[HN Gopher] Researchers generate hydrogen more efficiently from ...
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Researchers generate hydrogen more efficiently from water
Author : wglb
Score : 119 points
Date : 2022-11-15 16:56 UTC (6 hours ago)
(HTM) web link (phys.org)
(TXT) w3m dump (phys.org)
| srejk wrote:
| There are legitimate use cases for hydrogen. Trains are a good
| example - electrification of medium to long distances (through
| tough terrain) is prohibitively expensive, as is battery usage
| for the whole journey.
|
| Trains require a lot of energy to get started (where batteries
| work well), but then a relatively small trickle of power is
| needed: hydrogen fills this niche. Big companies are investing
| billions into this right now.
| Vvector wrote:
| Maybe we could power the trains along the rail, or in catenary
| above? Add a very small battery to power it maneuvering around
| the rail yard?
| [deleted]
| [deleted]
| bryanlarsen wrote:
| Trains are a silly use case for hydrogen. Electric trains have
| been used and viable for approximately 100 years. The only
| problem is how expensive it is to electrify thousands of miles
| of tracks.
|
| That problem is now gone, batteries can be used to bridge gaps
| in the catenary wires.
| srejk wrote:
| Think mountain passes or similarly difficult terrain. Or
| lower volume cargo trains, like into and out of industrial
| areas in the north. Catenary networks not only take a lot of
| money to set up, the maintenance is huge - especially in
| rough terrain or over long distances!
|
| ed: Not saying that all trains should be hydrogen, there just
| are use cases for some when we're talking zero-emission.
| pencilguin wrote:
| Power cables are an attractive theft target, many places.
|
| An extra insulated car filled with lightweight LH2 would not
| appreciably increase the cost of operating a train.
|
| Liquified ammonia under low pressure might be more practical,
| if safety worries don't dominate. We already move tanks of
| ammonia on trains. And much worse.
| bryanlarsen wrote:
| Liquid green hydrogen costs an order of magnitude more than
| electricity, and always will since it's created from
| electricity and uses electricity for liquification. It
| definitely will appreciably increase the cost of operating
| a train.
| pencilguin wrote:
| The weight of one extra car will increase the operating
| cost of a 100-car train by 1%, give or take a bit. Using
| cheap hydrogen instead of expensive kerosene may save
| much more than that. Moving light hydrogen instead of
| heavy kerosene may save more than that.
|
| If the electricity could be delivered directly to the
| train, the energy used would be cheaper, but installing
| (and replacing "shrinkage" of) many thousands of miles of
| "third rail" would cost a lot.
|
| The hydrogen is not yet cheaper than the kerosene, but
| costs on that side are falling fast.
| bryanlarsen wrote:
| You don't need thousands of miles of third rails or
| catenary wires. Just a ~mile every ~hundred, and a
| battery on the locomotive.
| Kuinox wrote:
| How do you restart the train after stopping in the middle of
| nowhere ?
| kobalsky wrote:
| hydrogen generators?
| [deleted]
| dontlaugh wrote:
| Electrification of existing lines and even new high speed lines
| are both much cheaper than the cars and fuel they can replace.
| sitkack wrote:
| > "This drop in performance, nobody has ever noticed it before,
| because no one has ever done the experiment in the dark," said
| Assoc. Prof. Xue.
|
| How many modern discoveries like this can be accounted for
| _somewhat_ sloppy experimental procedure? Sometimes there is not
| _enough_ chaos in science, just messing around can open up crazy
| avenues of research.
|
| Love it! Table top physics is still alive and kicking. We need
| more people doing more outlandish (seemingly) things.
| pencilguin wrote:
| Probably at lots of other labs their equipment worked in the
| dark, and they didn't try adding light.
| xsmasher wrote:
| >Aspartame was discovered in 1965 by James M. Schlatter, [...]
| He discovered its sweet taste when he licked his finger, which
| had become contaminated with aspartame, to lift up a piece of
| paper.
| rjmunro wrote:
| It would be good if there was some sort of indication of how much
| more efficient the process is. Is it a 5% improvement or a 50%
| improvement?
| AtlasBarfed wrote:
| Well, it's a typical hydrogen news story.
