Ram Bux Singh of the Gobar Gas Research Station in India talks about the process of turning waste into energy through anaerobic digestion.
Ram Bux Singh has personally overseen the construction of at least 200 bio-gas digesters in India.
PHOTO: MOTHER EARTH NEWS STAFF
It is now quite apparent that the days of unlimited and constantly increasing consumption of fossil fuels are "all over but the shoutin' ".
We maul and tear whole states with monster shovels, feed the coal we uncover to voracious power plants that belch out sun-darkening clouds of pollution, distribute the electricity that results through thousands of miles of ugly pylons and cables . . . and still watch our cancerous cities suffer an increasing number of "brown outs" and complete power failures each year.
Even the major oil companies (which have a vested interest in making us believe that the wild ride can go on and on) now ration their dwindling stocks of natural gas and predict that the world's reserves of petroleum will be exhausted in 30 to 50 years.
Clearly, something must be done . . . and most concerned environmentalists find it difficult to believe that the "something" is the development of nuclear power. At least not as long as the AEC stupidly continues to promote the fission process with its built-in dangers of runaway reactors, thermal and radioactive pollution. And fusion? Well, yes . . . maybe. But that approach to the controlled and sustained harnessing of nuclear energy is still only a dream.
Damn it, what we (and the planet) really need—first and foremost—is less instead of more: less human population and less per-capita consumption of power and the things wemanufacture with it. Secondly—and just as important—we must instigate an immediate crash program of research into ways of utilizing solar, wind, water, wave and other natural sources of the energy we do use. And that research must be relentlessly directed away from the development of centralized, capital-heavy, tightly controlled, "dirty" energy systems . . . and toward the nurturing of decentralized, inexpensive, controlled-by-individuals-at-point-of-use, "clean" power sources.
It's a tall order but, luckily, some good men have accepted the challenge. A few have even successfully demonstrated alternative sources of energy that both satisfy all the stringent requirements laid down in the paragraph above . . . and work. One of those men is Ram Bux Singh.
For almost 18 years, Ram Bux Singh has directed experiments at the Gobar ("gobar" is Hindi for "cow dung') Gas Research Station at Ajitmal in northern India. His primary responsibility there has been the development of low-cost and simplified digesters designed to convert plant and animal waste into composted fertilizer and methane for fuel.
In the course of his work, Singh has personally overseen the construction of at least 200 "bio-gas" digesters and has become possibly the planet's foremost authority on the construction of village and farm-sized waste processing units.
Ram Bux Singh's fame spread to this country only recently when a few dedicated ecology enthusiasts began combing the world's literature for information about natural and nonpolluting power sources. Eventually they discovered Singh's work with village and farm-generated methane—which is as natural and non-polluting as a compost pile—and called it to the attention of such U.S. publications as the WHOLE EARTH CATALOG and MOTHER EARTH NEWS. As a result of articles appearing in those periodicals, Mr. Singh now receives as many as 10 letters a day from the United States . . . all asking for more information about his experiments.
Thanks, in part, to his correspondence with individuals, government officials and universities in this country, Ram Bux Singh has developed a keen interest in helping to design, construct and promote the use of bio-gas plants here in the United States. "Two billion tons of manure is wasted annually in the U.S., " he says, "and that is actual food and actual power that you could save with the inexpensive composters we have developed in India. "
When MOTHER learned that Mr. Singh was visiting this country last summer, she immediately invited him to her Madison Ohio location to direct some of her people in the construction of a homestead-size bio-gas plant. MOTHER's staff found Ram Bux Singh to be an intelligent, alert, highly personable and extremely capable gentleman and they enjoyed his visit immensely. Mr. Singh speaks four languages—Hindi, English, Urdu and Persian—and (lucky for MOTHER) the following interview was conducted in English shortly after MOTHER EARTH NEWS' prototype methane generator was completed.
Ram Bux Singh, thanks largely to the WHOLE EARTH CATALOG and MOTHER EARTH NEWS, your efforts to convert manure and other natural wastes into methane have become fairly well known here in the United States. Did you originate the idea of producing non-polluting fuel from such sources?
Oh no. The idea of taking out the gas from farm waste, vegetable waste — even human excreta — is very old and was demonstrated at an exhibition in London in 1871. In 1905 a very large plant designed to produce both gas and good fertilizer from waste was installed in Bombay, India. Then, during World War Two due to the shortage of conventional fuels, the Germans built many bio-gas plants for both the fertilizer and the methane that the digesters would make. They compressed the gas and used it for driving tractors and farm machinery. The idea is not a new one.
