Bio-Gas

The cheapest source of energy:

L. M. SAMARASINGHE

There is a global problem relating to the use of fossil fuel. At the present moment the focus of attention is on the cost of the fuel. The cost has gone up and many do find this a painful problem. This is only the beginning of the problem.

The main problem is that the stocks of fossil fuel are getting depleted and within the next 25 years, it could become necessary to look for sources of alternate energy to run the vehicles. The fleets of heavy vehicles that burn large quantities, of fossil fuel would have to be put aside and they would cease to be utility items for transportation needs.

It has been said that the next source of energy would be solar power to run vehicles. But they would be much lighter vehicles. The users of heavy vehicles would have to readjust their systems to get used to the solar powered lighter vehicles.

Crowded cities like Colombo and other urban areas could adjust themselves to the use of Bio-Gas energy for cooking, lighting and many other energy needs. It is an extremely simple system to generate energy without the need for machinery and heavy equipment.

The slurry which is a by-product of the Bio-Gas units would serve as the finest fertiliser which could replace the expensive imported fertiliser. All that is necessary is the will to harness the cheap source of energy and enjoy the benefits.

Around 1981 when this writer was functioning as the Land Commissioner, an effort was made in association with a development NGO - National Development Foundation (NDF) to set up 20 Bio-Gas units in the Minipe Settlement Scheme with steel float chambers turned out at the Government Factory.

The farmers who got the Bio-Gas plants were also given gas burners and gas lamps. They were extremely happy with the performance of the biogas unit. The houses were well lit in the night and the ladies found the cooking process very much easier and much less troublesome.

Chambers

The slurry from the Biogas chambers were utilised as fertiliser for the paddy lands and also for vegetable cultivation in the high land blocks. That particular NGO set up Chinese type of gas chambers without steel floats using only concrete and bricks in a number of other settlement Schemes.

The technology involved in producing Bio-Gas is extremely simple and does not involve machinery. All that is necessary is to put the kitchen waste, animal waste like cow dung and human waste into the in let of the gas chamber.

If human waste is used the slurry need to be put in to the in let again to remove the offensive smell. But it produces more gas than the other inputs. The gas chambers get heated to a very high degree and all living things, germs and bacteria terminate the lives. In China it is human waste that is used mostly to produce Bio-Gas and it is a most impressive success story.

A remarkable success story in China is the use of Bio-Gas as a source of energy for a variety of purpose particulary in the rural areas.

The Chinese position

In many parts of China rural homes use Bio-Gas as a source of energy for cooking and lighting. It is reported that there are over 7,000,000 homes that use Bio-Gas units in China. The number of persons in the rural areas enjoy the benefits of Bio-Gas is said to be about 30 million.

Domestic

In addition to these domestic units more than 36,000 large scale digesters are reported to have been built in recent times for use by communes, production Brigades, State Farms, Wineries, Bakeries and Confectioneries.

The province of Sichuan takes the lead in China in carrying out essential research to develop the uses of Bio-Gas:

The Sichuan province office of Bio-Gas Development Chendu Institute of Chemistry. Chendu Institute of Biology. Sichuan Institute of Agricultural Machinery. Quxian Country office of Bio-Gas Development are some of the Institutes that devote much time and effort to the development of research on Bio-Gas.

Apart from the Bio-Gas digesters built for use by rural homes for the production of energy for domestic needs there are centralised installations with larger digesters for use by families living in housing flats. The gas centrally produced is delivered to each flat by separate tubing circuits through a central panel.

There is electricity available for those flats. As such the families living in them use Bio-Gas only for cooking. A minimal monthly charge of about 1-2 yuan is levied from each family for the supply of the gas.

This process is naturally an excellent method of managing human and animal waste in such crowded housing complexes. This is also a method for obtaining a ready supply of excellent quality fertiliser for use in farms.

Energy

Apart from meeting the domestic requirements of energy for cooking, lighting and even for pumping water in certain instances, Bio-Gas is utilised for a variety of needs of the community.

