This stuff is not competitive with electrochemical methods.
A big problem with these methods, besides abysmal efficiency is that the light that drives the photochemical processes has some probability of generating side reactions that destroy the artificial enzyme. Nature overcomes this with unbelievably complex protein repair structures that literally swap out defective proteins for new ones. We have zero chance of replicating this type of thing anytime soon.
Bio oil from algae is much closer to practical utility than this tech. And electrochemical CO2 reduction will be an even more scalable and practical solution in the near term in my opinion.
I'm not saying it's not a good song, or only appeals to older people, just that the probability distribution for a person's age adjusts upward (a lot) given the prior of liking that song :-)
Definitely no other way, because if woman cannot survive nobody will be around to painstakingly increment a counter each time the planet falls around its central star.
Was it a reference to “Dialogues Concerning Natural Religion” by David Hume? That book debunked the arguments by design 50 years before the watchmaker parabola was written:
“If we survey a ship, what an exalted idea must we form of the ingenuity of the carpenter who framed so complicated, useful, and beautiful a machine? And what surprise must we feel when we find him a stupid mechanic who imitated others, and copied an art which, through a long succession of ages, after multiplied trials, mistakes, corrections, deliberations, and controversies, had been gradually improving?“
It should be by a sculptor with a terrible eyesight! The sculptor analogy predates the watchmaker one by like 2200 years and for some reasons is much less known these days than watchmaker one.
“Socrates. But now if you had two sorts of things, the one of which presents no clue as to what it is for, and the other is obviously for some useful purpose—which would you judge to be the result of chance, which of design?
Ar. Clearly that which is produced for some useful end is the work of design.
Soc. Does it not strike you then that he who made man from the beginning (5) did for some useful end furnish him with his several senses—giving him eyes to behold the visible word, and ears to catch the intonations of sound? Or again, what good would there be in odours if nostrils had not been bestowed upon us? what perception of sweet things and pungent, and of all the pleasures of the palate, had not a tongue been fashioned in us as an interpreter of the same? And besides all this, do you not think this looks like a matter of foresight, this closing of the delicate orbs of sight with eyelids as with folding doors, which, when there is need to use them for any purpose, can be thrown wide open and firmly closed again in sleep? and, that even the winds of heaven may not visit them too roughly, this planting of the eyelashes as a protecting screen? (6) this coping of the region above the eyes with cornice-work of eyebrow so that no drop of sweat fall from the head and injure them? again this readiness of the ear to catch all sounds and yet not to be surcharged? this capacity of the front teeth of all animals to cut and of the "grinders" to receive the food and reduce it to pulp? the position of the mouth again, close to the eyes and nostrils as a portal of ingress for all the creature's supplies? and lastly, seeing that matter passing out (7) of the body is unpleasant, this hindward direction of the passages, and their removal to a distance from the avenues of sense? I ask you, when you see all these things constructed with such show of foresight can you doubt whether they are products of chance or intelligence?”
Then in «Against Physicists” by Sextus Empiricus this was cited as:
“Tell me, Aristodemus, are there some people you have admired for their wisdom? Yes, there are, he said. Who are they, then? Well, I have admired Homer for his poetry, Polyclitus for his sculpture, and Zeuxis of course for his painting. [93] And is it not because of the exceptional craftsmanship of their works that you approve of them? Yes, it is, he said. If Polyclitus’ statue, then, also took on life, would you not approve of the artist much more? Definitely. Well, given that when you saw a statue you said that it had been crafted by some skilled person, when you see a human being whose soul’s activity and whose body’s design are good, do you not think that he was crafted by some exceptional mind?”
If you don't know why we prefer the analogy of the blind watchmaker over the idle chats of some ancient Greeks then maybe it would be good to give the good book another read.
It will be better if the modern debunking of the design arguments refered to Socrates as the originator of the arguments, not rewording of the same arguments by a random guy from 200 years ago. And even as a debunking original Hume's one from 250 years ago about stupid mechanic that I sighted in another thread was more to the point than the modern talk about a blind watchmaker.
No, because Socrates was just a philosopher with no tools to justify his theories. And even is Humes' story is more elegant, it is also just a thought experiment. The blind watchmaker is a reference to an argument that is based in the knowledge of things that have been discovered, based purely in reality. The philosophers might come up with an argument that is sound, but they could not tell you if that argument is actually true.
Hume’s point was there was no intelligent design in things made by a skillful craftsman even with a good eyesight. It was not a thought experiment but simple observation of how things were made. It was all tinkering for a long time until something that worked appeared. That it is, it was not a design but evolution.
evolution is not exactly intelligent. It's close, but doen't quite make it. It doesnt take an intelligence to guess at an intelligent solution if it doesnt require intelligence to test that solution. Intelligence, in such a problem domain, is basically a measure of how many wrong guesses occur between correct ones.
