6 ms·
Mechanical power generation using Earth's ambient radiation
- HPsquared 11mo agoSomewhat different, but this reminds me of an approach that uses temperature gradients in the ocean to power a heat engine. https://en.wikipedia.org/wiki/Ocean_thermal_energy_conversion https://en.wikipedia.org/wiki/Ocean_thermal_energy_conversio...
- deleted 11mo ago[deleted]
- jasonpeacock 11mo agoOTECs are amazing, and step 1 of "The Millennial Project: Colonizing the galaxy in eight easy steps"[0] [0]: https://en.wikipedia.org/wiki/The_Millennial_Project https://en.wikipedia.org/wiki/The_Millennial_Project There's a shore-based research OTEC in Hawaii, but the best is a floating, closed-loop OTEC in the ocean.
- andbberger 11mo agowiki article states "Up to 10,000 TWh/yr of power could be generated from OTEC without affecting the ocean's thermal structure". which converts to about 500GW which... isn't that much
- pezezin 11mo ago10 000 TWh/yr is one third of the current total electric energy generation of the whole planet, is not a small amount. Source, page 39 of the full report: https://www.iea.org/reports/global-energy-review-2025/electricity https://www.iea.org/reports/global-energy-review-2025/electr...
- nine_k 11mo agoThis can't be correct. 10,000 TWh/y = 1e+7 GWh/y, divide it by 365.25 days/y to produce daily output of 27,379 GWh/day, then by 24 h/day to get pure power of 1,141 GW. It's still more than a terawatt, three orders of magnitude larger than the largest nuclear reactors.
- andbberger 11mo agooops. yes. still not that much though. i mean it's a lot but it's "one more large industrialized country" a lot not "kardashev 2" a lot
- AstroNutt 11mo agoInteresting link. I would think step 7 would come before step 6 though. I thought about this for a few minutes and can't come with a reason otherwise.
- adastra22 11mo agoThe timelines are increasing powers of 2. It’ll take much longer to colonize all asteroids than to settle Mars.
- AnimalMuppet 11mo ago400 milliwatts per square meter? That's interesting that they can do it at all, but that level is completely impractical for real use.
- aetherspawn 11mo ago> the generation of >400 milliwatts per square meter of mechanical power with a potential for >6 watts per square meter. Keep in mind the power is fully mechanical so no electricity or control circuit is required. And based on the simplicity it seems like a good candidate to power something that you need to last 100 years with no maintenance for example.
- abeppu 11mo agoI think the "last 100 years with no maintenance" is not likely feasible with this approach. The top plate has a coating that supports high infrared emissivity -- and I think it would need to be regularly cleaned to work well. And you can't really prevent it from getting dirty by enclosing it b/c that both substantially changes the performance and moves the maintenance burden to cleaning the enclosure.
- AnimalMuppet 11mo agoMechanical things don't usually work for 100 years with no maintenance. Bearings run dry, if nothing else.
- ufocia 11mo agoAir bearings always run dry without problems.
- contingencies 11mo agoUntil they are replaced with dust, pollution, hair, animals, leaf litter, aggressive plants, seismic events, pollen, skin particles, birdshit, fallen logs, slime mold, etc.
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- clickety_clack 11mo agoIn one of the later Foundation series books, Isaac Asimov had a whole world run on this.
- phyzome 11mo agoIf anyone is interested in passive sub-ambient cooling (not for power generation, just for "free" cooling) I strongly recommend https://www.youtube.com/@Nighthawkinlight https://www.youtube.com/@Nighthawkinlight -- he has been doing a lot of experiments in this space and releasing recipes as he goes. Stuff you can do in your kitchen.
- gsf_emergency_6 11mo agoVid of the engine in action, from the team that made the paper https://www.youtube.com/watch?v=5VSmBl8Rv_o https://www.youtube.com/watch?v=5VSmBl8Rv_o This one shows that it is not as unbelievable as it sounds :) https://youtube.com/shorts/9KuTdPGqhVo https://youtube.com/shorts/9KuTdPGqhVo
- jcims 11mo agoDIY radiative cooling paint from YouTuber NightHawkInLight - https://www.youtube.com/watch?v=N3bJnKmeNJY&list=PL1a2HkcVbmAWExiWT__qQypLEwkvijnIM https://www.youtube.com/watch?v=N3bJnKmeNJY&list=PL1a2HkcVbm... It has pretty impressive performance. Tech Ingredients did one or two vids as well - https://www.youtube.com/watch?v=dNs_kNilSjk https://www.youtube.com/watch?v=dNs_kNilSjk Was thinking of whipping up a batch for my rv.
- kumarvvr 11mo agoThis concept is used all over India to cool down homes that are on the top floors. https://www.amazon.in/EXCEL-CoolCoat%C2%AE-Reflective-Coating-Summer/dp/B09BFZ67XH?th=1 https://www.amazon.in/EXCEL-CoolCoat%C2%AE-Reflective-Coatin... Basically, have a highly reflective white coat on your roof, to reduce temperatures by about 3 Degrees Celsius. Almost all homes in Urban India are made from concrete and bricks, which can hold a lot of heat. I myself have been in houses that use this to cover only some rooms of the house (mainly the bedroom), and the temperature difference is definitely noticeable. It also makes the room livable in the extreme hot summers in India.