Today — in Algeria, in South Africa, in Korea, in France, in Hungary and in many other countries — thousands of bio-gas plants are in use. The idea does not belong to me or to the government of India.
But you have been experimenting with methane conversion for some time and your work in the field is considered quite important by scientists and technicians all over the world. Obviously you've contributed something of value to the search for ways to recycle waste into non-polluting fuel.
Yes, I have worked on this problem for some time. In 1955, the government of India appointed me to simplify the construction of bio-gas plants. There was no question that such units would produce methane but, up to that time, most gas generators were very large and costly. Even the small plants built in Germany during the war were quite expensive. So what we have done at the Gobar Gas Research Station in India is to simplify the construction of bio-gas generators. We have designed efficient plants that are small enough for a single village or one farmer to build and we have found ways to construct these gas generators for very little money. We have made the bio-gas plant economical for small farms.
Let me give you an example of what we have done. When recently visited a sewage plant at Charleston, West Virginia, the engineer there told me that seventy million dollars had been spent on the facility. If we were to try to scale down to: village or farm size the technology used in that plant, the smaller waste disposal unit might still cost half a million dollars Now, no village in India and no farmer — even in the United States — is going to spend a half million dollars to process waste. But we have designed bio-gas plants which both purify waste and produce non-polluting fuel . . . and some of these units can be built for as little as $100! With our designs and a relatively minor investment, then, a farmer or small group of people can now construct a self-contained system that will recycle plant and animal waste into high-quality fertilizer anti non-polluting fuel. The fuel can then be used to cook with, to heat the farmhouse and to power machinery. A bio-gas plant can make a farm more self-contained and independent.
In other words, while the radicals talk about it you're really bringing power to the people!
It's this idea of homemade power, you know, that has excited so many people in this country. The idea of running a car or heating a house with non-polluting fuel that is generated from waste right in one's own back yard is tremendously attractive to individuals fed up with oil spills, strip mining and smog. Yet I notice that you emphasize the fertilizer produced by a bio-gas plant just as much as you emphasize the methane which comes from such a unit.
Oh yes. The fertilizer is very important, especially in a country like India where the farmers do not have so much money with which to buy chemical plant food. You are rich enough here to purchase the commercial fertilizer and you do not think so much of conserving the natural nutrients for your crops. But I believe you will. As your population increases and you farm more intensively and the movement to cooperate with nature gains strength in the United States, I believe you will think more and more about conserving your natural plant foods. You will begin to think more and more of the bio-gas plant as a source of both power and high-quality fertilizer.
What do you mean by "high-quality"?
We have calculated through many university lab tests in India that the fertilizer which comes from a bio-gas plant contains three times more nitrogen than the best compost made through open air digestion. If you compost chicken manure, for example, the finished compost will have in it only 1.58 to 2%o nitrogen. The same manure digested in a bio-gas plant will analyze 6% nitrogen.
Where does this extra nitrogen come from?
It is already in the manure. The nitrogen is preserved when waste is digested in an enclosed bio-gas plant, whereas the same nitrogen evaporates away as ammonia during open air composting. The bio-gas plant does not make extra nitrogen; it does not create nitrogen . . . it merely preserves the nitrogen that is already there.
OK. I can see how the nitrogen is caught and contained when plant and animal waste is digested inside a closed bio-gas plant, but what about other elements? Is anything lost or eaten up by the bacteria in the tank? Do they take anything out of the organic material so that, over a period of years, you'll be putting back less and less on the fields you fertilize with waste processed in a bio-gas plant?
No, nothing is used up. This is the perfect fertilizer-making machine and it has been tested all over the world. There is no better way to digest or compost manure and other organic material than in a bio-gas plant. I think you can compare the bacteria in a digester tank to fish worms. Fish worms help the soil by eating organic matter, passing it through their bodies and expelling it as very rich fertilizer. They live by breaking waste material down into food for plants. It is the same with the bacteria in a methane digester.
Yes, that's a good example.
You may also think of it another way. Seven cubic feet of methane gas can be generated from one pound of dry leaves but only one cubic foot of gas will come from one pound of cow dung. The cow dung, on the other hand; is just that much richer a fertilizer than the leaves. You can say, then, that the cow has digested the leaves and partly turned them into plant food. When the cow manure is then composted in a bio-gas plant, the bacteria there merely further process — or refine — the former dry leaves into a still richer plant food. It is all very natural.
