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| Fuel cell [[electric vehicles]], or FCEVs for short, are vehicles powered by [[hydrogen gas]]. The fuel cell component takes in hydrogen (H<sub>2</sub>) and oxygen (O<sub>2</sub> from the air), and produces electricity to power the motor. The only exhaust is water vapor (H<sub>2</sub>O).
| | A '''fuel cell''' produces electricity using [[hydrogen gas]] fuel (H<sub>2</sub>) and oxygen gas from the air (O<sub>2</sub>). The only exhaust is water vapor (H<sub>2</sub>O). |
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| ==Viability==
| | {{considerations}} |
| It's '''uncertain''' whether this can be scaled up enough to replace even half of gasoline-powered vehicles.
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| Potential issues to be dealt with:
| | ===Efficiency=== |
| {|class="wikitable" | | {{sum|Good|good}} |
| |[[#Inefficient compared to batteries]]
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| |Unavoidable problem
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| |[[#Rare minerals in the fuel cell]]
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| |Manageable
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| |-
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| |Energy to manufacture the fuel cell
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| |Research needed
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| |Safety
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| |Mostly solved
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| |-
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| |Storing enough fuel in the vehicle
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| |Solved
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| |} | |
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| ==Inefficient compared to batteries==
| | Fuel cell vehicles are more efficient than [[hydrogen combustion vehicles]]. |
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| Whether fuel cells or batteries, the intention is to power vehicles with green electricity.
| | ===Platinum-group metals=== |
| * [[electrolysis|Converting energy to hydrogen]], then back to electricity again - is best-case only 40 to 48% efficient. {{x|80% efficiency for hydrogen production, multiplied by 50% to 60% efficiency for the best fuel cells}}
| | {{sum|Major problem|bad}} |
| * Whereas charging/discharging a [[lithium-ion]] battery - is 80% to 90% efficient.
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| In other words, with fuel-cell vehicles we would need twice as much green electricity!
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| 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).
| | Platinum-group metals (PGMs) are an essential component of fuel cells. Unfortunately, PGMs are very scarce, and fuel cells need too many of them. |
| | | * If the goal is to replace all gasoline or diesel vehicles with something electric, then fuel cell vehicles '''aren't''' the answer, because the Earth simply doesn't have enough PGMs. See [[hydrogen gas#Platinum-group metals|this page]] for details. |
| <!-- TALK: I think we should import some content from [[Calc:If all vehicles were electric]] -->
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| ==Rare minerals in the fuel cell==
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| 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.
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| The same metals are also in the [[wikipedia:catalytic converter|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{{x|Some scientists are working on reducing this amount, but it's hard to say how much progress can (or will) be made.}}.<!-- TODO: add links to some of that research. Replace {{x}} with {{p}} and put the links inside. -->
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| If all vehicles were fuel cell-based,
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| * Global [[Term:mineral reserves|mineral reserves]] would ''just barely'' be enough to meet the demand for PGMs.
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| * The mining would take awhile.
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| * It helps that PGMs can be recycled from old vehicle catalytic converters.
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| Some relevant calculations:
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| {{calc
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| |(toyota_mirai.pgm - catalytic_converter.pgm) * world.cars
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| |% pgm.reserves | |
| |new_pgm_needed
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| }}
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| {{calc
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| |new_pgm_needed
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| |years pgm.mine_production
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| }}
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| ^ Math will be fixed soon.
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| ==See also== | | ==See also== |
| * [[Hydrogen combustion vehicles]] | | * '''[[Hydrogen combustion vehicles]]''' - could be more scalable than fuel cells, '''if''' hydrogen gas fuel ever becomes abundant enough via surplus [[wind power]] |
| * [[Green hydrogen]]
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