Alternative energy sources to combat climate change: Biogas production using cost effective material

The shortage of energy in rural areas and the pollution of the environment from animal wastes due to lack of appropriate technology in Africa motivated the author to conduct research and write this book. In this research book an economically feasible, technically acceptable and environmentally friendly biogas plant is designed by using low cost plastic materials. This book is an essential reference for chemical engineering, environmental engineering and agricultural students. The concept solves global environmental pollution and the problem of lack of energy and organic fertilizer in rural communities at once. Moreover, this book plays an important role for agricultural researchers working in rural energy and environmental protection.



Text sample:

Kapitel 2.3, Theory of Biogas Technology:

Biogas technology refers to the production of a combustible gas (called bio- gas) and a value added fertilizer (Called sludge) by the anaerobic fermentation of organic materials under certain controlled conditions of temperature, pH, HRT, C:N ratio etc. A typical bio-gas plant consists of input unit for feeding the fermentable mixture, a digester where anaerobic fermentation takes place, a gas holder for collecting the bio-gas and to cut off air to the gas outlet pipe and out put unit for removal of fermented slurry (Vandana, 2004). The plant operates on the principle that when dung and other organic materials are fermented in the absence of air, combustible methane gas is produced (Vandana, 2004).

According to Grewal et al.(2000),biogas usually contains 50-65% methane (averaging 60%), 30-40% carbon dioxide (averaging 36%),1-5% of hydrogen,1% nitrogen, 0.1% oxygen, ,0.1% hydrogen sulphide and 0.1% water vapours (H2O).

2.4, Benefits of Low- Cost Plastic Biodigester Technology:

Global level: - Using biogas for cooking reduces the need for fuel wood and charcoal. Studies conducted by a Tanzania local energy NGO indicates that every 8 households clear fell one hectare of forestry each year through charcoal consumption alone (SURUDE,2002). When other causes of forestry destruction are added such as fuel wood, agriculture, construction and mining, deforestation rate in Tanzania is estimated at between 300,000 hectares and 400,000 hectares per year. Studies have further shown that each biogas unit is able to reduce scale of deforestation by 37 hectares per year. Since, it also uses cow dung that would otherwise have degraded, further green house gas emissions are avoided. This is realized by adapting to biogas in place of fuel wood and charcoal for cooking & heating (SURUDE, 2002).

National level:- Bio-gas helps to save foreign currency which is spent on kerosene and chemical fertilizers. Researchers have estimated that 5 lakh bio-gas plants will have 750 million liters of kerosene per year and provide 12 million tones of organic manure. Biogas helps in reducing the need for expensive energy distribution in rural areas. Due to inefficient distribution system almost 20 percent of the powers are lost during transmission. Biogas system would help in preventing the denuding of forests in a careless manner by the villagers for fire wood requirements. Today deforestation being a serious threat to environment in large parts of the country, as it is followed by the danger of soil erosion and several other ecological imbalances (Vandana, 2004).

Local level: - Reduced deforestation helps preserve forests and all of the services they provide, such as biodiversity and maintenance of water quality. In addition, the promotion of agro forestry practices in conjunction with livestock helps protect soil fertility, prevent erosion, and reduce the risk of overgrazing problems often associated with cattle (Duong et al., 2002).

Poverty Alleviation:- Biogas production integrated with cattle raising and farming provides a reliable source of cleaner fuel as well as increased in come and employment opportunities. Therefore, increased incorporation of cattle in to farming methods increases employment opportunities there by stimulating rural economy. The production of biogas also produces slurry that is very effective as a fertilizer. Farmers have effectively used it in agro forestry farming. Studies by Sokoine Agricultural University in Tanzania have shown that the use of this fertilizer helps maintain soil quality over time, there improving crop yields (SURUDE, 2002).

Poverty reduction through improved health:-Respiratory diseases and sometimes deaths caused by indoor pollution as a result of prolonged exposure to smoke from fuel wood and charcoal is avoided when biogas is used for cooking (Vandana, 2004). The utilization of biogas freed the house wives from eye- sore, eye and lung diseases. The use of bio- gas as a domestic fuel can be a thrilling experience for a house wife (SURUDE, 2002).

Reduced drudgery: - Women and children do not have to spend as much time looking for firewood. Cooking with biogas is also faster than with firewood. As a result, the drudgery and workload of women is lessened. Cooking by using a biogas cooker is easy and fast, this has two implications. On one hand it has reduced fuel wood collection and pollution laden cooking tasks on the part of women. On the other hand it has increased gender equity by involving men in domestic chores. Projects that provide direct benefits to woman are usually sustainable (SURUDE, 2002).

2.4.1, Environmental Benefits of Biogas Technology:

Biogas does not contain toxic carbon monoxide so no danger to health and no offensive odour, reduction in pollution as BOD and COD and facial pathogens are considerably reduced and environment improvement in rural area reduces illness and build up people’s health. Besides, in regions where biogas is used to generate electricity, cultural, recreation and spare time study conditions can also be improved. (Duong et al., 2002).

2.4.2, Social Benefits of Biogas Technology:

Biogas development brings about social benefits. As the problem of fuel for the farmer's daily use is solved, trees are protected and forests are developed. The protection of trees and increase in vegetation areas can reduce soil erosion and improve ecologic balance. The increase in organic manure can result in using less chemical fertilizer, improving soil and increasing production (UNV, 1983). Therefore, the use of plastic biogas plant saves the time that can be used for wage work, consumption of conventional energy sources for cooking, lighting or cooling and substitution of digested slurry in place of chemical fertilizers and / or financially noticeable increased in crop yields.



Bezabih Yimer (M. Sc.) grew up in Dessie, Ethiopia. He studied Land Resource Management at the Mekelle University and graduated 2001 with the Bachelor of Science. After he finished studying Agricultural Engineering and Mechanization at the Mersa Agricultural College with the degree “Master of Science” in 2008, he started working as a lecturer and natural resource utilization department head at the Mersa Agricultural College.