You may want to read this VERY carefully! Why? Because if EACH of us 75 million American families chooses to use (both uses of) this system, and we can each reduce our family's Carbon footprint from our current average 10 tons per year down to around 3 tons per year (which is mostly from our vehicles), that means "we", on a Grass Roots level, can eliminate (75 million * 7) over 500,000,000 tons of carbon dioxide emissions from the United States each year! This is a 25% National reduction from the two billion tons that the U.S. currently sends into the atmosphere (due to burning fossil fuels). Isn't that great? Politicians HOPE to reduce our National emissions by a few percent by the year 2050, but WE citizens and homeowners could reduce it by 25% by the winter of 2008-09! (I LIKE that!)
It seems likely that governments will love the fact that WE can create that 25% total reduction in the United States' total carbon dioxide emission without needing a DIME of any government's money or any money from any giant corporation! (I REALLY like THAT! No "billions of dollars of our taxpayer money" are necessary; not even a dime!)
Some of us live in milder climates, but if we 75 million American families now average $1,500 for winter and hot water heating, then please note that "WE" will collectively pay around $110 billion THIS winter, which goes to giant corporations and Mid-East countries, where NEXT winter, we could pay them ZERO! This should all appear as a win-win-win-win-win situation, except for those Mid-East countries and the Execs of those giant corporations!
By the way, we 75 million Americans currently average using up around 80 million Btus each of heating oil or natural gas each winter. Multiplying, this is around 6 quadrillion Btus of fossil heating fuels. Noting that the U.S. IMPORTS around 26 quadrillion Btus of fossil fuels (mostly petroleum, around 70% of all the petroleum we use up in this country is imported) each year, our individual decisions to heat our homes at minimal cost even has MORE benefits, regarding substantially reducing our dependence of imported fuel supplies!
Described below are several very practical devices that you can make (with the instructions which are included), which will allow you to GREATLY reduce your contribution to Greenhouse Gases and Global Warming, while also saving you a lot of money, and even being absolutely Green! It can provide a method of entirely heating your home, to a comfort level that you have come to expect, and with a simplicity and ease that is also now expected, with potentially no cost and no usage of any fossil fuels, to be absolutely Carbon Neutral.
Here is a "teaser" for you!
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It is extremely likely that WITHIN 60 PACES OF YOU RIGHT NOW, there
is a MASSIVE energy source which is absolutely FREE! It is on the scale
of 67,000 horsepower-hours of (heat) energy! Or 50,000 kilowatt-hours
(again, of heat energy). Or 170,000,000 Btus. That's an astounding
amount of heat energy! It is totally free AND it replenishes itself
NATURALLY every year!note 1 You probably collect and bag grass cuttings when you mow your lawn, as millions of others do. You call it Yard Waste! And you rake and bag leaves in the Fall. What if we told you that as all those leaves and cut grass blades decompose, they NATURALLY give off heat. A LOT of heat! In a single acre of lawn, forest or even weeds, the total amount of heat which IS NOW being released (over about a six-month period of decomposition) is around that 170,000,000 Btus. That's an astonishing amount of heat energy! YOUR innocent-looking yard has available an immense amount of absolutely NATURAL and GREEN heat energy, which is NOW being constantly released by simple natural decomposition of organic materials. All this while YOU are paying billionaires in Saudi Arabia for heating oil??? Take a look out your window at your yard! What if we now told you that every one of those bags of leaves or grass is therefore worth $3 or $4 or more? You probably now pay giant corporations around $2,000 every winter for fossil fuels to heat your home. Consider this: A 20-pound bag of ANY organic matter contains around 180,000 Btus of chemical energy, which was captured from sunlight by the photosynthesis of carbon dioxide and water vapor, and which will ALL necessarily be released as heat as the material naturally decomposes! We have Engineered a method of CAPTURING a large portion of that heat, to either heat your home or to heat your domestic hot water! You probably now pay at least $4 for heating oil or $3 for natural gas to heat your home - as much as one bag of that Yard Waste could easily provide. Do you still want to pay someone to haul those bags away? And ... the biggest bonus of all, by eliminating your need for fossil fuels, you will be contributing toward solving the global warming catastrophe. |
We will first present here some basic (technical) information that you may want to understand: (you can skip this section if you are not interested in understanding how and why it works!)
First, the preliminary solid scientific information that you may want to know and learn regarding Global Warming:
The REALLY interesting part is that it is the EXACT SAME CHEMICAL PROCESS of oxidation that is occurring as we do in burning our fossil fuels! It creates the same carbon dioxide and water vapor and energy. It's just that it occurs much, much slower. So slow that virtually no one ever even notices it. But it NATURALLY creates around FORTY TIMES all the energy that all humans now use up!
Do the math! You mow your lawn each week, for maybe 25 weeks. Even if you only get ONE bag each time, there's your 500 pounds! You certainly have far more than that available, if you actually collected it all.
That heat is not noticed because it is created slowly, over months, and over a large area, and winds and rain carry away and distribute that heat so that no one can tell it is there. But it IS there!
Gardeners and farmers will say that the composting process takes between six months and two years to complete, and that only around half of the weight of the material disappears. The remaining material is the humus or compost that they actually want, the material they then spread in their gardens or fields as a sort of fertilizer. However, most gardeners and farmers are not aware that there are "fast" ways to do composting. Some operations use an assortment of ways of tumbling the material in rotating drums, (such as what is referred to as In-Vessel processing) or with other devices (such as Tunnel Composting), and get the entire composting process to complete IN JUST 48 or 72 HOURS! They have also found that with certain conditions, it is possible to have the decomposition process proceed to nearly completely consume ALL the material rather than just half.
Actually, our process does NOT actually resemble what is called Composting, except for the fact that the basic chemical decomposition reaction is the same. Other than that, there are hardly even many similarities! We do NOT have significant material (humus) remaining and we do not need six months or two years to accomplish the process!
We do not see great value in having our home heating system perform quite that well, although it definitely can and has been experimentally proven to do so. A rather small system could be made that could only hold around 300 pounds of organic material (not much larger than a recliner chair), with that highest performance built in. The 2.7 million Btus of heat energy created is sufficient to entirely heat a fairly large home for the three days that it would be producing that heat (the 72 hours), but then that would mean that another 300 pounds of material would have to be loaded in every three days during the coldest part of the winter. That seems undesirably labor intensive.
Therefore, we describe systems below that are (generally) larger than that, with capacity for around 1500 pounds (for several weeks or a month of whole house heating before maintenance is needed) or capacity of around 9,000 pounds to provide all the heat needed for the entire six months of winter. A high-performance system IS included in the choices of what you can make.
Here is a graph of one of the first careful scientific experiments I did
on this concept, early in 2007. It truly impressed me, and I immediately
recognized how amazing this concept is! Grass was mowed in the early
afternoon on April 12th, when the outdoor temperature was around 80ºF,
and it was immediately dumped into a bin, which happened to be in my
basement, which was then around 61ºF. (all temperatures were
accurate to 1/10 degree Fahrenheit). Insulation of around R-20 was
placed around (and under) the bin. I expected to see SOME rise in
temperature, as I knew that composting gets the central pile temperature up
to over 100ºF after a few weeks. I did NOT expect to see the temperature
of the entire bin cross 100ºF in just 9 hours, BEFORE MIDNIGHT of
that very same day!You can see that the grass continued to rapidly rise in temperature, all because of lots of very active bacteria, and just 24 hours after I had dumped that newly-mown grass in the bin, the average temperature of the bin crossed 120ºF! I still find that mind-blowing!
That particular experiment was intended to be a preliminary one, and no source of additional oxygen was provided, which is what caused the curve to start flattening out. Other than the naturally moist cut grass, only a handful of black dirt was tossed in, as a reliable source for bacteria, nothing else! In the modest bacterial activity that I had expected, I thought they would have plenty of oxygen for at least a few weeks. They used up most of the oxygen in the bin in a day and a half! Later experiments where a tube was added that supplies air (oxygen) show that the graph stays straight longer, and only then levels off in the 140ºF to 150ºF range. THAT leveling off is actually because that excess heat starts to kill off some of the bacteria doing the work, so I make a point of keeping the bin temperature under around 150ºF. You might also notice an interesting detail that the ambient temperature of my basement rose a couple degrees after the warm daytime and dropped during the cooler nights, as we might expect.
