Challenge: Build the Solar Powered Air Conditioner

Ya, I have been thinking along the same lines ... but nothing I have read says the temperature required. One thing I did find was a fridge that listed 1700 BTU/hr required.

though I agree that it would need to be an evacuated tube (or better), I think the medium that is heated should have a higher boiling temperature then water, maybe something along the lines of a oil.

This site says something about an evacuated tube installation producing 2600 BTU/hr
-- http://www.builditsolar.com/References/Measurements/CollectorPerformance.htm

I would suggest improvement of evaporative coolers in dry climates like the southwest and better designs and innovations in cool tube technology. As well as better use of landscaping to provide the cooling effects of evapotranspiration, such as climbing vines on the surfaces of building walls. Not to mention heat reflection materials such as thermal paints like SuperTherm. Also adequate passive solar design with plenty of thermal mass and night time flushing. Most of these systems are much more passive and much less complicated than a solar ammonia absorption unit - even though these will also have their uses.

First I would look at Danfoss compressors. They have several models that run on 12 volts and are suitable for running off PV power quite efficiently. The compressors have been used in Waeco coolers to great low power sucess (www.waecousa.com).

Why not using a thermoacoustic device to cool air or water. This device use electricity and sound waves to generate cold.

look here: http://en.wikipedia.org/wiki/Thermoacoustics

This device could be powered by solar panels. Ben and jerry does it to cool ice cream:

http://www.sciencentral.com/articles/view.php3?type=article&article_id=218392316

What about Solar powered thermoelectric (Peltier Effect) AC device with heat sinks on the cool side of the thermoelectric and 12 volt DC fans, to distribute the cool air...

Why not use geothermal power and have the heat pump’s energy be supplied by photovoltaics?

http://www.hugg.com/story/New-Natural-Ventilation-heavy-on-acronyms-1/

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http://mb-soft.com/solar/saving.html
cooling a house from underground
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http://www.bagelhole.org/?page=43
There was a technique used or invented by the Romans a long time ago.

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http://lists.ibiblio.org/pipermail/permaculture/2003-June/018126.html
clues for summer coolness

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http://www.toolbase.org/techinv/techDetails.aspx?technologyID=194
http://en.wikipedia.org/wiki/Cooling_by_Evaporation
http://www.carolina.com/earth/evaporation.asp
evaporative cooling

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http://www.greenhouse.gov.au/yourhome/technical/fs15.htm
passive cooling

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And how about cheaper heating solutions? For the east coast AC is an issue, but not so much as HEATING for the winter. Most heating is gas, and gas prices are extraordinary. Any heating green heating solutions?

A few years ago I studied absorbtion chillers for use in cogeneration systems. As I recall, these were not suitable for use in diesel generators because of the low exhaust temp (~250 degrees F), however microturbine systems were suitable as they had an exhaust temp of ~550 degrees F. These chillers used a lithium bromine solution as its refrigerant, not amonia.

Andreas
Nice links you provided. I especially liked the cool tubes link. Thanks.

I would like to see a solution that transfers the collected heat to my hot water system. I can't get over the way I use an electric heat pump to extract heat from my house and dump it outside, and an electric hot water heater to bring energy from outside into my water heater!

Any official guidelines on this?
Closing dates?
List of official rules?
Places to submit entries?
Paper vision or actual working model required?
What type of panel of judges ill be used?
If you get more than one successful entry, what other judging criteria will be implemented? (BTU/hr output, aesthetics, off peak hours, etc?)
Does it have to be a closed loop Ammonia cycle?
You scoff at ice-cooled "pretend" air-conditioners, but there is a definite push in large energy consuming plants to implement these systems that allow for shifting energy needs to off-peak energy times; which is in itself a big help. If we're going to think outside of the box, lets not start by putting this contest in a box, eh?
You said you don't have a $10 million dollar X-prize purse, but if you formulaize this contest you might approach and get someone like Train, GE, or Kenmore to generously donate a prize purse: it's good PR for them and it could inspire new tech in their field.
Just some thoughts. Would love to see this as an official contest, and yes, I have my own ideas for the solution that I might enter under such conditions. :j

