We have had it good for many years, using and misusing fuels supplies at will for countless years. In the United States, the average consumption of oil equates to three gallons per day. That is for every man, woman and child of the population! This makes an annual consumption of over 2 billion gallons. This is probably the most wasteful of the developed nations, but still not extremely far ahead of the others. This practice will necessarily have to come to a halt at some point in the near future, since the present rate of consumption should exhaust the known reserves of refine able crude oil in about thirty years. The constant efforts of our oil companies to sell more and more of the black gold make it unlikely that today\'s consumption will not increase in the future. So what should we do about it? Obviously the number one priority is to do some serious thinking about the use of power per head and in total. The second pressing need is to find an alternative and ecologically sound source of power for the future, unless we want to face rocketing power prices and possible rationing in our lifetimes. And we already have possible alternatives on our doorstep. One huge source that has barely been used up to now is methane. 

Millions of cubic metres of methane in the form of swamp gas or biogas are produced every year by the decomposition of organic matter, both animal and vegetable. It is almost identical to the natural gas pumped out of the ground by the oil companies and used by many of us for heating our houses and cooking our meals. In the past, however, biogas has been treated as a dangerous by-product that must be removed as quickly as possible, instead of being harnessed for any useful purposes. It is only really in very recent times that a few people have started to view biogas in an entirely different light, as a new source of power for the future.One of these pioneers is  Ram Bux Singh, now the director of the Gobar Gas Research Station in Aiitmal, northern India. Research was done into this topic in Europe during the fuel shortages of the Second World War, and biogas in various forms was indeed used in a restricted fashion, but the world centre of biogas research is today to be found in India. There are good reasons for this: The pressure of population has reduced India\'s forests to a few scrubby trees way out on the horizon, causing extreme fuel shortages in rural areas. To compensate for this, about three quarters of the billion tons of cow manure produced annually is burned for heating or cooking. Anyone who has visited India will remember the acrid smell of burning manure. This, however causes tremendous medical problems. The acrid smoke leads to endemic eye disease, and the drying manure is a perfect breeding ground for flies of all types. The manure would also go a long way to improving the quality of the soil and hence increasing the harvest if these valuable minerals were returned to it instead of going up in smoke.

The Gobar Gas Research Station (Gobar is Hindi for cow dung) was founded in 1960 as the newest of a long series of Indian research efforts started some time in the 1930s. As one might guess from the name, the Gobar Gas Research Station has concentrated on studying the production of biogas from cow manure. Ram Bux Singh and his colleagues have biogasplants in operation ranging in size from about 8 cubic metres per day to 500 cubic metres per day. They have plants using heating coils, filters and mechanical agitators to test the change in efficiency, and have also tried various mixes of manure and vegetable waste. There is an immense amount of documentation of all their projects since every detail has been recorded for analysis and future reference.

    The facts about biogas from cow dung:

    Cow dung gas is 55-65% methane, 30-35% carbon dioxide, with some hydrogen, nitrogen and other traces. Its heating value is around 600 B.T.U. per cubic foot. 

  Natural gas consists of around 80% methane, yielding a B.T.U. value of about 1000. 

   Biogas may be  improved by filtering it through limewater to remove carbon dioxide, iron filings to absorb corrosive hydrogen sulphide and calcium chloride to extract water vapour after the other two processes. 

    Cow dung slurry is composed of 1.8-2.4% nitrogen (N2), 1.0-1.2% phosphorus (P2O5), 0.6-0.8% potassium (K2O) and 50-75% organic humus. 

    About one cubic foot of gas may be generated from one pound of cow manure at around 28°C. This is enough gas to cook a day\'s meals for 4-6 people in India. 

    About 1.7 cubic metres of biogas equals one litre of gasoline. The manure produced by one cow in one year can be converted to methane which is the equivalent of over 200 litres of gasoline. 

    Gas engines require about 0.5 m of methane per horsepower per hour. Some care must be taken with the lubrication of engines using solely biogas due to the \"dry\" nature of the fuel and some residual hydrogen sulphide, otherwise these are a simple conversion of a gasoline engine.

FERMENTATION

There are two basic types of  organic decomposition that can occur: aerobic (in the presence of oxygen), and anaerobic (in the absence of oxygen) decomposition. All organic material, both animal and vegetable can be broken down by these two processes, but the products of decomposition will be quite different in the two cases. Aerobic decomposition (fermentation) will produce carbon dioxide, ammonia and some other gases in small quantities, heat in large quantities and a final product that can be used as a fertiliser. Anaerobic decomposition will produce methane, carbon dioxide, some hydrogen and other gases in traces, very little heat and a final product with a higher nitrogen content than is produced by aerobic fermentation.

Anaerobic decomposition Is a two-stage process as specific bacteria feed on certain organic materials. In the first stage, acidic bacteria dismantle the complex organic molecules into peptides, glycerol, alcohol and the simpler sugars.  When these compounds have been produced in sufficient quantities, a second type of bacteria starts to convert these simplercompounds into methane. These methane producing bacteria are particularly influenced by the ambient conditions, which can slow or halt the process completely if they do not lie within a fairly narrow band.

ACIDITY  

Anaerobic digestion will occur best within a pH range of 6.8 to 8.0. More acidic or basic mixtures will ferment at a lower speed. The introduction of raw material will often lower the pH (make the mixture more acidic). Digestion will stop or slow dramatically until the bacteria have absorbed the acids. A high pH will encourage the production of acidic carbon dioxide to neutralise the mixture again.