It would be wonderful if they were actually likely to be able to do that! But it RARELY actually occurs! It seems likely that SOME DAY those claims may be credible, like twenty or fifty years from now. But for now, there is IMMENSE "optimism" involved! The companies that manufacture such things always do their "official tests" under absolutely perfect conditions. If it is solar, that means perfectly clear weather, exactly at noon, pretty near June 21 when the Sun is highest, wind blocked, and with all other conditions carefully controlled. So, when they advertise "can produce 7 watts per square foot", that is technically and legally true. However, when actual weather is added into the equation, and the fact that the Sun is NOT at that maximum height except for a few minutes on one day each year, and many losses, the REAL performance that people experience is rarely 1/10 of what salespeople generally try to promote. As far as I am concerned, that is outright deception, as it is the basis on which rather expensive products and systems are being sold. Yes, they are VERY careful to have done those very specific tests so they can minimize losing lawsuits, but beyond that, they generally seem to have just discovered some types of products where customers seem willing to pay out enormous amounts of money based solely on what a salesperson says! They see it as a gold mine!
There are separate web-pages on photovoltaic cells and on wind power in this Domain, linked at the end of this presentation, if you should want to better understand the actual Physics behind what ACTUALLY occurs. Since I am a scientist, and not trying to sell you anything, I have no reason to either puff up or denigrate any technologies. My interest in ALL these pages is simply to try to provide you with sufficient information where you might spend your money wisely, whatever you choose to buy!
AND, if you are patient enough to be prepared to wait twenty to fifty years, I suspect you might then be really pleased, except maybe with the costs involved!
In my opinion, most major purchases need to meet certain requirements regarding AMORTIZING their own cost. That is, they need to show me that they have a realistic chance of actually saving enough eventually so that they will likely eventually pay off their own cost. Only then could any of them be considered as ways to actually save people money, where they could ever be seen as a way of actually saving any money on energy needs! When someone spends $12,000 for a wind-turbine, and another $3,000 for a tower for it, my first thought has to do with how long it is likely to last and how much maintenance it will require. For discussion sake, say that it was likely to last about 20 years (relatively unlikely, as very few of the wind-turbines sold in the 1980s are still working), and that it was designed and built so well that ZERO maintenance was needed in those 20 years.
Thought: You could place that $15,000 in a Savings Account and earn maybe 5% interest over those 20 years, which would result in your then having $39,800 in the bank.
If you are an average family, you have monthly electric bills of between $50 and $100 per month, or $600 to $1200 per year. In 20 years, you would spend between $12,000 and $24,000 for electricity. Yes, the cost of electricity WILL go up, but unless the wind-turbine will supply you at least $39,800 of electricity (and it clearly would not, even with no maintenance and perfect operation for 20 years), it will never even pay for ITSELF, much less actually save you any money!
See the general approach to trying to figure out whether such things are worth buying?
How about the guy in Maine that constantly gets massive media attention regarding his "all solar" house? He freely admits that he paid over $50,000 for the equipment on his roof. He even says that he got special deals on that equipment and that it normally would have cost twice that, or $100,000! Reporters always visit DURING THE DAYTIME, AROUND NOON, IN THE SUMMER, and WHEN IT IS SUNNY, so they see the system providing all the electricity his house needs (at that moment), and even a little extra which he can sell to the electric company. However, even on such a sunny day, around 3/4 of the hours of the day are when the Sun is down or too low in the sky to be of much benefit. And, unfortunately, we only NEED to have lots of lights on AT NIGHT, when no Solar is being collected. So, all night, even his famous house needs to buy electricity from the power company. Since he is a very environment-aware person, clearly he does not leave lots of lights on in rooms that are unoccupied! And the net result, FOR HIM, is that over a summer month, he generally does not pay for electricity he uses.
Again, superficially, that seems incredibly impressive. However, his situation is much like the one discussed above, where during the expected lifetime of the solar panels, there is NO chance that his initial costs will ever amortize themselves. He even admits that, in telling reporters that his system will never actually pay for itself. But I wonder if his aggressive promoting of that approach doesn't mislead others into buying many thousands of dollars of solar equipment, under the impression that they are going to "save lots of money!"