We've heard much about your experiments with cow manure at the Gobar Gas Research Station in India. Have you successfully processed other kinds of waste?
Yes, we have experimented with many types of digesters in India and our most successful work has been with chicken manure. Chicken droppings are easily digested, produce large quantities of methane and — when processed — make a fertilizer with a very high nitrogen content.
What about human waste?
Human excreta is very rich and should produce much gas and very good fertilizer. The two or three plants we have set up for processing this waste have not been successful, however, because of the modern flush toilet. There is just too much water with the excreta . . . too much liquid for the digesters to handle. If we could separate the water from the human waste, though, I think we would find our own excreta to be the very best of all for recycling into fuel and fertilizer.
Over and above our excreta — our personal waste — have you experimented with human waste in general? Have you built a plant to handle all the garbage and waste paper and other sewage that people generate every day?
Yes, we have built plants of that type . . . sewage plants with the primary purpose of — not to make the gas and not to make the fertilizer — but to keep the city environmentally fit. We have done this in many cities in India. The biggest of these installations is in Delhi. There, four 400-horsepower engines are running on the methane from the plant and those engines drive generators which produce electricity. The fertilizer from the sewage plant is given to the farmers in the area.
There is one difficulty also with these installations however, and that is the high percentage of paper and related materials that people discard. This waste is not rich enough in nitrogen and it does not produce a great deal of methane nor does it make the best fertilizer. Too, just like the excreta, this material is usually accompanied by far too much water and it is difficult to digest.
You say that the ordinary sewage From a city is not rich enough in nitrogen for best digestion in a bio-gas plant. Isn't there anything you can do about that?
Yes, of course. You can seed the mixture — before it goes into the plant — with nitrogen. Let me explain:
The anaerobic bacteria that do all the work in a bio-gas plant consume carbon about 30 times faster than they use nitrogen. They work most efficiently, then, when the waste fed to them has that balance. When the carbon is 30 parts and the nitrogen is one part, the material put into a bio-gas plant will digest very rapidly and will produce much gas and good fertilizer. Results will not be as good when the carbon-nitrogen proportions are anything else.
For instance, sawdust has no nitrogen at all. Simply carbon is there. If you put nothing but sawdust into a bio-gas plant, it will not digest even in 200 days. But if you add enough nitrogen — either naturally, in the form of manure, or chemically — to make a 30-to-1 working ratio, the bacteria will rapidly process the mixture into methane and fertilizer.
So, for best results, you must analyze the material you put into a bio-gas plant?
Exactly. You cannot guess. Many people have written to me that they have installed a plant of a certain size and filled it with so many leaves and so much of this and that . . . and the unit does not produce gas. It does not digest the material. I write back and tell them that they have not calculated the ratio of carbon to nitrogen in the material. When you load a digester with grass, leaves and other high-carbon waste, you must also mix in enough nitrogen to make the material ferment.
In the beginning, if you do not know how much carbon or nitrogen is in the different materials you have to process, you can send samples to the nearest university lab or county agent and have the grass and straw and other matter analyzed. After that, you'll soon learn to judge the percentages.
And from then on, it's just a simple chemical reaction.
A very, very simple reaction. When a bio-gas digester is properly built, loaded with the correct mixture of carbon and nitrogen and held at the appropriate temperature, there is no difficulty at all. There is no way you can make it not work.
What is that "appropriate temperature" you've just mentioned?
When a digester loaded with the proper carbon-nitrogen mixture is maintained at 90 to 95° Fahrenheit, in 40 days the material will produce 95% of the gas it is capable of producing.
And if you maintain the digester and its contents at, say, 110°F?
Yes, you can use 110° . . . even up to 118°F. Above 110, however, much gas will come but the production is not easy to maintain . . . and above 118°, the bacteria will die.
Let's say you do use 110°F. What will the digestion time be then?
It would come down to about 28 days at that temperature.
And how far can we go in the direction of minimum operating temperature?
First-class digestion takes place between 90 and 100°F. Between 75 and 90°, a bio-gas plant works . . . but not nearly so well. At 60 to 75°, there is digestion but only very slow production of methane . . . and below 50 or 60°, the whole process is arrested.
OK, now. You've just said that a bio-gas plant loaded with a 30-to-1 mixture of carbon and nitrogen will, when held at a temperature of 90 to 95°F, produce 95% of the gas that the waste is capable of generating . . . and will do it in 40 days.
