Archive:000/Hydrogen gas: Difference between revisions

'''Hydrogen gas''' (H₂) is a combustible fuel that leaves behind nothing but water vapor (H₂O) when burned.

<!-- TALK: Maybe this is wrong if NOx emissions can be emitted too? {{qn}} If so, how to rephrase while maintaining simplicity? -->

There are '''no''' natural resources of hydrogen gas{{x|except in rare and extremely small quantities, not a viable way to supply [[energy]] in any meaningful amount}}.

To make hydrogen gas, you need to use some other [[energy]] source. In this way, hydrogen can be understood as a form of '''[[energy storage]]'''.

'''''This page is about how hydrogen gas could be used with renewable [[energy]].'''''

==Use-cases==

===Production===

* Storing energy from [[wind]] power, as the windy seasons and non-windy seasons both tend to last for months at a time.

* Storing energy from [[geothermal electricity]], which is only available in very specific geographical regions, usually far away from most [[population]] (power lines can't reach). The hydrogen gas can be transported to where people could use it.

{{pn|Research needed for this section}}

* Is it viable to repurpose natural gas pipelines? Or would it leak too much since H₂ molecules are much smaller than methane? {{rn}}

Hydrogen fuel cells are the opposite of the electrolysis mentioned above. A fuel cell takes in hydrogen gas (along with oxygen gas from the air), generates electricity, and leaves behind water vapor.

===Compared to status quo===

Most hydrogen gas today is used for making [[fertilizer]], and is produced from natural gas. Fertilizer production can continue with renewables. This is a relatively small amount of hydrogen, compared to a "net zero carbon emissions scenario" involving all the use-cases above.

===Platinum-group metals===

{{sum|Possible problem}}

Both '''electrolysis''' and '''fuel cells''' need platinum-group metals (PGMs):

{{minor|The mass of PGMs needed is proportional to ''peak power'':}}

* For electrolysis systems, the maximum '''rate of hydrogen production''' {{light|is limited by the amount of PGMs}}.

* For fuel cell vehicles, the '''horsepower''' {{light|is limited by the amount of PGMs}}.

** {{minor|But the vehicle can still achieve ''short bursts'' of higher horsepower if there's a battery or supercapacitor in parallel with the fuel cell.}}

|<nowiki>pgm.mine_production</nowiki>

|<nowiki>Global production of platinum-group metals (PGMs) from mining</nowiki>

|<nowiki>Global reserves of platinum-group metals</nowiki>

|<nowiki>fossil_fuels.energy</nowiki>

|<nowiki>Total consumption of coal, oil, and natural gas (worldwide)</nowiki>

|Without this, we'd be calculating for just personal vehicles. But we also need to factor in commercial vehicles such as buses and trucks. These vary widely in size, and data is hard to find, so for simplicity sake, we just assume that they'd add up to about the same as personal vehicles - thus doubling total energy storage needed. This assumption is based on the fact that freight trucks are a somewhat smaller share of [[energy demand]] than passenger vehicles, but the trucks probably need a longer range.

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<tabs><tab name="Estimate #1">

* that all of today's [[energy demand]] were to be met using hydrogen gas

* that all hydrogen gas were to be produced using [[wind]] power (or something with the same [[capacity factor]] as wind)

'''Tl;dr: There ''are'' enough PGM minerals in the Earth, but today's mining rates would be ''far too slow''.'''<br />

 

|energy.tfc / wind.capacity_factor * electrolysis.pgm_by_power

|grams per capita * world.population

|production_pgm

|world.cars * toyota_mirai.pgm

|grams per capita * world.population

|consumption_pgm

|PGMs needed for hydrogen-based electricity consumption:

|world.cars * catalytic_converter.pgm

|grams per capita * world.population

|PGMs recoverable from catalytic converters of old gas cars:{{minor|Old semi trucks (not counted here) could also provide a bit more}}</small>

|production_pgm + consumption_pgm - recyclable_pgm

|

|production_pgm + consumption_pgm - recyclable_pgm

|years pgm.mine_production

|

|Compared to current production rate:

This estimate is imperfect and oversimplified, but probably reasonable in a scenario where some vehicles use hydrogen combustion and some use fuel cells. In general,

* If more vehicles use hydrogen combustion, we'd need more wind power but less PGM.

* If more vehicles use fuel cells, we'd need less wind power but more PGM.

<div style="font-size:70%;color:#333;margin:1em;border:1px dashed #CCC">

* Hydrogen ''combustion'' vehicles are about as energy-efficient as gasoline combustion vehicles. But hydrogen ''fuel cell'' vehicles are more efficient. We'd need '''less''' hydrogen than this estimate calls for.

* Home electricity would be done with fuel cells too. We'd need '''more''' PGMs than this estimate. We'd need '''more''' hydrogen than this estimate, to make up for the losses in fuel cells (although those losses could be used as [[heating]] in some cases).

* Or if a large enough percent of all vehicles use combustion instead of fuel cells, then we'd need '''less''' PGM than this estimate.

* We didn't count the hydrogen needed in the vehicles that transport the hydrogen (hopefully would be minor, like with fossil fuel transport).</small>

* All this is based on status-quo energy demand, which relies on the fact that most of the world currently lives in poverty. If all nations were developed, a lot more resources would be needed.

* Wind power land estimates are based on status-quo installations which are likely on windier-than-average land. In which case, maybe crop land wouldn't be enough - but then again, there's also pasture and barren land that could be used.

</div></tab></tabs>

<!-- TODO: Uncomment this when done writing about PGMs above (a more immediate and important mention that should be on here first)

===Atmospheric losses===

{{sum|Probably minor}}

The concern would be that when hydrogen gas leaks to the atmosphere, it's so light that it ends up being lost into outer space via [//wikipedia.org/wiki/Jeans_escape Jeans escape]. At what point would this permanent loss of hydrogen affect ecosystems? Would it be on the scale of billions of years or millions of years or thousands? Per unit of energy, I bet there would actually be hydrogen loss than with [[nuclear fusion]]. {{rn}} {{pn|TODO: Estimate using the status-quo gas leak rate of natural gas.}} }}

Hydrogen is a colorless gas, but people sometimes ''name'' it with colors to indicate ''how it was produced'':

SCRAP: Not sure where to put this... it continues from "compared to status quo" but doesn't quite fit in that section...

 

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