I actually FULLY support such houses, as EXPERIMENTS! And I think it is wonderful that he is NOT causing massive global warming caused at the electric powerplant. Those things are fine! It is only the "misleading others into being receptive to things that salespeople are ready to tell them to sell expensive equipment," which bothers me!
If you have explored the energy-related pages in this Domain, you probably have noticed that most take a "blue-collar" approach to most things, of discussing LOW-COST approaches to such subjects. This is the case here, where a VERY practical electrical supply approach is presented, which actually allows you to live a pretty normal life! The people who are off-the-grid have to constantly be aware of whether it is sunny or not, regarding whether they can turn on a light bulb! They tend to have an ACTUAL available electricity supply of maybe 250 watts to 400 watts (IF the spent a lot for the equipment!) So they could NEVER consider using a vacuum cleaner or a toaster or a hair-dryer, that uses 1500 watts or so! I propose a "better approach" here, and it is also generally FAR less expensive!
This seems to suggest a REALLY simple idea! Consider getting TEN standard car batteries (for around $500 total cost, and maybe less if they give you a quantity discount, or far less if you get used ones.) and connecting them IN SERIES. You would then have a supply of 120 volt DC electricity. Better, a HUGE supply of it! Most car batteries are rated at being able to provide 500 amperes for a short time (to start a car) and around 100 ampere-hours total actual energy capacity. This means that each could supply a continuous 30 amperes for 3 hours before the batteries were drained! Being wired in series like that we would have a supply of around 100 ampere-hours times ten batteries total of 120 volts, or in other words 12,000 watt-hours (or 12 kWh) of available electricity.
Given that our normal family modern-lifestyle use averages only between 1,000 watts and 2,000 watts in the evening hours and far less during other hours, we are talking about LOADS of electricity with this battery approach! I am talking about MODERN life, where kids forget and leave lights on in rooms and all the rest. So you are looking at an electric supply system that can provide ALL the electricity your (NORMAL) life requires for something like 24 straight hours before being drained! And you CAN use things like the kitchen toaster (which operates for such a short time that it uses so little electricity from those batteries as to have virtually no effect whatever!)
You can estimate your current usage in other ways. Say your monthly bill is around $60, which means that your daily bill would be around $2. Part of the bill is for other things, so if your electricity rate is 10 cents per kilowatt-hour, this suggests that your daily usage might be around 15 kWh. This is comparable to the 12 kWh that we indicated available from the ten batteries, which confirms that we really DO have an electricity source that can realistically support a modern lifestyle for a family, without having to do Abraham Lincoln type reading by a candle!
(For all the devices that require AC current, you could buy an INVERTER, a device that takes DC current and converts it into AC current. The important point here is that you would have LOADS of available electricity to drive all your TVs and computers and refrigerator and hair-dryers and microwaves and all the rest!)
People who attempt to go off-grid tend to worry about using even 20 watts for a few minutes, and they rarely have more than one or two small lights on at any time. I am talking about being able to have a HUGE Christmas light display, for the hours from dusk to bedtime, every day!
Of course, you would have to be able to CHARGE those ten batteries! This is a bigger issue than it might first seem!
Since one horsepower is equal to about 746 watts, our daily use of 12 kWh to 15 kWh of electricity means that we used up about 16 to 20 horsepower-hours of electrical energy. This is a LOT, and it takes a SERIOUS effort to try to recharge that much electricity!
You COULD try to use photovoltaics to do that, although in my opinion, they provide a pitiful amount of electricity. IF you are going to seriously consider buying many thousands of dollars of them, find someone NOT working for that company who has used them for at least a year, to find out how much electricity they REALISTICALLY are able to use from the solar cells. You may be surprised. IF you had a waterfall or river nearby, you COULD build something to get electricity from a crude hydroelectric setup. But my favorite approach is to simply get a bunch (10) of discarded 55-gallon drums and an equal number of old car alternators (I prefer GM). You probably need to buy a single sheet of top quality exterior or marine grade 3/4" plywood (to make very large wooden pulleys!). Each setup will charge just one of the batteries.
So you cut ten of the drums in half, and make ten simple Savonius rotor wind turbines. In a 10.7 mph wind (the average here in the Chicago area) (that is around 16 feet per second), that Savonius rotates at around 3 times each second (with no load) and around 2 rps with a decent load. That is 120 rpm. The car alternator has a pulley on it that is about 2" to 3" in diameter. SO, if you cut a circle out of that plywood which is maybe 20" in diameter, and make the appropriate groove in the outer edge for a standard car fan belt to fit, you have essentially made a large wooden pulley to drive a fan belt, and you can then simply and easily cause the alternator to spin at 7 to 10 times as fast, that is 840 rpm or 1200 rpm. Most alternators can produce most of their power at those speeds.