Some of the community needs satisfied by the use of Bio-Gas are as follows:

1. Provision of energy for farm machinery with internal combustion engines.

2. Provision of energy for pumping water for irrigation.

3. Provision of energy for processing of grains.

4. Provision of energy for drying of agricultural products.

5. Provision of energy for fruit processing plants.

6. Provision of energy for generation of electricity to run machinery for lighting in urban areas, and for industrial units.

7. Provision of energy for pumping, cooking and distilling operations in horticultural farms.

8. Provision of energy for rural industrial units.

9. Provision of energy for milling wheat and breaking.

10. Provision of energy for the operation of rice hullers.

11. Provision of energy for burning of kilns.

12. Provision of energy for tobacco curing.

An important result of the propagation of the use of Bio-Gas in the rural areas of China is the reduction in the use of firewood as a fuel. This helps to save the forest cover and promotes the protection of the environment.

The provision of fuel for the various farm machinery with internal combustion engines is a major problem in many of the developing countries which do not have oil resources. China is not a country which is bedeviled by the problem of the escalation of the oil prices.

She has sufficient quantities even for export. But yet the progress made in the harnessing of Bio-Gas for the running of farm machines is a noteworthy contribution which could benefit all the developing countries which receives a complete knockout by the price hike in oil.

The task of pumping water for irrigation purposes is a major problem of the people particularly in the more drier parts of the developing countries.

Method

Ground water irrigation and lift irrigation necessarily involve high expenditure on fuel for pumping, and vast extends of land suitable for agriculture using ground water or lift irrigation are uncultivated in many countries purely because of the high cost of pumping and associated difficulties.

The Chinese example provides a simple method of solving the energy problem relating to the working of irrigation pumps.

An impressive sight which leaves lasting memories in a visitor to the Sichuan Province is the passenger buses that run on Bio-Gas. Ever since the oil price escalated, oil importing Third World Countries have run into serious difficulties with regard to passenger transportation. The cost of transportation has gone up over ten times in some of the Third World Countries.

The Chinese buses that run on Bio-Gas are normal passenger buses with seating capacity for about 50 or more. The biogas is stored in a flexible plastic/polythene bag mounted on top of the bus like a huge pillow and the bus runs 100km with one bag of Bio-Gas. Gas bags are available at the suitable points for replenishment.

As the gas gets used up the bag gets deflated and appears flat and could be easily unloaded.

The developing countries that do not have oil resources could conveniently go for Bio-Gas in a big way to solve the transportation problem.

Machines

About 70-90 per cent of diesel oil used on farm machines can be saved by the conversion of such diesel engines into Bio-Gas diesel dual-fuel engines. This process is adopted to save diesel oil on engines used for pumping, power generation, rice husking, wheat milling and breaking. In the Sichuan Province in China by 1979 there were 514 dual fuel engine stations with a total capacity of 5,542 H.P.

Advantages in the production of Bio-Gas

1.Cheap energy could be obtained for a variety of purposes.

2. The slurry provides excellent fertiliser essential for agriculture.

3. This process destroys harmful enteric bacteria, viruses and intestinal parasites that cause many diseases.

4. This in turn helps rural sanitation and public health.

5. It also controls and minimise environmental pollution.

6. Waste management ceases to be a problem. Instead it becomes a profitable venture.

Fertiliser

The application of high quality fertiliser is a key factor in agricultural productions.

Many of the developing countries depend on imported manure which is quite expensive. The establishment of fertiliser factories is quite an expensive process.

The Chinese experience has shown that recycling of organic substance through Bio-Gas digesters is the best way to obtain fertiliser for agricultural production.

The Academy of Agricultural Science in Chendu in Sichuan Province is one of the Institutions that is carrying out extensive research in the application of fertiliser for agricultural development.

The compost manure produced by the traditional process of composting of organic matter is much less efficient compared to Bio-Gas slurry.

The manure properties of the Bio-Gas fermentation residues exhibit a remarkable degree of efficiency. It has been found that this manure is 10 per cent more efficient than other types of manure.

The healthy looking green fields and plants and the high crop yields in the Sichuan Province speak much for the high efficiency of Bio-Gas slurry as a manure. Where a particular type of soil lacks phosphorus or other component and soil needs special treatment, the required chemicals could be added to the Bio-Gas slurry to produce the best results.