The refrigerant in modern refrigerators is far more suitable. To get more efficient you would use ammonia, which is banned in the US for consumer refrigerants because it is corrosive and eats the metal, then leaks and can asphyxiate people as well as explode.
I mean a compressed air system is an open loop version of the refrigerator which does a closed loop cycle but the same thing. it compresses on the hot side, and expands on the cold side. The issue with the open loop is that it builds up pressure on the inside of the refrigerator because the air has no place to go because you want to keep the cold in. And you are probably talking several hundred PSI to make it viable for a chilling effect to fridge/freezer temps.
Depending on the stream temperature, it isnāt unheard of to basically put a box in the water and let the water chill it for refrigeration.
OR
look at geothermal. The earth is a constant 50F(10C) below the frost line.
you can just bury pipes down that far, and pump the air or antifreeze through, then you just need a circulating fan or pump. Or you can bury a box down that far and it is a root cellar.
The problem is you MIGHT not be able to easily dig that far down because of rocks. But if you have a well drilled the water that comes out is 50C as well.
Iām still looking for what I call that mythical 50F. We have no real frost line. Snow usually comes early enough that the ground never freezes and yet my root cellar which is eight feet in the ground with a foot of dirt cover and years of leaves dumped on top just barely stays in the mid 30F range. Good for a root cellar but worrisome if we get one of those prolonged polar vortexes.
Ground temperature actually varies wherever you go. Itās approximately the average (mean) of your daily temperatures for a full yearā¦ the ground is just enormous thermal storage, it has to be an average.
Propane works well because itās stored as a liquid, which cools as it boils. It works well in a closed-loop system, which is probably not what you would do with air. That said, a vortex tube might improve the performance of an air-based system. I first saw these in an Amateur Scientist column in Scientific American, I think from the late 1950ās. I canāt find an online version of that article, but hereās a commercial product: https://www.exair.com/vt.html
There are tables of performance, which take some thought, but they can produce cold air without the high pressures normally needed. There is no free lunch, though; they use a lot of air.
I have an automotive tool carburetor choke chiller tool that can make frost with shop air.
I also have an air release vacuum pump for evacuating auto AC systems.
Air solutions using mass released air are NOISY!
Listen to air motor engine starters. Listen to air impact tools. Noisy.
Electric power solutions are quiet.
The wood gasifiers, the wood stoves are quiet.
Wood harvesting and prep? No so much so. But can be made so. Making electricity with an IC engine? Not so quiet either. But can be made so.
S.U.
One lab I helped with had oil-sealed mechanical vacuum pumps used to hold small wafers down for microscope viewing. 3/4 horsepower pumps. I replaced them with small air-powered venturi vacuum pumps. No wear, no oil vapor, no oil changes, instant on and off. But they did require foot cube boxes stuffed with foam to make them quiet enough for indoor use. Fortunately, the exhaust system for the rooms made enough noise that the little pumps didnāt need to be silent.
Hi Tom,
Usually the cold you are feeling in a basement in winter is due to the cold above ground pushing through the foundation to the basement and cold air accumulating there. Usually codes only specify a minimum of insulation on the inside of basement walls which serves almost no purpose in slowing down heat transfer through the walls hence the cold basement. Insulation outside the wall to at least 4 ft deep will allow the foundation to more truly reflect ground temperature. A good retrofit is to install 2 inches of foam at a 45 degree angle on the outside to a distance of 4 ft. Your basement would be cozy warm in winter and chilly cool all summer ā¦
Cheers, David Baillie
One off grid power source that scales up well is wind turbine power.
With 10-20 homes you might be able to justify a tall tower with a āfarm scaleā turbine. You arenāt going to be lofting a utility scale unit of course but a 50-100kw turbine on a 150-200ft tower might be a nice compliment to solar panels and a great place to site any utilities that benefit from āline of sightā IE radio antennas, wifi, security cameras, etc.
At the single family home scale the cost of the tower can be a challenge but with 10-20 homes you can scale up the wind turbine and the tower to reach those faster, more consistent winds.
