Science and TechnologyGreen aviationLiquid sunshineA way of combining atmospheric CO2 and water to make aircraft fuelMOST PEOPLE who think about such things agree that replacing fossil fuels with renewable electricity, either directly or indirectly, is the best way to decarbonise industry, transport and the heating and cooling of buildings.But there are some holdout areas where this is hard.Cement is one.Aviation is another, because batteries are too heavy and hydrogen (which could be made using renewable electricity) too bulky to do the job easily.Hydrocarbon aviation fuels are thus likely to be around for a while.But such fuels need not be fossil.They might be synthesised from the CO2 exhaust of various industrial processes.And a study just published in Nature, by Aldo Steinfeld of ETH Zurich, a technological university in Switzerland, and his colleagues, shows how they might literally be plucked from thin air.Dr Steinfeld and his team devised and tested a system that, in essence, reimagines the natural process of photosynthesis.