Hi,

It is possible to have a "zero" cost to operate "air conditioner" in every home NOW with a simple change at the time houses are built (could be retro fit, but more costly than original construction) The problem with air conditioning, heating and cooling are the associated stagnet air and humidity build up. Some places like toilets and pipes sweat enough to rot wood with the tempature difference.
Here is what I am building now in my home. All houses have a cold water feed into the house. This water is always colder than the existing air. I am building a 12 inch tube, under the ground, about 100 feet from the house, that brings in fresh air from outside. The warmer air inside the house is vented out of the top of the house through turbine vents, remember when warm air rises out of a house, it pulls cooler air in from behind to replace it. If this cooler air is directed/controlled as to source, climate control can happen. (plan on adding solar fans as money allows) To kind of kill a couple of birds with one stone, the cold water intake pipe is being retrofitted with a water radiator pipe with fins. The 12" intake pipe for the air will have the water pipe in the center to dehumidify and cool the incoming air AND warm the water entering the house, taking advantage of the gorund water and cooler soil tempatures to cool the air as it enters. The warmer tempature of the water will reduce the sweating effect common in most homes during the summer. Since code requires water feeds to be above drains in the ground, the 12" tubes condensation can be drained into that system.. In my case, the house is on a slope and the drain will be a gravity feed. In my case I have well water, which is substantially cooler than the air. This system will self regulate depending on outside tempature, humidity, etc. and keep the inside tempature cooler than outside air by about a 20 degree swing in summer, but with fresh air being added all the time, a failure of conventional air conditioners that tend to recycle air in the home. If installed with new construction, less than the cost of air conditioners would be added to the home, and with no cost to operate, no labor to repair, nothing to maintain, results in a net gain for climate control.

Donald,

What you're designing sounds very interesting, a lot like an air-source heat pump with ground source theories incorporated.

I do, however, see a couple of problems with your design:

1) you are making significant assumptions that wouldn't necessarily fit into everyone's design scope. Installing a 12" air tunnel 100 yards away from the home, or for that matter building a home around a heating and cooling system is a huge undertaking that is dramatically more costly than adding a solar powered air-conditioner. Solar powered air conditioners would be most effective in high density areas that result in high power load applications and specifically to impoverished families who can't afford the costs associated with conditioning air.

2) The fins on the water pipe inside the 12" air tube: I have doubts about your applications of the laws of thermodynamics here. Heat transfer in this system will require a very thin-walled piping or a very significant amount of these radiator fins, which in the first case wouldn't meet building and plumbing codes (and if applied without code would be prone to failure and costly repairs digging up your pipe and removing your fins to get to the thin-walled pipe), and in the second case would restrict too much of your airflow in a free-convection system (i.e. hot air going out the home's top vents will drag cold air in the bottom inlet). Geothermal closed loop heat pumps require thousands of feet of ground source exchange surface to accomplish this exchanging task. I don't mean to discourage your efforts, but the math seems shaky.

3) Psychrometric charts will tell you some of the effectiveness of the dehumidifying process that you're expecting. "Psychrometry is the science and practice of air (and in this case water) mixtures and their control. The science deals mainly with dry air, water vapor mixtures, with the specific heat of dry air and its volume. It also deals with the heat of water, heat of vaporization or condensation and the specific heat of steam in reference to moisture mixed with dry air. Psychrometry is a specialized area of thermodynamics. There are four main theories we're concerned with here: Dry-bulb temperature is the air temperature determined by an ordinary thermometer. Wet-bulb temperature reflects the cooling effect of evaporating water. Dew point temperature is the temperature below which moisture will condense out of air. Relative Humidity is a measure of how much moisture is present compared to how much moisture the air could hold at that temperature. The versatility of the psychrometric chart lies in the fact that by knowing just two properties of moist air, the other properties can be determined". ( This is taken straight from Wikipedia, but is the basic principles of the HVAC classes I took in college put it). The point is, that if you're thinking it's as simple as running ambient air over a dew covered pipe, then you're results are going to be disappointing and sporadic as best.

4) Finally, if you haven't gotten too far in this project of yours, I highly recommend that you look into an Open-Source Geothermal Heat pump. With some potable water grade PEX (cross-linked high denisty polyethylene) tubing, you could set up an exchange system using the on-site well you described as your heat sink, as well as for you drinking supply. This system would draw fresh cold water from the well, bring it into your house (possibly with a solar powered pump), run the water through an air/water exchanger, and then return your water back to the well to redistribute the heat gained from the exchanger. I highly recommend this system as much more effective and simplier than the system you're proposing.

