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My idea is basically giant Atmos Clock or Reverse icyball
that uses phase changes in a liquid with a low boiling
(butane, r134a, ammonia, methylene chloride) in order
take advantage of the changes in ambient temperature
between morning and evening. Basically you have a a
absorption refrigerator that converts the
of gas into mechanical energy (via pistons or turbines),
then from mechanical energy to electricity (via
Imagine two giant variable volume storage tanks. When
the day heats up the liquid in one tank (with the air
lowered via movable baffles) would boil and pass through
pipes to a turbine, then to another empty tank (adjusted
to maximum volume). During the night the gas would
back into a liquid. The volume of the tank would be
reduced (via movable baffles) and the process would
over the next day in the reverse direction.
There are many devices (sterling engines, peltiers, solar
thermal concentrators) that use the sun or geothermal in
in order to generate energy by having a hot side and cool
side to the device. What I am proposing is a device that
only depends on day being hot and night being cool.
(edit two hours later)I just read the thermal
hydroelectric idea on here. This gave me the idea...
Two tanks like before, but this time fixed volume. One
small tank at the bottom of a hill, one large tank at the
top. During the heat of the day the liquid in the small
tank turns into a gas and goes up hill through a pipe,
turbine, then into the top of the large tank on top of the
hill. When the gas cools at night into a liquid, it runs
through a pipe in the bottom of the large tank, down the
hill, through a turbine, and back into the small tank at
the bottom of the hill. The night pipe may need a one-
way valve in it to prevent the liquid from being pushed
up through it during the day gas/pressure phase.
This principal being used for cooling rather than energy generation [dlapham, Aug 05 2010]
This concept in a very small device. [dlapham, Aug 05 2010]
This idea is quite similar to mine and in fact the two could be combined. [dlapham, Aug 05 2010]
I like to do it in the desert
Like this but with less sand [Voice, Aug 08 2010]
||The maximum theoretical efficiency of a thermodynamic engine is 1-TempCold/TempHot.
||The daytime temperature rarely varies more than 15 C at most, 5-10C is much more likely. Converted to the absolute temperatures required in the formula above, thats a best performance of 1-273/283 (at 0 C night time) 3.5%. This will result in an output of .1 Wh per kg of air or 0.123 Wh per m^3.
||Note that this does not make the idea impossible, just that a huge system is going to be required to generate any appreciable power, and the cost of a plant in this size is likely to be significantly more than it can generate over any reasonable life-span estimates.
I realize that this would require a lot of volume. I
also realize that you would need a very volatile
fluid that has as much expansion as possible when
in gas phase, yet cools to liquid during the
||You would ideally choose a location with a hot
and dry climate for this installation in order to
take advantage of maximum day and evening
temperature swings. You could also use simple
solar thermal assistance to the process by painting
the tanks an infrared absorbing color.
||As far as expensive, I disagree. This is where this
idea shines. It is very mechanicly simple. Uses
very low cost materials, and can easily be scaled to
any size. I agree that the efficiency per square
foot is much lower than solar or wind. But energy
potential over the lifetime of the device per
dollar/euro invested in building and maintaining
the device and purchasing land, should be much
lower than solar and wind.
||//You would ideally choose a location with a hot and dry climate...//
||Yes, that would be ideal, but we did that one already. More than once, actually.