Long ago, Rankine found that undisturbed wind contains power
from kinetic energy (energy flux) equal to:
E = 0.5 * r * V3
* (area exposed to the wind).
Note that this is a simple application of the kinetic energy definition. r is the air density or 0.00237 lbf * sec2/ft4.
For the 16 fps average wind discussed above, and for a standard 55-gallon drum Savonius, we have 0.5 * .00237 * 163 * 10 square feet or about 50 ft-lb/sec. Since one horsepower is 550 ft-lb/second, this is therefore about 1/11 horsepower, as shown in the wind page analysis. We also learned there that the Savonius only has an efficiency of around 14%, so we really are only getting around 7 ft-lb/sec available to the alternator. That turns out to then be about 1/80 horsepower, or roughly 10 watts. So with a single simple Savonius made from an old 55-gallon drum, in an average wind, we can expect under one ampere of power to try to charge each of the batteries.
(A momentary aside here! You have heard friends brag about their "about to go off-the-grid and about to be making 2,000 watts continuously or 5,000 watts continuously from some sort of wind turbine that a salesperson has told them about! In our wind-energy page, we did the calculations that show that a LARGE farm windmill, 10 feet in diameter, at its higher efficiency of around 30%, can only create about 120 watts of mechanical rotational power! When people repeat what salespeople tell them about 2,000 watts or 5,000 watts, they have no idea how unrealistic that is! Except in a hurricane, yes, that would probably be true!)
Our 7 ft-lb/second from our little (and cheap) Savonius is around 1/80 horsepower, or around 9 watts of power. The belt and the alternator have mechanical losses, so 6 watts of actual electricity is pretty realistic for our 10.7 mph average windspeed. SO, we have TEN of these Savonius/alternator setups spread out in a yard or field, each connected so that it charges ONE of the ten batteries. This is rather slow charging, granted, about the equivalent to a trickle charger, around half an ampere of charging current. But because the GM alternators have voltage regulators built into them, they can merrily spin or not spin and always gradually be trickle-charging each of the ten batteries.
IF you insist on seeing impressive claims, we could have given performance for when there happens to be a 40-mph wind blowing near you. Yes, that happens, and salespeople seem ready to use things like that as an example. Because wind carries power at the third-power of the speed, when we nearly quadruple the windspeed, we then are working with wind that has around 50 times as much power in it. So we could have been discussing here charging currents of 25 amperes for each battery rather than just a half an ampere. And then we could be saying 25 amperes times 12 or 14 volts times ten alternators and we could be puffing about producing 3,500 watts of power being produced continuously. Sure, as long as the wind keeps going at 40 mph!
Now, getting back to reality!
Keeping in mind the massive electrical storage those ten batteries can have, you can merrily use up electricity as we are now all used to doing! I suppose you could even use an electric heater (1500 watts, around 5,000 Btus of heating) if you wished! But the chargers have to eventually give the batteries back the same amount of electricity. At 0.5 ampere charging current, it could take quite a while if you seriously deplete the batteries by very heavy use!
If you have a lot of space available, and a lot of scrap drums, you could make more Savonius rotor assemblies! If you made FOUR for each battery, then everything would charge at 2 amps, about 250 watts nearly continuously. In one average day, you could then charge the batteries with 24 * 250 or 6,000 watt-hours or 6 kWh. Our modern life, with all of our appliances, generally uses up around double that. SO, if you would want an ABSOLUTE NORMAL usage / wastage of electricity as we now do, where we use up around 12 kWh per day, all you need to do is make EIGHT Savonius rotors for each of the ten batteries! You probably would even have EXTRA electricity that you could share with neighbors! (In general, you have to figure that neighbors would NOT be pleased with your yard! When they would see 80 spinning old drums in your yard, it will be difficult for you to convince them that it is really just modern art!
People who try to be "off the grid" tend to only have one or two small lights on at any time. What we are talking about here is having the house blazing bright, and probably even covered by a gaudy Christmas display in that season!
