Computer powered by colony of blue-green algae has run for six months(newscientist.com) |
Computer powered by colony of blue-green algae has run for six months(newscientist.com) |
> 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
Taking up inorganic nitrogen is called nitrogen fixation and takes a bunch of machinery and energy. Also, oxygen inhibits the process, so for photosynthetic bacteria a bunch of extra steps have to be taken to compartmentalize photosynthesis and nitrogen fixation. So not all cyanobacteria can do it, and even the ones who are able to will prefer to take up organic nitrogen if available, and they grow slower when they have to use N2.
Nitrogen in air is not normally available to organisms. The triple bond between the 2 nitrogen atoms is very strong and takes a good deal of energy to break. Some bacteria can do this, and legumes famously have evolved to house bacteria capable of fixing nitrogen in their roots.
The main way we get nitrogen to agricultural plants today is by the industrial production of ammonia, which takes enormous amounts of energy and lots of fossil fuels as presently implemented.
> "Because the experiment ran without any significant degrading of the anode the researchers believe that the cyanobacteria are producing the bulk of the current."
1: Looking at an anode and saying "yup not corroded" is not how you check such things.
2: If they actually wanted to check it, there are several methods, they did none of them. They include: Weighing it, killing the algae and seeing if the power output changes, trying other metals for the anodes, trying other plants instead of algae in the water.
3: If you put salt water between two anodes you will get electricity. Period. If they claim this didn't happen, and "the algae did it", you're going to have to posit some method for the algae to prevent this, while substituting their own electricity. This will require new chemistry.
4: Algae are non-polar, so I don't see how they can direct the positive and negative current toward the proper anode to make electricity.
They also discuss the possibility that the algae are just promoting the oxidation of the aluminum, but do a series of assays I don't fully understand and conclude that some of the current produced is most likely from the algae themselves.
Link to paper: https://pubs.rsc.org/en/content/articlehtml/2022/ee/d2ee0023...
Some years ago, the efficency was at around 1 % vs. 20% with solar panels, meaning you would need 20× the space, meaning only dessert areas and big scale production worth it. And since no one did it big scale yet, means it is economically not worth it yet.
But the cost of further algae itself are zero, which makes the idea attractive in theory. Like I said, there is a breakthrough required in efficency, or some cheap big scale production/deployment system.
So, if they need 20x the area, just their support and installation will already cost some 5x more than a full solar plant.
Algae are living creatures just like humans and stuff, so keeping them alive is probably harder then with solar which is basically just nicely arranged rocks and crystals.
About the only other household application of electricity I can think of that would use around 10w is lighting and even with LEDs it isn’t much. Probably enough for a single room.
My point is if mobile phones aren't considered “low power”, then what would be?
I don’t know that there’s a standard definition, but in electronics I think it’s most common for “low power devices” to be referring to sub-watt power levels. There’s regular low power like Arduino, or ultra low power like in this article that consume at most milliwatts or microwatts.
> “It’s not entirely straightforward,” he says. “So putting one on your roof isn’t going to provide the power supply for your house at this stage. There’s quite a bit more to do on that front. But [it could work] in rural areas of low and middle income countries, for example, in applications where a small amount of power might be very useful, such as environmental sensors or charging a mobile phone.”
I don’t it’s wrong to think about the general applications but the title and research had a very narrow focus.
It’s also easy to miss that this was with a “AA” size container, and not the size of a pail or a dot battery.