Nick Lane covers this a little in the third chapter of his book Life Ascending: The Ten Great Inventions of Evolution. It might not be talking about the specific process OP was talking about but rather the Z Scheme of Photosynthesis
Electron transport in proteins is crazy complex and actually amounts to molecular circuits where energy is guided to different spots inside proteins complexes in a unidirectional fashion. This guy is the grand daddy of the field (https://www.youtube.com/watch?v=ge7m9-PEiB8).
The figure that stands out for me is according to this one fossil fuel animation on YouTube they calculate we are using 100 times the amount of carbon that exists in all living creatures on the face of the earth every year.
That's food for thought... Even if we used all the forests and all the sea life we still wouldn't have enough energy. So we really need to be eat more efficient than natural systems.
> they calculate we are using 100 times the amount of carbon that exists in all living creatures on the face of the earth every year
This doesn't seem right. Estimates put total biomass at 500-600 billion tons of carbon, and annual biomass production at 100 billion tons of carbon. Meanwhile global carbon emissions from fossil fuels/industry are 35-40 billion tons per year.
Good point. I've had discussions with friends about things like the Einstein-Slizard refrigeration and efficiency keeps coming up, and it's always a struggle to point out that we're trying to do things in an environment where there's tons of tropical and equatorial sunlight, and little or no access to electricity. Efficiency is not the primary factor when the energy source is free and unlimited.
Free yes, but not unlimited. It's not very dense, so you get area-limited depressingly quickly. That might not be a problem, depending on how much power you need.
That depends on how abysmal. It may be more effective to just build solar and wind farms to replace the power generated from existing natural gas, if the goal is to have more natural gas and less atmospheric CO2.
Either a methane or carbon monoxide fuel cell run in reverse, or using hydrogen to water gas shift and then further reverse steam reforming into methane.
When you add an initial water electrolysis to the sabatier process you can have
H2O + CO2 > O2 + CH4
That is water and carbon dioxide in, oxygen and methane out. Good for life support in space. If you had infinite free energy you can easily synthesize methane out of air and water.
Tax credits is often another way of saying environmental pollution.
They are appropriate in the short term IF they cause sufficient innovation or economies of scale to kick in.
Often they cause more waste, because tax credits often benefit less efficient and more polluting solutions. Without a very deep and very careful analysis, your best proxy for measuring environmental harm is simply the amount spent.
For example: corn subsidies for ethanol production are significantly harmful for carbon dioxide pollution (via indirect effects like fertilizer production).
What? If we have money to spend on subsidizing stuff, we should subsidize the most efficient methods, which as parent implies, are the electrochemical methods.
No, the tax credits should go to more efficient measures for atmospheric carbon capture. Tax credits are a limited resource because money's only use is to buy limited resources. If you increase the money supply to infinity, money loses its meaning.
> “The biggest challenge many people don’t realize is that even nature has no solution for the amount of energy we use,” said University of Chicago chemist Wenbin Lin. Not even photosynthesis is that good, he said: “We will have to do better than nature, and that’s scary.”
Aren't solar panels already more efficient at creating energy than photosynthesis?
It's true we haven't found an artificial method of photosynthesis that creates a fuel we can burn that is more efficient than nature, but do we want to?
Modern solar cells easily hit 20% efficiency under decent conditions.
> It's true we haven't found an artificial method of photosynthesis that creates a fuel we can burn that is more efficient than nature, but do we want to?
If we want to use airplanes to quickly travel long distances, yes. Or if we want to haul loads to many arbitrary locations.
Solar panels and photosynthesis drive different outputs, sure, but with the basically limitless electricity from the solar panels, we can then drive whatever output we want through applying the electricity to machinery or electrolysis
Electricity from solar panels is not "limitless" in any meaningful sense of the word. Solar panels deliver a limited amount of power per area. They require a non-zero area of land and non-zero resources for construction and maintainance, so you can't build and install an arbitrary amount of them.
Of course solar power is not limitless. Finite insolation, and finite land mass = finite resource.
But, you could generate the entirety of US energy usage from less than 100,000 square miles of solar panels, and quite possibly from less than 50,000 square miles, if you consider wind + solar. That's a lot of land, in one respect, but it's less than, e.g., the amount of land (circa 60,000 square miles) we currently use just to produce ethanol that accounts for less than 10% of just our energy use for small internal combustion engines. The challenge with solar/wind isn't limits on their production due to land, or even infrastructure, it's that they produce intermittently, and only produce electricity, and electricity is challenging to store for extended periods of time so you can match production to demand over time scales from hours to years.