|
| So while there is a lot of potential in hydrogen, a LOT of
| legitimate and useful use cases, and likely some real
| fundamental science in the article, the hyping of hydrogen is a
| desperate astroturfing campaign by oil/gas/nuclear to stave off
| EVs and wind/solar/battery which is eating their lunch in raw
| economics.
|
| Thus the lack of real numbers intentional. Hydrogen production
| isn't efficient compared to grid transport and battery/hydro
| storage, because water is a very stable molecule and splitting
| it will fundamentally take a fair degree of energy and
| thermodynamic/heat loss/entropy.
| Animats wrote:
| > Well, it's a typical hydrogen news story.
|
| Yeah, if you combined all the published results on generating
| hydrogen from water, you'd have perpetual motion. Search with
| Google for "hydrogen from water breakthrough":
|
| * Revolutionary technique to generate hydrogen
|
| * A breakthrough method uses solar energy to produce hydrogen
|
| * Israeli scientists make breakthrough on producing 'green'
| hydrogen fuel
|
| * CRUCIAL BREAKTHROUGH IN HYDROGEN ENERGY
|
| * Australian Lab Turns Hydrogen Into Green Energy With Secret
|
| * UCSC Makes Green Hydrogen Breakthrough
|
| * New breakthrough in the study of hydrogen production by
|
| * A new way to generate hydrogen fuel from seawater
| (Stanford)
|
| * SunHydrogen has developed a breakthrough technology to
| produce renewable hydrogen using sunlight and any source of
| water.
|
| * HyTech Power may have solved hydrogen, one of the hardest
| ...
|
| * Universal Hydrogen's decarbonizing technology is coming to
|
| These go back years.
| PaulHoule wrote:
| The difference is that there is serious interest in 2022 in
| green hydrogen to replace hydrogen from methane steam
| reforming or the shift gas reaction and coal.
| MichaelCollins wrote:
| Having a "serious interest" and earnestly wanting it this
| time doesn't change the fundamental fact that you need a
| lot of power to crack water apart. There's simply no way
| around that, all improvements found will be marginal at
| best.
| pencilguin wrote:
| The amount of energy to crack water is already only a
| small multiple of what you get back when you get the
| products back together.
|
| The improvements are in the cost of equipment per unit
| output capacity, and the production rate per unit volume
| of said equipment. Improvements are cumulative.
|
| Airports, steel mills, and ammonia synthesizers will need
| to produce huge amounts of H2, soon, so reductions are
| important.
| DesiLurker wrote:
| I wish somebody would do a very simple roundtrip
| calculation for each of these 'breakthroughs' and publish
| it.
|
| all i want to know is the efficiency, cost & power
| density these on consumption side so I can decide which
| applications this works best in. on the production side
| same thing except for power density. the fact that its
| incredibly hard to find these numbers makes me think that
| these are mostly puff pieces for hydrogen before BEV eats
| their lunch.
|
| green/blue/gray hydrogen is mostly BS.
| PaulHoule wrote:
| The main interest now is not for 'dispatchable energy'
| but for industrial uses of hydrogen, metallurgy, etc.
| There is a lot of competition for energy storage such as
| conventional batteries, vanadium flow batteries,
| compressed air, pumped hydro, etc. I think fuel cell cars
| have been dead since Tesla made attractive BEV cars.
| threeseed wrote:
| Exactly the same thing can be said about battery and solar
| technologies.
|
| But eventually research does reach a point where they make
| a difference to ordinary end users.
| edvinbesic wrote:
| This comment doesn't quite make sense. A hydrogen cell is
| still just a battery with a different name and those vehicles
| would still be EVs, no?
| codefreakxff wrote:
| I believe the name is hydrogen fuel cell. It takes hydrogen
| as a fuel and generates electricity like a battery, instead
| of combusting it like a typical gas powered motor
|
| The output of a hydrogen fuel cell is water, so it is a
| fairly sustainable loop if you can capture the water and
| generate hydrogen from it. But you need an efficient
| process to convert water into hydrogen
| PaulHoule wrote:
| That fuel cell is more like an engine than a battery. You
| have to get O2 into it, get waste heat out (harder than
| the engine because the temperature is lower), keep it
| from drowning in the water it makes, etc.
|
| It is hard to see the fuel cell EV competing with a
| battery EV.
