Using hydrogen doesn't emit carbon. But the principal way hydrogen is produced is called steam reformation. It's a process that turns methane (CH4) and water (2* H2O) into hydrogen (4* H2) and CO2 (i think, I'm not an expert). So all the carbon get emitted as co2. So it's not better, and there are a bunch of inefficiencies too. (The reformation process itself, and transportation challenges, and leakage). But theoretically, it does centralize the emissions which would make them easier to sequester so there's that.