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Engineers harvest clean, continuous energy from air
- u32480932048 3y ago"But this will suck up all the air and there will be no more birds!" - An oil industry-backed "environmental" group, soon
- deegles 3y agoThe paper says a cubic meter of the material could generate more than a kilowatt (per hour?)... sounds promising if it actually gets commercialized. I assume it would only work well in places where there are significant humidity swings, I didn't read the paper very carefully though. https://onlinelibrary.wiley.com/doi/epdf/10.1002/adma.202300748 https://onlinelibrary.wiley.com/doi/epdf/10.1002/adma.202300...
- amelius 3y ago> more than a kilowatt (per hour?) Not sure what you mean, Watt already has a unit of time in it.
- naich 3y agoNope.
- wlesieutre 3y agoWatts are a rate of one joule per second. If you want to talk about a quantity of energy rather than a rate of energy production/consumption, the units would be either kilowatt hours or joules (1 kWh = 3,600,000 joules).
- jrockway 3y agoYup, kilowatt hours are a cursed unit that simply reduces to joules (a nice and easy to remember 3.6 million of them).
- wlesieutre 3y agoYeah I have to work that out every time
- deegles 3y agoThe paper just says "an estimated energy density of >1 kW/m^2"
- amelius 3y agoThat's quite an amount, about 3-5x the amount of energy generated by solar cells of the same surface area. It would mean the device would generate $2000-$4000 on a yearly basis.
- Phenomenit 3y agoDidn’t it say cubic meter, not square?
- pdonis 3y ago"Energy density" is a misnomer, it should be power density, since the kW is a unit of power (rate of energy generation), not energy.
- joak 3y agoA kilowatt is unit of power. Joule is the unit for energy. A Watt is 1 Joule per second. A another common unit for energy is kWh (kilowatt.hour) A kilowatt generator can produce one kWh/h (by definition)
- Animats 3y agoThe good info is apparently in table S2 of "supporting materials", where they compare energy harvesting devices. That's not part of what you can read for free. Some kind of energy harvesting device that could generate a few milliwatts in ambient indoor conditions would be very useful. We have lots of things with AA batteries in them that use very little power but need a new battery every year or so. That's the potential here. This isn't going to replace oil.
- gs17 3y agoI got a copy, it says "~0.0001-0.05" W/m^2 for their material, which they put at the same order of magnitude as "Hydrovoltaic" harvesters, and several orders below something like wind or solar. But they do list theirs as the only 3D scalable, "continuous and ubiquitous" harvester.
- okwhateverdude 3y agoPresupposing completely optimal 50mW/m^2, could you origami that surface? Because then you could probably have something pretty useful.
- oidar 3y agoNews releases like this are always optimistic, but there always some hidden cost they don't tell us about.
- oidar 3y agoPreviously: https://news.ycombinator.com/item?id=36112815 https://news.ycombinator.com/item?id=36112815
- chrisbrandow 3y agoDespite being a chemist, I don’t fully follow this, though it seems legitimate. But if there’s that much latent energy, I really have to think that there could be some kind of atmospheric, “local ecological” side effect on microorganisms or “something” at scale. It’s not like nature lets massive amounts of energy go completely unused.
- purpleflame1257 3y agoCompletely? No. But consider how much of a given square meter of sunlight on the ocean is photosynthesized by bacteria and algae, and how much becomes waste heat immediately.
- throwup238 3y agoThat's not "waste" heat as far as the ecosystem is concerned. It creates the ocean thermocline which drives ocean currents and nutrient exchange between layers. Without it everything in the ocean would starve from lack of basic minerals or suffocate due to lack of dissolved oxygen except around river deltas.
- amluto 3y agoThe article is quite vague. I assume they’re saying that a humidity difference drives a net flow of water vapor through their machine. So you seal one side and stick something hygroscopic in it as a big humidity sponge and expose the other side to the atmosphere. Then, about twice a day, you get a current if your climate has large diurnal humidity changes.
- soperj 3y agoI don't really see anything harvesting the wind aside from us?
- thaumasiotes 3y agoPlants do it all the time; the basic plant strategies for colonizing new territory are floating on the wind, floating on the water, and fruit.
- H8crilA 3y agoWe really need an "absurd level of clickbait" button on HN, to burry such headlines.
- BobaFloutist 3y agoYou should flag anything that you don't think meets the criteria to be worth posting.