| jsight wrote:
| Yes, but they have very different characteristics. You
| can't just plug a hydrogen car into the grid and charge it
| anywhere, so the overnight charges that EV owners are
| accustomed to go away. The hydrogen fuel cells tend to be
| large and heavy, so they don't save weight and also lose
| luggage capacity relative to an EV of similar size.
|
| And without great advances in hydrogen production, they
| tend to cost more to operate than gasoline powered
| vehicles.
|
| The one perk is faster fillups for road trips or lacking
| infrastructure. Most EV owners wouldn't switch just for
| that.
| Realpolitikok wrote:
| mattwest wrote:
| Your comment has an air to it which makes you sound no
| different than the same dogmatists you seek to discredit.
|
| Framing the raw economics of renewables as superior to fossil
| fuels is wrong in many ways, mainly due to the
| narrowmindedness of viewing it through the lens of _just_
| energy. Do your views encompass the the vast network of
| global production tied to fossil fuel derived goods and
| processes?
|
| No one should view it as a competition between fossil fuels
| and renewables. Phasing out fossil fuels has huge
| implications beyond energy production and if you're not at
| least attempting to model the "raw economics" to include
| things like plastics, fertilizers, etc., you're doing a
| disservice to achieving a sustainable future.
| dv_dt wrote:
| The fossil fuel industry certainly sees it as a
| competition, and they're playing for a very different goal
| of preserving profits at pretty much any cost - including
| broad social costs. Trying to play that off as "no
| competition between fossil fuels and renewables" seems very
| naive at best.
|
| I do think it is an interesting question on "phaseout" of
| fossil fuels as a carbon emitting energy consumable, vs a
| feedstock for various chemical processes, like fertilizer
| production. But the fossil fuel industry very much does not
| want to go from a centralized role in energy vs a smaller
| role in chem feedstocks.
| pitaj wrote:
| I understand the oil/gas industry produces hydrogen from
| methane. But why would nuclear care whether their electricity
| is used for electrolysis or battery EVs?
| VBprogrammer wrote:
| There was recent news on this calling it purple hydrogen or
| something silly.
|
| We're so far away from having sufficient green (or green
| adjacent) hydrogen supply to cover existing industrial uses
| that it's pointless even considering it for transportation.
| pfdietz wrote:
| If anything, cheap electrolysis is a deadly threat to
| nuclear. Green hydrogen solves the last remaining problems
| for a 100% renewable grid (the rare dark/calm periods and
| seasonal leveling.) Cheap electrolysers mean nuclear is
| defenseless against much lower LCoE renewables.
| AtlasBarfed wrote:
| nuclear sees themselves as a provider of heat/electricity
| for industrial hydrogen generation.
|
| I didn't say it made sense, but it might give them gravitas
| for subsidies to keep them afloat. Political calculus is
| totally different than economics or logic.
| PaulHoule wrote:
| Gen 4 Nuclear could use sulfur-iodine or other
| thermochemistry to make hydrogen directly rather than
| spinning a turbine and doing electrolysis.
| parkingrift wrote:
| Passenger vehicles account for about 16% of greenhouse gas
| emissions. Electric power is another 25%. The rest is
| industry, commercial & residential, agriculture, and other
| forms of transportation. It is these areas of the economy
| which will need hydrogen.
|
| You'll probably die of old age before there is even a whisper
| of a battery powered passenger plane the scale of a 787. But
| you may live to see a hydrogen powered passenger plane.
| pencilguin wrote:
| Once LH2 airframes start being delivered, displacement of
| kerosene airframes will happen very fast, probably limited
| mainly by production capacity of synthetic hydrogen. The
| changeover will certainly have started by 2040.
| indymike wrote:
| > the hyping of hydrogen is a desperate astroturfing campaign
| by oil/gas/nuclear
|
| I'm not sure why it would be an astroturf. This really reads
| like an institution that is promoting the work they are doing
| and they are trying their best to make a newsworthy story.
| The second they add in words like "thermodynamics" and
| "entropy", or add anything boring like actual science, they
| are no longer newsworthy. Nothing to see here, just (over-
| hyped) marketing.
| PaulHoule wrote:
| Hydrogen is needed to do chemistry and is a possible path to
| make metals. Fuel cells for cars don't look like a good idea
| compared to battery EVs, but they might find a niche.