You didn't provide an email so even though this is lengthy I can't send it to you directly. None the less, I applaud your efforts and ingenuity; these are great ideas that get people thinking and that everyone should strive to incorporate whenever they can. As mentioned earlier though, not everyone has this luxury of design and the intent of the article was to inspire thought, I think, on ways to improve the air-conditioner toward an off-the-grid design that a vast majority of people could benefit from in terms of both ecological and comfort factors. Just my two cents, though.

Thanks Jason,

Your 2 cents appreciated.....

Urban Sprawl......one of the most significant problems of our growth in the U.S. People are flocking to the urban areas where homes do have enough space to incorporate other ideas. Too many of us look at complicated math to solve problems related to mother nature. You gave me good "food for thought" however I tend not to let my appitite get tempted. I was told a solar charged electric scooter would never work, the "math doesn't support it" a very renowned scientist told me, however it continues to give me rides to town on a regular basis. What I am working on can be incorporated into most homes at minimal cost. How modern housing is built spends too many dollars on appearance over practicality, a bad flaw with the American lifestyle.
As far as what I am building, it is planned to solve more than just the air conditioning problem. We have gallons of "sweaty pipes" here and the heating of the intake water is as important as the cooling of the house. Solving 2 problems with one solution....as for size, length, and thickness of pipes, normal, code approved radiator pipe like that used for warm water and steam heat exceeds code and lasts for years and years, even when exposed to humid environments under high pressure. Using 100 feet of this from my pumphouse to the house will replace the 100 feet already there (in a 4 inch tube now). A perfect solution, not, however it does work, and does so with minimal environmental impact. I appreciate the input....we need to aim an air conditioner to be not only solar powered, but to have little negative environmental effect with the chemicals and parts used to manufacture it. A home "breathing" to regulate the tempature inside is a win win solution with a steady stream of fresh,cooler air replaced on a continuous basis being much better than a cold, noisy blower mushing the same air round and round....thanks again for the input.....got any change??

Ref SolarAC. The Copper association built a house in north Tucson AZ. back in the early 1970 that was cooled by solar ac. I think it was a lithium bromide system. The house was very up scale. Used by visiting VIPs. System was complex. Don't know what ever happened to the house or how well it worked long term.

Your idea of using ammonia as a refrigerant for automobiles is a good one, but why use solar heat? It's only available during the day (ever been to Phoenix or Vegas in the summer at night?). Why not use the exhaust manifold of the vehicle, wrapped in a heat exchanger? You can get all the heat you need as long as the engine is running. Utilizing that waste heat would be great.

Jason, I can tell by your post that you have a lot of experience in this field. I'd like to communicate directly with you if possible on a project that I'm working on.

About thirty years ago I read an article in a magazine about a zero-cost home air conditioning system. It really is simple and it can't do anything else but work.

The design was called a "Cool Tube", and it required only a trench about 4 feet deep and a couple of hundred feet of duct.

The operating principle is very easy to understand. Anyone who has ever visited Carlsbad Caverns in New Mexico knows how cold it is underground. This system takes advantage of the low temperature of the soil several feet down.

There is an inlet at one end, and the air flows through the pipe, drawn in by a fan at the house. The heat of the outside air is conducted through the duct into the ground, and air at about 55 F enters the house.

That's all there is to it. The duct itself is the heat exchanger, and the ground is the source of the cooling.

Jason, if you read this post I'd like you to email me at reallygoodquotes@yahoo.com. I'd really like to talk to you about it.

This is something that may work where I live in Bullhead City Arizona, AKA Hell. Last summer we has 9 days of 127 degrees, this summer is really cool for here at around 106. Summers her usually have a temp of 110-115 degrees most days. The ammonia type system may work here with a solar heater. I live in an RV and have used an ammonia frig for the last 10 years.
I will see what I can do.....