In case it is not clear, THIS is a "carbon-neutral" situation. Plants live and grow, and REMOVE 300 billion tons of carbon dioxide from the atmosphere every year, naturally, by photosynthesis, in forming the glucose and other organic molecules of life. When that material dies and decomposes, it completes the cycle, what is called the Carbon Cycle. Fossil Fuels cause a problem because they had removed their carbon dioxide from the atmosphere many millions of years ago. The fact is that we are now mining and pumping all the fossil fuels we can find, and then burning them at very high rates, that now releases huge amounts of carbon (dioxide) that had been trapped in those fuels for those millions of years. The carbon dioxide itself is not a problem! The fact that we are RAPIDLY ADDING a lot of "new" carbon dioxide to the atmosphere IS! The organic-decomposition-based concept here is entirely different, simply keeping the EXISTING carbon in the biosphere and atmosphere in circulation. Totally NATURAL and Carbon-neutral.
Those materials were going to decompose NATURALLY anyway! We are just causing that natural process to occur where we can capture the heat it creates.
Of that home gas consumption, around 4/5 is toward heating the house with the other 1/5 going toward providing domestic hot water. We have provided a separate page regarding the version for heating of hot water An Earth-Friendly Water Heater you can make, which will also eliminate that $200 you spend every year for heating water! If you should become interested in THIS concept (heating the entire house) we really suggest that you first build the smaller and simpler water heater version of the same basic concept.
Conventional furnaces have substantial energy wastage due to thermal transfer efficiency, often around 80% overall efficiency so the actual net heating effect is only around 40 to 60 MBtu per winter. This is often the actual heating loss of such a house in such a climate.
On a different subject, you may be familiar with a Compost Pile. This is where a farmer or a gardener simply piles up grass, leaves, twigs, corncobs, and other plant residues, with actually very little else even being required (although additions can make it work faster), and those materials gradually decompose, over a period of from six months to two years. From the gardener or farmer's point of view, they like the fact that undesirable scrap is removed without any hauling expense but also because what is left after the composting is a material that is very rich in the phosphorus, nitrogen and other nutrients (called compost or humus) that all soil benefits from.
Farmers are aware that the compost pile generates some heat, and scientists know that different types of bacteria are most effective at breaking down the material at different temperatures. Initially, certain types of bacteria (mesophilic, which are common in the soil) do most of the work, up to around 85ºF to 100ºF or so. Mesophilic bacteria tend to only be able to break down certain simple hydrocarbon and carbohydrate molecules. Above that temperature, those bacteria tend to die off and a higher temperature bacteria (thermophilic, heat-loving) take over, and they are far more efficient at causing the breakdown of nearly anything containing carbon and/or hydrogen. Standard Composting practice is to try to get the middle of the Compost pile to about 55ºC or 130ºF, because at those temperatures, most human and animal microbial pathogens tend to be killed, which tends to make the whole process a sterilizing process (from an infectious viewpoint!) So farmers and gardeners know that it is good to have some heat inside the compost pile, to make it work better!
On a more technical level, the bacteria which do this process are actually doing it for their own purposes. Depending on how much oxygen is available to them, there are two very different processes which can occur. We will briefly discuss Anaerobic decomposition later. In aerobic decomposition, what we feel is more desirable, it is common that bacteria can initially convert around 40% of the energy of the glucose into Adenosine Triphosphate (ATP), which is the primary energy source found in all living things. The remaining 60% of the energy in the glucose is released as heat. The bacteria use the ATP as the source of energy for their existence. When ATP loses one phosphate group, it degrades into ADP and 7 KCalories of usable energy. Nearly all biological processes in all living things use the ATP-to-ADP process to power transmission of nerve signals, the synthesis of proteins, the movements of muscles and cell division, among many other processes. (I realize that 99.99% of people do not really care about such details!) When bacteria eventually die, this ATP and all the other components of the bacteria decompose like everything else. This has the effect of increasing the final amount of heat produced from that 60% to very nearly 100% of the amount of energy that photosynthesis first installed into the glucose. It makes the decomposition process amazingly efficient from an energy perspective. In comparison, we note that modern automobiles have around 21% overall thermal efficiency regarding the energy in the gasoline they use up (which is up from the 15% of the 1970s).
It might be useful here to present a graph from another early
experiment, also from April 2007. In this run, only leaves were used (no
grass) and so it is to be expected that the bacterial activity would take
longer to develop (for what farmers call BROWN compost material,
rather than GREEN). This run was actually to compare the performance
WITH and WITHOUT the excellent insulation around the bin.Notice that WITHOUT the insulation, the bin temperature rises, but rather slowly. This is actually the situation of a conventional compost pile, where it takes months to get the CENTER of the pile up to the most productive hotter temperatures. In six days, it only rose by about 3 degrees! WITH the insulation, we can see that the leaves rose by over 20 degrees, around seven times as fast.
The high level of insulation is a critical component as to why this system works so amazingly well.
We had found that the molecular weight of the glucose was 180, which means that 180 grams of glucose is one mole of that material.
That means that when photosynthesis CREATES 180 grams of glucose, 686 Kcal of energy (from sunlight) is required, and when that glucose later decomposes back into carbon dioxide and water vapor, 686 Kcal of energy is released. In most biological functions, much of that energy is used for building cell components or transporting materials, but in the very end, it necessarily always winds up as heat energy.
In case this technical metric stuff is losing you, 180 grams is around 0.4 pound, and the 686 Kilocalories of energy is around 2700 Btu. This means that a pound of glucose contains around 7,000 Btu of energy in it, relatively similar to the known energy content of firewood and all other organic materials (6,500 to 10,000 Btu/lb). Sorry about the technical nature of some of this stuff, but we wanted to make sure to prove why this works as it does!
Say we arrange a BIG pile of dead plant (leaves, grasses, weeds, crop residues, straw, hay, corncobs, feed corn, etc) (and even animal) materials which is around ten feet square by eight feet high, or 800 cubic feet. (THIS is the size of the largest chamber that we are going to discuss below!) That material is not packed very well, so it is common that it only weighs around 20 pounds per cubic foot, or a total of 16,000 pounds of matter involved.
For reference sake, in case this sounds huge, it is approximately the total amount of plant growth (and death) that occurs on a single acre of lawn, forest, cropland, meadow, or weeds, per year.
A quick estimate of the chemical energy in that pile of organic material as being 7,000 (to 9,000) Btu/pound times 16,000 pounds or around 112,000,000 (to 144 million) Btus of chemical energy (which will eventually ALL be released as heat).
We can calculate more accurately how much energy of decomposition is in that pile. We first change the weight into metric, 7,250 kilograms or 7,250,000 grams. As we had done before, we then divide this by the 180 grams in a mole to find that we have 40,000 moles of glucose (which was initially created by photosynthesis in plants). Multiplying this by the 686 Kcal/mole tells us we have 28 million Kcal of chemical energy in the glucose in that pile. We can convert this back to the English system to see that we confirm that we are looking at about 110 million Btus of chemical energy present. (This is a significant amount of energy, as a medium-sized house in Chicago requires around 40 to 60 million Btus to actually heat it for an entire winter!)
This amount of energy is actually more than the amount of energy that a gas- or oil- or electric-furnace produces in around a six-month period of winter. So we know that we have a large enough pile of material to decompose to provide all the heat we will need! Note that we are really only considering the organic matter created each year by just ONE ACRE of lawn, field, forest or weeds. So even though the pile might seem large, it is easily LOCALLY available, and probably for free!