| scythe wrote:
| >Hydrogen production isn't efficient compared to grid
| transport and battery/hydro storage
|
| _Electrolytic_ hydrogen production and consumption is not
| efficient. Mostly because of the consumption end of the
| equation (~50%, fuel-cell) rather than the production
| (~70-80%, electrolysis). But nuclear-driven _thermochemical_
| hydrogen production is currently being developed, and can
| theoretically exceed the thermal- >electric conversion
| efficiency of the nuclear power plant:
|
| https://www.sciencedirect.com/science/article/pii/S095965262.
| ..
|
| https://www.sciencedirect.com/science/article/pii/S036031992.
| ..
|
| For applications where energy is used for incineration,
| direct chemical use of hydrogen, or when power-to-weight
| efficiency is critical, it has some potential: we are really
| comparing thermal->electric->thermal with
| thermal->hydrogen->thermal in that case. Such applications
| account for a decent fraction of total energy use.
|
| >campaign by oil/gas/nuclear
|
| Oil and gas companies have always worked against nuclear.
| There's no association there.
| pencilguin wrote:
| Nowadays coal companies promote nukes, because a new nuke
| started means at least a decade of continued coal sales.
|
| They know coal is doomed, so the best they can do is put
| off the inevitable. Solar, wind, or tidal would start
| displacing coal almost immediately. The nuke, furthermore,
| costs so much it eats budget that could have been spent on
| displacing much more coal than the nuke will when it is
| finally turned on.
| lob_it wrote:
| Notice how solar mppt controllers (or wind turbine
| controllers with dump load resistors) are lacking a "hydrogen
| electrolysis" load connector for excess?
|
| Enough trickles make a flood (butterfly effect scaled), but
| on the same token, its like converting a pretty yard into an
| edible organic yielding space.
|
| Diversification is now offering a lot more options that do
| not have toxic byproducts.
|
| Just using excess capacity from solar transforms local
| hydrogen harvesting into a boost to many local economies
| (emptied/harvested weekly/monthly/quarterly to power local
| infra for example using an onsite storage cylinder and
| scheduling similar to trash pickup).
|
| The sardine can neighborhoods cannot gaudy retrofit any of
| it, but an energy shed 50ft from a residence with new
| construction makes the applicable opportunities more than a
| pipe dream. They have to relocate the fire-hazard solar
| panels to a ground array anyways for reasonable insurance
| rates and right-sizing options for expandability as the
| technology progresses.
|
| Wealth breeds health :)
| edhelas wrote:
| Why the issue with nuclear ?
| mjhay wrote:
| Doubly so because the same oil and gas industry has spent
| quite a bit of money over the years to spread anti-nuclear
| hysteria, including covert support of environmental groups
| such as the Sierra Club. The effects can be seen now in EU,
| where gas has been labeled "green", while nuclear isn't.
|
| https://www.forbes.com/sites/kensilverstein/2016/07/13/are-
| f...
|
| This link provides a breakdown (be aware that is from an
| explicitly pro-nuclear group):
|
| https://www.ans.org/news/article-930/sierra-club-natural-
| gas...
|
| The oil and gas industry has tremendous incentive to expose
| nuclear. It's still the only game in town for truly
| replacing them.
| mschuster91 wrote:
| > The effects can be seen now in EU, where gas has been
| labeled "green", while nuclear isn't.
|
| Gas plants have been labeled a _transition_ technology on
| the path to a fully renewable grid, because they are
| cheap, fast to construct and can serve as peaker plants
| burning biogas. While they are currently burning fossil
| fuels, the emissions are way lower than for other fossil
| fuel plants - per each kWh produced, less CO2 gets
| emitted, and particulate emissions are additionally way
| lower.
|
| In contrast, nuclear plants take an _extremely_ long time
| to plan and build - the EPR design took almost two
| decades alone for building it in Olkiluouto and almost as
| much in Flamanville. Add to that the many years of
| bureaucracy in obtaining permits, purchasing land and
| other activities, and suddenly you 're looking at 25+
| years until the plant is operational, and dozens of
| billions of euros in sunk cost.
|
| The future is many things, but certainly not nuclear
| fission!
