h a l f b a k e r yWhy did I think of that?
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In the desert, the days are brutally hot and the nights are brutally cold. I think we can use this to our advantage. All we need to do is carry a lot of water through the area of desert where you want to be and but it in a giant glass box with a black bottom.
The idea is not just to evaporate the
water and run a steam generator, but to run it in an enclosed system so you don't have to run back for more water.
since the steam can still be heated to rise when it goes through the generator, you can make it rise into a tower with insulation on the roof and with an anti spring-pressure system so that it contains the steam and condense the steam back into water. the water relieve the pressure so the steam generator can continue without much hold back (probably 3% energy loss or something). then at night, the temperature is around zero degrees, which will condense the all steam into water. That's when you relieve a pressure valve to allow the gathered large amount of water in the tower to use gravity to spin generators as it returns to the steam generator.
I forgot to say but the insulated roof is for the water to condense but the reason why completely insulating it wont work is because the night air need to reach it too.
(note: if cities used this system then we could improve the efficiency of all steam generators)
[link]
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//In the dessert, the days are brutally hot and the nights are brutally cold.// |
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What are you eating, man!? |
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lol, i don't know the extents of the actual tempuratures plus i wanted to make it seem like it would work :3 i heard about hot days but really cold nights in the dessert on tv D: |
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Subtlety doesn't work with this one, it seems. |
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Hey, [xXxGenasai]! [21Q] is trying to make you notice that you have a misspelling: //dessert// is something you eat, not a place to put generators! |
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wouldn't work: based on say 500Wh/m^2 and even with a high figure of 10h worth of direct straight-above sunlight, that's only 5kWh/m^2/day. |
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heat of vapourisation of water is 2.257mJ/kg.
A kg of water is 10x10x10cm. You'd need 627Wh of energy to turn that into steam. |
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A m^2 of water (nice acryllic cube with a black bottom), you'd need roughly 627kWh... you're a bit short. |
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You could raise the temperature of a cubic metre of water roughly 5 degC during the course of the day. |
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I'd go with a lot less water and a Sterling engine; using 10l of water over a m^2 area (1m x 1m x 1cm) you could raise the temperature *almost* to boiling then have a nice temperature differential all night for the Sterling to work with. |
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This doesn't actually improve the efficiency of the generator. Sorry. The only way you will have significant reserve of energy for nighttime generation is if you heat a significant mass of water during the day and then cool it during the night (which you pay for the next day when the water is cold and you have to heat it up). Steam=/=Free energy. |
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I just logged in to post a similar idea, except that rather than the desert, I was thinking of the lunar terminator; the boundary between the lit side of the moon and the dark side. |
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Imagine a vehicle that straddled this line. The back half of the vehicle would absorb heat from the sun to vaporize ammonia or a similar liquid. The back front half would be on the dark side of the terminator and would disapate the heat into space, or to the cold lunar soil. Note that the vehicle would always be traveling into the dark part of the moon, so the soil would have had a month or so to cool. |
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Such a vehicle might mine minerals from the lunar soil. |
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Even better, it could potentially move in two directions: North/South and East/West to eventually traverse a substantial part of the moon's surface. |
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If the desert doesn't have enough heat to boil water then you can either use a lens to magnify the sun light or you can just let the water vaporize into the tower for the night generator. |
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that type of scale seems waist-full to me though /: but its just an idea :3 |
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Liquid water is evaporated into steam and expands through a turbine, generating energy. So far so good. |
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Possible bad science: If the spring pressure system actually compresses the steam, then it is bad science because this pressure must be overcome by the turbine, so no efficiency is gained. If the spring just supports the weight of the tank's roof so the tank acts like a bag, then nevermind. |
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//use gravity to spin generators as it returns to the steam generator//...as long as you don't get back pressure on your generator from the big tank, maybe. |
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I assume you'll have a well-insulated and shallow black box, or some mirrors aimed at the water, or are building this on Mercury. |
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//(note: if cities used this system then we could improve the efficiency of all steam generators)// I, too, have had the joy of believing I was sitting on an industry-changing, billion-dollar idea, only to be disappointed by physics. |
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dude xD since night time is cold it will condense which is why you don't insulate it and the spring pressure system works like a bag. |
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Does the water ever condense during the day? The post says yes but your comment says no. |
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I'm still not convinced the steam would actually condense during the day. Say you have 100C saturated steam coming out into a steel tank in the desert sun on a 30C day. Yes, the steam's heat will gradually be lost through the tank, but if you are able to get the steam to condense back down again you might as well run the water right back into the evaporator, since the freshly condensed water will be warmer than the cold water from the night before. |
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I still don't like the water-falling part either: The steam's energy is lost through 1. generating electricity or 2. rising. Why does the steam rise? |
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But, [+] for making me care. |
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//I aspire to make ideas but laziness permits me not too// Me too, buddy. Me too. |
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" I still don't like the water-falling part either: The steam's energy is lost through 1. generating electricity or 2. rising. Why does the steam rise?" |
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For the same reason HELIUM rises... it's lighter than air.
Other gas lighter than air: hydrogen, HHO, methane, ammonia, neon... |
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Water is an anomaly for liquids, it is VERY DENSE AS A LIQUID.
That is why heavy oil from leaking tankers float on it.
That is why the ocean level GOES DOWN when ice melts!
That is why clouds float in air and ice floats in water.
That is how "hot air" balloons REALLY work. |
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if you have the steam rise through something like a see through tube, then the sunlight will continuously re-heat the moisture up into the tower. The energy gain is when the steam in the tower condenses and gains pressure since its higher than the steam generator. This pressure then runs a smaller generator as the water falls back into the steam tank (best if at night for more water pressure). |
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simply put, it's like a water fall effect |
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//it's lighter than air// I know that xD. This is a closed system, so there's no //air// to rise through. What I'm trying to say is that any energy you get from the falling water you could have gotten more easily from the steam, unless your steam tank is miles high. |
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Sounds like a lot of building and water carrying(and sweating). If you've got enough heat difference maybe carrying a thermopile would be easier. Drink the water, it's hot out there. |
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