be demonstrated that 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 is feasible.
It will take further R&D efforts and proof of the economic viability of the process as well as required policies to bring these solar fuels to market.
Would you prefer to fly knowing you are definitely carbon neutral?
What alternative solutions are you backing?