| edhelas wrote:
| Yup :)
| telotortium wrote:
| Renewables will still require some form of long-term utility
| energy storage though. Hydrogen seems like it could be a
| useful medium for that - batteries have gotten a lot better,
| but it's not clear that they'll become cheap enough when
| everything else wants batteries as well. Pumped hydro can
| only be installed in so many places (not to mention the
| tremendous environmental impact of building it).
| lstodd wrote:
| Hydrocarbons for energy storage are and will stay way more
| efficient and safe than pure hydrogen or batteries.
| pencilguin wrote:
| Using synthetic hydrocarbons for energy storage will
| always cost more than storing hydrogen underground, or
| bonded to nitrogen as ammonia.
|
| There will be reasons to synthesize hydrocarbons, but
| energy storage won't be among them.
| acd wrote:
| Sounds similar to photosynthesis. Light+Water is converted into
| chemical energy. Interesting that lights boost hydrogen
| conversion in a similar fashion.
| wrycoder wrote:
| Nature article:
|
| https://www.nature.com/articles/s41586-022-05296-7
| PaulHoule wrote:
| 'No ignition is needed' is wrong. It doesn't take much to ignite
| hydrogen but you do need a spark. You can always find a spark in
| an industrial environment so you can count on the Centaur blowing
| up in the Space Shuttle bay or the hydrogen bubble in a nuclear
| meltdown causing an over pressure event if not a consequential
| explosion.
| pencilguin wrote:
| What makes electrolysis expensive is a whole bunch of secondary
| details. Impurities in the water foul the catalyst, or steal
| power for side reactions that may contaminate the product or the
| water. The best catalysts are expensive metals that you would
| like not to erode and be carried away.
|
| After you get the hydrogen atoms separated from the oxygen, the
| oxygen atoms bond to become O2 molecules, releasing heat
| uselessly, and will later need to separated again (other oxygen,
| of course) when you burn the hydrogen, consuming much of the
| released energy; and likewise for hydrogen molecules.
|
| The recent story about using water vapor as the feedstock might
| signal a solution to the impurities and erosion problems that
| introduces new problems to solve before it can be used.
|
| Efficiency of the process is becoming unimportant as the cost of
| solar and wind-generated energy continues rapidly down, making
| other things like the cost of equipment and the volume of
| production more important.
|
| The frequent reports on improvements to electrolysis indicate not
| hype, but research cumulatively improving an important process,
| just as improvements in production techniques drove and still
| drive down the cost of solar panels.
| PaulHoule wrote:
| According to Wikipedia existing electrolysis systems are
| between 70-100% efficient. It's not fundamentally difficult to
| do (when I was a kid I made a "rechargable bomb" that would
| fill a balloon with hydrogen+oxygen and blow it up) but if you
| are doing it at scale you are going to be very concerned about
| capital cost and energy efficiency so there is room for
| improvement.
| pencilguin wrote:
| The important number when using hydrogen to carry energy is
| the round-trip efficiency. It has been hard to improve the
| efficiency of the energy-releasing side. We are fortunate
| that the number's importance is declining.
| PaulHoule wrote:
| I don't think the main interest is energy storage today, I
| think it is to replace other sources of hydrogen in
| industrial processes. Hydrogen as a fuel to say cook food
| or run a power producing turbine competes with many other
| energy sources and carriers but for industrial purposes
| there is often no alternative or the alternative is carbon
| heavy. (E.g. carbon monoxide is used to reduce iron in a
| blast furnace, hydrogen is substitutable for CO for many
| metallurgical functions.)
| pencilguin wrote:
| As cost to produce falls, it will be used in more places.
| Ways to store and transport energy will be among those.
|
| LH2 is very attractive as aircraft fuel.
|
| But I take your point: for _other_ uses, the production
| efficiency counts more. Conversion to raw heat is pretty
| good, losing only what it takes to split the H2 and the
| O2, and then whatever of that heat you fail to direct to
| the end use, e.g. the steam that rises past the sides of
| your saucepan.
| PaulHoule wrote:
| It competes with heat pumps for space heat, particularly
| given that air source heat pumps have gotten a lot better
| in 20 years. 20 years ago the word was that you needed a
| ground source heat pump in upstate NY but today air
| source heat pumps are completely practical.
| dheera wrote:
| Is there any chemical way to store hydrogen in a car without
| pressurizing it? Driving around with a pressurized tank of
| combustible gas doesn't sound fun.