Note that all this is FAR less expensive than the $10,000 or more that you probably would need to spend for a pitifully inadequate bought photovoltaic or wind-charger system, and it performs easily ten times better! However, if you have close neighbors, they probably would not appreciate looking out and seeing 80 Savonius rotors always spinning! Worse, they sometimes squeak when they rotate (like some rooftop ventilating fans do). If you use GM car alternators, they each already have built in a voltage regulator, which keeps it from over-charging the battery, so the alternator can simply be directly connected to the battery. As to finding enough scrap drums and alternators, that would be up to you!
Obviously, it would be possible to BUILD Savonius Rotors that were larger, say 3 times taller and 3 times wider, so that a single rotor could provide all the electricity for one battery. THEN you would only have ten of these buggers in your yard! Notice that the single car alternator still has massive extra capacity. We would still be only charging at around 4 amperes (the equivalent of eight of the 0.5 amp drum-versions), and car alternators are generally rated at around 60 amperes. Yes, when you have a storm and 30 mph winds, where (27 * 4) 108 amperes of charging could be available, you would be limited to the 60 amperes that the alternator would allow, but that really only means that you could turn on even MORE lights when it is stormy!
There is one further issue to consider. Say that one of the Savonius rotors seizes up or falls over, or a belt breaks or falls off, or an alternator fails. It would be good if you could know that! Otherwise, ONE of your batteries might no longer be charged and might completely get drained. However, there are really simple solutions to this! One of the very simplest is to get 10 electronic resistors of 100K value. Wire them in series, and across the entire 120 volt DC output of your system. Connect a wire from each wire between batteries to the same wire between resistors. Add sensors, voltmeters, or assorted other things to monitor the voltages between each pair of resistors. As long as everything was working right, the voltages should always stay very close to 0, 12, 24, 36, 48, 60, etc. IF any of the voltages got more than a volt away from those known values, you would know that something was wrong in a battery, alternator or rotor. Simple, cheap and easy.
Personally, I like the idea of making an INDEPENDENT set of wiring inside the house for 120 volt DC. The same SIZE of wire, 14 gauge or 12 gauge, is fine, but I recommend getting some different color wire, such as pink or blue so no one would ever confuse it with the house's 110 AC wiring! Each room could have two separate ceiling lights, possibly in a single device, one being a bulb that was supplied by 110 AC and the other bulb that was supplied by the 120 DC. Wiring the light switches might be an adventure, but certainly easily solved.
Therefore, far better than any of the above is the HeatGreen 3a unit which YOU can build with around $200 of common local materials! Two web-pages are important regarding that device, the first of which explains what it is and why it works, at:
http://mb-soft/public3/globalzc.html
The second contains all the instructions to build one!:
http://mb-soft/public3/globalzl.html
Finally, if you do not want to have to carry grass and leaves to put into a HG 3a for heating, there is an alternative, but it is somewhat more expensive to have. It is the NorthWarm whole-house 100% solar heating system. There are two Versions. The first is most efficient, where the house is built with the Version 1 system intimately being part of its structure:
http://mb-soft/solar/index.html
The Version 2 is a more limited variation of Version 1, for existing houses, where a separate out-building must be built and with underground heat tunnels between that structure and the existing house.
http://mb-soft/solar/solar2.html
The Version 1 of the NorthWarm system is so efficient and so effective that it INCLUDES an air conditioning system as part of Version 1! That air conditioning system has been made available to the public (for free) beginning late in 2000, and it is the Free A/C system discussed below.
When people try to go off-grid, they often do not realize that if they need to have a deep well drilled, the pump then necessary uses a LOT of electricity in raising that water a thousand feet or whatever! On top of the fact that often the giant trucks that carry the well drilling equipment often cannot get to really remote locations, and huge extra charges are then involved in boring the well in the first place. These systems do not require boring a well or even having a powerful pump.
http://mb-soft/solar/saving.html
A rather different system can be used in extremely hot climates, where the Free A/C does not perform very well because the ground is not cool enough. It will be discussed and presented just below, as it is actually a variant of the Refrigeration and Freezer system.
You would need a good deal of 4" PVC pipe (this time it must be the Schedule 40 thicker kind and not the thinwall field tile type.) You also would need to make at least one of those Savonius rotor windmills, and you would need nearly any old V-8 car or truck engine.
