Fuel cell vehicles
Fuel cell electric vehicles, or FCEVs for short, are vehicles powered by hydrogen gas. The fuel cell component takes in hydrogen (H2) and oxygen (O2 from the air), and produces electricity to power the motor. The only exhaust is water vapor (H2O).
Viability
It's uncertain whether this can be scaled up enough to replace even half of gasoline-powered vehicles.
Potential issues to be dealt with:
| #Inefficient compared to batteries | Unavoidable problem |
| #Rare minerals in the fuel cell | Manageable |
| Energy to manufacture the fuel cell | Research needed |
| Safety | Mostly solved |
| Storing enough fuel in the vehicle | Solved |
Inefficient compared to batteries
Whether fuel cells or batteries, the intention is to power vehicles with green electricity.
- Converting energy to hydrogen, then back to electricity again - is best-case only 40 to 48% efficient.
(...)( 80% efficiency for hydrogen production, multiplied by 50% to 60% efficiency for the best fuel cells ) - Whereas charging/discharging a lithium-ion battery - is 80% to 90% efficient.
In other words, with fuel-cell vehicles we would need twice as much green electricity!
It's already hard enough to meet energy demand with renewables as it is (hence most energy comes from fossil fuels currently). Hydrogen vehicles would make it somewhat harder. The good news is it's still more efficient than combustion engine vehicles (no matter the fuel).
Rare minerals in the fuel cell
Inside a fuel cell, there are surfaces coated in a thin layer of platinum, palladium, rhodium, and/or iridium. These are called platinum-group metals (PGMs) and are extremely scarce. PGMs are needed as a catalyst to make the hydrogen and oxygen to react properly.
The same metals are also in the catalytic converter of gasoline and diesel vehicles, but in lesser quantities. A catalytic converter has about 3 to 7 grams of PGMs, while a fuel cell vehicle has 30 to 60 grams
If all vehicles were fuel cell-based,
- Global mineral reserves would just barely be enough to meet the demand for PGMs.
- The mining would take awhile.
- It helps that PGMs can be recycled from old vehicle catalytic converters.
Some relevant calculations: (calculation loading) (calculation loading) ^ Math will be fixed soon.