Hydrogen is a liquid resource split from Water in an Electrolyser, together with oxygen. A Refinery burns it with that oxygen into Fuel, and combines it with carbon into polymer, which takes no oxygen.
A refinery makes fuel from hydrogen faster than from carbon, and uses no carbon doing so. The cost is the extra steps and the power an electrolyser draws. Hydrogen's source, ice, is found from the Static outward and is richest in the Fade. As a liquid, hydrogen goes aboard only a tanker or the hull.