Determining the superiority and amount of Biogas produced from different Ugandan feedstock.

Determining the superiority and amount of Biogas produced from different Ugandan feedstock.

Introduction.

Biogas refers to a gas made from anaerobic digestion of agricultural and animal waste. Also Biogas refers to a colorless gas made from anaerobic digestion of organic agricultural waste and animal manure; it burns with a clear blue flame similar to LPG gas, thus it is useful as a fuel substitute to firewood, manure, agricultural residues, diesel, and petrol. Its by-product (slurry) can be used as an organic fertilizer to boost agriculture hence promoting food security in a community. Biogas can also be used to run a generator to produce electricity.

Biogas originates from bacteria during the process of bio-degradation of organic materials under anaerobic (without air) conditions. The natural generation of biogas is an important part of the biogeochemical carbon cycle. Methanogens (methane-producing bacteria) are the last link in the chain of micro-organisms that degrade organic materials and return the decomposed products to the environment. It is in this step of the biogeothermal carbon cycle that biogas, a source of renewable energy, is generated.

 Farming is the major rural activity in Uganda, but this does not generate sufficient income. As in most of Africa, fuel wood and charcoal are the primary sources of energy for Uganda’s rural and urban population. On average each rural household spends ten hours per week searching for fuel wood. In urban or peri-urban areas, households spend considerable amounts of money on fuel wood and charcoal. Consumption of charcoal and fuel wood is a serious factor in deforestation, air pollution and carbon diox­ide emissions. When all forest uses are included, the deforesta­tion rate in Uganda is around 100,000 hectares per year. In addition, Uganda’s 15 million cattle also produce greenhouse gas emissions; dung that is left to degrade produces significant amounts of methane and carbon dioxide.

Problem Statement;

According to the renewable energy policy for Uganda, Uganda’s forest resources are an essential foundation for the country’s current and future livelihood and growth and over 90 percent of the energy consumed is obtained from the forests for cooking. This leads to deforestation and high carbon dioxide (CO2) emissions in the atmosphere.

Furthermore, the burning of wood and charcoal leads to serious indoor air pollution, which is especially for women and children a health risk. The use of biogas for cooking can reduce deforestation, carbon dioxide (CO2) emissions and indoor air pollution, since burning biogas is much cleaner than burning wood and charcoal.

The energy deficit in poor household results in practical setbacks such as inadequate lighting (paraffin lamps, candles or wood fires), inadequate cooking fuel and thus fewer hot, cooked meals. The setbacks caused by energy poverty in turn have consequences in the standard of living of the poor through illness on a more frequent basis (with consequences on income), difficulty in doing schoolwork and so on. Access to clean and convenient energy services are therefore vital to the alleviation of poverty.

Therefore, biogas is an essential component for socio-economic development. Poverty shows itself in a number of ways, and is particularly evident and can have drastic consequences in energy affairs. The inability to access convenient, clean, energy services leads to outcomes that make it harder for those trapped in poverty to escape it. The effort and time often associated with the utilization of low quality fuels and energy conversion technologies decreases the overall productivity of households and communities. The cost of cooking and lighting energy in households, large institutions (schools, prisons, hospitals etc) is very high. In these institutions, there are potential sources of organic matter from either meals prepared/waste product (like peelings, mowed grass, leaves from trees) which are susceptible to ferment for biogas production. Biogas would reduce the wastage of organic waste like vegetable and slaughter remains and transform it into energy and fertilizer. Also, the impact on the natural resources would be limited as firewood is substituted by biogas for cooking. Biogas as a renewable energy source could be a relative means of solving the problems of rising energy prices, energy deficit, waste management and in the long run creating sustainable development.

Energy is an essential ingredient for socio-economic development and economic growth. From the foregoing, it is clear that energy is an essential input to all aspects of modern life (Prenma consulting, 2010). If the use of biogas in Uganda could be propagated, it would ensure more energy autonomy at rural, semi-urban and urban locations.

Major Objective:

The main objective of the project is to identify among the different available local feed stocks in Uganda (banana peels, rice strays, pineapple waste, cow dung, pig dung, and maize stocks) the best for Biogas production in terms of quantities and quality of the gas produced.

Specific Objectives:

• To design a prototype biogas digester for laboratory use, that can easily be transformed to suit rural, semi rural and urban settings. Thus, this work will focus on building biogas plant prototypes which will use selected feedstock available in Uganda and testing the quality and quantity of biogas produced.  
• Identifying Feed stocks (banana peels, rice strays, pineapple waste, and maize stocks) available in Uganda; location and quantities of the feedstock will be recorded since different feedstock varies in their physical, chemical and biological characteristics, and biogas potential.
• To design a method for shredding the selected feedstock available in Uganda. The shredding method will be used to reduce the size of the feedstock before fermentation.
• Fermentation of the identified feedstock to produce biogas.
• Measuring the quantities/amounts of biogas produced by the different feedstock 24 hour.
• Determine appropriate amount of biogas from each feed stock needed in cooking given amount of food as a measure for the quality of the produced biogas.

