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Eternal Flame - Rwanda
Rwanda’s troubled past has led to a huge increase in the prison population. Severe overcrowding has put overwhelming pressure on the prison infrastructure, especially the sanitation system, leading to health and environmental problems. Another other serious environmental concern is the huge pressure placed on the
local forest for cooking fuel wood. The Kigali Institute of Science and Technology has devised a solution to solve these problems in an environmentally friendly way.
Background
Civil strife between the Hutu and Tutsi tribes has blighted the history of Rwanda. Many of Rwanda’s 120,000 prisoners are being held there awaiting trial as war criminals following the 1994 genocide. With five times the intended number of inmates, prisons were stretched to bursting point. Sewage seeped from drains and septic tanks, creating not only a direct health risk, but also a pollution hazard to the local water sources. Forests were also under pressure because of the demand for wood to fuel the prison stoves.
The Kigali Institute of Science and Technology (KIST) has devised a solution that deals with both these issues – a biogas plant which processes the human waste into usable fuel and safe fertiliser.
Biogas Technology
Biogas typically refers to methane gas that is produced by the fermentation of organic matter such as manure. The organic matter is broken down by microbiological activity. The process occurs in a digester, which must be strong enough to withstand the build-up of gas pressure and must provide suitable conditions for the bacteria inside. There are three main stages.
- The first stage involves the large molecules being broken down by bacteria to produce sugars, amino acids and fatty acids.
- In the second stage bacteria convert sugars into short-chain acids, mainly acetic acid.
- Bacteria under anaerobic conditions, i.e. without oxygen, carry out the third stage in which the acids are converted into methane.
The digestion of organic matter yields several benefits:
- It produces methane for use as a fuel.
- The digestion process eliminates disease organisms from the waste.
- The waste is transformed into safe fertiliser for crop production, as it contains plant nutrients and water.
Prison Biogas
Biogas processing is generally done on a small scale in rural areas. However, KIST wanted to tackle the problems in the prison by developing an institution sized biogas plant, scaling up the system so that it could cope with the 50,000 litres of waste produced in each prison each day. Ainea Komaro, a Tanzanian engineer, who has a lifelong interest in biogas, took up the challenge to design the prison digester as well as the associated equipment.
The digester is constructed in a large pit. It consists of a series of brick built, beehive-shaped chambers, each with a capacity of 100 cubic metres that are connected together in series. Once the chambers have been constructed they are completely covered over with earth.
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| Biogas plant under construction – Gitarama prison, Rwanda. |
The wastes flow by gravity from toilets into the bio-digester, where they ferment and generate biogas. To maintain a self-sustaining process a ‘compensating chamber’ is attached to the domes to replenish the supply of bacteria. At the beginning, it requires about four weeks to establish the right combination of bacteria that generate sufficient quantities of methane that can burn. But, from there on, the process is continuous, and every 100 cubic metres of waste generates 50 cubic metres of biogas daily. The Biogas installation at Kigoma prison has a capacity of 1000 cubic metres, and generates about 500 cubic metres of biogas daily.
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| Hemispherical domes nearing completion. |
Once the biogas plants have been set up they need little maintenance and should last for over thirty years.
Planning and construction of large biogas systems require extra care to make sure that every stage performs satisfactorily. On every building site, KIST provides a qualified engineer, experienced technicians and masons. Among other roles, the KIST team carries out on-job training for civilians and prisoners. The majority of people on the building site are prisoners who work as engineers, technicians, masons and helpers. Some of the prisoners have acquired additional engineering and building skills that they can put to good use when they return to their communities.
Impact of the Project
Half the prisons in Rwanda now have biogas systems, and these fulfil about half of the energy needs in each location. Cyangugu, one of the largest prisons with holding 6000 prisoners, is a typical example. Previously its poorly treated sewage threatened nearby water sources, putting the livelihoods of local farming and fishing communities at risk; in the meantime over £25,000 ($44,000) was being spent on wood fuel. Now the biogas plant has removed the risk of pollution, and the prison has substantially reduced its energy costs.
Just in terms of fuel, the payback costs would be covered in less than seven years; but there are associated benefits from improved sanitation facilities, better health and the by-product of fertiliser. This odour-free material is used by prisoners to enrich the surrounding gardens where crops such as maize, tomatoes, and even fuelwood trees are grown.
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| Garden of Cyangugu Prison, with biogas system under the ground at this point. |
Overall Rwanda’s prison service annual wood-fuel costs of over £550,000 (nearly $1 million) have been reduced by 50 per cent.
Although the waste would have a bad smell in open space, its isolation underground makes the environment free of odour. The outputs are liquid fertiliser (which does not smell), and biogas that is connected to the kitchen through underground pipes. Biogas burns with a clean blue flame and produces no smoke. Prisoners have accepted this technology, and are happy to eat food that has been cooked using this gas.
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| Cooking on biogas in prison |
Future Plans
There are continuous research efforts to make biogas systems generate more gas per unit volume of organic material, and use the bio-effluent more effectively for production of crops and fish to raise food security, create employment and improve the quality of life of the people.
KIST will intensify training of the private sector and improve mechanisms for quality control. The aim is for modernised biogas plants to take root more widely in the region, for homes, schools, dairy farms, and prisons, with the objective of obtaining better energy, better fertiliser, and improved sanitation.
The achievements of this project have been recognised in the annual Ashden Awards. The Kigali Institute of Science, Technology and Management (KIST) won the first prize of the Special Africa Award of £30,000 ($50,000) based on its 'Management of Toilet Wastes Through Anaerobic Technology' project. His Royal Highness, the Prince of Wales, congratulated Ainea Kimaro on this impressive work that makes a significant contribution to alleviating poverty and helping protect the environment.
Acknowledgements
Hands On would like to thank Ainea Kimaro of KIST for help and advice in putting together this case study.
Special thanks are due to the Ashden Awards for highlighting these
projects and funding the filming
Participating Organisation
Kigali Institute of Science, Technology and Management (KIST)
Avenue de L' Armée,
B. P. 3900, Kigali - Rwanda
Tel: + 250 - 574696/ 574698/ 751927/ 571929
Fax: +250 - 571925/ 571924
E-mail: info@kist.ac.rw
Website: www.kist.ac.rw
Further Information
Ashden Awards
The Ashden Awards reward outstanding, inspirational and innovative local sustainable energy schemes that both protect the environment, tackle climate change and make real improvements to people's quality of life. They are designed to encourage wider take-up of local energy solutions worldwide – proving to the public and policy makers alike that such schemes offer viable, practical ways of tackling poverty, resource shortages and climate change.
Website: http://www.ashdenawards.org/
The Awards are currently looking for applicants for next years awards and
the appropriate information and application form is available on their website.
Resources
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