I've been reading a lot about solar powered AC's and refigerators lately. And these systems exist already but they are huge and meant to cool like an entire block of houses, hotels, hospitals etc. As far as I know domestic size AC's are still under developement. Industrial size absorption coolers use ammonia or Lithium bromide (LiBr). Ammonia is highly toxic as was mentioned before, LiBr is very expensice. And these systems operate under high pressure. Instead of aBsorption, there is the alternative of aDsorption where either zeolite, silica gel or Calcium Chloride (CaCl) are used with water as the refrigerant. these materials are non toxic, environmentally friendly and operate under low pressure. I found articles about adsorption systems that operate with low temperatures of 60C to 90C, but also systems that require higher temperatures up to 200c (zeolite based systems). The principle is exactly the same as with the ammonia and water system described here. It's a lot harder (if not impossible) though to achieve temperatures below the freezing point of water, but as we're not in the icemaking business, who cares. Air that is 10c will do just fine in an AC. I'm not skilled in physics unfortunately, so designing an efficient system will be quite a challenge. anybody interested in figuering things out with me? I live in the Netherlands, but the AC will be for a horticultural project in suriname (South America) where the sun almost always shines and temperatures average at about 30c every day.

Here are some links with info about adsorption regrigeration:
http://www.containedenergy.com/html/architecture.html
http://www.limsi.fr/Individu/mpons/exp2.htm
http://193.175.120.23/an/pt/solar/publish/euros-00.pdf
http://homepower.com/files/solarice.pdf (absorption system ice maker....ok it's ice, but it can easily be converted into an AC)
http://www.ilkdresden.de/de/leistungen/forall/pdf/vortrag_experiences%20with%20a%2015%20kW.pdf#search=%22solar%20absorption%20chiller%22
http://www.inive.org/members_area/medias/pdf/Inive%5Cclima2000%5C1997%5CP301.pdf#search=%22adsorption%20refrigeration%20systems%22
I have a lot more information, but don't want to pollute this site. Send me an email of you are interested.

I found an article on the web with descriptions of many different adsorption systems for ice making, water chilling and air conditioning.Might be helpful for those of you who want to take up the challenge and desgin a solar powered AC. Check out
http://www.sjtuirc.sjtu.edu.cn/news/060904-Adsorption%20refrigeration%E2%80%94An%20efficient%20way%20to%20make%20good%20use%20of%20waste%20heat%20and%20solar%20energy.pdf

Ammonia absorbtion uses water to absorb the ammonia refrigerant, but some of the water may evaporate with the ammonia, reducing the efficiency.
Lithium Bromide AC uses LiBr to absorb the water refrigerant. LiBr does not evaporate at normal temps, and is much less toxic than ammonia. Calcium chloride could be substituted for LiBr, but CaCl does not absorb water as well as LiBr. Water is an excellent AC refrigerant, though it cannot achieve sub-freezing temps.

Peltier devices are compact and lightweight, but are not very efficient - much less efficient than standard Freon refrigeration. Good for small portable fridges where small size is more important than efficiency.

I read an article dated 2001 about a University of Florida experiment with solar generation of electricity and refrigeration. The concept was to boil ammonia (which boils at much lower temperatures than water) use the ammonia steam to power a turbine generator and capture the cooling effect as AC. The concept was to create about a 5kw power system with a byproduct of AC. I tried to find out how the experiement went, but the web link has been discontinued. Anyone know anything about this? Seems like that would be the answer to two problems for those of us solar dependant.

This has been done in China using the excess heat from an evacuated tube solar thermal system the hot water heats the building in the winter and provides all the hot potable water,then in the summer the excess heat powers an absorption chiller,the product is under devolpment for listing in the USA.With proper building design-insulation orientation and glazing this will work great in combination with the night breze system[esentialy a whole house fan with a brain to control intake of outside air to cool the home at night] to cool a home for very low operating cost.......someday.

I've been trying to crack this one myself. I thought the "ICY Ball" http://www.ggw.org/~cac/IcyBall/crosley_icyball.html was a great Idea. I have some experience in commercial air conditioning service. It seems that the system pressures should change the ammonia boiling point. Here is another link that might be helpful. http://www.sustainablevillage.com/servlet/display/microenterprise/display/14

Here is another thought about the needed heat. I had a friend who worked in the production business with me setting up large video wall displays. The screens on the displays had a fresnel lens ground into the back of the screen and a lenticular on the front. He told me that if he positioned the screen just right the fresnel lens would concentrate the heat of the sun so much that it could melt pennies. Let me know if anyone needs more hints.

Ammonia only has to be heated to 140 degrees.

