A hydrogen powered zero-emissions big rig in the Port of Stockton recently drew attention. However, some say hydrogen vehicles have a bigger carbon footprint than traditional vehicles, so what’s the point?
The problem is, hydrogen does not exist freely on its own. It takes energy to separate it. Plus it needs to be stored and transported in high pressure systems, and that takes more energy.
The most most practical source if hydrogen is from water–hydrogen and oxygen. But the energy needed to separate the two is the same as the power generated in the truck engine if done at 100 % efficiency. But there is no way this can be done at this efficiency. Then the hydrogen must be compressed to extremely high pressures and run through costly (because of the high pressures) distributions systems in order to be used This uses up more energy (which cannot be recovered)
Yes, it takes energy to create H2. Same with ethanol and other non-fossil vehicle fuels. Corn-based ethanol actually takes more energy to produce than it contains. (Fossil fuels also took energy to create – they are sort of like an energy savings account that we have been burning through at an appalling rate.)
Yes, H2 takes a distribution system – so do gasoline and diesel. No, it doesn’t have to be high pressure. The H2 fueling station I saw in Los Angeles last time I was there stored it as a liquid. There are already many trucks on our freeways carrying liquid H2 for industrial purposes. It’s far from impractical.
Also, it’s worth noting that H2 fuel cells get close to 50% efficiency. Compare that with roughly 20% efficiency for the internal combustion engine. And it’s the cleanest fuel around. Its production creates oxygen, and its consumption creates water. Even ethanol can’t compete with that.
It may also benefit us to look at hydrogen as a means of recovering and storing energy that would otherwise be wasted. This has been done on a small scale. Why not use solar and wind to produce hydrogen, then use the hydrogen whenever it is required?