Artificial leaf's making fuel:

https://techxplore.com/news/2020-03-nature-inspired-green-energy-technology-important.html

Now makes CO but they are working to turn that into methanol.

@sonhouse said
https://techxplore.com/news/2020-03-nature-inspired-green-energy-technology-important.html

Now makes CO but they are working to turn that into methanol.

I once considered writing a book about this but I think they are using a flawed strategy. That's because what they are talking about there is converting sunlight energy directly into chemical energy. But, for reasons to subtle and tedious to explain here (which is why I once considered writing a whole book about it), I believe I can show that the stategy that would likely result in the maximum energy efficiency of conversion from sunlight energy to chemical energy is, perhaps counterintuitively, not do so directly in one step but rather in a clearly divided two-step energy conversion of first converting light energy to electrical energy and only then converting that electrical energy to chemical energy.
And the best way to do that is first generating electrical energy with a solar panel designed to be at least 90% efficient (and I have research this and calculated that, contrary to popular belief which is base on some flawed assumptions, the maximum energy efficiency of a solar panel is over 99% although for various practical reasons 90% to 95% would be much more realistic in the real world with 99.99% being way too problematic) and only then convert that electrical energy to chemical energy using a device that works a bit like a room-temperature fuel cell but working in reverse (not sure what such a device should be exactly called). I worked out such a device would have a theoretical maximum energy efficiency of over 99%.

I don't know why but many researchers often keep making out that photosynthesis in nature is hugely energy efficient and often keep saying so; It isn't. Its very inefficient actually. Most of the energy is simply wasted. This false idea that photosynthesis in nature is hugely energy efficient is at least one idea where the flawed strategy of trying to artificially convert sunlight energy directly into chemical energy keeps coming from.

P.S. I noticed someone gave your OP a thumbs down even though it contained no provocative statement to anyone so I gave it a thumbs up to compensate.
I think we all now have a pretty good idea who has the kind of infantile mentality required to keep giving your non-provocative first posts of a new thread a thumbs down.

@humy said
I once considered writing a book about this but I think they are using a flawed strategy. That's because what they are talking about there is converting sunlight energy directly into chemical energy. But, for reasons to subtle and tedious to explain here (which is why I once considered writing a whole book about it), I believe I can show that the stategy that would likely result ...[text shortened]... le mentality required to keep giving your non-provocative first posts of a new thread a thumbs down.

I think a suitable term for your reverse fuel cell is just "reactor".

@sonhouse
It would be cool if we could genetically engineer an alcohol plant that makes alcohol and grows like a weed (an alcohol melon?). I believe the pollutant from burning alcohol is simply water vapor.

@bunnyknight said
@sonhouse
It would be cool if we could genetically engineer an alcohol plant that makes alcohol and grows like a weed (an alcohol melon?). I believe the pollutant from burning alcohol is simply water vapor.

If combustion is complete the reaction is:

C₂H₅0H + 3O₂ --> 2C0₂ + 3H₂0

so carbon dioxide is produced as well.

@deepthought said
If combustion is complete the reaction is:

C₂H₅0H + 3O₂ --> 2C0₂ + 3H₂0

so carbon dioxide is produced as well.

But the mythical alcohol plant would extract the carbon from CO2 in the air and
therefore using the alcohol (needn't be ethanol) as fuel would be carbon neutral.

@wolfgang59
Anyway, there are chemical means to convert CO2 to methane so it could be a closed loop if it worked.

@humy
Do you have any idea how to pump up to 80 or 90% solar cell efficiency? Can you imagine solar paint with that kind of figure coating a car? It would seem to me you could have a full battery, go to work, park in the sun and when you go home the battery is full again, or extend the driving range of a full battery.
But did you figure out the energy % efficiency for this artificial leaf idea?

