DESIGN AND FABRICATION OF A MEDIUM-SIZED HOUSEHOLD BIOGAS PLANT
1.1 BACKGROUND OF THE STUDY
Energy is one basic tool for development. Its application ranges from domestic uses to industrial applications for heating furnaces, lighting and running electric motors and other transport applications. It can thus be referred to as a cornerstone of economic and social development (El-Saeidy, 2010). Due to over-dependence on biomass and fossil fuel, developing countries like Nigeria face added dilemmas regarding environmental protection. Adaramola and Oyewola (2011) opined that Nigeria is endowed with huge volume of conventional energy resources (crude oil, tar sands, natural gas and coal) as well as reasonable amount of renewable energy resources (e.g. hydro, solar, wind and biomass). However, there is energy shortage in Nigeria because of less potential energy to harness, making hydropower a less desirable energy source (Okoye, 2007). Projected refining capacity only supports 445,000 barrels a day and actual output of these refineries is far below capacity (Okoye 2007).
Scarcity of petroleum and coal threatens supply of fuel throughout the country. This and problems associated with poorpetroleum products combustion has led to research on renewable energy resources. Solar energy, wind energy, different thermal and hydro sources of energy, biogas are all renewable energy resources. Biogas is distinct from other renewable energiesbecause of its unique characteristics of using, controlling and collecting organic wastes and at the same time producing fertilizer and water for use in agricultural irrigation. Biogas does not have any geographical limitations it does not require advanced technology for producing energy.It is very simple to use and apply(Okafor., 2010).
Fossil fuel is one of the principal sources of energy. 86% of all the energy consumed comes from fossil fuels(Kaliyan and Morey , 2009). There are many problems associated with fossil fuels such as high costs and fluctuation of prices, increase in demand, disruption in supply, and environmental pollution. These problems arise because fossil fuels give off carbon dioxide when burnt thereby causing a greenhouse effect. It is therefore a major contributory factor to global warming experienced today.
Agricultural residues and animal wastes are increasingly being diverted for use as domestic fuel to displace fossils fuel and reduce environmental pollution and reduce emission of greenhouse gases. Cassava solid wastes, amongst other plant wastes have been widely used(Oladeji, 2012). Agricultural residues in their natural forms cannot yield desired result as they are mostly loose and are of low density. More so, their combustion cannot be effectively controlled (Oladeji, 2012). Agricultural residues are thus combined with animal wastes and used in production of biogas.
Biogas is a mixture of methane and carbon dioxide, produced by the breakdown of organic waste by bacteria without oxygen (anaerobic digestion). It contains methane and carbon (IV) oxide with traces of hydrogen sulphide and water vapour. It burns with pale blue flame and has a calorific value of between 25.9-30J/m3 depending on the percentage of methane in the gas. Biogas production is a profitable means of reducing or even eliminating the menace and nuisance of urban wastes in many cities in Nigeria. Consequently, biogas can be utilized in all energy-consuming applications designed for natural gas.
1.2 PROBLEM STATEMENT
Energy consumption in Nigeria increases on a relatively high rate. On a global scale. (Iywayemi, 2011)Opined that the Nigerian energy industry is one of the mostinefficient in meeting the needs of its customers. Poor energy supply has led to energy scarcity and fluctuation in prices. This is most evident in the persistent disequilibrium in the markets for electricity and petroleum products, especially kerosene and diesel. The dismal energy service provision has adversely affected living standards of the population and exacerbated income and energy poverty in an economy where the majority of the people live on less than 2USD a day.
Coupled with high level of environmental pollution and contamination as a result of present poor management of solid wastes, call for the design and fabrication of a simple, low cost and effective device for the management of the selected solid wastes on one hand and production of fuel (Biogas) on another hand. Anaerobic fermentation is a simple and low cost process which can be economically carried out in rural areas where organic wastes are generated aplenty which otherwise pollute environment and pose health hazards (Labatut A. , 2011).
Unfortunately, biogas technology has not been optimally used on large scale in Nigeria compared with the level as obtained from reports in other countries as China, Korea and Philippines. According to Ezeokoye et al (2013) there is need to popularize biogas technology in Nigeria in view of large population of brewery plants and agricultural. This is to provide effective utilization of brewery effluents and good check of environmental pollution caused by its disposal. This project is therefore meant to come up with a prototype design and fabricated unit that will optimally produce biogas for household in Delta state and Nigeria as a whole.The large quantities of agricultural residues produced in Nigeria can play a significant role in meeting her energy demand.
