In Pabal, there are multiple power cuts during a day. Businesses that rely on electricity become less efficient and lose profits as a result of power losses. The government has no short-term plans to address the electricity problem in rural India so an alternative power solution is needed to alleviate the problems caused by power cuts.
Biogas is a reliable, cheap and sustainable alternative to, or creator of electricity. About fifteen years ago, there was a government-level biogas drive, but the government only made generators available at a cheap rate and did not provide proper advice and maintenance, without which the generators were misused. The generators relied on cow dung, which presented an extra problem in Pabal, Maharastra. Due to the severity of the dry season (January - May), the local farmers must transport the cows to a nearby village, which has a wetter climate. This meant that there was no cow dung available for the generators for four months of the year. As the generators require 21 days start up time (where the bacteria in the dung can build up to a sufficient level), the generators became hard work to use. The generators would be non-functional for about 5 months in a year. Any farmers that did try the generators ended up stopping their usage. Another factor was that farmers also wanted to use cow dung as free fertiliser for their crops. Because of this cow dung is not a viable main fuel source for a biogas generator.
A small-scale biogas generator needs to be developed, so that it can run on different forms of biomass and serve a household in a localised situation. A small generator would be the most sustainable solution, as less power and energy would be wasted than if a community-based, larger generator was designed. The localised small biogas generator would limit any losses from electricity and/or biogas distribution.
utility of the solution
The community can use biogas generators to convert organic biomass into biogas. The NGO located near to Pabal, Vigyan Ashram, has experimented in the past with biogas generators. They concluded that large-scale community generators (which are bigger than 20 m3) are not practical, as providing service to the whole community creates extra costs and requires the use of more materials. This is because the biogas or electricity produced by the community biogas generator must then be supplied to the community via gas lines, electricity cables or a compressor and canisters.
A sustainable design would therefore be small enough for a farmer to use permanently as a generator and back-up for power cuts. A design has been developed that uses half a kilogram of spoilt flour. The flour grains can be black and this is a good example of an appropriate solution. The design of a sustainable generator should take size into account: the biogas generator should be designed to cater for a typical Indian household of 6-10 people. Such a generator would allow families to use the biogas plant for their own individual needs and they would be able to create biogas in a small rear garden or even a kitchen if the design is small enough.
economic benefits / required training / major impacts
An implemented project would bring constant electrical power to the community. With the power cuts that are present throughout the vast majority of rural India, a design for a cheap biogas generator (providing power for a family/business) would provide a reliable power source for much of the population. The power cuts lead to a loss of trade for many businesses and slow down the technological growth of the community, causing much of the rural population to want to migrate into cities. A back-up power supply would be really useful in bringing direct economic benefit to many businesses in Pabal.
If a cheap design is proposed it could be implemented in many places. This would require a large amount of biomass, involving the use of 'oil cake' (see below) or crops directly from the fields. There would be encouraged demand in the manufacture of oil cake and/or farming, either way potentially increasing jobs within the area and/or profit for those community sectors. If a truly effective design were to be reached, it could benefit the community to completely replace its connection to the electrical grid with power generation from the community's own biogas generator. If such a solution can be reached then the pay back time on the initial investment should be deduced, as an offer for the local community.
Other economic benefits are also present. Large-scale biogas generators have the capacity to produce ethanol. If a small-scale biogas generator is designed and can collect a supply of ethanol, it may have the following benefits:
The major impacts of implementing a biogas generator solution to Pabal would concern safety primarily. The generators would need to be safe, easy to use and easy to teach about, as any major accidents attributed to the generator failure would be unacceptable. The generators would have to have a long working life, as such a generator would be a large investment for most family in Pabal. Another impact of using biomass could be that the price of crops and 'oil cake' would increase. This could possibly make it harder for the community to buy food. The 'oil cake' is currently used as cattle feed and an impact of using it in biogas would be that farmers would have to find another cheap source of cattle feed.
description of current local situation & resources
Vigyan Ashram has experimented with the use of other organic, cheap material in the biogas generator. Paper (Rs. 1 /kg) was tried, but was found to be too slow to work when shredded and when treated with enzymes to break down the paper. 'Oil cake', a waste product from the peanut oil milling industry (see Optimisation of Pabal Peanut Oil Mill Project Proposal), (Rs. 11 - 13) was found to work well in their generator. There are many seeds and starch-based plants grown in the area. For a biogas generator to be sustainable and practical, the organic substance used needs to be grown within a season, otherwise the farmer/owner of the generator would have to wait a long time (maybe even years) before he can use the generator.
The floating head generator has also caused problems, as there the gas is produced at atmospheric pressure. This means that the supply of the gas often fluctuates (often a person has to stand on the floating head to get gas out). Therefore, for a generator to be really useful this design flaw would have to be optimised by operating the generator at a higher pressure or by another method, which would give a constant production and collection of gas that may be used when required, i.e. when the power cuts occur.
The NGO's generator is 1 m3 in size and has a 'floating dome' top to it (as opposed to a 'fixed dome'). This means the gas can expand and occupy extra space in the roof. Vigyan Ashram has also commissioned the building of a biogas generator in a nearby village. This is a larger scale generator (15 m3). A similar generator has been built on a local farm and serves a number of farms which are clustered together. This solution works, but an optimised solution could be created on a smaller scale to provide for single-family households, which are more common.
In a nearby village to Pabal, a biogas generator has used human excrement as a power source. This option could be researched as the design feature of such a generator would have to be modified. This could be linked to the human waste disposal project proposal.
Below: Biogas generator used at Vigyan Ashram; Biogas generator used at a local farm
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Previously Completed Solutions
Joanna Read, Biogas Generator (March 2008)
Researcher Bio: Pursuing a Bachelor degree in Mechanical Engineering at the University of Toronto.
Abstract: "This project proposes the design of a novel biogas generator suitable for use in rural villages in developing countries. A ‘plug flow’ type digester is presented, with feedstock moving linearly between inlet and outlet throughout the digestion process. Biogas is stored in a separate gas holder until it is required for use. The gas holder contains two
inflatable spheres which act as pressure regulators."
Read Joanna's Design Challenge solution.
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