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TIL about bifacial solar cells which produce electrical energy when light hits either side
(en.wikipedia.org)
this post was submitted on 04 Jul 2026
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What would you use the azolla for? Animal feed? Which source of nutrients would you feed it with? Intensive harvesting of azolla would quickly deplete the nutrients in the water.
Great question. Several uses. especially if squeeze and dried, can be used as nitrogen fertilizer. Given the fact that azolla fixes nitrogen from the atmosphere.
Biochar: Organic carbon permanently locked into a solid form that remains in the soil for over 1,000 years, generating high-value Carbon Dioxide Removal (CDR) credits.
High-Protein Animal Feed: A cheap, highly nutritious feed supplement rich in protein and amino acids to replace land-intensive soy and alfalfa for cattle, poultry, and fish.
Organic Biofertilizer: Nitrogen-rich pellets made directly from the nitrogen-fixing fern, allowing farmers to completely bypass expensive, fossil-fuel-derived synthetic fertilizers.
I missed that azolla could fix nitrogen, knew that about duckweed but azolla is not my strength to be honest. However the question still remains, where would you get the potassium and phosphorus required to grow the azolla? All 3 of your examples involve continually harvesting azolla and not getting the nutrients back in. You could add chemical fertilizer to grow azolla into organic fertilizer but that would be kinda dumb wouldn't it? Not to say that hasn't been done multiple times before, looking at you alfalfa fertilizer pellets.
In a way wood is a great way to produce biochar because nearly all the nutrients in the tree are in the leaves and the branches. When harvesting wood we only take the trunk. This means we can grow wood generation after generation and we don't have to use fertilizer. The same is not true for something like azolla. A good setup to make it cyclical would be to put the azolla right next to the animal farm whose animals are fed the azolla. And use the manure to grow azolla. However then I wonder if the hygienic quality is acceptable.
You need to learn about the growth rate of azolla to understand why it's superior, the cycle rate is insanely fast, it grows rapidly. Yes potassium and phosphorous would need to be introduced, it would be inexpensive.
Introduced from where? That's my whole question. Apparently you don't know but phosphorus is a finite resource which will run out in the next 100-300 years. It's just as fossil as fossil fuel. Any solution that uses mined phosphorus is not sustainable.
You need to learn about mass balances.
What do I need to learn about it?
Duckweed works better for animal feed since it produces far more biomass and protein per day although azola is still pretty good. Thx problem with both is dewatering and getting high enough consumption. It works as an additive but certain animals don't like to eat pure azola or duckweed. Processing it into protein concentrate helps out though so you can feed far more to animals that would otherwise start refusing rations made with too much of either.
One thing worth thinking of would be a cooling jacket on the back of the solar panels that also heats the pond water. That makes the panel's more efficient, only needs a small electric pump to circulate it, and makes the pond plants grow faster when it's cold or even allowing them to be productive in the winter in certain places?
I think azolla has been floated (hah!) as a scalable way to quickly fix atmospheric carbon. Maybe fish aquaculture for nutrient restoration?
You can feed the azolla waste water from a fish farm for sure. But then what do you feed the fish? The nutrients always have to come from somewhere and they have to end up somewhere. If you're simply dumping azolla in a mine somewhere as carbon storage that then turns into a huge waste of nitrogen, phosphorus and potassium. It's a very nutrient dense plant.
Yes you're effectively sucking out nitrogen and carbon directly from the atmosphere and turning it into a solid. Furthermore, if you squeeze out all the water you get extremely dense cakes. You can use the energy generated from the solar panels to mechanically squeeze the azolla, use the squeezed out water back into the system.
I think the easiest option that works at the largest scale for the least money is dewatering it and pyrolysing it into carbon. You might get some of the nutrients back but most would be lost I think which is the downside. The only way to get those nutrients out is to turn it into ash which destroys nitrogen but liberates potassium, phosphorus, and other minerals.
One other option is to use it as a soil amendment. Biochar has a massive impact on crop yields (for soils that dearly need it. This isn't universal) and the effects can last for decades or even centuries. It takes a lot of biochar to have that effect though, which azola or duckweed carbon fixing can produce in bulk.
I've heard something like 8-30 tons per hectare of bio char. The other benefit is while some of the carbon releases naturally over time it's a slow process. The big benefit is water and nutrient retention without water logging your crops (in fact it helps with drainage in low permeability soils.) More beneficial bacteria and a healthier soil ecosystem.
Biochar is best made with manure and composte afterwards to preload it with nutrients otherwise it actually has a net negative effect on yields (since it's like adding activated carbon. It absorbs everything until it's fully loaded up with nutrients)
Happy cake day, and yes, both. Carbon sequestration and animal feed.