There is one other consideration we need to consider: The RATE at which heat for a house is produced and how quickly the system can recover once we have drawn a lot of heat for an extremely cold night! We can calculate this fairly easily. We know that we have 110 million Btus produced over about a six-month period (4,320 hours). We can divide and see that our pile will be actually creating about 25,000 Btu/hr of continuous heat. If we need to consume heat at the rate of 50,000 Btu/hr during a brutally cold night, we will wind up starting to cool down the entire pile. We obviously want to keep it at least around the 130ºF that the thermophilic bacteria like. So, if there are likely to be brief periods of intense cold weather, it may make sense to either provide some method of storage for that heat (as by the sub-basement system that we describe elsewhere in this domain) or to build the whole thing larger. This is noting that we have designed a system that is capable of producing a CONSTANT supply of heat, and that during the daytime, especially on sunny days, there may be very little heat needed by the house.
You might note here that a house might require 40,000 Btu/hr during some nighttime hours when the temperature is -10ºF but that during the following sunny afternoon, that house may only require 10,000 Btu at a warmer outdoor temperature. The average heating load for that 24-hour period would therefore be around the 25,000 Btu/hr continuous that this system is designed to be creating. Without some method of storing at least a little heat, this situation could cause significant variations in the temperature of the decomposing material. The house itself might not experience noticeable temperature changes, because the circulating blower would turn on and off by a standard wall thermostat (for maximum occupant comfort). While the house was warm enough (as during the sunny daytime), that blower may generally be off, only turning on for short periods to bring some extra warm air into the house, but which could cause the material to start to overheat. During that very cold night, that circulating blower might be on nearly continuously, constantly removing heat from the system and possibly causing the material to cool down. Some simple method of storing some heat for a few hours can be advantageous. Many established technologies exist for this.
One wonderful aspect of this system is that even if you happen to build it slightly too small, you could always build another one later on, OR you could occasionally toss in some common chemicals that farmers sometimes add to compost piles to speed up their decomposition.
We are therefore going to enable that entire pile to decompose, essentially naturally, over maybe six months (or faster), where the glucose (C6H12O6) oxidizes aerobically [chemically combines with oxygen from the air] ( the 6 O2 molecules) and therefore breaks down to create ONLY molecules of water (H2O) and carbon dioxide (CO2) and a MASSIVE release of energy!
We are greatly simplifying things here! Organic materials are not simply glucose! Plants and animals use glucose as an energy source to create all the more complex molecules that are needed for the living process. However, all those complex carbohydrates are still able to decompose into the same water and carbon dioxide, USUALLY releasing even more energy that we have described here. In fact, much of the glucose gets connected together into long chains of molecules called cellulose, which is the primary structural component of all plants. The cellulose you toss into your pile therefore actually has even more energy in it than we have been calculating. The advantage is actually an increase of around 20% extra available chemical energy.
Firewood is a good example to prove this. It is primarily cellulose. If a pound of (dry) firewood were simply glucose, our molal calculations would show that we had 454 grams or 2.52 moles of glucose in the pound of (dry) firewood. At 686 Kcal/mole, we have 1730 Kcal/pound of wood. This is around 6,900 Btu/pound of glucose. But we know that the high heat value (dry) for firewood is around 8,660 Btu/pound. That difference is primarily due to the energy added to the glucose to bind it together into the cellulose that plants and trees use for their structure. This proves that the actual performance would be around 25% better than we have calculated!
There is also another possibility that can occur in a conventional compost pile (which we will intentionally choose to avoid) where there is no available oxygen to participate in that decomposition. In that case, in an anaerobic process, the glucose (C6H12O6) can simply break down, without using any oxygen, into carbon dioxide ([3] CO2) and methane gas ([3] CH4). This is currently considered a doubtful desire, because it forces an incomplete decomposition and therefore a smaller release of the chemical (heat) energy, but if the generated methane could be collected and compressed, it is essentially what we call Natural Gas. This might provide some limited ability to store some of the energy provided by this process, and specifically as a fuel that can burn at a much higher temperature (around 3,800ºF) for possible needs of such high temperatures.
For now, we intend to simply use the natural aerobic process to generate all the heat possible from this process. For this, we will therefore need to ensure that there is always a sufficient supply of air/oxygen inside the pile of material.
There is one other detail to mention. The chemical reaction we have been discussing regarding photosynthesis and the opposite glucose decay have been technically incorrect. On BOTH sides of that equation are another six water molecules that are actually involved in the chemical reactions. We had left that out to simplify the equation as long as we had been discussing energy content issues, as the same molecules on both sides obviously cancel out. The main reason this is mentioned here is that a supply of water is also important inside the pile, which we will also need to ensure.
There seem to be endless variations as to how this can be done! We will present some general themes here, as basic starting points.
Get 8 sheets of 1" thick BLUE foam building insulation, each 4' x 8'. You could get more sheets as well, or some bundles of standard fiberglass home insulation of at least R-19 rating. Place the 8 sheets on the floor, two sheets at a time to cover an area of eight feet square, and stack them four high. (This creates a bottom insulation of R-20.) (around $80 cost)
Get a standard (plastic) tarp, either 16' square or 20' square, and place it centered on top of the stack of foam sheets. (around $30 cost) It should be a TARP (reinforced) and not just thin plastic sheeting, in order to reduce tearing and to last longer.
Get (a) around 40 bags of cut lawn grass and 40 bags of leaves (should be free); or (b) 15 to 25 standard bales of straw ( at around $2.50 each) or hay (at around $3 each); or (c) one of the giant round bales of straw or hay, (at around $35) and dump them/stack them/place it on the center of the tarp (for the second two, you still need grass (or other green compost material) or chemicals to provide enough nitrogen for the desired 30:1 C/N ratio to the carbon) (max total cost $0 to $80) A few handfuls of black dirt should be tossed into the mix to provide plenty of mesophilic bacteria.
You are going to raise up all the edges of the tarp to create a giant "airtight and watertight bag" which will enclose everything. It will resemble a really large, tied-closed garbage bag when you are done! But first there are some pipes that need to be placed in the very center, standing vertically. They will be described below, but they will provide the air/oxygen needed by the bacteria, with a small blower; provide any added water needed by the bacteria; remove the carbon dioxide created in the decomposition, and also in that bundle will be the sensors for digital thermometers and a digital hygrometer (humidity).
Once all the edges of the tarp are securely attached to the bundle of tubes, and any gaps are sealed, it is pretty much in operation! If WET grass is used, water may not need to be added, but if DRIED BALES are used, a LOT of water must be added to get everything soaked inside the bag.
The fiberglass insulation is then placed so that it surrounds the entire bag, on all sides and the top. This creates at least an R-19 level of insulation on all sides of the tarp/bag. When we mentioned MORE sheets of blue foam insulation before, it was to possibly line two walls of a room corner with four layers thick of that insulation, where the bag would then be placed in that corner. In that case, less fiberglass insulation would be required.
This simple and crude version allows the bacteria to quickly get the INSIDE of the bag up to their desired 130ºF to 150ºF. Some experimental runs have gotten up to that 130ºF internal temperature within two days! The heat generated gets the ENTIRE pile up to those temperatures, which then also makes the surface of the tarp/bag be at that temperature. Heat would make its way through the insulation to heat the basement around it, and the heat from the basement would rise and heat the floors of the rooms above it, thereby providing much of the needed heat for the house above.
The temperature inside the bag would be monitored. If it started getting near or above 150ºF, some of the fiberglass insulation would be moved away, allowing the 150ºF bag surface to conduct and convect more heat out to the room, which would also cool the interior of the bag down. If the inside temp dropped below 130ºF, that could mean that the material had all decomposed; that your insulation was not thick enough; or that some other problem had developed.
This very crude version would contain around 1500 pounds of material to be decomposed, which contains roughly 13 million Btus of chemical energy in it. It is clear that the heat created cannot really get lost anywhere, so most of that heat should therefore provide heating for that basement. (There is a tiny amount of heat loss in the 150ºF exhaust, but that airflow rate is quite slow and the total heat loss there is nearly insignificant.)