Which brings up the point that—once a definite length of time is established for the digestion of material in a bio-gas plant—the unit can then be operated in either of two ways.
Yes. We have designed some bio-gas plants for what we call "batch feeding" and some for "continuous feeding". We can even switch some of our units back and forth from one method of operation to the other.
For the batch cycle, a bio-gas tank is opened and filled with the waste material to be processed. The digester is then sealed and the methane gas collected as the matter inside decomposes. After 40 days, the tank is again opened and the composted fertilizer is taken out. The digester is then filled again and resealed for another cycle. Actually, the tank does not have to be opened if it is designed properly. Instead, with the proper inlet and outlet pipes and a pump, the waste—in slurry form—can be pumped in and out.
With the continuous feeding method, a bio-gas plant is filled once. Then, as the bacteria inside begin to change the waste into methane and fertilizer, new and undigested matter in the amount of one-fortieth of the volume of the tank is added each day. If the digester is properly designed, the digested one-fortieth of the material in the tank will be forced out as the fresh waste is piped in. In this way, new material is constantly added to the mass in the bio-gas plant and spent matter is constantly expelled. The unit, then, steadily consumes waste and just as steadily produces methane and fertilizer.
But how do you make such a digester operate so efficiently? How do you make sure that only digested material is forced out as you pump in the fresh matter to be processed?
It is very simple. Unprocessed waste is heavy. As the bacteria digest it, the matter becomes lighter and lighter. Merely by positioning the inlet pipe in the bottom of the tank and by placing the outlet at the top of the mass, we use this natural principle to our advantage. The tank can hold only so much and—as we force a small amount of new material into the bottom of the digester every day—a corresponding amount of processed matter is forced to overflow through the outlet.
Very clever and very interesting!
Yes, and we have taken that idea one step further in our more complex bio-gas digesters. Because we have found, you see, that a really big plant works more efficiently on a 60-day cycle and we have also learned that the material in such a tank gets lighter during its first 30 days of digestion and again heavier during the last 30 days. So we build those big bio-gas plants with both inlet and outlet near the bottom and separated by a wall that goes all the way across the tank.
We operate such a plant by filling the first half once and then, when digestion begins, we pump in fresh material . . . one-sixtieth of the digesting mass' volume. As we force this fresh matter in at the bottom of the first half of the tank, the partly digested material on top flows over the wall into the second section of the plant. There, the waste slowly sinks as its processing is completed until, finally, the completely digested material is forced out the outlet pipe in the bottom of that second half of the tank.
With such a system, approximately 80% of the methane produced comes from the first half of the digester and 20% comes from the second section
Yes, and I see here in some of your drawings of those bigger bio-gas plants that you call for rather complicated and expensive-looking heating coils and agitators out in the middle of the tanks.
Such mechanisms are necessary in the larger plants. The manure and waste being processed must be warmed and stirred uniformly so that it will all digest at the proper rate.
But the small bio-gas plant you've designed for MOTHER EARTH NEWS , doesn't have any heating coils or agitators in it.
No. They are not necessary in such a little digester. When the jacket around the holding tank is filled with hot water, the material in the main tank will be warmed quite well all the way through. In the same way, this digester is small enough that merely pumping the waste matter in and out of the main chamber will sufficiently agitate the fermenting mass.
At that, I understand that MOTHER's bio-gas plant is somewhat more complicated than most of the homestead-sized digesters you install in India.
Yes. In India, where it is warmer, there is no need to put a water jacket around the main tank and there is no need to wrap a bio-gas plant in insulation. This digester however, has the additional features because it is expressly designed for the colder climate you have here in the northern United States. The additions make it both more complicated and expensive to build than most small bio-gas plants constructed in India.
I think you've told some of the people who helped build this plant for MOTHER that it can be operated several ways.
It is a batch feed digester but it can also be operated on a daily-feed, a weekly-feed and on a 15-day-feed cycle. We have designed this bio-gas plant to work in many ways so that you may learn about our ideas and report on them in MOTHER EARTH NEWS. There is much interest in methane gas production in the United States but, so far, there have been hardly any bio-gas systems built here.
We wanted this one to provide you with as much information as possible.
As I understand it, you're setting up MOTHER EARTH NEWS digester with a water jacket in which heated water will be circulated to keep the main tank at its optimum temperature of 90-95°F. The design also calls for a heavy duty mud pump—run by a two horsepower electric motor—to force the waste material into the bio-gas plant, to circulate the matter as it ferments there and to push the digested material out of the tank.
