The energy crisis is one of the crucial issues in Bangladesh as well as across the world. Our national grid is facing a severe shortage of gas after installation of new power plants in the country. The government is coming up alone or entering joint ventures with the private sector to set up new power plants. But the population, industrial production and demand are increasing more rapidly. As a result, the crisis of gas is getting worse day by day. Now the government is setting up a nuclear power plant. But the equation says the crisis will not ease that much or will get even worse in future. In such a situation what we need to consider is how waste materials can be converted into energy. We need to think about how we can manage our waste and save our nation from slipping into an energy crisis and thus ensure energy for all.
Biogas is a very familiar word in the energy lexicon. When it comes to biogas, what flashes through the minds of most of the people in Bangladesh is that it is the traditional way of fermenting organic waste into gas on a limited scale. It is true that biogas production involves a fermentation process. But it is no more a traditional system in developed countries. But, unfortunately, we are still following the old and traditional system of fermentation and remaining happy with what we get.
In the country there are about 80,000 biogas plants of varied sizes-from very small plants applying traditional technology to two medium-size modern plants. Still a half of the people are not getting gas connections. The government is trying to increase power production, but the demand may not be met even in one hundred years. It is also true that even after putting the best infrastructure in place, the government may not be able to provide power connections to all the households. It is simply impossible for any government to ensure electricity for all the people from the national grid. But it is very easy for the government to provide power connections to all the people by turning waste into energy. We all need to treat our bio-waste as our wealth and think about how to convert this wealth into energy. The bio-waste use in power generation will help save a substantial amount of fossil fuel.
All fossil fuels have a limitation. No fossil fuel is unlimited and there will be a time when there will be no more fossil fuel left. Costs of the fossil fuel also increase day by day. On the other hand, the bio-waste is unlimited. As long as the world exists, there will remain the bio-waste, which is the raw material for energy. The reserve of this raw material will never run out, rather it will increase with the growth in population and the advancement of civilisation.
The traditional biogas plants can meet the need of a family or a small community. But they cannot meet the large-scale demand. We need big or medium-size plants and state-of-the-art technology to serve that purpose. Bio-waste can be used to produce biogas, run generators and thus produce electricity. Unlike the traditional way, the modern technology helps process the waste materials for biogas as suitable for an engine.
Let us have a look at the composition of biogas as follows:
Biogas with H2S can damage an engine. In our country biogas is used in most of the engines without removal of H2S. So, many of the biogas engines go out of order within a very short time. That means the life of a generator is always shorter, if biogas is used without removing the H2S. Â
Biogas generation has some technical aspects like the anaerobic process or fermentation of biodegradable materials, modern technology of biogas generation, wet digestion, dry digestion, digested manure or organic fertiliser, biogas-to-natural-gas conversion, CNG conversion, biogas-based power plant, etc. Biogas can ensure energy for all for a certain period. The best advantage of a biogas plant is it requires one-time investment and provides the lifetime energy solution subject to good maintenance work.
Unlike biogas, the other energy sources like coal, diesel, solar-power or even hydro-power involve high costs in running any plant for generating energy. Moreover, fossil fuels are expensive and the prices are increasing day by day, as no fossil fuel is unlimited. So, we need to look for alternative sources of energy like biogas.
Coal-based power plants are there. Power from coal involves high costs-from mining to firing coal. It also causes environment pollution. When it comes to diesel-based power plants, the government is giving heavy subsidies on the fuel and then supplying the electricity at much lower rates. Hydro-power is also a reliable source, but the maintenance cost is very high. The case is same with the nuclear power. On the other hand, in the case of biogas, one has to make the investment once and then the energy is ready to be used at a much lower cost. The raw material for bio-gas is organic waste. Waste management is a big problem facing any household, community or factory. If the waste is dumped at a particular place as designated by the city authority, it can be easily used for producing biogas. Building such plants in all cities is the best way of waste management.
The main advantage of producing biogas in the traditional way is it is very flexible and can be produced anywhere from any amount of organic waste. It also does not require that much investment. For a small family it is good, but for a community-based or industrial biogas plant, the traditional way is not applicable. The community-based or industrial biogas plants need modern technology, which is very expensive but very effective in ensuring a constant supply of gas for electricity generation or for other purposes like supplying compressed natural gas (CNG) after purification of the biogas as natural gas.
When it comes to commercial or industrial production of biogas, there are many aspects of it. If the project is big, it has a good chance of becoming viable. But smaller plants may not be that viable as far as the amount of investment involved is concerned. Then a process is also needed to be followed in supplying waste materials from a kitchen to the city waste dumping point or from a poultry farm or dairy farm to the nearby biogas plant. If the discipline is not maintained properly, such a project may fail.
There are two ways of processing biogas. One is Wet Anaerobic Digestion and the other is Dry Anaerobic Digestion, commonly known as Wet AD and Dry AD. Wet AD is a process in which waste water is added to the waste to pump it from one process to another. Mainly all kinds of manure like cattle farm waste, chicken litter, etc. are processed by applying the Wet AD. It can also be applied to processing the city waste or agriculture waste, but the problem remains with handling the liquid manure or liquid fertiliser which is a bi-product. The Wet AD can be applied on a limited scale in the traditional way of biogas production and on a large scale in the use of the most modern pre-processing and fermentation technology.
 On the other hand, the Dry AD is good, especially for management of municipal solid waste (MSW) or agriculture waste. This process is characterised by energy generation from biomass with garage-shaped digesters or fermentation containers. The digesters are constructed gas-tight. In the Dry AD method the quantity of biogas is much higher than that produced in the Wet AD method.
Biogas is the ultimate solution to the energy problem in Bangladesh as well as all over the world. It can ensure clean energy and clean environment and it involves no extra cost as is the case with fossil fuel. Let us draw up a long-term plan on biogas and ensure access of all to clean energy.
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Biogas: The ultimate solution to energy crisis
Ekhlasul Haque | Published: December 14, 2013 00:00:00 | Updated: November 30, 2024 06:01:00
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