This crude version is NOT intended as a long-term heating system, but mostly as a rather inexpensive arrangement where you can prove to yourself how well it works! (In Third World countries, it might represent a quick and simple heating system.) You would either use free cut grass and your leaves or buy $35 or $70 of straw or hay from a local farmer, and spend another $130 or so for insulation and PVC pipe, for a grand total cost of around $130 to $200 (max) for this whole thing. Since its size is such that it should supply around 1/4 of your winter heating bills, this experiment should save you maybe $400 in natural gas or $500 in heating oil. Not bad for "an experiment!"
For the "creative and inquisitive sorts" among you, it is possible to economically set up a simple way to continuously WEIGH the entire assembly! So, if you find that (accounting for any added water) the total weight dropped by 50 pounds in a specific 24-hour period, you would be able to conclude that roughly 50 * 9,000 or 450,000 Btus of heat were created during that day. Such a weighing analysis is not really accurate, as some weight of carbon dioxide and water vapor would leave through an exhaust and some weight of air/oxygen would be added in intake air, but it would be moderately close. A separate web-page can be provided if there is interest in doing this sort of measurement.
We will describe here an arrangement that will generally resemble a (separate) conventional small, bedroom-sized frame-built building. It will be highly insulated and it will include several other unique features. There are MANY variations from this specific plan possible! This general theme provides warm air which is blown into the house rooms by the existing furnace blower, primarily using existing furnace ducting (with some additional ducting needed). It enables the standard wall thermostat to control that blower and therefore provides very accurate control of the temperature of the house. Occupants should not even know that the house was being heated by anything other than the old conventional fossil-fuel-burning furnace.
You will make it of common, locally available materials. It will be sturdier than normal small buildings, partly because it has to be able to contain and support around 16,000 pounds of material in its bin! The floor structure will therefore be made of 2x8 lumber, while the side walls will be made of 2x6 lumber. The top will again be 2x8, mostly so that more insulation can be used.
NOTE: There will actually be two structures here. You HAVE to make the inner one (the bin) absolutely airtight! (this is the equivalent to the airtight, watertight bag discussed above). Inside the bin, the conditions will be extremely hot and extremely humid, where virtually anything will quickly disintegrate and decompose (which is actually the whole idea!) By making that bin absolutely airtight, you will be able to keep the moisture/humidity inside the bin, so that the space OUTSIDE the bin will become hot but actually have extremely LOW relative humidity! (It is where a conventional humidifier should be installed.) This being the case, the wood construction of the building and the conventional insulation will be fine and will last a long time. However, if you should leave even a small path for humid air to get out of the bin into that space, the entire structure could quickly disintegrate as well. You do NOT want that to happen!
These guidelines related to thickness of insulation are related to the local climate. These dimensions are generally universally useful; they are actually calculated for the climate of Chicago, Illinois; however, in very southern climates, less insulation might be used, while in Alaska, thicker insulation might be appropriate.
The floor structure is a simple framing pattern using 2x8 lumber
and a standard 3/4" plywood subfloor. It is made to be 12 feet
square.

With the subfloor nailed on top, the floor would look like this.
It may be possible to make the inner bin slidable across the floor,
and so it might be important that it be flat and smooth, for any
rollers which may be able to roll the bin back and forth across
this floor:

We can then build the 2x6 walls, again using standard practices.
We will build the walls to be standard 8 feet tall. Notice that there are
only three walls built, with (this) front wall entirely missing!
An important detail is that the boards surround that front opening
be all flat and plane, as there will later be another (movable)
structure with some gasketing on it that will slide in to be against
that opening to seal it up.

ALL of the inner surfaces of the building have conventional fiberglass house insulation installed, and then they are all covered with EITHER cheap paneling or even drywall. The important fact is to make everything air tight, where no heat can leak out.
We can examine the heat loss that will occur given our choices of insulation and the local climate. We will have 420 square feet (floor and walls) of R-19 insulation, and 100 square feet (ceiling) of R-30 insulation. If we assume that the interior of the decomposing material is generally at 140ºF and that the average outdoor winter temperature is 40ºF (a Chicago winter is around 30ºF in the worst part of the winter but is milder for the other months, so 40ºF is a reasonable average estimate for an entire winter), then we have an average temperature differential of 100ºF. Standard insulation analysis gives us a total heat loss of around 2500 Btu/hour. In our expected main six months of processing, there are 4320 hours. At the beginning and the end of the process, the maximum heat will not be generated, but this suggests that for this level of insulation, we can expect the total six-month heat losses to be roughly 11 million Btus. We knew that we had 110 million to start with, so we will wind up with 100 million Btus for us to actually use. If you think about it, that 100 million Btus really cannot go anywhere else, and so we will be able to put it to use in heating up air or water to heat the house!
We chose the insulation levels to provide limited losses while considering reasonable expense. You can use this same approach to see whether you might find any value in increasing the insulation to R-30 or higher.
Note that this small room/building must NOT be inside the house (mostly because of the possibilities of odd smells from the decomposing materials depending on what you pitch into it) but it should be as near the house as possible to shorten the ducting or hydronic plumbing connections. Those connecting ducts or pipes need to be extremely well insulated, at least R-50 and higher if possible.
The small building should probably have a standard peaked roof such that rain would not stay on top and leak through.
If this is set up as a "forced-air" installation, two large ducts must connect the house with this building, a cold-air-return and a warm-air-supply. They would connect into the house ducting in very conventional ways. It can also be set up as a PARALLEL heating system to an existing conventional furnace, where a separate furnace blower is used.
The existing standard wall thermostat would now simply turn on the furnace blower. It would blow house air out through the one large duct into the space between the bin and the highly insulated building walls. This creates a pressure which pushes some of the warm air in the building into the other duct, and back toward the house. That heated air (actually much hotter than normal furnace air normally is, commonly 150ºF instead of the 120ºF of most conventional furnaces) then goes into the existing duct system and is distributed to all the rooms of the house.
As the heated air is removed from that space outside the bin, the metal walls of that bin act as heat exchangers to transfer additional heat into the air. We have provided a very large area of this heat exchanger surface (420 square feet) and the material inside the bin remains near the 150ºF temperature, and so the additional (relatively cool, 65ºF) house air that is sent to this building is quickly heated up, to provide a constant supply of nicely heated air for the house.
This variant actually could allow quite small assemblies, if, for example, there was a willingness to do the emptying/cleaning/refilling every week or every other day or every day! The Version 2 described above is intended to be large enough to contain in a single filling, all the heat needed for a house from October through March, the entire winter.
Our research is actually starting to suggest that this version has some real advantages over the others presented here, as well as being fairly small, about the size of an upright piano.
There are two obvious approaches to this structure, with several other variations possible. We will briefly discuss here making a bin out of wood, but prefer metal. The metal version would be more durable, and have far better short-term energy heat exchange performance. The wood version might be worth a first stage to try, even though you know it may only last a year or two. It seems to allow many more options and easier changes to experiment with different arrangements of the components. So we will first discuss a wooden bin.
Basically, we will make a bin that can fairly easily fit through the eleven-foot wide and eight-foot tall opening. We will want to consider having it on some sort of rollers so that the rather heavy filled bin can be slid into place after more easily filling it outdoors. This might make the difference between being able to use a farm tractor or Bobcat and having to toss in the material by hand. However, rollers might be a problem in that the bin will contain around 16,000 pounds of organic material, so the filled bin will weigh as much as six automobiles!
We suggest making the bin ten-feet wide so that it has about six inches clearance on each side as you are moving it. The height of the bin would be just under eight feet. This would give a metal bin the inside dimensions used above in the performance calculations. (Obviously, a metal bin would be larger inside than a wooden one.)
The FRONT wall of the bin needs to have flanges extending outward on both sides and across the top. This flange will have standard door weather-stripping attached to its rear side. In this way, once the bin is slid completely in place, that area overlaps the building door frame for a good tight fit. This vaguely resembles the way a dresser drawer overlaps the dresser body hole, but without any gasketing!)