I have read all the comments to your question and I think there are some things missing. I pursued a similar thought and I do not feel that producing electricity with a generator is worth it on itās own, unless you are profiting highly from the end result.
The basic thought is that an engine is about 20% efficient when seen as a rotary motion output. That is a steep price to pay for just gaining electricity. The only way to really get usable power is to recover the heat that is lost to cooling the engine. Remember you have to lose something as the exhaust must be above 350F because you want to moisture and acids to be carried away with the exhaust. So 25% power full load, 25% exhaust and 50% radiator.
If you use the heat for domestic hot water and heat, you will have an abundant supply. In summer weather you can us an adsorption or absorption chill to comfort cool. The largest problem is a size for one or two houses is close to the price of one that will cool 30 houses. This means cental pipes, but low cost fan coils or just a fan blowing across a radiator in the house. Hospitals and large installations use the because they are highly efficient systems.
I will say you want to transport heat with water because it take 3500 time the volume of air to do the same as water. That means a 8 x 14 duct will be needed instead of a 3/4 inch pipe. Fans are horsepower hogs, where small circulators are misers.
The electricity is a tricky problem. I feel the only way to benefit from electricity is use in instantly. Runs an electric freezer for a couple of hours and put extra insulation to keep is cold for a few days. A frozen foods company uses this method, so it works.
Lead acid batteries are low cost, but the deeper you cycle them, the fewer cycles you have in their lifespan. You can get thousands of cycles but you get only 20% discharge. This means your battery bank needs to be five times the capacity needed.
As far as hydro, I know in Texas the water is all regulated and you absolutely cannot just make a small dam. You will get arrested so fast you will think the speed of light is slow. I will let you decided what you want to do there.
Wind is a great thought but you are putting it in batteries and I know wind does not blow when you need it.
My advice is to use the smallest amount of electrical possible and possibly 12 volt for lights etc. I cook with 12 volts. Stay away from air as a cooling as it is so wasteful that it is only used for such things as cooling high speed sewing needles and spot cooling.
I have done research into high temperature oil systems, but the oil is expensive and dangerous at 400F. It would be a great oven, but too risky.
Considering the individual systems verses the community system. I will paraphrase one of the famous Greek philosophers. If no one owns the piazza, no one cleans the piazza. I always say you have to have skin in the game to care. Hope anything I spewed out helps, I have already been down that road and I am building an individual system.
If I were doing it over I would definitely insulate the outer walls of that Root cellar. But I didnāt and just poured the walls and backfilled up to them with only visqueen as a waterproofing. Iād kick myself in the ass but I really didnāt have the money to do anything else at the time.
Iād love to see some numbers on that Anthony. For Utilities they are the cheapest electricity going but for the home owner or small community wind stopped making financial sense when the cost of solar panels dropped to less than $1 a watt.
I agree that solar looks cheaper per kilowatt but the sun doesnāt always shine (nor does the wind always blow). Solar with battery backup for any length of time is still expensive, though chargas backup-backup can lessen the cost. A wind turbine in the production mix would help smooth production, especially in windy but dark winter periods. Iām not sure 10-20 homes is enough scale to justify adding wind but itās worth a thought.
A lot of quasi commercial turbines from the 90s and 00s are getting upgraded to bigger models and the old ones go for a song if you have the ability to rehome them: Endurance E3120 ā¢ by HITWIND Turbines
A quick google finds dozens of similar options. This turbine is in the UK but maybe one is close to the original poster. It is listed to weigh 4 tons so the logistics are not trivial. The poster didnāt identify where they were located but the name suggests Eastern Europe? Could as well be Missouri so thatās an open question.
@abreaks , @dbaillie, @mveljko78 Re: Economics, and making things not commercially availableā¦
You can build your own wind generator. Proven plans available, time tested in real life situations. I will make you look up these links, because not everyone is a ābelieverā.!