I have 3 old ArkLA Servel (Arkansas Louisiana gas company) Absorption gas fired ac's (ammonia). There are only 2 tech's from Southern Calif. Gas company that know how to service these units. One tech, (Ed) told me
1. the ammonia only needs to be heated to 140 degrees.
2. Heat rises, so the solar heat could be targeted on the bottom of the ammonia tank.
3. He pointed out water in a pvc tube left in the sun would heat water to 140 degrees, surely the sun could do the job.

FYI: One of these units cost me $1 per hour to run (gas of $1.21 per therm). Not cheap. But it appears the gas burner can be removed from in front of the ammonia tank and replaced with a

I have a 4th extra unit on the property (2 or 3 tons). If anyone is interested in retrofitting it with a parabolic solar collector let me know.

contact me via....www.SuCasaIdeal.net

check out this site for a solar powered AC

http://www.scusolar.org/technology.thermal

robert

Several COST EFFECTIVE solutions exist. I am a mechanical engineer and run my own energy consulting business.

First off, absorption chillers are extremely inefficient, so these should not be considered unless you have money to burn and like the novelty of a thermally-powered air conditioner.

Secondly, any other option that is expensive or inefficient should be discarded. For example I have seen a suggestion for thermoelectric devices, et cetera.

Freezing ice overnight for daytime cooling is an excellent option and cost-effective when daytime electricity costs at least 1.5x overnight electricity. Generally daytime electricity costs 2x in most places in the U.S. at the retail level. Most utilities offer a time-of-use rate and you can run multiple meters at your house for time-of-use equipment.

Wind power - the most cost-effective residential wind power is something you build yourself on the wind turbine and tower side and then something custom-built by a professional for the compressor / heat pump side. You should build a vertical axis wind turbine so that maintenance is easy and something that pumps water, storage unit can be built at the top as well, the pipe that comes down should be valved. Enlist a professional plumber if needed. You need at least a 30 feet tall turbine. You can then use the stored mechanical power in the water to drive a compressor that provides air conditioning. I have built several of these units and even in low wind speed areas have effectively produced 9c/kwh energy on 5-year levellized costs.

Solar powered air conditioning. To save money on electricity you do the following things first - get solar hot water heaters - solar hot water heaters can easily provide 4-12 c /kwh levellized costs when installed and sized correctly for your home. This is much cheaper than energy delivered by solar powered a/c. Also, blocking the sun from hitting your house is cheaper than building a solar powered a/c. Trombe walls, et cetera should be considered.

IF you can get your $/watt installed cost for solar BELOW $2, which in california, florida, and hawaii you can after incentives. THEN you could build a PV-powered 12volt direct current solar-assisted compressor with about a 30 SEER using the correct refrigerant. What refrigerant you need depends on your specific area as suggested refrigerants can vary as I have suggested over 100 working fluids in my career. If you do all of these things then your levellized energy cost should be around 8c/kwh on a 5-year cost, after which the energy is free and as long as your system is still working.

Anything that costs more than grid power or the available cheaper alternative I have never recommended.

costellosolar@gmail.com

While improved evap coolers would help, a combination evap/refrigeration would be best. Partly because even Arizona has high humidty days and partly because of the large amount of water used (we gotta reduce water waste) and because a balanced unit could provide for even less energy and a smaller refrigeration unit.

I am working on a proto type now based on an idea I got from when my dad owned a gas station years ago. He had a very old coke machine which was nothing more than a chest cooler with water in it ( a water bath) that the cokes set in to get cold. So my idea is a chest freezer, I see them for about $200 dollars, they use only 2.5 amps, and advertise $25.00 a year operating cost. It will be lined and filled with a water and coolant solution, thus a water bath. I use the coolant, so I can take it down near freezing but not freeze expand and damage the freezer. The coolant will always stay in the freezer. I am making myself a heat exchanger out of coils of cooper tubing that will sit down into the water bath, The two ends of the tubing will exit the freezer and conect to a large condensing coil that I salvaged from a 4 ton air conditioner. This creates a closed loop system which is also filled with coolant along with a 12 volt pump to circulate the coolant between the heat exchanger down in the water bath and the condensing coil that is above the freezr that I'm using basically as a radiator that will have a squirrel cage fan behind it to blow out into the room. I'm wanting to get the condensor coil down as close to the temp that an evapoator coil would get on a standard air conditioner. I guess I'm going along the lines of a chiller, but I'm using a freezer to chill the water. I live in south east Texas where the Humidity is high and I hear a chiller doesn't work well in humid areas. The reason I'm going with a chest freezer are their low wattage draw, more solar panel friendly. I do like the sound of the 12v compressor from the earlier comments if it could be made to fit on the freezer and has less wattage draw. At the moment I'm working with 5 - 115 watt evergreen solar panels, my inverter is a 2000 watt with a 4000 watt surge, and I have 6 - 12v - 115 amp/hr. storage batteries. system will be set up to click over to grid if the batteries run low at night. The pump is super low draw, the fan is moderately low draw. I like the amonia freezers, the price is real high and they seem small. The bigger the freezer capacity for the water bath the better the chance for whole house cooling. Looking to tie into the existing duct work later on. I would like some feed back from you guys, and some ideas as well.

