Hydrogen gas: Difference between revisions

Revision as of 05:22, 30 August 2023

Not to be confused with nuclear fusion of hydrogen atoms.

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

There are no natural resources of hydrogen gas(...)( 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.

Hydrogen gas can be produced using electricity to split water molecules (H₂O) into hydrogen gas (H₂) and oxygen gas (O₂). This process is called electrolysis.

Transport

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? ^{[RESEARCH needed]}
How about pressurized storage tanks on trains? ^{[RESEARCH needed]}

Usage

Combustion

for cooking (much like natural gas stoves)
for heating homes / buildings

Fuel cells

for vehicles
for home electricity, in some cases^{[ELABORATION needed]}(...)( waste heat could also be used to heat the home )

Just like natural gas, hydrogen gas is non-toxic and odorless but highly flammable. For safety in consumer applications, small quantities of some non-toxic but smelly gas(...)( such as methyl mercaptan or hydrogen sulfide )should be added to it, so people can smell if there's a gas leak.

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.

General

Compared to batteries,

Hydrogen is better for long-term energy storage.
Hydrogen is better for transporting energy.
Hydrogen is worse in terms of energy recovery.
- Electrolysis is at most 80% efficient.
- Fuel cells are at most 60% efficient.
- Thus, best-case electricity recovery is only 48%(...)( in other words, 60% of 80% ). Far less than most batteries which have a charge-discharge efficiency of 80% to 90%.

Batteries may be better for storing solar energy from the daytime and using it at night.

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.

Considerations

Platinum-group metals

Possible problem

This section has not been filled in yet.

Color terminology

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

"Grey hydrogen" is made from natural gas (steam reforming) - high greenhouse gas emissions. Currently the vast majority of hydrogen is produced this way.
"Blue hydrogen" is made from natural gas the same way, but with carbon capture. This is supposed to reduce emissions, but in practice it doesn't help much.
"Pink hydrogen" is made from electrolysis using nuclear energy.
"Green hydrogen" is made from electrolysis using renewable energy.