It's limitless in that it's not outside the bounds of physics or economics if we really wanted to replace 100% of our energy with solar, night time/inclement weather storage notwithstanding
There's nothing but a lack of willpower preventing us from being on 100% solar and wind
It's limitless in that in a closed system not connected to the grid, it's not automatically a bad thing if you waste it. Waste some solar power, nothing happens. Waste some coal or oil and you either have a slick on the ground or a ton of new CO2 in the air
Solar fuels has a niche in that it allows us to make reduce the net CO2 released by carbon fuels. It would help blunt the level of changes needed to stave off worse climate disaster giving us more time to wean off of things like NG fired power plants and cars.
Photosynthesis covers the vast majority of land and ocean available on Earth while solar panels cover far less. So in a way, photosynthesis is more efficient - in a scalable way.
In the reductive view, yes. But at some point one must also consider the entire ecosystem. Plants are very efficient in keeping the entire system running; fossil fuels are quite efficient in making it less hospitable to humans. That consideration goes beyond just talking about energy input or output per volume or mass (although in the end it cannot and should not divorce itself from those considerations lest it turns into pseudo-science like the many, many inane techno-scams are prone to do).
I would bet the the current yearly growth rate of energy harvesting is greater for solar panels than plants :) and plants have a billion year head start. (This is of course a silly argument)
Yeah but that's a function of self-replication. If you could engineer a tuber or vine which did nothing but try to build up a huge H+ ion gradient between it's roots and it's tip, then we could just let that grow indefinitely and use it as a battery directly.
Similarly most models of "grey goo" would functionally be this: machines autonomously covering the biosphere in more efficient light harvesters.
We have, but it's not a single process. We can convert light to electricity quite cheaply and efficiently with solar PV panels and then use that electricity to electrolyze hydrogen from water and capture CO2 from air(or seawater). Then there are a variety of processes, such as the Sabatier reaction, to convert the hydrogen and carbon into a hydrocarbon. I believe Prometheus Fuels is combining the hydrogen electrolysis and CO2 capture into a single step. Terraform Industries is also working on this problem, but is focused on driving down capital costs of electrolysis so that carbon neutral fuel producers can afford to have electrolyzers sitting around unused 75% of the year and only working when solar electricity is so abundant that it's practically free. Electrolysis and carbon capture takes a lot of energy, but assuming that all electricity comes from solar panels, it is far more space efficient than biofuels. An acre of corn or sugarcane can produce about 400-700 gallons of ethanol per year, or about 36-64 gigajoules of fuel. An acre of solar panels (laid nearly flat to maximize space efficiency) that is converted to methane at 30% efficiency (efficiencies around 50-60% are very normal and state of the art is around 75%, but 30% is much easier and cheaper) can produce about 350 gigajoules of fuel per year.
There's also some research on converting hydrogen and CO2 to edible carbohydrates, either chemically or through hydrogenotrophic or methanotrophic bacteria. That will be a huge revolution for either increasing the carrying capacity of the planet or decreasing humanity's impact on the planet. It will also be a huge boon for countries without much arable land to be able to feed their people without relying on imports. Electricity to food is not quite ready for scaling up yet, but synthetic fuels are absolutely ready to go as soon as solar electricity prices drop just a bit more or fossil fuel prices rise a bit more.
Technically, biological photosynthesis consists of two different major processes. You’ve got a membrane complex called „photosystem“ (of which they are two types) and an enzyme called Rubisco. The former drives the light reactions oxidizing water into hydrogen and oxygen (and thereby creating reducing agents and a proton gradient). The latter drives the dark reactions reducing CO2 into various forms of sugar.
In some plants CO2 fixation runs at night and, hence, at a different time than the light reactions. In others, it happens in different cells and, hence, physically separated from the light reactions. CAM and C4 plants, respectively, are more efficient in hot or dry biotopes.
I'm not sure what they mean anyway. The amount of solar energy hitting earth is a lot larger than human energy utilization. Like by a factor of 10000 (tens of terawatts vs ~100 petawatts).
Sure, but if carbon capture is the goal there are easier methods than artificial photosynthesis. The point of artificial photosynthesis is to create a fuel you can eventually burn again.
Re-using the CO2 in the atmosphere certainly beats simply adding to it, I'm guessing that's the point here.
For it to be truly sustainable the carbon needs to be stored in a way that humans wouldn't get at out of greed ever again. So it would need to be in some useless form like maybe diamonds or something.
A ton of CO2 is produced by about $150 worth of fuel (oil). So if you can do carbon capture for less than $150/tCO2 it would make more sense to sell the fuel and capture more carbon.
> So if you can do carbon capture for less than $150/tCO2 it would make more sense to sell the fuel and capture more carbon.
How does this math work?
If it's $149 to recapture, who's paying for this $149? Is the person buying $150 worth of fuel now paying for it also, at ($150 + recapture cost)/gallon?
The $1 profit goes towards paying for capturing carbon. Every 150 barrels of captured fuel you sell, you make $75 profit you could spend on either not selling a barrel, or some more efficient way of reducing our climate impact like maybe buying a solar panel or sponsoring a windmill.