Why you shouldn't use Ammonia in your air conditioner, straight from wikipedia, enjoy: Refrigeration - R717
Ammonia's thermodynamic properties made it one of the refrigerants commonly used in refrigeration units prior to the discovery of dichlorodifluoromethane[18] in 1928, also known as Freon or R12.

But ammonia is toxic, gaseous, irritant, and corrosive to copper alloys, and over a kilogram is needed for even a miniature fridge. With an ammonia refrigerant, the ever present risk of an escape brings with it a risk to life. However data on ammonia escapes has shown this to be an extremely small risk in practice, and there is consequently no control on the use of ammonia refrigeration in densely populated areas and buildings in almost all jurisdictions in the world.

Its use in domestic refrigeration has been mostly replaced by CFCs and HFCs in the first world, which are more or less non-toxic and non-flammable, and butane and propane in the 3rd world, which despite their high flammability do not seem to have produced any significant level of accidents. Ammonia has continued to be used for miniature and multifuel fridges, such as minibars and caravan refrigerators.

These ammonia absorption cycle domestic refrigerators do not use compression and expansion cycles, but are driven by temperature differences. However the energy efficiency of such refrigerators is relatively low. Today the smallest refrigerators mostly use solid state peltier thermopile heat pumps rather than the ammonia absorption cycle.

Ammonia continues to be used as a refrigerant in large industrial processes such as bulk icemaking and industrial food processing. Since the implication of haloalkanes being major contributors to ozone depletion, ammonia is again seeing increasing use as a refrigerant. Ammonia is increasingly popular in commercial applications, such as in grocery store freezer cases and refrigerated displays.

Has anyone ever tried running your well line into your central a/c return plenum immediatley after it leaves the bladder tank? It seems to me that if you could have the maximum amount of water line (pex?) coiled up thru the plenum without restricting air flow too badly you could benefit from it. For one thing this is water which would be entering your house anyway so their is no waste. Heat exchange would not be extraordinarily efficient but it seems it would have to count for something. The most benefit should be achieved if the air handler is left in the "on" position to take advantage of the cool water as much as possible. This should result in the a/c not having to kick in as often. The only issue is condensation which could easily be diverted out of the bottom of the return chamber by way of pcv and gravity. This way every time water is turned on antwhere in the house new cool water would enter the air return. Also an added energy savings would be warmer water entering the hot water heater thus causing it to have to work less. It seems to me the only expense would be the water line. I know pex is expensive but it is not the only option. You would also need a few various fittings and couplers. If you are real thrifty you could also capture the condensation in a barrel outside and use it for plants/animals thus resulting in even greater conservation of resources.
I am thinking of trying this since it should be quick to install and easily reversable if it dosn't prove beneficial.

Just to throw in my thoughts. I have been thinking about this for two days now.
First, there is a large solar power plant being built in Souther Nevada. Instead of trying to convert sunlight the old way they are using it to super heat water. They then run steam turbines with the water.
Second, in the recent edition (August 2008) of Popular Mechanics there is an article on the DIY Rally. In the article it shows a radar dish the someone glued 5400 mirrors to. He cooks hot dogs with the dish in 12 seconds. It produces a tempature of 1200 degrees. He has a sun tracker automatically move the dish.
Third, combine the two ideas. Use the dish to superheat water.
The hot water will provide the heat for a lithium bromide absortion air conditioner. You will still have to have a power source, possibly solar panels, to run two pumps and the air handler.

