- The long journey from electricity back to electricity again!
- Chicken and egg
- It’s hard to store
- But it has a role in green steel and maybe the airlines?
1. The long journey from electricity back to electricity again
Think of it hydrogen as a battery, and not a very good one. Electricity splits water into hydrogen and oxygen, and the hydrogen can be burned back into water. Sounds fine, but it’s very inefficient and therefore more expensive than just charging a car directly with electricity.
EG: If you have enough electricity for 100 miles and charge an electric car, when that car runs it will return maybe 86 miles of it. It’s about 86% efficient. Hydrogen only gets you about half that, only 43 miles. It’s only 43% efficient.
Why? Hydrogen takes more energy conversions and due to physics (second law of thermodynamics) we lose a bunch of energy along the way.
Each step loses energy.
- Split water to get hydrogen – lose 20%.
- Freeze the hydrogen to cram this gas into a small tank – lose 5%.
- Run it through a fuel cell – lose 40%.
- What have you achieved? You’ve turned electricity into a gas and back into electricity again. It’s a long, lossy, round-about way of using electricity.
An electric car just dumps the electricity straight into a battery ready to go! The Wiki on the hydrogen economy has this graphic which illustrates the losses. (Click to view larger).
2. Chicken and egg
Hydrogen suffers from the chicken and egg problem. No one wants to buy a hydrogen car until there is a “hydrogen highway”, and no one wants to build a hydrogen highway until there are enough customers to guarantee they get their money back and some.
3. It’s hard to store
Hydrogen also leaks, corrodes pipes and tanks, and is explosive. Storing it long term is difficult. But as it only requires electricity and water and a manufacturing factory, I imagine we would not store it for long but manufacture close to the point of use. Which brings me to:-
4. But it has a role in green steel – and maybe the airlines? (See Airlines.)
Just have a Think – December 2020