This is not a solution. CO2 emissions in the upper atmosphere are problematic regardless of how you make the fuel. We need a different propulsion system for a

This is not a solution. CO2 emissions in the upper atmosphere are problematic regardless of how you make the fuel. We need a different propulsion system for aviation, period. The generally accepted "impact" multiplier for aviation emissions is 2.6, so let's say the fuel was "carbon neutral" - wouldn't it then be 1.6? Not 0. Edit: Unless we're talking about straight hydrogen-fueled engines, is that where this article is aimed? Biofuels and Synfuels are still carbon-based AIUI, but TFA is a bit ambiguous here.