| mappu wrote:
| Fraunhofer are doing this thing:
| https://en.wikipedia.org/wiki/Powerpaste
| uagenzlepe wrote:
| It can be stored as metal hydrides. Hydrogen atoms can
| penetrate he crystal lattice of certain metals to form a metal
| hydride, usually a very fine powder. These are stable at
| pressures a little higher than earth's normal atmospheric
| pressure.
| stasmo wrote:
| Liquid fuel can be created from carbon dioxide and hydrogen.
|
| https://www.nationalgeographic.com/science/article/carbon-en...
| Maursault wrote:
| Sounds a little like the plot from _Chain Reaction_ (1996).[1]
|
| [1] https://en.wikipedia.org/wiki/Chain_Reaction_(1996_film)
| photochemsyn wrote:
| Technically this is about evolving oxygen gas from water more
| than it is about the hydrogen end of the electrocatalytic
| reaction. Since this is a cathode (2H+ + 2e- -> H2 gas) vs. anode
| process (2H2O -> 4H+ + 4e- + O2) linked up by a wire to close the
| circuit, you have two chemical processes to manage. The oxygen-
| evolving one tends to be slower, i.e. rate limiting. For an
| overview:
|
| https://sci-hub.se/10.1039/c9cs00607a
|
| Song, et al. (2020). "A review on fundamentals for designing
| oxygen evolution electrocatalysts." Chemical Society Reviews.
|
| >"Therefore, the OER is the key process that governs the overall
| efficiency of electrochemical water splitting. To date, IrO2 and
| RuO2 have been state-of-the-art OER catalysts. However, both of
| them are made of precious metals and the cost is high. Therefore,
| it is imperative to seek low-cost alternative materials that can
| effectively reduce the kinetic limitation of OER and improve the
| efficiency of water splitting."
|
| So, they discovered that the catalyst used at the OER end has
| some light-activation property, which is pretty interesting, i.e.
| they discovered a kind of photovoltaic electrocatalyst. Whether
| it will prove to be industrially useful is anyone's guess. There
| are similar systems but they're not very practical (i.e. they
| require high-energy UV):
|
| https://physicsworld.com/a/light-activated-catalysts-make-ne...
|
| As far as hydrogen-from-water tech, again it has three plausible
| large-scale cleantech industrial uses: ammonia from atmospheric
| N2, reduction of iron ore to sponge iron, and methane (and
| plausibly jet fuel) production from atmospheric CO2.
| PaulHoule wrote:
| Hydrogen has numerous uses. Petroleum refineries produce and
| consume hydrogen in numerous places, if they find they are
| steam reforming they could use green hydrogen instead, together
| with storing waste Carbon dioxide to green operations.
|
| Even if we quit refining oil from the ground we will still be
| doing chemistry like petrochemisty with other feedstocks.
| photochemsyn wrote:
| If you can figure out how to get the carbon feedstock from
| the atmosphere at scale, why would anyone bother with
| refining a mixed muck coming out of the ground? What we call
| 'petrochemistry' today will be called 'aero-hydro-chemistry'
| tomorrow.
| PaulHoule wrote:
| I've looked into the chemistry you'd use to turn a
| carbonaceous asteroid into useful products such as plastic
| films or material for a biosphere and the old C1 chemistry
| (manufactured gas and PVC from acetlyene) and the new stuff
| for utilization of CO2 turns out to be very relevant.
|
| For instance you are going to get CO2 as a waste product
| and you will not throw it away because it is precious so
| you will add energy to recycle it. You might just get O2
| from processing of metals and stones, burn the carbon and
| feed the CO2 into some system for further processing. The
| difference with earth is you have 24 hour sunlight and the
| anility to concentrate it with weightless mirrors.
| marshray wrote:
| There really is very, very little carbon in the atmosphere,
| famously ~410 ppm. (Yes, that little bit is enough to
| absorb significantly more heat from the sun).
|
| So, whatever capture system you use, you'd need to move _a
| lot_ of air through in order to produce a small amount of
| something like liquid hydrocarbon fuel.
|
| It will require thousands of times more air, by mass. Since
| the output fuel product is hundreds of times more dense, it
| would require a crazy large volume of air to extract the
| carbon necessary to fill a fuel tank.
|
| A corn field combined with a methanol fermentation and
| distillation facility is an example of a machine that does
| that. Very large.
