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Duh, we can read summaries, I know... Okay kids, compressed air can be used for lots of things. Is it feasable to use it to power a refrigerator, the most energy consuming appliance in many homes? I need a workshop so badly..... carjug@yahoo.com
(?) Compressed Air Taxis
http://www.mapcruzi...ews/news102600a.htm
Drives 200 km at 90kmh on a tank of air. [BunsenHoneydew, Oct 17 2004, last modified Oct 21 2004]
UPS with air storage + generator
http://www.activepower.com
click on the "TACAS thing" on the right [mr2560, Dec 13 2004]
Air Car hybrid
http://www.theaircar.com
self explanatory [mr2560, Dec 13 2004]
Air powered airplanes
http://www.fuellessflight.com
no gas shortage up there! [mr2560, Dec 13 2004]
Air powered ships
http://www.abc.net....ips/historyeuro.htm
obviously ancient technology [mr2560, Dec 13 2004]
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I'm not sure what you're proposing here. |
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Are you suggesting that a windmill's shaft be used to drive a compressor's pump which pressurizes a reservoir of compressed air which is then used to power equipment (such as refrigerators), |
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Or are you suggesting that some kind of wind scoop thing feed into a compressed air tank which is then used to power equipment (such a refrigerators)? |
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The second one seems a little dubious; wind never really has all that much pressure. |
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The first is replacing generator-battery-motor with compressor-tank-airmotor. Which might be more efficient, but it seems like it would be hard to store very much energy without an enormous tank. The standard electrical solution has the benefit that you can also send power onto the grid or borrow power from the grid depending on how the wind is blowing. (And, of course, you don't need to scour the planet to find air-powered versions of all your appliances. I have yet to see an air-powered light...) |
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Wind driving a compressor is actually a pretty good idea, if you don't have the luxury of selling excess capacity back to the grid In reality. Its not that far off what big industrial users do for load balancing and minimizing peak demand. When you are using 20MW/hour, you are charged for peak demand. Often times co-generation is a huge money saver. The big guys use natural gas and lots of excess steam capacity for co generation to cover the demand. If one went small scale to compressed air storage, it seem reasonable. As egnor said, a wind powered light is unusual. On the other hand, all you need is a air motor and small efficient gen set. Compressed air could easily power a fridge. A fridge has is a mermetically sealed electric compressor, it wouldn't take much to design an air powered version |
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Thanks Amuron, I didn't know about air motors. I might get a chance to try this one out, I am a carpenter and I have pneumatic equipment. All I need is a small compressor unit and a willingness to tresspass on my ex-landlady's property... |
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Good one. Air motors are commonly used to drive industrial tools like drills and jackhammers. That's why you see those big yellow air compressors on trailers next to road work. |
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At least they are yellow around here. |
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A low-tech storage tank could be built like an old-school gasometer, ie an air chamber, open at the bottom, floating in a water tank. The weight of the the air tank would create a constant pressure, determined by how many concrete blocks you pile on top of it. As more air is stored, the air tank rises. As air is used, it sinks. |
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Thus you would not have to rely on super-strong, high pressure tanks to store a great amount of energy, making it more feasible for the home or farm builder. |
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There are many wind driven air compressors on the market, mainly used for pond aereation or water lifting. We make a wind mill that belt drives a standard one cylinder compressor to raise water via air injection. Works great. I woul like to make one to drive a compressor hooked to an air conditioning system but don't know enough about the gas expansion valve. Can anyone help? |
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I am an Air conditionning Tech. I am interested in experimenting with using wind to belt drive an a/c compressor. I'm on the net trying to find more info about such a compressor. All the a/c compressor that i've seen is hermetic (sealed). Only the big refrigeration and commercial compressor are belt driven. I can answer questions on the a/c side. I like to learn more about wind power. |
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Comfort, Please note my "Backyard Power" ideas, and I do have an unrelated question about refrigerators/freezers (or is it unrelated? does the end justify the means?) For those of us who live in cold winter climates, it has always seemed rather absurd to build a box and heat it (a house), then put a smaller box within the bigger box, and expend even more energy just to cool it again (a freezer). Although it's true that the heat pump output from the freezer does go towards warming the house, it still seems something really basic is lacking here. How about cutting a couple of 2" holes in the freezer and running insulated PVC pipes to the outdoors, and then having a lil thermostat controlled computer fan in one of the pipes that would circulate the sub-freezing outdoor air as needed, for about 1/1000th of what it costs to run the compressor? (Leave the compressor connected, but with a higher thermostat setting for when it gets too warm outside for this scheme to work in Spring, then cap the pipes at the freezer.) The only thing wrong with this idea that I can think of is: the price we pay for "convenience" (e.g. who wants to cut holes in their freezer, and who wants an extra set of pipes running through their kitchen?) |