@@ Line 1: / Line 1: @@
-Hydrogen gas (H<sub>2</sub>) is a fuel that when burned, produces no pollution and no [[climate change|carbon emissions]] - only water vapor (H<sub>2</sub>O).
+: <small>''Not to be confused with [[nuclear fusion]] of hydrogen atoms.''</small>
+[[Category:Energy storage]]
-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]].
+'''Hydrogen gas''' (H<sub>2</sub>) is a combustible fuel that leaves behind nothing but water vapor (H<sub>2</sub>O) when burned.
+<!-- TALK: Maybe this is wrong if NOx emissions can be emitted too? {{qn}} If so, how to rephrase while maintaining simplicity? -->
-==Production==
+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]]'''.
-===Electrolysis===
-Electricity can turn water (H<sub>2</sub>O) into hydrogen gas (H<sub>2</sub>) and oxygen gas (O<sub>2</sub>). This process is called [[electrolysis]].
+'''''This page is about how hydrogen gas could be used with renewable [[energy]].'''''
+{{considerations}}
-The electricity could come from renewable sources such as [[solar]], [[wind]], [[hydro]], or [[geothermal]]. But even if we manage to scale up those energy sources, there is still an issue with scaling up the electrolysis itself: [[electrolysis#need for catalyst metals|the need for rare metals]] in the electrolyzers.<!-- TODO: say more decisively whether this scaling is viable or not: but first there are questions to resolve on the [[electrolysis]] page -->
-===From fossil fuels===
+==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.
+Hydrogen gas can be produced using electricity to split water molecules (H<sub>2</sub>O) into hydrogen gas (H<sub>2</sub>) and oxygen gas (O<sub>2</sub>). This process is called ''electrolysis''.
+===Transport===
+{{pn|Research needed for this section}}
+* Is it viable to repurpose natural gas pipelines? Or would it leak too much since H<sub>2</sub> molecules are much smaller than methane? {{rn}}
+* How about pressurized storage tanks on trains? {{rn}}
+===Usage===
+Combustion
+* for cooking (much like [[natural gas]] stoves)
+* for [[heating]] homes / buildings
+Fuel cells
+* for [[fuel cell vehicles|vehicles]]
+* for home electricity, in ''some'' cases{{en}}{{x|waste heat could also be used to heat the home}}
+<small>Just like [[natural gas]], hydrogen gas is non-toxic and odorless but highly flammable. For safety in consumer applications, small quantities of some non-toxic but smelly gas{{x|such as methyl mercaptan or hydrogen sulfide}}should be added to it, so people can smell if there's a gas leak.</small>
+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.
+===General===
+Compared to batteries,
+* Hydrogen is better for ''long-term'' energy storage.
+* Hydrogen is better for transporting energy.
+* Hydrogen is worse in terms of energy recovery.
+** Electrolysis is at most 80% efficient.
+** Fuel cells are at most 60% efficient.
+** Thus, best-case electricity recovery is only 48%{{x|in other words, 60% of 80%}}. Far less than most batteries which have a charge-discharge efficiency of 80% to 90%.
+Batteries may be better for storing [[solar]] energy from the daytime and using it at night.
+===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.
+==Considerations==
+===Platinum-group metals===
+{{sum|Possible problem}}
+{{empty}}
+<!-- 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.}} }}
+-->
+==Color terminology==
+Hydrogen is a colorless gas, but people sometimes ''name'' it with colors to indicate ''how it was produced'':
+* "Grey hydrogen" is made from natural gas (steam reforming) - high [[greenhouse gas]] emissions. Currently the vast majority of hydrogen is produced this way.
+* "Blue hydrogen" is made from natural gas the same way, but with [[carbon capture]]. This is ''supposed'' to reduce emissions, but ''in practice'' it doesn't help much.<!-- TODO: cite that article I found awhile ago -->
+* "Pink hydrogen" is made from electrolysis using [[nuclear]] energy.
+* "Green hydrogen" is made from electrolysis using renewable energy.
+<!--
+SCRAP: Not sure where to put this... it continues from "compared to status quo" but doesn't quite fit in that section...
+===Production from fossil fuels===
 Currently most hydrogen is produced from [[natural gas]] via [//wikipedia.org/wiki/Steam_reforming steam reforming], but this emits just as much CO<sub>2</sub> as burning the natural gas itself.
 There's another (similar) process called [[methane cracking]] which takes in natural gas, and produces hydrogen gas + solid carbon (not CO<sub>2</sub>). The main problem is that it's a ''net loss'' of energy {{x|it takes a lot more energy than you ultimately get by burning the hydrogen gas}}. In theory, it doesn't have to be.
 {{p|Chemistry equations:<br />CH<sub>4</sub> &rarr; C + 2 H<sub>2</sub> &emsp; (endothermic: &nbsp; 75 kJ/mol)<br />2 H<sub>2</sub> + O<sub>2</sub> &rarr; 2 H<sub>2</sub>O (exothermic: &nbsp; 572 kJ/mol)}}
 ==Usage==
 Most hydrogen gas today is used in making [[fertilizer]]. However, there are other things that could be done with hydrogen if production was scaled up enough:
 * Hydrogen gas can be burned.
@@ Line 29: / Line 85: @@
 *** "electricity &rarr; hydrogen gas &rarr; back to electricity" is ''at best'' only 40% to 48% efficient{{x|This is the combined energy-efficiency. The electrolyzers are about 80% efficient, and the fuel cells are about 50% to 60% efficient.}}.
 In this way, [[fuel cell vehicles]] are not as efficient as [[battery electric vehicles]]. At least they're still more efficient than [[hydrogen combustion vehicles]].
+-->
-==Color terminology==
+<!-- TALK: maybe refactor the page to start with a section called "basics" that explains fuel cells, electrolysis, steam reforming and methane cracking? -->
-Hydrogen is a colorless gas, but people sometimes ''name'' it with colors to indicate ''how it was produced'':
-* [[Grey hydrogen]] is made from natural gas (steam reforming) - high [[greenhouse gas]] emissions. Currently the vast majority of hydrogen is produced this way.
-* [[Blue hydrogen]] is made from natural gas the same way, but with [[carbon capture]]. This is ''supposed'' to reduce emissions, but ''in practice'' it doesn't help much.<!-- TODO: cite that article I found awhile ago -->
-* [[Pink hydrogen]] is made from electrolysis using [[nuclear]] energy.
-* [[Green hydrogen]] is made from electrolysis using renewable energy.