> Christopher Howe at the University of Cambridge and his colleagues built a small enclosure about the size of an AA battery out of aluminium and clear plastic.
That's REALLY not a lot of power, which of course is reasonable, but I do wonder how far can it scale, can it reach any generally usable.
Let's take a very conservative estimate of watt-hours of an AA battery of 2 Wh. The computer used in the paper could run for 2,000,000 µWh / 0.3 µW = ~6,666,666h.
Let's convert to a more human friendly numbers: 6,666,666h / 24h = ~277,777 days. 277,777 days / 365 days = ~761 years.
I probably calculated all of this incorrectly, but I still have a feeling that blue-green algae might not be very scalable... :/
Actually, the idea is, that they are very scalable, because to make more solar panels you have to manufacture more panels.
To make more algae(and get more power), you just let it grow.
So you still have to build more sun exposed tanks but this is very low tech, compared to cleanroom solar panel manufacturing. What is missing is probably a breakthrough in genetic modified improved efficeny, which is currently indeed very low (way lower than solar panels per area)
So no, this isn't scalable.
On top of that despite them saying the anode was not corrected, it's almost certain the algae aren't making any electricity at all, it's all coming from the cathode and anode oxidizing.
It's easy enough to tell - just let them die and let's see if there is a different in energy output. I can almost guarantee there will not be any difference.
That being said, I'm sceptical about the scalability of the algae generator because it's efficiency would have to increase by about 1000x (if we assume that right now it can generate what the computer used while calculating).
Today an average AA battery has t the capacity of 3Wh some even 4Wh. And at 3Wh you could, theoretically, charge your phone at 5V 1A for like half an hour or there about.
Our in other words, what I'm talking about when I question the scalability is energy density. That's the reason why you can do more then 700km with a car that runs on fossil fuels and maybe 350km if it's not too hot and not to cool with an electric car.
Could we engineer there algae to be 1000x times more efficient or even just 500x more efficient, since as long as the algae is alive you don't really need to charge anything. You do need the sun though, these are, from what I understand photosynthetic algae.
How many m^2 of algae is required to equal a m^2 of solar? From there you could calculate relative costs, given reasonable assumptions of lowered tank/algae costs as the tech matured.
The same thing is happening here - it's not the algae producing energy, it's the metal anode and cathode.
Also, how much does it "capture" carbon as part of the photosynthesis ?
https://www-cyanosite.bio.purdue.edu/media/table/media.html
Mostly they need nitrogen, phosphate, and sulfur to make protein and nucleic acids, and trace metals,ions, and some vitamins to use as cofactors for enzymes. In the wild, the limiting nutrient for cyanobacteria is often iron or nitrogen.
They don't need an added carbon source in their media since they get to eat dissolved CO2 from the air. Every carbon atom in newly synthesized molecules comes from CO2, and there are (very roughly) 10^10 carbon atoms per bacterial cell. http://book.bionumbers.org/what-is-the-elemental-composition... . So if you know the growth rate you can estimate the carbon fixation rate.
How can nitrogen be a limiting factor if ~78% of air is nitrogen? I'm assuming they also take the CO2 out of the air, which just makes up 0.04%.
Carbon is captured through photosynthesis and is stored as biomass. But when the microalgae dies the carbon is released again. So to truely store carbon the microalgae needs to be cultivated and buried / contained.
There are all sorts… some MIT wonks built one that plays tik tak toe that's made of tinker-toys and powered by a crank… in Neal Stephenson's Cryptonomicon, a computer built from a church pipe organ is used to decrypt third reich punch cars… all quite feasible.
But yeah, this is algae-for-electricity… pretty cool regardless, but it does make me wonder if some sort of bio-abacus could be possible
So stack a bunch of these vertically, but have a light-pipe to each little window to the algea to feed them photons.
Trickle charge batteries?
https://pubs.rsc.org/en/content/articlehtml/2022/ee/d2ee0023...
The paper: https://doi.org/10.1039/D2EE00233G
