Biogas and Uses..

The term 'biogas' is commonly used to refer to a gas which has been produced by the biological breakdown of organic matter in the absence of oxygen. The gases methane, hydrogen and carbon monoxide can be combusted or oxidized with oxygen and the resultant energy release allows biogas to be used as a fuel.

In the same way that ethanol and biodiesel have been around for a long time, biogas has a long history. Back in the 13th century, explorer Marco Polo noted that the Chinese used covered sewage tanks to generate power. The author of Robinson Crusoe - Daniel Defoe (shown above) – referred to biogas technologies back in the 17th century. Biogas has been used widely in the UK for centuries and back in 1895, the city of Exeter used gas from sewage to power its city street lamps. An anaerobic digester that treats farm wastes or energy crops is commonly called a 'biogas plant'.

The speciality of the biogas plant is that along with the production of cooking gas, it keeps the surroundings clean and it is very safe to use. It occupies only a very small area and it is portable. It can also be easily transferred from one place to another. No labour work or digging a pit is required for this.

Special models of biogas plants are available for hotels, fast food shops, vegetable shops and fruit shops along with subside. You can save more than 70% of LPG gas.

Biogas is a commonly used biofuel around the world and is generated through the process of anaerobic digestion or the fermentation of biodegradable materials such as biomass, manure, sewage, municipal waste, rubbish dumps, septic tanks, green waste and energy crops. This type of biogas comprises primarily methane and carbon dioxide. The actual composition of biogas will vary depending upon the origin of the anaerobic digestion process – ie the feedstock.

Anaerobic digesters can be fed with energy crops such as biodegradable wastes <http://en.wikipedia.org/wiki/Biodegradable_waste> including sewage sludge and food waste. An air-tight tank transforms the biomass waste into methane producing renewable energy which can then be used for heating, electricity, and many other operations that use any variation of an internal combustion engine.

One particular type of biogas is known as 'landfill gas' (LFG) or 'digestor gas'. LFG is produced by wet organic waste decomposing under anaerobic conditions in a landfill. In the same way that a compost heap works, the waste is covered and then compressed by the weight of the new material that is deposited on top. This material prevents the oxygen from escaping and encourages the anaerobic microbes to thrive. The gas slowly builds up and is released into the atmosphere if the landfill site has not been engineered to capture the gas.

It is important for many reasons to ensure that landfill gas is contained – firstly, LFG becomes explosive when it escapes from the landfill and mixes with oxygen and secondly, the methane contained within biogas is 20 times more potent as a greenhouse gas than carbon dioxide - so uncontained landfill gas may actually significantly contribute to the effects of global warming.

The floating gas storage is designed to collect and store low pressure biogas produced from small quantity of kitchen waste. They are made with biogas resistant PVC or polyurethane two side coated with polyester fiber reinforced membrane, embeded with polyester iso resin coated metal reinforcement. the design is made to maintain constant low postive biogas pressure.

Its mainly used for house hold kitchen waste. The input materials for Elegant biogas plants are daily vegetable waste, food waste, meat waste etc. Apart from this, manure and dung can also be used . These plants are portable models and its space requirement is only 1 square meter for house hold units and it has an output of 2 hrs per day.

Biogas has a wide variety of uses and can be used as a relatively low-cost fuel for the generation of energy and heating purposes, such as cooking. For example, basically any facilities which need power are able to use biogas to run engines, or to generate either mechanical or electrical power.

Biogas can be compressed, similar to natural gas, and is able to be used to power motor vehicles. As an example in Britain, biogas is estimated to have the potential to replace around 17% of vehicle fuel. Biogas is a renewable fuel, so it qualifies for renewable energy subsidies  in some parts of the world.

It is possible to concentrate the methane within bio-gas to the same quality standards as fossil fuel derived natural gas to produce bio-methane. If concentrated and compressed this bio-gas can then be used in vehicle transportation. Compressed bio-gas is becoming widely used in Sweden, Switzerland, and Germany for cars, trucks and trains.

The growth of the use of gas-fueled vehicles both large and small around the world has been substantial, particularly in Europe. In the United States bio gas is quickly becoming a popular source of energy and a wide variety of feed stocks are being tested. It has been estimated that the methane bio gases derived from cattle, pigs and chickens could be used to power millions of homes around the world whilst still reducing billions of metric tonnes of greenhouse gas emissions.

In  India the biogas produced from the anaerobic digestion of manure in small-scale digestion facilities is called 'gobar gas'. It is estimated that such small-scale facilities exist in over two million households in India 

In other parts of the developing world, domestic biogas plants can convert livestock manure and night soil into biogas and slurry, the fermented manure. This technology is feasible for small scale users with livestock producing 50 kg manure per day – the equivalent of about 6 pigs or 3 cows. This manure has to be collectable to mix it with water and feed it into the plant and toilets can also be connected.

Advantages and Benefits of Biogas

1. Provides a non-polluting and renewable source of energy.
2. Efficient way of energy conversion (saves fuelwood).
3. Saves women and children from drudgery of collection and carrying of firewood, exposure to smoke in the kitchen, and time consumed for cooking and cleaning of utensils.
4. Produces enriched organic manure, which can supplement or even replace chemical fertilizers.
5. Leads to improvement in the environment, and sanitation and hygiene.
6. Provides a source for decentralized power generation.
7. Leads to employment generation in the rural areas.
8. Household wastes and bio-wastes can be disposed of usefully and in a healthy manner.
9. The technology is cheaper and much simpler than those for other bio-fuels, and it is ideal for small scale application.
10. Dilute waste materials (2-10% solids) can be used as in feed materials.
11. Any biodegradable matter can be used as substrate.
12. Anaerobic digestion inactivates pathogens and parasites, and is quite effective in reducing the incidence of water borne diseases.
13. Environmental benefits on a global scale: Biogas plants significantly lower the greenhouse effects on the earth’s atmosphere. The plants lower methane emissions by entrapping the harmful gas and using it as fuel.

Disadvantages of Biogas

1. The process is not very attractive economically (as compared to other biofuels) on a large industrial scale.
2. It is very difficult to enhance the efficiency of biogas systems.
3. Biogas contains some gases as impurities, which are corrosive to the metal parts of internal combustion engines.
4. Not feasible to locate at all the locations.

Prepared Collection by: M.Ajmal khan.