Sayong they are converting water to fuel focuses on the wrong (least important) part of it. The point is that it fixes CO2 from the air into hydrocarbon fuels via generating carbon monoxide and using the Fisher troph process to assemble fuel molecules. This is really just congealing electrical energy into hydrocarbon fuel. For now in the lab, you still get that energy from fossil fuels. Presumably in the future you would use this process to congeal extra solar or wind energy into fuel rather than keep them stored in batteries
In this particular case, they are planning to take energy from carrier's nuclear power plant.
More generally, either hydrogen or fuel synthesis requires energy to come from somewhere; In this regard it is no different than re-building airplanes to use hydrogen, as the original article suggests.
The point is that we might have better chances synthesising fuels usable in existing planes, versus re-building majority of aviation to use hydrogen.
