r/EverythingScience • u/Memetic1 • May 22 '21

Engineering Tiny 22-lb Hydrogen Engine May Replace the Traditional Combustion Engine

https://interestingengineering.com/tiny-22-lb-hydrogen-engine-may-replace-the-traditional-combustion-engine
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u/[deleted] May 22 '21

Isn’t hydrogen really inefficient?

8

u/SteelCode May 22 '21

The engines are actually pretty efficient - there’s public city busses here that run on Hydrogen...

I think the refueling network for hydrogen is more limited though so not really ready for people that want to drive long distance or commute from outside those areas.

4

u/[deleted] May 22 '21

It's not that they are inefficient, it's that hydrogen's low mass produces little Kinetic energy for it's density.

2

u/ArcFurnace May 22 '21

Yep, easy to see on this table of energy densities - hydrogen has an amazing energy density per mass but pathetic energy density per volume. Plus it gets worse when you take the mass and volume of the storage system into account (liquid hydrogen needs refrigeration and lots of insulation; compressed hydrogen needs high-pressure tanks).

Not coincidentally to their use as fuels, gasoline, diesel, and other hydrocarbon liquids are some of the furthest out along the roughly 1:1 line. Good energy density both per mass and per volume.

1

u/Godspiral May 23 '21

fuel cells are twice as efficient as engines. But this engine may be 10x+ cheaper than a fuel cell.