Why are we trying to kid ourselves.The conventional air conditioners are the most desired unit in every car.So they waste energy.How about the comfort that they offer.Yes I love air conditioners for the very reason that I love fast food(call it empty calleries).We used to make excelent cars in this country till we tried to down size them.Please let us enjoy life as it is and call me ignorant if you wish.
Regards
E Shojaie

I agree with the last commentor, our natural resources, though a bit harder to get to these days, are not in short supply but they are also certainly not un-limited. We can be prudent, and if at the same time we can save some of our families money then we must. Life is short and we ought to enjoy it, lets just not get carried away, there are future generations to consider. I believe that there are many wonderful alternatives to oil and we must not only explore these but take some risks and start acting on them. I watched a news program last night about a billionaire oil man in Texas who happens to be a big supporter of wind power. He has invested much of his good fortune to build this infastructure in Texas and is pushing congress to do the same in the rest of the states where wind is plentiful. The biggest hold back though was the estimated 100 billion dollar price tag to get a sizeable operation up and running which would actually be able to make a noticeable difference to our power-grid. If only our people could look back and remember President Stump..I mean Bush, as the president who got this wonderful thing off the ground instead of throwing this money to the wind (pun intended) in Iraq.

Hey guys, Google (Go Ogle? ha ha...) 'vortex tube'.
Uses compressed air only - achieves temp drop of -50 f.
Yeah, that's fifty degrees BELOW ZERO.

Think about it.

Jerry, your idea about using a chest freezer to chill water is interesting and creative. However, I think you need to take into consideration how the manufacturer came up with the energy use and annual cost. Generally people put food in a freezer for a longer period of time. It takes energy to lower its temperature to the freezing point. After that the main use of energy is to counteract the heat gain through the sides, top and bottom of the freezer. That of course varies according to what the ambient temperature is. So the manufacturer's calculations are based on a predefined situation. In actual use there will be a difference in energy use depending on whether the freezer is in a home kept at 75 degrees or a garage that in the summer may be 100 degrees.

In your proposed situation you need to keep in mind that you won't be using the freezer as intended. You will be constantly bringing warm or hot water into the freezer that will need to be chilled. In normal use the compressor may only need to run five minutes per hour. In your scenario it would probably be running non-stop. Obviously that would mean using 12 times as much electricity and the cost would be 12 times higher.

Another thing to consider is the cooling capacity of the chest freezer. An air conditioner removes heat from inside the building. Central air conditioners are rated in tons. One ton equals 12,000 Btus per hour being removed from the building. (See http://answers.yahoo.com/question/index?qid=20081206204257AANlSvg for a definition). A home may need a 3 ton air conditioning system to keep the home cool on a summer day with outside temperatures of 95 degrees. That would be 36,000 Btus per hour.

I was not able to find the Btu rating for electric chest freezers but I was for propane freezers. At http://www.cetsolar.com/crystalcold.htm I found a Blizzard Model BF10F, 10 Cubic Foot Propane Chest Freezer for Price: $2204. It is rated at Fuel Consumptions: 1.25 lbs / 24 hrs / 1750 BTU / hr. I would imagine that the cooling capacities are similar.

In any case, a freezer would not come close to providing the cooling. It would take 20 of these freezers to do what a 3-ton air conditioner does.

My thoughts have been to install a radiant cooling system circulating cold water. I would like to use ground water for a large part of the cooling and a chiller to provide the rest of the necessary cooling of the water.

Hey thanks for the input Neil, I do see the points you make on the freezer idea. When I lived in California the old swamp cooler was so great. I had bought one second hand that came off a factory roof top. The squirrel cage fan was so big when I turned on every door in the house would slam, but keep the house cool. In Texas I can't use a regular swamp cooler, have been looking toward indirect type. We want the comforts but screw the grid, especially now that they're going to hit us with bigger energy bills, last I heard $1800 more per year. A conventional 4 ton air conditioner is the way to go, just figure out how to run that compressor without electicity, on an external power source like a car air conditioner does. I've seen old style home units that did just this but still used an electric motor. Alot of advances going on. Why can't the compressor be run by a small diesel engine with this biofuel from waste oil. I'm looking at steam engines for charging batteries with permanent magnet alternators instead of solar. The dollar a watt solar panel just isn't comming out fast enough. As far as fuel for the boiler, methane looks to be a good free fuel. looked at simple hydrogen, using water salt and a solar panel. Saw a guy that made it and stored it in tanks in his back yard. A bomb in your back yard soundes kinda scarey but dang he had zero electric bills. Already have a water collection system for the steam engine but would want to look into recycling the spent steam. Saw homemade steam engines using brass hydraulic cylinders, looked cool, so I got one, lol, now that's where I'm heading. Any ideas you guys can come up with is cool, I just can't see paying someone else for electicity making them rich when we could keep that money in our own pockets, so lets put our heads together on this, dang start out own business, lol.

