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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 but maybe manageable
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| |-
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| |[[#Rare minerals in the fuel cell]]
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| |Might be impossible to solve
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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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| |Hydrogen fueling stations
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| |Solvable
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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 [https://en.wikipedia.org/wiki/Catalytic_converter catalytic converters] in gasoline and diesel vehicles, but in lesser quantities. A catalytic converter has about 2 grams of PGMs{{x|2 grams for a typical car; large trucks have proportionally more}}, while a fuel cell car 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: find the source that I got the '30 to 60 grams' from; add citation -->
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| If all vehicles{{x|Is that too extreme a scenario? Then go with 'only half of all vehicles' and consider the numbers below to be the ''total'' PGM demand, assuming that an equal amount of PGMs are also needed for hydrogen production.}} were fuel cell-based,
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| * The amount of PGMs needed is well within the limits of global [[Term:mineral reserves|mineral reserves]].
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| * The mining would take a ''very'' long time.
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| * It helps ''slightly'' that PGMs can be recycled from old vehicle catalytic converters.
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| Some relevant [[calculator|calculations]]:
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| {{dp
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| |<nowiki>toyota_mirai.pgm</nowiki>
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| |<nowiki>30 grams</nowiki>
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| |<nowiki>Amount of platinum-group metals (PGMs) in a Toyota Mirai (fuel cell vehicle)</nowiki>
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| |<nowiki>The Toyota Mirai is a common example of a hydrogen-powered vehicle.</nowiki><br /><nowiki>
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| </nowiki><br /><nowiki>
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| https://www.heraeus.com/media/media/hpm/doc_hpm/precious_metal_update/en_6/20181031_PGM_Market_Analysis.pdf</nowiki>
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| }}
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| {{dp
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| |<nowiki>catalytic_converter.pgm</nowiki>
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| |<nowiki>2 grams</nowiki>
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| |<nowiki>Platinum-group metals (PGMs) in a catalytic converter of a gasoline-powered car</nowiki>
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| |<nowiki>Countless automotive forums say 3 to 7 grams for a typical car.</nowiki><br /><nowiki> | |
| </nowiki><br /><nowiki>
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| But ThermoFisher (which is more reputable, perhaps) says "The recoverable amounts of Pt, Pd, and Rh in each [vehicle] can range from 1-2 grams for a small car to 12-15 grams for a big truck in the US." - Are There Precious Metals in Catalytic Converters? https://www.thermofisher.com/blog/metals/platinum-group-metal-recovery-from-spent-catalytic-converters-using-xrf/</nowiki><br /><nowiki>
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| </nowiki><br /><nowiki>
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| I assume they mean 1-2 grams ''total'', not 1-2 grams ''of each'' Pt Pd Rh, right? That would make sense considering they also mention that the ratios vary as metal prices/availability change over time.</nowiki><br /><nowiki>
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| </nowiki><br /><nowiki>
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| 1 to 2 grams total recoverable is also consistent with the following study: Yakoumis et al 2018 IOP Conf. Ser.: Mater. Sci. Eng. 329 012009 - Real life experimental determination of platinum group metals content in automotive catalytic converters - https://iopscience.iop.org/article/10.1088/1757-899X/329/1/012009/pdf</nowiki><br /><nowiki>
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| </nowiki><br /><nowiki>
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| Still no word on what percentage this ''recoverable'' is of total PGMs - how efficient is the recycling process? Unknown</nowiki>
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| }}
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| {{dp
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| |<nowiki>world.cars</nowiki>
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| |<nowiki>1.446 billion</nowiki>
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| |<nowiki>Number of cars in the world</nowiki>
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| |<nowiki>Last updated in 2022</nowiki><br /><nowiki>
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| www.carsguide.com.au › car-advice › how-many-cars-are-there-in-the-wor...</nowiki><br /><nowiki>
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| hedgescompany.com › blog › 2021/06 › how-many-cars-are-there-in-the-...</nowiki>
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| }}
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| {{dp
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| |<nowiki>pgm.reserves</nowiki>
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| |<nowiki>70000 tonnes</nowiki>
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| |<nowiki>Global reserves of platinum-group metals</nowiki>
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| |<nowiki>Includes platinum, palladium, ruthenium, rhodium, osmium, iridium.</nowiki><br /><nowiki>
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| </nowiki><br /><nowiki>
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| Platinum-group metal reserves worldwide by country 2021</nowiki><br /><nowiki>
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| Statista - https://www.statista.com › statistics › platinum-me...</nowiki><br /><nowiki>
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| </nowiki>
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| }}
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| {{dp
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| |<nowiki>platinum.mine_production</nowiki>
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| |<nowiki>186000 kg/year</nowiki>
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| |<nowiki>Global production of new platinum from mining</nowiki>
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| |<nowiki>Using data from 2019.</nowiki><br /><nowiki>
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| </nowiki><br /><nowiki>
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| Source: USGS Mineral Commodity Summaries 2021</nowiki>
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| }}
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| {{dp
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| |<nowiki>palladium.mine_production</nowiki>
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| |<nowiki>227000 kg/year</nowiki>
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| |<nowiki>Global production of new palladium from mining</nowiki>
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| |<nowiki>Using data from 2019.</nowiki><br /><nowiki>
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| </nowiki><br /><nowiki>
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| Source: USGS Mineral Commodity Summaries 2021</nowiki>
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| }}
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| {{dp
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| |<nowiki>pgm.mine_production</nowiki>
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| |<nowiki>platinum.mine_production + palladium.mine_production</nowiki>
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| |<nowiki>Global production of platinum-group metals (PGMs) from mining</nowiki>
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| |<nowiki>Assumption: that the other PGMs (iridium, rhodium, osmium, ruthenium) are in such small quantities that it's ok that they aren't counted here (because data is unavailable)</nowiki>
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| }}
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| {{calc
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| |(toyota_mirai.pgm - catalytic_converter.pgm) * world.cars
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| |% pgm.reserves
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| |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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| That's a long time - [[climate change|too long]]. Then again, suppose the mining industry were to hire 10 times as many people{{x|due to economics perhaps, if fuel cell vehicles ''did'' become a major market}}, could it all be mined 10 times faster? Does mining work that way, or are there other bottlenecks?{{rn}}<!--Some companies would certainly get rich either way.-->
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| <small>Keep in mind that a similar amount of PGMs would ''also'' be needed for green hydrogen production.</small>
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| More data is needed:
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| * How many human labor hours would it take to mine this much?
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| * How much dirt would have to be dug out, and what would be the environmental impact?
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| If the answers are bleak, then the only hope is in designing fuel cells that contain no more PGMs than a catalytic converter ([[Research:Reduce mineral content of fuel cells|research?]]).
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| <!--
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| Ways to maybe estimate how much labor is involved in mining PGMs:
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| - try to find actual data on how many people are currently employed in PGM mines, globally
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| - if that's not available, then: look at the price of platinum or palladium. Assume the average worker is paid $4/hour or something (is that an accurate international average?) and that 1/3 of the metal price is due to worker wages (the other 2/3 being capital costs and company profits).
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| -->
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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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