Yes, that is correct.
Well, it's going to take some energy to heat that water and run the pump. Will the methane generated in the plant be worth it?
Oh, yes. Each month, this plant should make about 6,000 cubic feet of methane. The digesting material needs to be stirred only 20 minutes a day or a total each month of about 10 hours. Since a gasoline engine consumes 18 cubic feet of' methane per horsepower per hour, the two-horsepower engine necessary to drive this bio-gas installation's pump will use about 360 cubic feet of the gas each month. If we were to fuel the hot water heater with methane, we would find that the gas it consumes would be much less than this . . . we could even cut that further by warming the water jacket with waste heat from the engine. In all, we should net more than 5,000 cubic feet of methane and much valuable fertilizer from this plant every month. A generator like this one should pay for its initial investment in three years.
And just how good will this methane be?
In India, when we process cow dung in a biogas plant, the methane that results tests about 650 BTU per cubic foot. I think it will be higher in this country because you feed your cattle so much grain. I think it will be also higher here in the United States because your cow manure from the barn is already in a slurry and contains the urine, whereas—in India—the cow dung we use is dry.
Well, let's just say that we do as well as you do in India. Let's say we generate methane with a value of only 650 BTU per cubic foot. How does that compare to the natural gas that is piped out of the ground for heating, cooking and industrial use?
Natural gas, in this country, is about 1100 to 1200 BTU per cubic foot.
So the methane from a bio-gas plant is only about half as efficient as the natural gas we buy.
Yes, but that is not bad. In England, for example, they take a low-grade coal and process it into coal gas which is then piped into factories and homes as fuel. This coal gas is a very important source of power in England at this time, yet it only has a BTU rating of 450. The methane from a bio-gas plant, then, is one-and-one-half times more efficient than that.
But even this is not the important point. The important thing to remember is that, in England, they are going to the trouble to process the coal into gas with a BTU value of 450 . . . while, in this country, you are making really no effort to save and use the 650-BTU gas that is evaporating and going to waste on every farm.
Well, we're making the effort now . . . that's why we have you here!
Actually, it goes past even the methane and fertilizer we're wasting on the farms. I believe you're working on plans for a prefabbed bio-gas plant that can be be installed in city houses.
Yes. Much real and potential energy goes to waste even in the cities of the United States. I here is all the garbage—the vegetable trimmings, the spoiled food, the leftovers—that most families have. There is the dung from pets and the human excreta. The grass clippings, the weeds and the leaves. All this cyan be composted into much usable methane and fertilizer.
There is also other waste that could be used to operate a bio-gas plant. For example, the average temperature of bath water is 150 to 180°F. Even after use, the water has a temperature of 110° and, in the United States, you use about four to six cubic feet of this water per person per day. If you were to run this spent water into the jacket of a digester, it would warm the bio-gas plant to its optimum operating temperature and keep it there at absolutely no cost.
But what if everyone takes their bath in the morning or only once every two or three days?
It makes no difference. If the bio-gas plant is properly insulated; it will need this hot water only once every 72 hours. The spent bath water alone is enough to heat the plant.
That makes a lot of sense. By recycling city wastes the way you suggest, we could go a long way toward making our lives more enjoyable while we preserve the planet's resources and drastically curb the way we pollute.
Yes. That's why I would like to work with a factory in this country to develop and mass-produce a series of prefabbed digesters that people could buy and install and put into use quite easily. One of these bio-gas plants should be heavily insulated for your northern states and the other could be designed less expensively for your hotter climates. Both digesters should be available in two or three sizes. With only a little work, a manufacturer could develop a line of bio-gas plants that would sell quite well in this country. If any factory owner wants to manufacture these plants, I will work with him and help him to do it.
And in the meantime?
In the meantime, I am getting five, six, seven . . . even ten letters a day in India sent to me from the United States. These are letters from people who want to know how to build and operate a bio-gas plant . . . from people who want to buy my books on the subject. I answer the letters and send the books, but it takes much of my time and the mail from India to here is often slow and the books are sometimes lost.
I would like it if soon a book written by me should be published by MOTHER EARTH NEWS. Then you can answer those letters and make the book available here and help the people in this country to learn about the bio-gas plants.
We'll publish that book, Ram Bux Singh; just as soon as we can. For the present, though, we'll have to 'be content to test the digester you've helped us build and to continue reporting on your work in our magazine.
That is very good. Thank you.
And thank you, sir.
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