3 ms·

Please don't say CH4 is "kind of bad". It's an atrocious threat for the planet (and Humanity) right now (thawing of permafrost and of oceanic floor, etc). Be i

Please don't say CH4 is "kind of bad". It's an atrocious threat for the planet (and Humanity) right now (thawing of permafrost and of oceanic floor, etc). Be it 11x more potent that CO2 or just 1x, it's completely enough that H2 has a GHG effect, and that H2 leaks are impossible to prevent due to the size of the molecule. For me, that's enough to make it less desirable than batteries, especially if we are speaking of policies of mass investment on a planet scale!!! Also, you use a leakage at 1bar then you transpose it to a plane which would obviously not transport the H2 at 1bar but at a much higher pressure. Finally, if it is not zero-carbon, then it is not. Even "a little" is not zero. We need to account for it, and never put ZERO on this CO2e accounting line, that's all.

semi-extrinsic 4y ago
Oh I agree that methane is a horrible threat if it is released at massive scale, like from the permafrost. We should absolutely do everything we can to avoid that. My point is that if you compare hydrogen on propulsion equivalent basis and with realistic leakage rates, it is so much better than today's solutions that we should absolutely use it. When it comes to batteries, yeah, that's just not going to happen for anything over 20 passengers and 200 mile operating range. It's physically impossible to obtain sufficient Wh/kg to run even a small airliner on batteries. Airbus is investing heavily in liquid hydrogen fuelled jets, and it's not because they are stupid. > Also, you use a leakage at 1bar then you transpose it to a plane which would obviously not transport the H2 at 1bar but at a much higher pressure. So this part was probably too brief in my first post to be perfectly clear. Imagine that you have the 700 bar pressure tank of the Toyota Mirai, and the entire leakage out to 1 bar (the atmosphere) happens in a single point. Then you put a ballon over that point and measure how quickly it grows. That rate is reported as "2 mL/min at 1 bar".
- henearkr 4y ago
  Ok, thanks for the clarification about the calculation. (I should have seen that, as a gas stored at 1 bar will not pour out of its container very well) That is fine to employ H2 technology if all is accounted for and the leaks are included in the big picture (at consumer end-points as well as producer end-points). Because, as a reminder, about emissions, we do not only need to "do a lot better" than now, we need to do zero (scratch that, we need to do negative). -- As an aside: > Airbus is investing heavily in liquid hydrogen fuelled jets, and it's not because they are stupid. Well, I would not use that as an argument. For example Toyota invested a lot in the wrong direction (and now they cling on their hybrid vehicles even if it makes no sense). (Even worse, see the diesielgate with Volkswagen. Huge corporations can do stupid things)

semi-extrinsic 4y ago

Oh I agree that methane is a horrible threat if it is released at massive scale, like from the permafrost. We should absolutely do everything we can to avoid that. My point is that if you compare hydrogen on propulsion equivalent basis and with realistic leakage rates, it is so much better than today's solutions that we should absolutely use it. When it comes to batteries, yeah, that's just not going to happen for anything over 20 passengers and 200 mile operating range. It's physically impossible to obtain sufficient Wh/kg to run even a small airliner on batteries. Airbus is investing heavily in liquid hydrogen fuelled jets, and it's not because they are stupid. > Also, you use a leakage at 1bar then you transpose it to a plane which would obviously not transport the H2 at 1bar but at a much higher pressure. So this part was probably too brief in my first post to be perfectly clear. Imagine that you have the 700 bar pressure tank of the Toyota Mirai, and the entire leakage out to 1 bar (the atmosphere) happens in a single point. Then you put a ballon over that point and measure how quickly it grows. That rate is reported as "2 mL/min at 1 bar".

henearkr 4y ago
Ok, thanks for the clarification about the calculation. (I should have seen that, as a gas stored at 1 bar will not pour out of its container very well) That is fine to employ H2 technology if all is accounted for and the leaks are included in the big picture (at consumer end-points as well as producer end-points). Because, as a reminder, about emissions, we do not only need to "do a lot better" than now, we need to do zero (scratch that, we need to do negative). -- As an aside: > Airbus is investing heavily in liquid hydrogen fuelled jets, and it's not because they are stupid. Well, I would not use that as an argument. For example Toyota invested a lot in the wrong direction (and now they cling on their hybrid vehicles even if it makes no sense). (Even worse, see the diesielgate with Volkswagen. Huge corporations can do stupid things)