Now see a Methane plant is probable the most useful little tool you can make in a survival situation. The transformation of sewage into increasingly precious fertiliser and fuel may seem complicated, magical and mysterious but instead, it's actually one of nature's simplest, most basic and straightforward processes.

This 44-gallon drum digester (below) is small enough to construct quickly but large enough to make about one cubic foot of gas from one pound of cow manures at 75oF per day. This is enough gas to cook a day's meats for 4-6 people.

The temperature can be stabilised by:

1. painting the drum black.
2. taking a small sample of the gas produced and using it to heat the digester (this can be by way of burner directly below or a chimney through the centre of the drum.
3. Running hot pipes through the digester (either from a motor or from your house waste water or solar water heater panel)
Yep! It really is easy to make your own methane however, the fuel can asphyxiate you or explode if mishandled. Read this entire section before you begin your first experiment with the gas and always observe all the precautions.

Points to remember.

1. The slug needs to be mixed with care to create the correct carbon mix.

2. Methane can explode (so make sure you don't mix it with air or any other gas, ensure that any hoses used are well earthed)

3. From what we have found here the gas has no smell and burns very clean. (SO CLEAN YOU CANNOT SEE THE FLAME so look out!)

4. Methane can be compressed into gas bottles but ensure your compressor, the pipes and bottle is well earthed and does not heat up too much. By too much I mean if you hear a bang and see your maker it was too much. As a rule you should be able to hold your hand in all parts, any hotter and kiss your bum good-by OK.

5. Methane can also be used to run motors but from what I have found it's a bit of a waste. About 225 cubic feet of gas equates one gallon of gasoline. The manure produced by one cow in one year can be converted to methane which is the equivalent of over 50 gallons of gasoline. However a gas engines require 18 cubic feet of methane per horsepower per hour.

6. Cow dung slurry after digestion is composed of 1.8-2.4% total nitrogen (N), 1.0-1.2% phosphate (Pz05), 0.6-0.8% potash (K20) and from 50 to 75o% organic humus.

7. Mans/womans dung is the best, followed by pig's, then the rest. I recommend mixing the lot.

8. A water trap (flash-back suppressor is HIGHLY RECOMMENDED) look at my drawing. For this I used a plastic bottle (3 litre) and put the tube with gas from the plant down under the water and the pipe to the stove above the water. The gas bubbled up through the water and gave me the illusion of being safe from flash-back. Well it didn't flash-back anyway.

Ok here's your basic plant plan.

Now look at this beauty .. a totally gravity feed plant. Something like this is running your home.

GLOSSARY OF METHANE TERMS

AEROBE: A micro-organism that can live and grow only where free oxygen is present.

AEROBIC: Able to live or grow only where free oxygen is present

ANAEROBE: A micro-organism that can live and grow where there is no free oxygen. Anaerobes get oxygen from the decomposition of oxygen-containing compounds.

ANAEROBIC: Able to live or grow in the absence of free oxygen.

BIO-GAS. A term apparently coined by Ram Bux Singh in the early 1950's to denote the mixture of methane (54-70%), carbon dioxide (27-45%), hydrogen (1-10%), nitrogen (.5-3%), carbon monoxide (.1%), oxygen (.1%) and hydrogen suifide (trace) formed in an anaerobic digestion tank.

HYDROGEN SULFIDE.. H2S. A poisonous, flammable gas with the nauseating smell of rotten eggs.

METHANE: CH4. A colourless, odorous, flammable gas which may be formed by the decomposition of vegetable matter. Methane is the main constituent of natural gas and is used as a fuel and for illumination.

NATURAL GAS: A mixture of gaseous hydrocarbons, mostly Methane, that forms naturally from fossil deposits in certain places in the earth. It is used as a fuel.

FERMENTATION

There are two kinds of organic decomposition: aerobic (requires oxygen) and anaerobic (in the absence of oxygen). Any kind of organic material-animal or vegetable may be broken down by either process, but the end products will be quite different. Aerobic fermentation produces carbon dioxide, ammonia, small amounts of other gases, considerable heat and a residue which can be used as fertilizer. Anaerobic decomposition on the other hand creates combustible methane, carbon dioxide, hydrogen, traces of other gases, only a little heat and a slurry which is superior in nitrogen content to the residue yielded by aerobic fermentation. Anaerobic decomposition takes place in two stages as certain micro-organism feed on organic materials. First, acid producing bacteria break the complex organic molecules down into simpler sugars, alcohol, glycerol and peptides. Then and only when these substances have accumulated in sufficient quantities a second group of bacteria converts some of the simpler molecules into methane. The methane releasing micro-organism are especially sensitive to environmental conditions.

TEMPERATURE
Anaerobic digestion of waste material will occur at temperatures ranging from 32deg F to 156deg F. The action of the bacteria responsible for the fermentation decreases rapidly below 60deg F, however, and gas production is most rapid at 85-105' and 120-140' F. Different bacteria thrive in the two ranges and those active within the higher limits are much more susceptible to environmental changes. Thus, a temperature of 90' to 95' F is the most nearly ideal for stable methane gas generation.

ACIDITY
The proper pH range for anaerobic fermentation is between 6.8 and 8.0 and an acidity either higher or lower than this will hamper fermentation. Ale introduction of too much raw material can cause excess acidity (a too-low pH reading) and the gas-producing bacteria will not be able to digest the acids quickly enough. Decomposition will stop until balance is re- stored by the growth of more bacteria. If the pH grows too high (not enough acid), fermentation will slow until the digestive process forms enough acidic carbon dioxide to restore balance.

CARBON-NITROGEN RATIO
Although bacteria responsible for the anaerobic process require both elements in order to live, they consume carbon about 30 to 35 times faster than they use nitrogen. Other conditions being favourable, then, anaerobic digestion will proceed most rapidly when raw material fed into a digester contains a carbon-nitrogen ratio of 30:1. If the ratio is higher, the nitrogen will he exhausted while there is still a supply of carbon left. This causes some bacteria to die, releasing the nitrogen in their cells and eventually restoring equilibrium. Digestion proceeds slowly as this occurs. On the other hand, if there is too much nitrogen, fermentation (which will stop when the carbon is exhausted) will he incomplete and the "leftover" nitrogen will not be digested. This lowers the fertilizing value of the slurry. Only the proper ratio of carbon to nitrogen will insure conversion of all available carbon to methane and carbon dioxide with minimum loss of available nitrogen.