- prismz 3y agoWhat's wrong with it?
- vajrabum 3y agoHere's the paper behind the story. There is some interesting detail there. From their result it seems that this sort of mechanism can be constructed with a wide range of materials both organic and inorganic. So there a lot of possibilities for how to apply the idea. https://onlinelibrary.wiley.com/doi/epdf/10.1002/adma.202300748 https://onlinelibrary.wiley.com/doi/epdf/10.1002/adma.202300...
- raphaelj 3y agoSomething similar happened when I put a dehumidifier in my bedroom. Basically, I noticed that the room was heating significantly when I turned it on. Way faster than what you should expect from its power usage (about 250W avg.). Correct me if I'm wrong, but by converting air moisture to liquid water using a compressor, the dehumidifier is releasing the latent energy of water vapor (0.627Wh/L) in addition to its own energy usage. I measured that my dehumidifier required +/- 1kW/h to get 1L of liquid water from the room. This it's overall heating efficiency is about 1.6x, which is way better than any electric heating system that is not an heat-pump.
- Ekaros 3y agoDehumidifiers are heat pumps. The heat source is latent energy in water vapour.
- NegativeK 3y agoGiven that a dehumidifier is doing the opposite of a swamp (evaporative) cooler, this makes sense.
- laweijfmvo 3y agodoesn't humid air "feel" warmer, though?
- AnimalMuppet 3y agoWarmer if it's warm, colder if it's cold. I think the deal is that it's more efficient at transferring heat to/from your skin.
- pdonis 3y ago> Warmer if it's warm Yes, but not quite for the reason you give. See below. > colder if it's cold. This I don't agree with. Cold air can't hold any significant amount of water vapor to begin with. It is true that a cold, rainy day feels colder than a cold, dry day with the same air temperature, but rain isn't humidity; rain is water, not water vapor. > I think the deal is that it's more efficient at transferring heat to/from your skin. Not quite. The deal is that your body sheds heat by evaporation of water (sweat), but water can only evaporate if the surrounding air is not already saturated, and the closer the surrounding air is to being saturated, i.e., the more humid it is, the less heat your body can shed before the air is saturated. In cold conditions your body wants to retain heat, not shed heat, and the humidity in the cold air doesn't really affect that at all, because, as above, there just isn't enough of it in cold air to make a difference. What does affect your body's ability to retain heat is dampness or rain, i.e., water, not water vapor; the extra water (far more water than you would generate by sweat on a hot day, or than exists as water vapor in cold air) sucks heat out of your body because the water is colder than you are and has such a high heat capacity (even if it doesn't evaporate).
- black6 3y ago> Plus, it’s tiny, meaning thousands of devices could be stacked atop one another without upping its carbon footprint. What does this mean? Was this written by AI that can't distinguish between a physical footprint and a figurative carbon one?
- hex4def6 3y agoFeeling a little skeptical, but I'd love for someone to explain where the energy is coming from. From the paper: In fact, an Air-gen device made from protein nanowires, which was kept in the ambient environment for over 3 years, still produced a similar voltage output ...These time spans are much longer than the typical hydration time, supporting the sustainable mechanism based on a dynamic equilibrium ... The Air-gen device is not a “perpetual motion engine”, because the energy comes from the electrostatic energy (not kinetic one) of discrete water molecules in a vast open source. Does this mean that the energy they're harvesting is a result of imparting a charge on otherwise neutrally charged water molecules, but because it's infinitesimally small compared with the "vast source", you can disregard any net effect from the perspective of the harvester? If so, this doesn't feel "right", because this implies that a charged particle's state is at a lower energy state than a neutral one. If that were so, wouldn't the universe tend to that lower energy state by default? Again, I'd appreciate if someone could tell me where the energy is supposed to be coming from, because "TANSTAAFL" seems to be being violated here.
- capitainenemo 3y agoAren't they basically harvesting incredibly diffuse lightning? These charge imbalances that accumulate naturally before discovering that lower energy state dramatically? Presumably it doesn't instantaneously happen due to insulating effects in the air.
- aredox 3y agoThe movement of the water molecules is what is generating the charge difference. In effect, this is using the wind - or just the movement of air, but not in a mechanical way. It is just using the wind to generate static electricity - the same way you generate an electric potential by rubbing felt on a balloon. Movement -> electricity. Of course it is fairly weak, but it is continuous and simple. There has to be uses for it.