1.3 AIM AND OBJECTIVES OF STUDY
1.3.1 Aim of the Study
The aim of this project is to design and fabricate a medium sized household biogas plant, the developed plant will operate on animal wastes, household waste and any other decomposable waste as feeds.
1.3.2Objectives of the Study
The specific objectives are to:
To collect waste from bioorganic raw materials. Optimization and characterization of substrates. To design and fabricate a prototype biogas plant for household use. To test the biogas machine with the optimal solution. To produce manure as by-product of the process that can be used for backyard farming.
1.4 Justification for the Research
Biogas is a form of energy produced when organic materials such as animal excrement or products that are left over from agriculture are fermented easily and at low cost. The advantage of biogas is that it replaces other energy sources for example charcoal, firewood, electricity, liquid petroleum gas and oil. After animal excrement had been fermented in the gas plant it becomes a good quality and odorless substrate, which is better than fresh manure in improving the soil for the agriculture. As an energy source, it prevents deforestation and animal excrement from causing pollution, smell, flies and water pollution in the community. Further, problem of agricultural waste disposal is posing challenges to the farmers and to the general public as this waste constitutes a nuisance to the environment andis an eyesore to the public. Therefore if these wastes could be used to generate energy, it would be a welcomed solution to the problem of waste pollution, disposal and control (Enweremaduet al., 2008a).
Nowadays the use of bio-gas has spread from small farms to big animal farms. It is expected that biogas will be a significant source of energy in the future to preserve the environment, solve the pollution problem and to promote better health to agriculture and community.
1.5 Scope of the Study
This study is limited to the production of biogas from cow dung from Uti cattle market, chicken droppings from the poultry section (deep litter) in Agbarho, Delta State.
2.0 LITERATURE REVIEW
2.1 HISTORICAL DEVELOPMENT OF ANAEROBIC DIGESTION TECHNOLOGIES
Historical evidence indicates that the anaerobic digestion process is one of the oldest technologies. Very old sources indicate that using wastewater and so-called renewable resources for the energy supply is not new but were already known before the birth of Christ. (Monnet F, 2011). The first allusion to animal manure comes from Humphrey Davy, who reported early in the nineteenth century the presence of this combustible gas in fermenting farmyard manure. Davy is known for the invention of the miner’s safety lamp.
However, the industrialization of anaerobic digestion began in 1859 with the first digestion plant in Bombay. By 1895, biogas was recovered from a sewage treatment facility and used to fuel street lamps in Exeter, England (Monnet, 2011). Research led by Buswell (Monnet,2011) and others in the 1930s identified anaerobic bacteria and the conditions that promote methane production. As the understanding of the anaerobic digestion process and its benefits improved, more sophisticated equipment and operational techniques emerged. The result was the use of the closed tank, heating and mixing systems to optimize anaerobic digestion.
In 1900 a methane (biogas) generating plant from human wastes was constructed in a leper asylum in Matunga, India. In the years around 1940, many municipal sewage treatment plants in the United States and elsewhere were already employing anaerobic “digestion” as part of the treatment of municipal waste and thereby generating methane which was used to generate electricity for the plant. This indicated that for pollution control, the anaerobic digestion process is proven effective with additional benefits in the form of a supply of a useful gas(Mindy, 2013). In Indonesia, fixed dome type biogas plants of 18m3 capacity with biogas purification plant have been constructed across communities. Efforts are on to develop the technology to the level of gas bottling and electricity generation,(Widodo & Hendriadi, 2014).
In Kaunas – Lithuania, the Rokai pig farm biogas plant operates on a daily 60m3 of manure from 11,000 pigs. The produced biogas is by co-generation converted into electricity and heat. About 600m3 of biogas is produced per day and 2,400kwh of electricity per day (Maramba, 2014). Carrasco et al. (2011) studied the feasibility of dairy cow waste being used in anaerobic digestive systems. Because the animal’s wastes are more reactive than other cow wastes, the study suggests dairy cow wastes should be chosen over other animal wastes.
As Taleghani and Kia (2005) observed, the resource limitation of fossil fuels and the problems arising from their combustion has led to widespread research on the accessibility of new and renewable energy resources. Solar, wind, thermal and hydro sources, and biogas are all renewable energy resources. But what makes biogas distinct from other renewable energies is its importance in controlling and collecting organic waste material and at the same time producing fertilizer and water for use in agricultural irrigation. Biogas does not have any geographical limitations or requires advanced technology for producing energy, nor is it complex or monopolistic..