- kragen 11mo agoThis is the opposite. It says, "Refelects [sic] 90% of solar infrared rays," because of its "High IR reflective Pigments [sic]," so its emissivity in the infrared is 0.1, but the IR-selective paints we're talking about here are optimized for high infrared emissivity, which means they absorb a lot of infrared. Maybe there's some wiggle room here because solar infrared is mostly near IR and MWIR, and the place where we want high emissivity (absorptivity) is longwave IR, but to the extent that the advertisement makes any claims about infrared emissivity, it claims very low infrared emissivity, not high. A paint with low emissivity across the spectrum will slow down the temperature rise when the sun is up, but also slow down the temperature drop when the sun is down. This can still make rooms livable, but it isn't the same as what you get with regular whitewash, where the temperature of the roof is actually lower than the temperature of the air around it.
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- rriley 11mo agoGreat! Now I desperately need this Stirling engine for my morning coffee: https://a.co/d/6Ja2LeF https://a.co/d/6Ja2LeF Video of how it works: https://www.youtube.com/watch?v=Q5QEBqjkNjo https://www.youtube.com/watch?v=Q5QEBqjkNjo
- kogasa240p 11mo agoSince we're talking about stirling engines, I've always wondered how using geothermal heat for a larger stirling engine would work. https://youtu.be/duuk_r--lqU?t=99 https://youtu.be/duuk_r--lqU?t=99 Even though the video uses the sun to heat the oil, I would think it would be feasible to use geothermal heat instead.
- not_kurt_godel 11mo agohttps://en.wikipedia.org/wiki/Organic_Rankine_cycle https://en.wikipedia.org/wiki/Organic_Rankine_cycle
- kogasa240p 11mo agoVery fascinating article.
- fooker 11mo agoYou boil water :)
- cameldrv 11mo agoNot an engine, but some friends of mine got a mylar sheet that's black on one side and reflective on the other. We tried it out in the desert tied onto trees/vehicles. You put the shiny side down, so the hot IR radiation of the earth is reflected away, and the black side sees the extremely cold (in IR) desert sky. If you put a little hole in the middle and put a bucket under it, you get a fair bit of water, because the mylar sheet gets about 20 degrees C below ambient and a lot of water condenses on it. (even in the desert)
- wombatpm 11mo agoNow you just need a couple of droids and you could go into the moisture farming business
- jeffrallen 11mo agoNah, those are not the droids he's looking for.
- sigmoid10 11mo agoWhat I really need is a droid that understands the binary language of moisture vaporators.
- timdiggerm 11mo agoBut can he speak Italian lawn games?
- deleted 11mo ago[deleted]
- nmeagent 11mo agoI was going to look into this once, but instead I opted to go into Tosche station to pick up some power converters and unfortunately never quite got around to it.
- viraj_shah 11mo agoFascinating 20 degrees C is huge. What's a fair bit of water? At what time of day and how long did you collect water?
- Animats 11mo ago> 400 milliwatts per square meter About two orders of magnitude weaker than solar panels, even over 24 hours. E = (T2-T1) / T2
- kragen 11mo agoYes, but it works at night! Not sure if you can get the MTBF on Stirling engines higher than on LFP batteries, though.
- gsf_emergency_6 11mo agoAnd in the day time, if transparent and applied to solar panels, the "efficiency" gain (~10W psqm) itself will dwarf other considerations.( Remembering that bulk of radiative cooling shouldn't happen below ~1300nm) And then there's beating the efficacy of carbon capture at mitigating warming by orders of magnitudes Nothing to sneeze at. Just be careful of midbrow high-effort dismissals from the old and wise:) These guys are applying them to solar panels: https://www.i2cool.com/tideflow/uwJVdixI.html https://www.i2cool.com/tideflow/uwJVdixI.html "Case Study 2: Solar Farm in Dubai Problem: Solar panels lost 15–20% efficiency at 55°C+ temperatures. Solution: Coated panels with i2Cool’s film. Results: Panel surface temperature: ▼25.7°C (from 58°C to 32.3°C) Power output: ▲8% (equivalent to adding 2,400 new panels to a 30MW farm)"
- kragen 11mo agoThanks, that's staggering!
- scoopertrooper 11mo ago>400 milliwatts per square meter of mechanical power with a potential for >6 watts per square meter.
- Animats 11mo agoWhat miracle gets a Stirling engine to be 15x more efficient? Stirling engines have been around for over a century.
- carabiner 11mo agoCost to build, maintain this machine? $/watt?
- bilsbie 11mo agoI wonder if you could harness different temperatures at different water depths.
- thijson 11mo agoYou can, it's called OTEC: https://en.wikipedia.org/wiki/Ocean_thermal_energy_conversion https://en.wikipedia.org/wiki/Ocean_thermal_energy_conversio... Just like this scheme, it's not very economically efficient. Carnot efficiency is proportional to the temperature ratio between the hot end and the cold end in degrees Kelvin. If both temperatures are in the 200's, then efficiency will be low. OTEC does provide lots of potable water though, so that's one advantage.
- throwaway34564 11mo agoSlightly off-topic - I was momentarily excited this was a replication of https://journals.aps.org/prapplied/abstract/10.1103/PhysRevApplied.6.014017 https://journals.aps.org/prapplied/abstract/10.1103/PhysRevA... (Electric Power Generation from Earth’s Rotation through its Own Magnetic Field) I've been stalking the citations for this paper for a while now. Surely people would be scrambling to replicate these results. It could truly be transformative for the world if it works and is scale-able. The science looks good to me
- cindyllm 11mo ago[dead]
- burnt-resistor 11mo agoDavis is so frickin windy, wind power would be my first choice. Secondarily, using a deep ground source heat pump to power a Stirling cycle engine would probably be much more powerful than harvesting a few mW from ambient temperature gradient between surface and air. That's my 2 centidollars.
- blacksmith_tb 11mo agoStirling engines are of course fun, but I wonder if the same approach but with the specially-coated radiator on a Peltier instead would net much - it'd avoid the moving-parts problem, at least.