The simple answer is that electrolysis is no secret, but hydrogen production isn't being done this way. For whatever reason suits them, the major commercial producers are all using filthy wasteful processes to produce hydrogen from fossil fuel, venting CO, CO2, other harmful gasses and heat into the atmosphere in the process. This is already happening on a major industrial scale in California, you can't pretend that some alternate clean and efficient supply is just going to magically pop up to replace it because that would be sweet. This is just another of many examples where ignorant but well meaning environmental nuts make awful choices because they are incapable of looking at the entire system.