@wolfgang59
"the mythical alcohol plant "
That instantly reminded me of elves, unicorns and dragons.
But I suppose a steam locomotive was just a mythical metal monster back in 1245 AD.🙂

@sonhouse said
@humy
Do you have any idea how to pump up to 80 or 90% solar cell efficiency?

Just two ideas on that;

1, Instead of having just one semiconductor layer in the solar cell, have many with each one optimized to absorb only one relatively narrow range of frequencies and convert that range to electrical energy with at least ~90% energy efficiency.

2, don't have any semiconductors in the solar cell but use what are called 'nano-antennas' and use a combination of other quantum effects to achieve high efficiency by avoiding the limitations of semiconductors.

Can you imagine solar paint with that kind of figure coating a car?

I really do not know and cannot imagine how that would be supposed to work. As the paint sets and dries, wound the molecules in the paint self-organize in the complex multilayered structures required to convert sunlight into electricity? I am very skeptical and suspicious of the whole idea of this so called "solar paint" which seems to me like a wildly over-optimistic magical wishful extremely-simple quick-fix solution; -just get a tin of solar paint and an ordinary paint brush and slop on the paint and its done! Just as simple as that? Really? I doubt if it would ever pan out.

But did you figure out the energy % efficiency for this artificial leaf idea?

I once did with the assumption that it works like a natural leaf by absorbing CO2 directly from the air. With that assumption, for various reasons it will inevitably have very poor efficiency just like photosynthesis in nature does and for a very similar set of reasons. One such reason is because of what is called in biology the "carbon dioxide gradient" that massively limits photosynthesis in nature in strong sunlight although much less so in very dim light conditions.
See;
https://en.wikipedia.org/wiki/Photosynthetic_efficiency
The thing is, there really is no 'easy' way around the above limiting factors because the laws of physics kind of indirectly get in the way.

The efficiencies I calculated vary massively with conditions esp with temperature and intensity of light.

My above misedit;
"..As the paint sets and dries, wound the molecules..."
should be
"..As the paint sets and dries, would the molecules..."

@humy
The problem with stacking bands is every one you stack and now there are units with 3 bands the cost goes up tremendously. You wouldn't gain much if you got a 90% cell if it cost a thousand dollars per square foot. You could do it horizontally I suppose but that would just mean real estate devoted to band A, real estate devoted to band B and so forth which wouldn't gain much either, the cells would have to have transparency to most bands and say the bottom band responding to IR and a higher up band responding to red and so forth but the expense would make that technique useless for commercial sales, maybe good for space use where it costs thousands of dollars a pound to get stuff in orbit but outside of that, not much help if the cost goes up 100X over a 20% cell.
Another way to do that would be to have stacked cells able to take high temperatures and then use concentrator mirrors to get sunlight on a cell of high efficiency, that would offset some the cost of stacking cells.
I think people will be as happy as pigs in poop if we got to 40%......

@sonhouse said
@humy
The problem with stacking bands is every one you stack and now there are units with 3 bands the cost goes up tremendously.

Yes, at least using conventional manufacturing methods although I have envisaged that far future manufacturing methods would be done at room temperature and pressure using artificial enzymes that would reduce those cost by thousands if not millions of times and thus make that cost no longer an issue.
Still, that would take a long time and thus that is one of the reasons why I think option 2 I said above is the more hopeful option i.e. use other quantum effects ( nano-antennas, quantum dots, etc) to achieve high efficiency by avoiding the limitations of semiconductors.
Fortunately there really are doable workarounds here; it just just a matter of when, not if, they would be finally developed & implemented.

@humy
I eagerly await such developments.

@sonhouse said
@humy
I eagerly await such developments.

Don't hold your breath; Unless an AI singularity is achieved in our life time (which, for what's is worth, I will try and make happen if I can), it is very unlikely that any of those things would happen in our natural lifetime.
For example, I have read about some research into artificial enzymes but really we are nowhere near the kind of development of that to even begin to do those things I envisage; At the current rate of progress, more like ~400 years time if we assume no AI singularity to do research & development for us.