First, the general description. There is an underground tube system, essentially a smaller and simpler version of the Free A/C, but where the air ONLY comes into it from the house air. In other words, this is a RECIRCULATING system, very much like all home heating/cooling systems in the United States. As that air passes through the underground tubes, it gets cooled to near the ground temperature. For discussion sake here, we will say that is for a climate probably too warm for the Free A/C, where the ground temperature is around 65ºF (which is also described by around 525ºR, a temperature system based on absolute zero).
You have dug a pit a few feet deep where you have the car engine sitting, completely below the surface of the ground! A lot of it gets removed, and only the main engine components are needed here, as we essentially use it as a simple air pump or air compressor. It is actually incredibly convenient for us! The way an engine normally works is that it SUCKS IN air through the intake manifold as the pistons move down in their cylinders and then the air is PUSHED OUT into the exhaust pipe when the pistons move upward. The engine already has valves that open and close to cause this to happen. We are simply going to use this Air Pump aspect of an automotive engine without any of the other parts of how it works! Unfortunately, because of the way auto manufacturers make the engines, they always include camshafts which do not really excel at trying to build up high pressures, but these concepts do not need high pressures anyway (unless you intend to be making dry ice [frozen carbon dioxide] at around -100ºF!)
(Also unfortunate is that automotive engines are nearly all 4-cycle Otto design engines, which causes our usage to waste some effort in compressing and then releasing the pressure during two of the strokes that we do not need. In the vehicle, those were called the Compression and Power strokes. All we are interested in are the other two strokes, Intake and Exhaust!)
You will simply dig at least one trench to bury maybe 100 feet of the 4" PVC pipe. (If you are going to do A/C, you may need to dig several trenches and put several PVC pipes in, to be able to provide the amount of airflow necessary for cooling a whole house.) The entrance of that pipe is connected (underground) to the house air. So step one is to COOL the air in the underground tube down to near the deep soil temperature
The exit of the PVC pipe is connected to send the air into what is called the intake manifold of the engine. The Savonius windmill, spinning above the engine at around two times per second, turns the crankshaft of the engine (which then spins at around 120 rpm, far slower than when used as a car or truck engine).
This then creates (generally slightly) compressed air, which you collect from the outlet of the exhaust headers. Here is the first really important part here. In the process of compressing air, it heats up! This is a natural situation which always occurs. So Step two is to compress the air to CAUSE it to heat up like that! Air is pretty close to what is called an Ideal Gas regarding such things. This is technically called an isentropic compression, because it does not change the Entropy of the air in the process of the compression. There are simple and standard equations (provided below) that can calculate the temperature the (compressed) air gets up to, due to this effect of the compression. Since most car engines have a compression ratio of around 8:1, the maximum they can create is a cylinder compression pressure of around 105 PSIG to 120 PSIG.
IF you could actually collect the air at this pressure (which is quite hard to do due to the camshaft issues mentioned above) the formulas show that the air should wind up at 940ºR or 480ºF. How can this be a good thing??? Well, say you then ran that hot compressed air though a SECOND underground PVC pipe system (another hundred feet of PVC is good), where it was again cooled down to near the ground temperature of our 65ºF. (All that heat would be transferred into the soil, and then conduct away through the soil.) Now you have some compressed air inside the PVC tube at our new 65.ºF This is step three of the process, cooling the compressed air back down with the deep soil.
When you RELEASE that pressure, the same formulas apply again! But this time, since we are releasing the pressure, the air COOLS DOWN. This is the fourth and final step in the process, where cool or cold air is produced! Again, if we assume the extreme limiting case of our compressed air being at around 105 PSIG pressure, when we now use the formula, we find that the released air winds up at around 293ºR. That is around -165ºF, impressively cold! Only a very small quantity of that high a pressure air could be generated, but it could actually be used to produce very small quantities of dry ice at -100ºF!
If you have ever used a carbon dioxide fire extinguisher, you know that frost forms around the outlet, and the valve can even freeze up and clog! It is NOT because carbon dioxide is naturally cold or anything! But it was COMPRESSED when it was put into that fire extinguisher. When that pressure is released during use, the rapidly expanding carbon dioxide that comes out can become extremely cold, due to this exact same Ideal Gas effect we are discussing here.