None of the walls of the bin are insulated EXCEPT THE FRONT. The front needs to have at least R-19 insulation. One possibility for this is to make the front out of 2x6 lumber instead of 2x4 or 2x3 as the rest of the bin would be built of, so that it could have fiberglas R-19 insulation installed in it. Another possibility is to use BLUE foam house insulation, in several layers so that it is 4" thick for R-20 insulation.
The bin must have some special features.
To start with, none of them are in the bin, and filling is begun. Once the organic material got up to around the height of the lower pipes, they would be slipped in through the front hole and jammed into the closet flange. (The bought 10-foot-long pipe having been cut so that it extends about 6" past the front outer wall.) The holes in the pipes should be lined up top and bottom. More material is tossed in the bin, and the upper pipes slipped in at the appropriate time. This allows filling the whole bin without any void spaces under the pipes. When the whole process is done, these pipes may be easily removed so that the resulting humus can be removed from the bin so the next filling can be made.
Water flow rate might be experimented with. A very slow flow tends to cause most of the water to drain out through the first hole in the pipe, while a surge of water tends to go all the way to the end and pool there before draining out at the last holes. A mid-flow-rate can get water to drain out fairly equally along the dimension of the pile.
These thermometers are so cheap that three different thermometers could be installed in the same pipe, such that the sensors were 1/4, 1/2 and 3/4 of the way back across the bin. It would then be possible to monitor how evenly the decomposition was occurring, as even temperatures would indicate consistency while great differences might suggest that something was not ideal.
The second of these two electronic components is a humidity sensor. Only one of them is probably needed, for the very center of the pile.
There are many ways this can be provided. One obvious way would be to buy several "Earth augers" which would be installed parallel to those piles, with their end sticking out the front wall. At any point where it was felt that it would be beneficial to turn the pile, a wrench could be used to rotate each auger shaft, which would turn the auger inside the bin.
Given that this should be a minimal need, it seems that a far more economical approach might make sense. Get several more of the PVC pipe, but drill 1/2" holes through opposite walls, such that a foot-long piece of 1/2" metal rod could be stuck through and secured. The result would be the pipe having 4" long Barbs sticking out from opposite sides of the pipe. If maybe a dozen such rods were securely attached through such a pipe, and the pipe was installed similar to the air pipes discussed above, a pipe wrench on the stub of this pipe sticking out would be able to rotate it, which would force those barbs to stir up the material in the bin.
Higher-tech and more expensive variations of this are obviously possible. It is tempting to wonder if the air pipes could also handle this duty.
If that temperature does not rise or drops, check the humidity, to make sure it is in the 40% to 70% range. If it is low, add water. If it is high, you have added too much water.
If there is the smell of ammonia, that is an indication that you are not providing sufficient oxygen for the aerobic decomposition to fully occur. It is an indication that you probably need to add more air. Depending on what materials you use, they might stay tangled together (as hay seems to tend to do) where the air/oxygen cannot get to some parts of the organic material. This could indicate that the material needs to be stirred up or turned over to break up such clumps of material. The supply of air/oxygen and its ability to get to all the material is probably the most important factor to maintain.
If the humidity seems fine and the temperature starts to drop, the only additional thing you could do would be to turn the pile, to stir up the organic material, in case some of it had not had good access to the oxygen or the water.
If the temperature drops anyway, after an extended time, it might mean that the thermophilic part of the process is done.
If the temperature starts to rise too high (above 150ºF) then you need to NOT encourage the thermophilic bacteria! But you could try to send more (cold) air through all the pipes to try to chill down the reaction.
To some extent, you need to find out how your own system responds to such things, so you can learn how best to help or slow the process in the future.
There is one other possibility. If you put in things that will only decompose slowly, such as tree branches, OR if you neglected to toss in organic material that contained sufficient nitrogen, the bacteria may not be able to fully thrive, and the temperature will never rise very high.
You can probably see that there are an immense number of variations possible in using this system!
We prefer the idea of starting out with the standard natural decomposition, with the idea that it would then have to be emptied and refilled just twice a year, maybe in the Spring and Fall. A faster decomposition process might require refilling it in the dead of winter, possibly unpleasant but possibly with little source of organic material to toss in!
We know that there is a maximum of around 300 Btu/sq.ft/hour of sunlight that comes to us. Let's consider one acre, or 43,560 square feet. That area would then receive a maximum of about 13 million Btus/hour. Say that you have the entire acre planted with ANYTHING! Lawn grass, field grass, flowers, a garden, or even crabgrass or weeds! In nearly all cases, the photosynthesis process is around 1% efficient. This means that 131,000 Btu/hour are actually used by that collection of plants. This is 33,000 Kcal of energy. Since we know that the photosynthesis formation of one mole of glucose takes 686 Kcal, we can divide to find that we would be creating about 48 moles of glucose during that hour. Since we know that a mole of glucose has a mass of 180 grams, we can multiply to get 8,600 grams of glucose formed in that hour in that acre of plants. This is 8.6 kilograms or 19 pounds. Sunlight in the morning and afternoon is less intense, and we can estimate that the total daily effect is around that of 5 hours of that best situation.
We now know that in that whole day, our acre of land produces around 95 pounds of glucose (i.e., vegetable matter). Now, depending on the climate, we might estimate that grasses and weeds and some other plants can grow during a six-month growing season, 180 days. If we are able to produce 95 pounds of vegetable matter every day, for 180 days, we would have roughly 17,000 pounds of vegetable matter (glucose) created during the year from our one acre.
We had assumed above that we would toss 16,000 pounds of vegetable matter into our bin to be able to heat the whole house for the whole winter. Is it clear that only around one acre of land would really be needed to provide all this? This isn't like that you have to collect all the organic debris from Vermont! Just one acre of it! (You would not actually be able to recover all 17,000 pounds of organic material, since some of it are roots and other of it are seeds that were carried away by animals or birds or blown away. Still, an acre is fairly close!
The reality is that would not likely be necessary! If you let ten neighbors know that you would be willing to do them a favor by "hauling away" their bags of grass clippings and bags of autumn leaves, you should have a simple and plentiful source for more material than you would likely ever need! You could even return their bags to them! If there is a local farmer, he accumulates a lot of corn cobs, and straw, and many other organic materials, which you could take off his hands. You could even let all the neighbors know that you would be willing to take their used coffee grounds away! Actually needing to FIND material does not figure to be much of a problem, at least until all the neighbors are also heating their houses this way!
However, there is a wide range of organic materials which is ideal for this process, all of which is normally considered annoying trash which needs to be disposed of! Consider the following energy contents, remembering that our glucose that this is all calculated on has an energy content of around 6,900 Btu/pound:
| sawdust | 8,660 Btu/pound |
| corncobs | 9,300 Btu/pound |
| coffee grounds | 10,000 Btu/pound |
| wheat straw | 8,500 Btu/pound |
| rice straw | 6,000 Btu/pound |
| cattle manure | 7,400 Btu/pound |
| bagasse | 8,390 Btu/pound |
(Bagasse is the material remaining when the juice is squeezed out of sugar cane, relatively similar to all the plant parts left in a farming field after a harvester has removed the crop.) Note that all of these materials have attractive energy contents, and these each decompose fairly rapidly by the action of bacteria.
There are also entirely different processes that occur if the decomposition is done without sufficient air/oxygen. In that anaerobic decomposition, the process is always slow, and there are often foul-smelling gases produced. If you are properly doing aerobic decomposition, with moderately close C-N ratios, there should be virtually no smell created.
This device should produce an average of around 47 cubic feet of carbon dioxide every hour. It cannot be pure carbon dioxide but is limited by Dalton's Partial Pressures to around 4.4% of the air. This indicates that there could be around 1,100 cubic feet of air saturated with carbon dioxide which accumulates near the bottom of the bin every hour, air which has a carbon dioxide content of around 110 times that which exists in the natural atmosphere (44,000 ppm rather than 380 ppm). The reality of this system is that the airflow is generally around 2.5 times this, which makes the local concentration of carbon dioxide around 40 times the natural concentration.
So say that a very small fan is provided which could extract this gas. The removal of that gas would draw in new fresh air through the higher-up tubes, to supply the thermophilic bacteria the oxygen they will need. But we now could have a supply of carbon dioxide rich air.
