Quote from: K-Dog on Apr 27, 2024, 12:49 PMBut regardless of positive benefits, hydrogen is only a transport mechanism. Hydrogen is not a source of energy. You can't mine hydrogen. If you could mine hydrogen it would be a source of energy. One way or another all hydrogen must be produced, and that always takes more energy than you get from using the hydrogen.
Iron powder is also just a transport mechanism. You can't mine it, it's not found in ore in reduced form. It's already been oxidized. You have to put energy in by smelting the iron to get it as an element, then gring it to a powder. When you oxidize the powder, you get the energy back from the smelting process. There is some loss of course.
The oxidized form Hydrogen is found in nature is Water, the chemical name for it is Hydrogen Hydroxide. When you reduce it, yu get Hydrogen and Oxygen in their elemental form. Burn the hydrogen in the presence of oxygen, you get the energy back you put in to reduce it, just like with using iron.
Fossil Fuels are also a transport mechanism, using Carbon as the element that goes through the oxidation-reduction process. The difference is with FFs the reduction was done over millions of years under high pressure and heat underground after the life process which left it in a partially reduced state. You oxidize it when you burn it to get CO2. It's not a source of energy either, that came from the Sun and the geological processes.
Iron isn't good as a transport fuel because both as an element and combined with oxygen it's a solid. You need your fuel to be a gas after the combustion in order to do work in a combustion engine. The gas expands and pushes he pistons. Or in the case of a Jet engine, the expanding gas directly powers the vehicle.
All planes are flying bombs, jet fuel is highly volatile and if a fuel line ruptures it goes BOOM. If hydrogen escapes its pressurized containment system, it goes boom also. Same with natural gas. Cars run on NG or H that get in accidents will probably go boom too. Clearly the engineers building these devices believe they can make them safe and reliable enough not to go boom too often. On a society level, we're willing to accept a certain percentage of death from high speed travel, car accidents kill more people every year than heart disease or cancer. Air travel is pretty safe overall by comparison.
According to the articles I have read thus far, they seem to suggest enough hydrogen fuel can be carried aboard a plane to fly it the necessary distances. Running a prop engine plane they definitely could. Range might not be quite as much as FFs, but I think the NY-London route would be feasible. Non-stop NY-Beijing or London-Sydney is probably out.
Anyhow, it's way cleaner overall than batteries and electricity, and for propulsion works better too. So I still consider it plausible.
RE