OK. Now we will consider the more practical pressures that we will be using! Consider instead of 105 PSIG pressure, we only compress the air to just around 8 PSIG. This is REALLY easy to do! A lot more air is involved here, and the issues with the camshaft become nearly irrelevant. But after our minimal compression, the air only rises to around 599ºR or 140ºF. This rather warm air goes through the second underground tube system and is cooled to near the 65ºF. When we later release that pressure, we find that the air gets cooled by around 65ºF. For this climate being discussed, this would result in air at 0ºF, which would be excellent for sending into a food freezer.
But in a hotter climate, as in an African jungle where the ground temperature is near 100ºF, this would result in air at around 35ºF, suitable for sending into a refrigeration box, not cold enough to create ice, but still plenty cold enough to preserve food.
You might see from this example that you may want to select a specific pressure for the system depending on the climate that is present.
For refrigeration in our example climate, you COULD simply allow a smaller amount of the 0ºF air into a refrigeration box, but you could also use a lower pressure for the system. If you used 4.5 PSIG pressure, the air warms to around 105ºF, you cool that down in the second underground tube system, and when you release that pressure, the air drops by around 37ºF down to around 28ºF, perfect for sending into a refrigeration box.
And if your only interest was in providing air conditioning, you might choose 3 PSIG pressure. The air warms to around 95ºF due to being compressed in the engine, and then drops by around 26ºF when the pressure is released, down to around 40ºF. That is low enough (below 60ºF) to cause water vapor in that air to condense, which dehumidifies the air to the desired level. That air would then be sent directly back into the house (where it had initially come from!) as cooled and dehumidified air!
All three of these functions will work fine no matter how hot the climate is! So any house or building anywhere in the world can have refrigeration, a food freezer, and air conditioning, without using any electric power at all! Even a remote hut in a jungle can therefore have air conditioning! And more importantly, safe food preservation!
Here is the main formula which is used for these calculations:
T2/T1 = (P2/P1)(n-1)/n
n is a number that is specific to a type of gas and the process occurring. For air in isentropic expansion or compression, n is very close to 1.4. This results in that exponent being around 0.287.
However, the food cooks rather slowly, much like a Slow-Cooker or a Crock-Pot.
So, as either a side-benefit of the HG 3a heating the home, or as an independent system exclusively to service the greenhouse, the HG 3a unit can enable a small greenhouse to produce five times the fruits and vegetables during a normal growing season, in addition to the possibility of heating the greenhouse all year and thereby producing far more crops yet. Generally, really small greenhouses are hardly worth the effort as they produce so little, but if that same small greenhouse can produce five times as much, or possibly ten times as much food as normally, the whole concept of self-sufficiency regarding food becomes far more realistic.
One of the central aspects of attempting to be Independent is that you would not need a steady stream of repair people coming to fix things that had gone wrong! Another is that the ONLY sources of energy required for these things are absolutely GREEN! The HG 3a unit operates entirely on leaves and grasses that you can certainly find locally. The refrigeration and freezer and electricity recharging MIGHT require some wind power from some very simple and crude Savonius rotors (unless you have a waterfall nearby or other obvious source for mechanical power). The devices to provide safe drinking water are equally independent of any power-grid or LP gas delivery truck or any gasoline tank!
The Earth's Rotation as a Source for Energy
Waste Nuclear Power For Making Electricity And Heat?
The Physics of Efficiency In Electric Power Plants
Individual Ways of Reducing Your Energy Usage
Methods of Storing Energy for Later
How Much Energy Comes From the Sun? And Why is there Global Warming?
How does the Sun create so much energy?
Inventions Which Might Help Deal With Coming Energy Catastrophes
An Invention to Efficiently Make Electricity from Solar
Enormous Heating of the Atmosphere by the Alaska Pipeline
Air Conditioning without Huge Electric Bills and without Freon
A Method of Storing Summer Heat to (Nearly) Entirely Heat a House all Winter
An Extremely Highly-Efficient (and Fast, 200.0 mph) Transportation System for People and Products
The Sophisticated Woodstove I Invented in 1973
The Physics of Wood as a Heating Fuel
Why is the North Pole Heating Faster than the rest of the Earth?
A Possible way to greatly reduce Aerodynamic Drag of Airplanes
( http://mb-soft.com/public/index.html )
C Johnson, Physicist, Physics Degree from Univ of Chicago