There have been thousands of research experiments which have shown that virtually all plants grow better, faster and larger in an atmosphere of excess carbon dioxide. For example, Chen, K., G.Q. Hu, and F. Lenz, in 1997, (published in a German Journal) found that strawberry plants (fragraria x ananassa Duch. cv. 'Elsanta') grown in 1995 and 1996 had remarkable improvements in an atmosphere of excess carbon dioxide! For the two-month growth season, those strawberry plants were constantly in atmospheres of 300, 450, 600, 750, and 900 ppm CO2. (The highest of these was around three times natural concentration, with the first being relatively near natural). They found that flowering and fruit ripening started earlier and lasted longer where the higher carbon dioxide was present. Second blooms generally also developed. Fruit productivity was enhanced by increased pedicel number per plants, fruit setting per pedicel, fruit size, and dry matter content of the fruits. They found that the average fruit yield was (considering the 300 ppm as 100% yield): 450 ppm gave 170%. 600 ppm gave 370%. 750 ppm gave 460%. 900 ppm gave 510% yield!
They found that fruit quality was improved as well, and the total sugar accumulation in the fruits, especially sucrose was increased and that titratable acid content was reduced. Essentially all wonderfully desirable results!
This seems to suggest that if this discarded carbon-dioxide-rich air is sent into a nearby greenhouse, where the carbon dioxide concentration might be increased to three times natural, maybe five times as much fruit and vegetables might be grown from the same plants!
Note that the carbon-dioxide-rich air provided to the greenhouse is also around 150ºF so that it can even provide natural heating for the greenhouse, reducing the need for artificial heating!
Thousands of other research experiments have been performed regarding a wide range of plants, which have all had similar results. Even crops like wheat and soybeans, and trees like cherry and spruce and white oak, have similar growth benefits.
(Some of those researches have found that carbon dioxide concentrations higher than around 1200 ppm are NOT as beneficial.)
Yet another possible Green benefit from this system!
You might note that this combined system actually collects the carbon dioxide that is naturally generated anyway, and then it allows those greenhouse plants to REMOVE IT FROM THE ATMOSPHERE! This is a tiny effect, but it actually tends to remove some of the excess carbon dioxide that we have put into the atmosphere due to our massive burning of fossil fuels!
This second enables production of FAR more heat than was described above, for much greater usable heat output, but it also then consumes the organic matter far more quickly! One of the basic desires of the system as described above was to not need any maintenance at all for the six month period of a winter (October through March). If the system is operated in a high-performance mode, it might produce ten times as much heat output per hour, but the organic materials would then be consumed ten times as fast, in three weeks instead of six months. Is that desirable? Each owner would have to decide that! To be able to generate enough heat to heat an entire house from a garden-shed-sized system is certainly an attractive idea, but to then have to empty and re-fill it every three weeks during the winter does not seem very enjoyable!
We have described the density of collected organic materials as being around 20 pounds per cubic foot. However, it might be less than that, depending on your methods. If grass clippings are not "squeezed" into a container, 10 lb/cf can be more normal. Also, what we are interested in is the actual weight of organic material, and if you collect sopping wet leaves, much of the weight might be just water leaving less of actual organic material.
We have described the bacterial activities as being entirely decomposition of the cellulose and glucose into water vapor and carbon dioxide. That is not entirely true, as the bacteria are actually doing this for their own purposes, including growth, so there is a percentage of the gross heat produced from the decomposition that gets used for the growth of the bacteria themselves. However, those bacteria will eventually die and decompose, and so that effect tends to become minimal.
We actually have materially altered the normal process of decomposition. In normal composting, once the thermophilic bacteria have completed their high temperature work, they tend to die off, which allowed the mesophilic bacteria (remaining in cooler portions of the compost pile) to quickly re-multiply and do the remaining lower temperature decomposition. But since we have enabled the entire pile to get up to the high temperatures, there really are virtually no mesophilic bacteria that can still be alive anywhere in the whole pile! Instead of the temperature dropping from the 150ºF to 85ºF for the final phases of the decomposition, it might instead drop to ambient, until and unless some mesophilic bacteria are again able to enter the scene.
However, this absolutely natural process is SO effective at creating heat energy, that no matter what you do, you are certain to get great benefits!
There are also some existing technologies, such as those based on the Seebeck Effect (discovered in 1821) which are thermoelectric generation. Semiconductor materials seem capable of decent potential efficiency levels, even at these very low temperatures, but new research would probably be required.
This could be created above ground or in the ground. In a remote Third World location, bales of straw might be used as the insulation, or many other locally available materials. The chambers should be resistant to rats and larger animals chewing through, either to get to food scraps or to a heated location during a winter. A thermometer is very useful because there is a common tendency to cause too great an airflow through the bin, which then does not allow the material to get up to the most effective operating temperature. Also, given the extreme amounts of heat energy which gets generated, overheating and killing the thermophilic bacteria can occur without knowledge of the temperature actually within the decomposing material.
This concept has only very recently been invented (February 2007). It figures to take two to three years before rigorous University Research Studies can be done to fully document it. If you have read the contents of the four associated web-page presentations, it must be clear that I am not sure the planet or civilization actually HAS an extra two or three years to delay in doing this. This presentation has tried to refer to the many hundreds of years where standard composting has been done, where farmers have realized that heat develops in the middle of a compost pile. We have tried to also present the appropriate Biochemistry and Physics so that a reader might understand the science behind WHY it works. We have tried to present the math, in a relatively painless way, such that any reader might confirm or deny for him/herself the validity of this reasoning and the numbers presented.
So, each reader is free to wait those several years until University Research Studies prove it. However, we hope that we have presented things sufficiently so that many people will not see the need to wait those years and might decide to build this fairly simple system sooner. If so, and you decide to do this, you will certainly have your own ideas about how to do certain things. You might decide to install more or fewer tubes, of larger or smaller diameter. You may decide that the whole thing should be tall and skinny or short and wide. You may decide that there is some reason to tilt the whole thing! It will certainly work in any case! Maybe better or maybe not. We hope that people who try variations of what we have described will later e-mail us regarding any potential variations or improvements, and the actual results you achieved. If we could have a thousand people each doing this during this coming winter (07-08) and the next (08-09), we think we may be able to greatly refine the system, even before any official Research Studies get even initial data.
A few newscasts are starting to finally indicate how urgent and how drastic our problems are regarding Global Warming. If we wait for the governments to act, as slowly as they always seem to work, even their optimists are only expecting to make modest reductions by the year 2050. That will certainly be FAR too late. The premise of this page and this concept is that if instead a "grass roots" effort of countless millions of homes being heated in this way, we might actually be able to achieve in two or three years what Politicians seem to only dream about for more than 40 years from now! When TV ads say for you to "do your part to save the planet", this is the sort of thing they are probably intending to refer to!
So we are figuring that those first thousand people who make these will each have slightly different configurations, or they will have tossed in different organic materials. Some will discover brilliant insights in the process. It may actually turn out to be a wonderful thing if some bacon grease is included, or food scraps, or a small amount of used motor oil! No one will really know until someone tries such things! If this sounds potentially exciting, I think it is, because if YOU happen onto some awesome variation, this site can enable millions of others to also benefit from it!
The 170,000,000 Btus of chemical energy is simply sitting there! It no longer has any function regarding the biological operation or development of the living plants of which it used to be part. It is simply sitting there, as the organic materials are waiting to (slowly) NATURALLY decompose, which releases all that chemical binding energy as heat energy. It can be equally accurately described as 67,000 horsepower-hours of (heat) energy or 50,000 kilowatt-hours (again, of heat energy). They all mean the same thing. They are NOT mechanical energy or electrical energy, or even heat energy, but rather a potential energy of the chemical binding energies of the atoms in the complex carbohydrate molecules in organic materials. However, Newton told us that Energy must be Conserved, that is that such energy cannot simply disappear. It MUST continue to exist, but it can be changed in form from one type of energy to another, as long as the total energy does not change. All REAL processes do not have perfect efficiency when changing from one form to another, where all the energy that might appear to be lost had simply been converted to heat energy, possibly as frictional losses or radiation or convention losses.