Or what the sibling suggests, you keep the money as profit / funds for growing the business so you displace traditional oil and you prevent the increase of CO2 in the atmosphere that way.
That would be valid once we stop extracting carbons from other sources (oil, gaz, coil…). Since that won’t happen at a global scale soon, burning the captured carbon won’t stop the carbonification of the air/water.
Not the same fuel but as far as "energy shortage", just a reminder we allow the fracking industry to burn-off $100 Million of natural gas into the atmosphere every day in the USA
Simply so they can get to the more profitable oil.
Algae fuel makes little sense. To grow enough algae for fuel usage, you would have to use a lot of fertilizer. The fertilizer would be made from natural gas. So it would just be a giant scheme of hiding natural gas usage behind green fuel, but worse since it would take more natural gas than just using it directly.
It seems that the proposed system is an improvement over plants, but not necessarily over the Sabatier reaction driven by energy captured by solar cells. Is that right? How would these compare?
Is there a deficit of methane? Methane is 80x more potent a greenhouse gas than CO2, and is responsible for 30% of Global Warming. Methane production is higher now than it has ever been. Hopefully this breakthrough leads to something useful, because we already have all the methane we could ever need.
The important distinction is where the carbon comes from. If the methane comes from the ground, it's adding carbon to the carbon cycle. This is why we're in such a pickle. If the carbon comes from the air, or trees, or anything that pulled it from the air recently, then the methane is just another form of the carbon already in our atmosphere.
Yes, it's a potent greenhouse gas - but it isn't a permanent one. Methane is oxidised in the atmosphere into CO2 eventually.
No, it's not the same. Producing methane from CO2 and sun is exactly the way to go green. Because we're not adding more, but just recycling methane from CO2. The issue for global warming is adding more CO2 and more methane to the atmosphere by taking it from underground, while this approach does not.
This looks interesting enough, but it really won't scale, as it relies on complex molecular assemblages with an iridium center, and iridium is quite rare as far as elements go. The paper is paywalled but the linked supplemental information shows the structures (pdf), Fig 8 is probably the most informative:
Practically, separating the hydrogen production from water step from the carbon dioxide reduction step is the more plausible route to industrially significant production. Fundamentally I'm pretty sure making what's called 'synthesis gas' (H2 + CO) and feeding that into the well-known Fischer-Tropsch process is the route to long hydrocarbons (i.e. jet fuel) starting with atmospheric CO2 and water, the challenge there is making the CO from the CO2 efficiently.
Alternatively, hydrogen and CO2 can be directly reacted over a cobalt catalyst, producing smaller hydrocarbons like methane and perhaps up to five-carbon molecules at present:
"Cobalt Catalysts Enable Selective Hydrogenation of CO2 toward Diverse Products: Recent Progress and Perspective (2021)"
Trying to do it all in one go is scientifically interesting, but not very practical. Even plants break it down into the light reactions (splitting water while generating ATP and NADPH, energy-carrying coupler molecules) and dark reactions (capturing the CO2 and incorporating it into a bisphosphorylated sugar prior to feeding it into the reductive reactions that utilize the products of the light reactions).
It's also not too surprising that plants are not super-efficient at this process, they're under broad evolutionary pressure for a wide variety of processes, such as taking up water and nutrients, reproducing, etc. that don't necessarily revolve around fixing as much carbon as fast as they possibly can. It similar to industrial nitrogen fixation in that manner (of course, atmospheric N2 is 80% of the atmosphere while CO2 is only, what is it now, 420 parts per million).
Only once that can be done cheaply. Which so far is not the case.
Basically electric cars are cheaper to drive than cars burning fossil fuels which in turn are cheaper to drive than cars burning synthetic fuels.
As prices of things like batteries and renewables come down. Synthetic fuels might become cheaper than fossil fuels since you typically need lots of energy for producing synthetic fuels. If the amount of energy gets low enough it might get close enough to simply charging a battery with the energy and using it. But we're a very long way from that.
Combustion vehicles have other externalities, like contributing to the city heat island effect. All in all even a compact car going through the city is equivalent to a 5-10kW heater.
Also gasoline combustion doesn't just produce CO2. Emissions include NOx, CO, unburnt hydrocarbons - even in this day and age it's a significant amount.
I've been biologically creating methane fuel for as long as I can remember, so does this mean we need to destroy the sun in order to prevent global warming?
A big problem with these methods, besides abysmal efficiency is that the light that drives the photochemical processes has some probability of generating side reactions that destroy the artificial enzyme. Nature overcomes this with unbelievably complex protein repair structures that literally swap out defective proteins for new ones. We have zero chance of replicating this type of thing anytime soon.
Bio oil from algae is much closer to practical utility than this tech. And electrochemical CO2 reduction will be an even more scalable and practical solution in the near term in my opinion.