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Home shop and industrial air compressors are very inefficient. This is in part because of frictional losses, but mainly because of extremely high pressures used. Much of the power is wasted on generating heat. Instead of small, high pressure pumps and small tanks, lower pressure and extremely large tanks would be MUCH more efficient. Suppose you have a home in a windy area. You could build a very large concrete tank in the back yard that resembles a basement. Extrordinary strength and bracing would be unnecessary because you would only be dealing with 15-20 PSI. It would be safe, because it could have 5 or 6' of soil on top of it. The pump could be a high volume, highly efficient type, becaues it would never see the wear and heat associated with high pressure pumps. The air "tank" would be like a huge battery that lasts forever. (batteries are the main problem and expense with photovoltiac and wind power generation schemes). |
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(Am a recent arrival to this madhouse) If the tank is underground, would it even need to be a "bunker"? Here in NZ there is a great supply of old concrete water tanks. Would one of these do as a low pressure air battery? Also wondering how feasible it is to convert the pressurised air into electricity as you need it. Anyone got a working model? |
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This aligns somewhat with an idea I had. Wind Generators are designed to operate at a specific rotational speed. The vanes adjust to the wind speed to maintain this rate, often "spilling" energy from the wind to maintain that rate. The torque generated by the blades needs to just overcome the resistance from the generator.
If that excess torque (from higher wind speeds) could instead be used to drive a compressor through a variable transmission, again achieving the constant rate of rotation, the compressed air could in turn be used to maintain the rate of rotation when there is insufficient wind to otherwise do so. This would then tend to smooth out the peaks and valleys in the wind speed, perhaps making windmills practical in locations not experiencing constant winds. |
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I have considered this in detail to the point where I figure that only really electric lights and video and computers need electricity, and the windmill powered air compressor is an excellent idea. It's clean and green and kicks solar's butt halfway around the world. The last puzzle (air powered heat) is not even so hard. Air beats hydrogen; remember the Hindenburg. |
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Bucky Fuller suggested that if this was used, we would have a threefold energy surplus (no crisis at all). My brother manufactures boat motors, and I suggested with sailboats in mind, that air motors could save his job if/when oil gets to be about 20$ a gallon/5E a liter. |
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It would be entertaining to have a compressed air socket ti cool your computer from. Trite, compared to saving the environment, but entertaining. |
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I have seen chiller units that work on compressed air by centrifugul cooling. They have no moving parts, ejecting hot air out one side and cold the other. Using the cold side to blow through the fridge/freezer we could make a fridge with the only moving part the thermostat valve. |
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Most of the heat from an air compressor is from the imput air rather than from friction. This heat becomes more available (concentrated) as the air is compressed (adiabatic curve) and must be replaced to recieve all of the usefull work from the compressed air. This is similar to a steam engine in reverse. |
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I was doing a fairly serious search for this topic, and once again find the Halfbakery. |
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I like using windpower to compress air, as the heat of compression can just be blown away, and the loss of efficiency just accepted. (Or, of course, recaptured in an advanced design.) If compressed far enough, liquid air could be produced. Co2 liquification and extraction is also possible. |
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// the heat of compression can just be blown away, and the loss of efficiency just accepted // |
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It's people like you that are bringing the Heat Death of the Universe ever closer, faster than is absolutely necessary. |
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// Co2 liquification and extraction // |
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At 0.039% of your atmosphere, that's going to be hard work. |
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gonna be even harder if you trust the Borg's math. |
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Trust us .. go on, you know you want to ... |
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Baked by some Amish people, I thought. I haven't found a good link yet. |
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// At 0.039% of your atmosphere, that's going to be hard work. // |
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I am doing my best to bring the CO2 levels up. |
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// old concrete water tanks. Would one of these do as a low pressure air battery? // [salient] |
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Indeed. Supply water to the bottom of the tank via a hose. Calculate the head of water required to compress the air to the desired pressure (15 - 20 PSI as quoted?). Fill the hose from a small body of water that vertical distance uphill of the tank. (a farm dam, small header dam on a spring or creek, a second open-topped water tank on a hill or tower, etc) |
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Self-regulating constant pressure, and no risk of explosions. The worst that could happen is that the air forces all the water out of the tank and up the pipe, and you lose pressure until it fills again. Even so, the first escaping bloop of air out the uphill end of the water pipe should drop the air pressure sufficiently to allow the water to re-enter the pipe. |
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