In this case, that 67,000 horsepower-hours of energy gets released very gradually and slowly, spread out over that entire one acre area. But still, during that six-month period (4,400 hours), there is an average of over 15 horsepower continuously released, although it occurs very irregularly in reality. That can also be described as being an average of around 11 kilowatts for that entire six month period! This seems impossible since no one has ever noticed it! After all, we don't have to run across the yard in winter because it is so hot!
We can see why this is the case if we consider it as the 170 million Btus of energy. Again, this is released over 4,400 hours, so we would have an average of around 39,000 Btu/hour. Keep in mind that this is normally spread out over the area of an acre, or 43,560 square feet. This is therefore around 0.9 Btu per square foot per hour, a rather small amount when we stick space heaters under our desks which produce 5,000 Btu/hr! Is there any wonder that no one has ever noticed a heat source which is less than 1/5000 of that of a lowly electric space heater?
The actual natural heat production is very irregular, as the mesophilic bacteria which operate at the lower temperatures are very affected by the temperature of the material they are trying to break down for energy. On intensely cold days, there is extremely little activity, while on milder Spring days, substantial decomposition occurs.
Note that the technology which we have developed generally relies on entirely different types of bacteria, the so-called thermophilic ones. They are far more efficient at the process BUT they also require an environment which is around 125ºF to 150ºF. This means that they rarely get a chance to do much, except on really hot sunny summer days when inside a pile of animal dung or similar compost materials. This actually explains why the thick and effective insulation is so centrally important in the operation of this concept. If there should ever be found some bacteria which thrive on even warmer temperatures, like 170ºF to 180ºF, it figures that they might be even more rapid in accomplishing these functions. If there were ever to be any future in using this approach for vehicle fuels, that might a likely way to accomplish the rapidity needed in the energy release.
For the record, the first Footnote in the first Global Warming presentation of this series discusses that around 893 watts of incoming sunlight arrives at each square meter of area (due to the Solar Constant and the Earth's Albedo). Our one acre is around 4010 square meters, so the acre can receive a total of around 3.6 * 106 watts of sunlight. Due to day and night and other geometric effects, the actual daily average is 1/4 of this or 9.0 * 105 watts. Multiplying by 86400 seconds in a 24-hour day, this is 7.7 * 1010 watt-seconds, or 2.15 * 107 watt-hours each day. If we consider a growing season in the middle US to be half a year or 182 days, that means that roughly 3.9 * 106 kilowatt-hours (kWh) of sunlight energy had arrived on that acre during a single growing season.
We have just determined that the actual plant growth absorbs around 50,000 kWh of energy into the chemical binding energy of the organic molecules. We have just mathematically confirmed that the photosynthesis process has around 1% overall thermal efficiency (50,000 / 3.9 * 106). The second Footnote in our second Global Warming presentation provides the complete analysis of where all the thermal efficiency losses are in the natural photosynthesis process.
The other calculations in these connected pages were generally from the approach of Biochemists. The following is more strictly pure Physics. (Except for the fact that we will try to stay in the more familiar American units of measurement.)
We learned earlier that a mole of glucose is 180 grams and that it produces 686 Kcal or 2,722 Btu of energy. This is 15.1 Btu / gram of the glucose.
We also know that the chemical reaction is C6H12O6 + (6) O2 produces (6) H2O + (6) CO2. The six moles of oxygen are provided by air, which is only 21% oxygen and 79% nitrogen, which means that we also have 22.6 moles of nitrogen, which do not participate in the reaction but will have to be heated up along with the other produced gases.
For calculations, we will assume that the air enters at 60ºF. The thermal capacity of each gas is available in charts or equations for any temperature. For example, the heat capacity of Oxygen gas (between room temperature and 5,000 degrees) is given by 11.515 - (172 / (T0.5)) + (1530 / T) [where T is the absolute temperature R and the result is in Btus per pound-mol of the gas]. Specifically (in Btu of energy in the gas per gram):
| Temperature | H2O | N2 | CO2 |
|---|---|---|---|
| 520ºR or 60ºF | 0 | 0 | 0 |
| 580ºR or 120ºF | 0.663 | 0.650 | 0.934 |
| 600ºR or 140ºF | 0.885 | 0.870 | 1.256 |
| 700ºR or 240ºF | 2.445 | 1.974 | 2.907 |
Therefore, our 6 moles of water vapor is 6 * 18 [molecular weight] or 108 grams. Given the values in the table above, we know that that amount of water vapor must contain 108 * 0.663 or 71.6 at 120ºF or 108 * 0.885 or 95.6 Btu of energy at 140ºF. We can do the same for the other gases and other temperatures, finding that we have 6 * 44 or 264 grams of carbon dioxide and 633 grams of nitrogen.
We therefore can total up the heat which must be transferred to the gases, to raise them to a specific temperature, which necessarily participated in the chemical reaction as follows:
| Gas | 120ºF | 140ºF | 240ºF | 260ºF |
|---|---|---|---|---|
| Water vapor | 71.6 Btu | 95.6 Btu | 264.0 Btu | 297.4 Btu |
| Nitrogen | 408.4 Btu | 550.6 Btu | 1271.0 Btu | 1415.1 Btu |
| Carbon dioxide | 246.6 Btu | 331.5 Btu | 767.6 Btu | 854.8 Btu |
| TOTAL | 726.6 Btu | 977.7 Btu | 2302.6 Btu | 2567.3 Btu |
We know that the mole of glucose will produce 2722 Btu of heat. However, the water vapor created must be evaporated with some of that heat, which is easily calculated as being 249.8 Btu. (That water vapor will later condense in other parts of the decomposing pile which recovers that energy.) So we have 2472 Btu of heat which must get taken away by the gases created. We can interpolate to learn that the maximum possible temperature of this process would be 253ºF, given this situation of no excess air being provided. Of course, the bacteria would all have died far before that and this is merely the theoretical maximum possible.
It is more desirable to provide excess air, to increase the chance that each reaction site will have sufficient oxygen present and to reduce the chance of anaerobic decomposition. If we provide 50% excess air, these calculations are altered where another 14 moles of air which would have to be heated. This causes the maximum theoretical temperature to be lowered to 204ºF.
Similar calculations show that if we provide greater than around 200% excess air, there would be so much cool air passing through the decomposing material that it would not be able to maintain the desired 150ºF for the thermophilic bacteria to thrive. This gives a maximum limit to the airflow. It also provides a guide for how much airflow is necessary in the event that the temperature starts to exceed the 150ºF where the thermophilic bacteria might be endangered, to rapidly cool down the pile. In other words, the size of a suitable blower that might be automatically started by an excessive temperature inside the pile.
We have shown here that it is not theoretically possible to have this concept create heat above around 250ºF. This establishes that the performance of the decomposition is limited by the survival of the thermophilic bacteria.
We also know that six moles of oxygen is needed for the aerobic decomposition of each mole of glucose, which is 192 grams of oxygen. At the incoming temperature, this oxygen takes up around 5.5 cubic feet of volume. The incoming air therefore takes up around 26.2 cubic feet for each mole of glucose fully decomposed. If we have a situation where we have 25,000 Btu/hour being created, we know that we are decomposing around 9.2 moles of glucose (about 3.6 pounds) each hour, which therefore requires 240.5 cubic feet per hour, or around 4 CFM of incoming airflow. With 50% excess air, that would be around 6 CFM of incoming airflow. The outgoing airflow is slightly greater (about 20%), due to the higher temperature and the greater number of moles of gas leaving.
These are very minimal airflows and do not really need any significant blower (nearly all of which move over 100 CFM of air), although a computer cooling fan might be useful. As noted above, it is undesirable to inject greater than 200% excess air (12 CFM in this case) due to excessive cooling of the pile which would adversely affect the rate of decomposition and energy production.