| ravenstine wrote:
| You mean _ethanol_ , right? I don't think it's produced
| by fermentation, at least not without a secondary process
| that removes the other hydrocarbon.
|
| That aside, yes, plant biomass to alcohol is a carbon-
| neutral tech that has already existed for a really long
| time. Let plants take carbon out of the atmosphere,
| ferment the starches and sugars into fuel alcohol, feed
| the remaining cellulose to animals, burn the fuel, eat
| the animals, and return most (but not all!) of the carbon
| back to where it came from. It's really an incredible
| process, but obviously its existence is a threat to the
| oil industry. If you've ever noticed the propaganda that
| ethanol is bad for engines and worse for the environment,
| well, _just follow the money_.
| pencilguin wrote:
| It takes a very great deal of hydrocarbon fuel to produce
| the ethanol going into our engines. When EVs displace
| gasohol-burning cars, the ag production, 30% of the maize
| crop, can go back to feeding people (or, more likely,
| feeding chickens); and we may hope the fuel used will be
| synthetics from atmospheric feedstocks.
|
| Brazil's sugar cane operations seem to produce more fuel
| than the process consumes.
| nine_k wrote:
| But there are CO2-rich exhausts in chemical plants and
| power plants, with concentrations well above 50%. This is
| where the capture could work efficiently. These likely
| produce a sizable portion of the carbon dioxide surplus.
|
| Capturing carbon from a jet engine will remain
| problematic, or slow. Maybe we should just grow more
| trees, extract solid carbon from them (by burning or
| otherwise), and bury it in old coal mines.
| photochemsyn wrote:
| Plants pull 100 gigatons of carbon out of the atmosphere
| every year and convert it to biomass (essentially, oxy-
| ammonia-hydrocarbons like sugars, proteins, fats, etc.).
| Humans pull about 6 gigatons of carbon out of the ground
| each year and pump it into the atmosphere.
|
| The reason this cycle doesn't exhaust the atmospheric
| pool, of course, is that animals and fungi (more the
| latter) break down biomass into CO2 and release it back
| into the atmosphere.
|
| That's not what I'd call 'very very little carbon'.
| lazide wrote:
| On a planetary atmosphere level? It's still tiny.
|
| Literally .0441%
|
| Getting anything at that concentration out is...
| generally not easy.
|
| Doable! But not easy.
|
| That it's chemically low reactivity makes it even harder.
|
| Plants have spent billions of years evolving to do it,
| and from an energy perspective aren't very efficient at
| it.
|
| Unless we want to burn even more oil trying to power the
| process or just make a tiny dent in it, we'll need to not
| only figure out a somewhat efficient way to do it, but
| also figure out how to generate a massive amount of power
| without burning oil to power it.
| ravenstine wrote:
| For even more perspective, human breath can be easily
| composed of somewhere between 20,000 ppm and 40,000 ppm,
| and tens of thousands greater than that with enough
| energy expenditure. (I know this because I've actually
| measured this myself with research grade NDIR CO2
| sensors)
|
| 441 ppm can be "a lot" depending on the gas and the
| expected effect. You don't want to breathe in 441 ppm of
| chlorine gas. But CO2 being fairly non-reactive makes 441
| ppm of it relatively minuscule in contrast to the other
| predominant atmospheric gases. It's also nowhere near
| enough to cause outright catastrophe.
| pencilguin wrote:
| 441 ppm CO2 turns out to be quite close to enough to
| cause global catastrophe.
| lazide wrote:
| Eventually. But no one is going to keel over dead due to
| suffocation today because of global CO2 concentration,
| which is 'outright'.
|
| Pretty sure global minimum temperatures above 100F would
| also count as 'outright'.
| pencilguin wrote:
| There are already places where being without a cooling
| method other than sweating would be fatal, at least one
| day of the year.
|
| In many more places, crops are failing.
|
| People necessarily leaving these places will need to go
| where other people already are.
| PaulHoule wrote:
| The advantage of attempting it mechanically is that you
| might use less water and less fixed nitrogen. Water
| consumption is directly linked to how plants absorb CO2
| from the atmosphere, see
| https://ripe.illinois.edu/blog/difference-
| between-c3-and-c4-...
| Proven wrote:
| [deleted]
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