this post was submitted on 03 Sep 2023
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Hydrogen made from methane reformation, or from coal powered electrolysis?
Solar panels exist... Just use electrolysis from green sources. If we can't figure out electricity without coal, then fuel is the least of our problems...
The problem here is round trip efficiency.
Using a battery to store solar power is about 95% efficient. A small amount of energy is lost to heat when charging and discharging.
Using hydrogen as energy storage is about 30% efficient. A small amount of energy is lost when making the hydrogen, but a large amount is lost when converting it back to electricity.
Unfortunately this isn't even a solvable problem. The fundamental limit of efficiency due hydrogen to electricity is about 50%. Physics and entropy prevent it from being any higher.
Burning hydrogen for heat is about 100% efficient, but heat pumps (running from electricity) can be over 600% efficient. Heat pumps get the extra efficiency by moving heat rather than creating heat directly.
If you wanted to use hydrogen from electrolysis, we would need 3 to 6 times as many solar panels than if we just used batteries.
Hydrogen can be clean, but it's rarely the best option.
Agreed. But in cases where a large amount of energy is needed on one tank/charge (large freight haulers, long-distance busses, trains, etc.) hydrogen might be a good alternative to petrol while we work on improving battery capacity and recharge times.
You're never going to see 95% efficiency doing that. You'll realistically lose around 20% or so from things like parasitic losses, AC-DC conversions, transmission losses, etc. And that's ignoring the energy needed to make the battery in the first.
That's completely wrong. An electrolyzer is an electrochemical system. It has about the same level of efficiency as charging a battery. People are just regurgigating BEV propaganda here.
In reality, hydrogen is far more scalable than batteries. What people don't realize is that you will fail to capture all of your renewable energy with batteries. You end up with a lot of curtailed power. You actually have to use hydrogen for this, and in fact you'll have fewer solar panels in the long run.
Solar oven isn't a possibility? I was always wondering why it's not something done to crack the molecule, I don't think you can make something greener than a bunch of mirrors oriented on one spot
Also, couldn't it be offshore? Making drinkable water as a bonus? I guess I'm missing so much knowledge on this because in my head it's like just perfect, well too perfect to be real
As far as I'm aware, heating water with mirrors will just get you some really hot steam. I don't think it's feasible to split hydrogen from water using heat. Please let me know if I'm wrong.
You can get green hydrogen via electrolysis using power from green sources such as wind and solar. I don't thinknits practical to do via heat at all. Though not much hydrogen is produced like this most coming from 'blue' and 'grey' sources which are just greenwashing attempts from fossil fuel companies.