Actual processes are never perfect, so all that theoretical energy cannot be actually obtained. We saw above that only around 2722 Btu of available chemical energy is actually involved in the glucose molecules. Any real organic material has components that are not C, H, or O. Some is material that is not organic related at all, considered ash after combustion. Other involve elements that get used in many complex organic molecules for specific purposes, such as the iron that is critically important in our blood, or the many other trace elements like that. Also, nitrogen from the air gets used in many organic molecules, as do phosphorus and other elements that are critically necessary (and even supplied to soil as needed nutrients!) Finally, especially in combustion, it is not possible for every molecule of oxygen from the air to be precisely where it is needed to enable the oxidation of every atom of carbon or hydrogen, so there is always necessarily some incomplete combustion, where some carbon and hydrogen is always left after such an oxidation. The Physics approach only looks at the theoretical maximum possible, meaning all real values have to be slightly less!
This is useful here in order to evaluate cellulose a little better. Cellulose is a long string of C6H10O5 assemblies (slightly modified glucose molecules linked together). With this analysis approach, we can see that we still have the same amount of Carbon fuel, but now ten Hydrogens instead of twelve. We therefore have a total of 3580 Btu of theoretical energy. Since this molecule has lower atomic weight (162 instead of 180), it contains slightly HIGHER energy per unit weight, 22.1 Btu / gram or 10,000 Btu / pound. This is the theoretical reasoning behind why cellulose has a higher energy content than glucose. It also shows that all actual fuel materials (as presented above) have slightly lower actual HHV measurable quantities than the theoretical energy contents of the fuel components themselves!
We can also add here the specific information for cellulose rather than the glucose we had generally been discussing. The following is generally available information, for example from the Incineration section of Mark's Standard Handbook for Mechanical Engineers.
The molar description of the cellulose decomposition:
C6H10O5 + 6O2
gives 6 CO2 + 5 H2O
is 72 + 10 + 80 + 192 = 264 + 90 (by separate elements weight)
or 162 + 192 = 264 + 90 (by molecule weights).
By ratios to carbon, this is 1 + 0.14 + 1.11 + 2.667 = 3.667 + 1.25
By ratios to cellulose, it is 1 + 1.185 = 1.63 + 0.555
For calculating the needed air, first determine the needed oxygen for
each of the carbon and hydrogen:
carbon: 12 + 32 = 44
ratio: 1 + 2.667 = 3.667
hydrogen (full molecules): 4 + 32 = 36
ratio: 1 + 8 = 9
For a (gram-)mole of cellulose, 162 grams, we therefore need an amount of oxygen equal to 72 * 2.667 + 10 * 8 or 272 grams. If the air is 23.15% oxygen, this means we would theoretically need 1175 grams of air. The air generally does not perfectly go to where it is needed, and so EXCESS AIR is always provided, in this case, 40% excess air is suggested. This is now 1645 grams of air that should be provided for each 162 grams of cellulose that is to be completely decomposed.
This is 10.15 pounds of air that should be provided for each pound of cellulose, or around 132 cubic feet of air. These figures are similar to the calculations presented for glucose decomposition. For the 25,000 Btu/hr production we calculated above for the glucose, we get slightly greater needed airflow, but still around 6 cubic feet per minute.
We note that the "high performance" version of this system (Version 3a, the tumbling one) produces an easy 45,000 Btu/hr to heat a home and has experimentally shown to produce about double that, around 90,000 Btu/hr. We also note that 2,544 Btu/hr is the same as one horsepower of power. See where this is going? That fairly simple unit can CONSTANTLY produce around 45,000 / 2,544 or over 17 horsepower! And it has been shown to produce over 35 horsepower. Granted that it is as simple heat and not as mechanical power. But given that we have millions of active minds in our country, maybe someone can figure out a way to EFFICIENTLY convert that "low grade heat" into mechanical power???
So, just before bedtime, you take your car to a store to get a "bin" filled with bales of a high-performance variation of this decomposing material. Noting that we have already done some experiments with standard mowed lawn grass, where just 24 hours after being cut, it was already impressively producing heat from bacterial decomposition, say that someone discovers even faster ways to get this process rolling. So you get your (5?) compressed bales of this organic material of maybe 200 pounds total weight. We learned above that each pound of the organic material contains at least 8,000 Btu of chemical energy in it, so we are talking 1.6 million Btus of chemical energy total (in a fairly small bin). For comparison, a gallon of gasoline contains around 126,000 Btu of chemical energy, so we are talking here of the equivalent of around 13 gallons of gasoline. Starting to see why thing seems interesting?
It really does NOT seem to be much of a stretch to think that the 200 pounds of material that you put in your bin might be able to completely decompose in say, 12 hours. After all, in-vessel composting already nearly accomplishes that, certainly in 24 to 48 hours! So we would have 200 pounds of material decomposing in 12 hours which is about 17 pounds per hour. That is around 155,000 Btu/hr or the equivalent to 61 horsepower. That may not represent sports car type of power, and it would tremendously depend on whether an efficient way to convert that heat energy into mechanical energy could be found, but we are here discussing driving for 12 hours, at highway speed, (where a medium sized vehicle generally requires around 40 horsepower (mechanical) to push its way through the air and against tire friction), all potentially from a bin full of cut lawn grass???
Yes, a bin that can hold 200 pounds of this stuff would be much larger than a car's gas tank, but still! This is an approach that involves NO FOSSIL FUELS and therefore no global warming effects! AND there would certainly be that delay of some hours while the rather slow decomposition process was working, to build up enough stored energy for you to actually drive somewhere the next morning!
Now, it may not be possible to actually DO this! During that night while you slept, it would be necessary for the bacteria to totally go berserk in generating heat, and then somehow that heat would have to be captured and saved for when you wanted to drive somewhere. Could anyone find some very unusual bacteria that could work that fast? Or, could some really ideal mixture of decomposing materials be found where the effect is fast enough? Like in a compressed, Swiss-cheese structure where oxygen could get everywhere fast enough? Could someone find some way to efficiently collect and save and store that much heat? Hard to say! But it certainly seems like an interesting idea to think about! IF someone actually comes up with something like that, EVERY vehicle on the planet would soon be built to use that method. Somebody probably has an opportunity to get fairly famous!
As to capturing and storing the heat, we mentioned above the Seebeck Effect and the possibility of a low pressure steam engine as being possible ways to produce some amount of electricity from this general effect. Neither of those is probably able to convert more than a few percent of the heat generated into electricity, though, so the idea of using electrical batteries might be a non-starter. But there are an immense number of very creative people out there (maybe including YOU) and someone might find a way to accomplish this process!
By the way, such an approach would almost certainly completely end the problem of smog in cities, and NOx pollution would also no longer occur.
However, it IS true that no present technology is remotely efficient at capturing low-grade heat to convert it into electricity. But it sure seems to me to be worth giving a lot of thought to!
The house-heating and hot water heating work great, and they have extremely high overall efficiency. That might NOT be possible with the idea of trying to convert that low-grade heat energy into either electricity or motive power. The reason is that there is something called the Carnot Cycle Efficiency, which is believed to always apply to all "thermal processes". Unfortunately, low-grade heat sources have extremely low Carnot Efficiencies (around 11% for this situation). This situation may therefore NOT allow the "efficient conversion" of those 40 or 60 horsepower of thermal energy discussed above into other forms of energy. But, the incentive seems to be there, so maybe someone can find some method of conversion that does not have the Carnot Cycle limitations. Note that the Carnot Cycle is actually a statement of the Second Law of Thermodynamics, which should indicate that it is very reliably true! A vehicle propulsion system where only 4 to 6 horsepower would be available might not be very attractive! But an electricity generation system which converted 11% of 13 kilowatts would provide a family with a constant supply of around 1.4 kilowatts of electric power, 24 hours each day, which DOES seem very attractive, even complying with Carnot Cycle Efficiency. Better yet, the remaining 89% of that low-grade heat energy could probably then still go to heating the home and domestic hot water. An interesting possibility!
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
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C Johnson, Physicist, Physics Degree from Univ of Chicago