Google: āscoraig windā , āHugh Piggottā , āotherpower(dot)comā
Related to these, and on their sites are articles about micro-hydro generation.
A refrigerator that operates on compressed air and uses air cooling during expansion is complete nonsense, we get very little āusefulā energy for cooling, I can say, practically nothing. For the cooling system to work fairly effectively, the conversion of condensation and gasification must take place at relatively low pressures, which is why liquefied petroleum gas is now used, and in some larger systems also CO2, but this does not achieve such efficiency and the system is much more demanding.
When I look back in history, our ancestors lived and survived without electricity, oil, internet,ā¦ well, we all would like to be independent, but we would not give up the benefits of āmodernā society, it is written: āgive to the emperor , that which is Caesarās and to God, that which is Godāsā.
Many people canāt really wrap their heads around this but outside of towns, there was no grid power in much of this area until just after WW2. My grandmotherās brother was a Danish immigrant who came here and built a large cherry orchard. Also had a small herd of dairy cows to keep busy with when the cherries were picked. He was a go getter. Had two Jacobs wind turbines that he used to power his milking machines and lighting for the barns and house. I think he was the only one around that did this because it was pretty much outside the skills of the average farmer. Everyone I have known in my many years of dealing with self sufficient people who had wind plants were bald because they pulled out their hair trying to keep the running though 12 months of often harsh weather. Wind blows 10-15 mph most of the time here from the west off Lake Michigan. Doable for modern windplants but they arenāt built like the old Jacobs units. Getting far enough off the ground is always an issue Servicing a thing 50, 70 or 100 feet in the air probably takes bigger nuggets than I have and I am used to working at heights. Then power losses because the tower is generally a distance from the house and enough noise that people have sued and won lawsuits because of the annoyance. So that is what I see as the up and downsides of wind power. A very expensive set of components owned by someone with above average skills to maintain it or a world of downtime and frustration.
While Iām babbling I may as well say that as we as a society go through these years of a transition period into a new paradigm freeing ourselves from our current master/slave systems, the owners of our old infrastructure will no longer have the means or interest in maintaining them. except for a very few people, you are not going to replicate the energy you now buy with your home made or constructed off grid systems. At best the smart ones will have extremely scaled down power available and the vast majority of people will have pretty much none. They will not survive like that. Where purchasable power is available it will be so expensive that it will eat you alive anyway. If you think everything that is going on is just a fixable glitch you would be wrong. Frank Lloyd Wright powered all his facilities at his Wisconsin home/school complex with a hydropower generator. That is just about the only constant source electricity that I can think of.
Well the upside to all of these ideas is @mveljko78 has stated realistic each household electrical power expectations.
Somewhere between 600 to 1200 watts.
Every single individual personal scale hydro-electric system Iāve seen in the Pacific Northwest wet-side was destroyed by the third to fifth year.
Stream flows vary over 100 to 1.
The closest official weather reporting station announced we had 1.23" of rain in the last 2.5 months. Stream flows are almost nothing now. It IS raining now for the first full day in nearly 85 days. It will take 15-20 more days of our gentle raining to bring fall-stream flushing to occur. Ha! The spawning fish wait still out in the Columbia River tidal zone.
Look at the flash flooding, muds flows pictures from California, Nevada recently. Everything in their paths was destroyed.
Now a woodgasifer out in a shed, fueling an IC engine, driving an electrical generator; an air compressor; a hydraulic pump; even refrigerant pump . . . you own. You control. You can protect from much of what-come-may.
Except an aggressive Caesar of the Land and his minor tax-collectors and regulators.
And these levels of technology can, and should be kept at a See-Do level. Batch operated 2-4 hours a day in a morning and evening cycles.
Mr Veliko has been asking the right make energy questions within realistically affordable possibilities IMHO. As long as it is done individual household to individual household in duplicatable pattern made systems.
Steve Unruh
This is aimed at vehicle use. Still, the basic concepts could be used for a stationary system. The heat storage system he describes is important.
Rindert