Hey thanks for the input Neil, I do see the points you make on the freezer idea. When I lived in California the old swamp cooler was so great. I had bought one second hand that came off a factory roof top. The squirrel cage fan was so big when I turned on every door in the house would slam, but keep the house cool. In Texas I can't use a regular swamp cooler, have been looking toward indirect type. We want the comforts but screw the grid, especially now that they're going to hit us with bigger energy bills, last I heard $1800 more per year. A conventional 4 ton air conditioner is the way to go, just figure out how to run that compressor without electicity, on an external power source like a car air conditioner does. I've seen old style home units that did just this but still used an electric motor. Alot of advances going on. Why can't the compressor be run by a small diesel engine with this biofuel from waste oil. I'm looking at steam engines for charging batteries with permanent magnet alternators instead of solar. The dollar a watt solar panel just isn't comming out fast enough. As far as fuel for the boiler, methane looks to be a good free fuel. looked at simple hydrogen, using water salt and a solar panel. Saw a guy that made it and stored it in tanks in his back yard. A bomb in your back yard soundes kinda scarey but dang he had zero electric bills. Already have a water collection system for the steam engine but would want to look into recycling the spent steam. Saw homemade steam engines using brass hydraulic cylinders, looked cool, so I got one, lol, now that's where I'm heading. Any ideas you guys can come up with is cool, I just can't see paying someone else for electicity making them rich when we could keep that money in our own pockets, so lets put our heads together on this, dang start out own business, lol.

Three years on and this posting is still fascinating and informative. Thanks to everyone for sharing so many creative ideas.

I am not an expert in thermodynamics, nor am I an accomplished engineer, but I will be moving to Phoenix soon and am trying to wish to learn more about harnessing the sun (I hear that there is plenty of it down there). Here are my two cents.

From the reading I've been doing, it seems like conventional freon refrigeration is the most energy efficient method, which is no doubt why it has been commercially mass produced. Therefore, rather than experimenting with building your own heat engine, does it not make most sense to take an old air conditioning unit, where all of the hard bits are already built for you, and find a way to power it from the sun? The most obvious method would be to use photo voltaic cells to power the electric motor that is already built into the unit. Another option, off the top of my head, would be to boil water (or some other liquid) in the sun and then push the steam through a turbine that connects to the AC unit.

Has anyone experimented along these lines?

Regarding Donald & Jason

I tend to agree with Donald. Jason, you sound smart, but ideas you say won't work (i.e. radiator fins) do work. I know, I have a working system.

My air conditioner in my house cools the air with chilled water radiator and fan. The chilled water enters the radiator at about 55 degrees fareheit and exits the radiator at about 63 degrees. It works so well, I can't keep the AC on too long or it will get too cold in the house. I live in the Palm Springs, CA desert, where it gets 125 degrees.

The water is chilled by a Arkla Servel natural gas fired amonia chiller, located about 40' away.

The gas fired broiler that heats the amonia cannister could be replaced with a parabolic solar collector to heat the amonia. Or hot water above 180 degrees, could be circulated around the amonia cannister.

Hi, Thank you all for all the great ideas been displayed here, I live in Mérida,Yucatan, Méxo, with our average temperature is 95 F with a maximum of 107 on certain summer days. Our problem here is that yucatán is a huge calcite rock so diggin a trench is extremly expensive, it is done with heavy machinery and dinamyte. I have an alternate idea, also here we have underground rivers, with a water temperature of 77F, if I make that water flow through a radiator and using a Fan I can have my AC, however I have a two big questions, What is the apropiate size for the radiator? and what water flow it is going to be needed to cool a room 16m2?