Hypothesis

Different feedstock materials of the equal quantities produce different quantities and quality of biogas

Justification

Biogas technology offers a good potential energy option for Uganda through its various advantages. The promotion of biogas plants supports the achievement of the millennium development goals in Uganda in the following ways:

MDG: 1 Eradicate extreme poverty and hunger; Reduce extreme poverty by half Biogas plants reduce financial and economic costs expended on fuel for cooking and, to a lesser extent, also lighting. The produced bio-slurry is a potent organic fertilizer and may reduce the use of chemical fertilizer. In general, biogas households are not typically the ones in developing countries that suffer from extreme poverty, although many of them are poor. However, the biogas dissemination process and the resulting reduced claim on common ecosystem services do affect the livelihood conditions of (very) poor non biogas households through:  Construction and installation of biogas creates employment. Also Biogas saving on the use of traditional cooking fuels increases the availability of these fuels for (very) poor members of the community.

MDG 3: Promote gender quality and empower women; Eliminate gender disparity in primary and secondary education. Women and girls predominantly spend time and energy on providing traditional energy services. Housekeeping and absence of proper illumination creates barriers for women and girls in accessing education and information, as well as their mobility and participation in ‘public’ activities. Domestic biogas reduces the workload – collection of firewood, tending the fire, cleaning soot of cooking utensils - by two to three hours per household per day. Biogas illumination is highly appreciated for lighting, facilitating reading / education / economic activities during the evening.

MDG 7: Ensure environmental sustainability

Domestic biogas can help to achieve sustainable use of natural resources, as well as reducing greenhouse gas (GHG) emissions, which protects the local and global environment. Application of bio-slurry improves soil structure and fertility, and reduces the need for application of chemical fertilizer. Use of biogas can halve the proportion of people without sustainable access to safe drinking water and basic sanitation. Biogas reduces fresh water pollution as a result of improved management of dung. Connection of the toilet to the biogas plant significantly improves the farmyard sanitary condition.

MDG 6: Combat HIV/AIDS, malaria and other diseases

The target of MDG6 is to have halted by 2015 and begun to reverse the incidence of malaria and other major diseases. Half of the world’s population cooks with traditional (mostly biomass-based) energy fuels whose collection becomes increasingly cumbersome. Indoor air pollution from burning of these fuels kills over 1.6 million people each year (The World Health Organization), out of which indoor smoke claims the lives of nearly one million children under age five per year. Diseases that result from a lack of basic sanitation, and the consequential water contamination, cause an even greater death toll, particularly among young children: Biogas stoves substitute conventional cook stoves and energy sources, virtually eliminating indoor smoke pollution and, hence, the related health risks (e.g. respiratory diseases, eye ailments, burning accidents). Also Biogas significantly improves the sanitary condition of the farm yard and its immediate surroundings, lowering the exposure of household members to harmful infections generally related to polluted water and poor sanitation.

Methodology

Design the prototype biogas digester

Design and build affordable prototype biogas digesters for fermenting different feedstock; this should be simple and easy to operate.

 Capacity of the prototype digesters (6) will be 10 liter, with diameter of 60 cm and height of 90 cm. They will have an inlet (influent) and outlet (effluent) pipes, gas pipes, gas holder (gas collection bag), water traps (to control pressure) and gas burners.

The pilot plant (prototype biogas digesters) will be located at Faculty of Science, Kyabogo University where it will be monitored and all the necessary parameters recorded (quality and quantity of gas produced from the individual feedstock).

Sketch of a proposed biogas digester is shown below

Six 50 liter plastic buckets will be purchased with all the required pipes and accessories. A circular hole of about two inches will be made at the lower part (ten centimeters from the bottom) of the poly tank, this is where the inlet 1 inch PVC pipe will be fixed. Another hole of about 2 inch will be made on the opposite side of the poly tank for the outlet PVC pipe.

A gas pipe with its accessories will be fixed at the top of the digester and then connected to the gas storage bag. Please, refer to the budget for the needed materials.

 Assumptions

Digester of 50 liter capacity can produce biogas required for quantity and quality establishments.

Life span of the digester is at least 4months

Rate of biogas production depends on several factors (temperature, type and nature of feedstock, pH, C/N, TS, VS)

1 kg of feedstock banana peelings can produce 0.1 m3 of biogas; m³ is a cubic meters (a unit of measure)

 Retention time for each feed stock for example banana peelings is 20 days Retention time: This is the average length of time the liquid influent remains in the digester for treatment. Retention time varies with feedstock and digestion temperature; precooked feedstock needs short retention time compared to raw feedstock and manure.

Determine appropriate amount of biogas for cooking 250ml of water as a measure for the quality of the produced biogas.

Appendex

Budget

Materials needed for a biogas  project
material	Units	Unit cost	Amount(UGX)
PVC Bucket diameter 96 cm, height 88 cm 50 L capacity	6	40,000	240,000
Plastic funnel	2	1000	2000
Sealant (to seal all connections etc )	36	2500	90,000
Contingencies
Gas pipe, 1.905 cm diameter, length 6 m	6	20,000	120,000
Flexible rubber tube (5 m)	6	10,000	60,000
Valves	12	2000	60,000
Fittings	12	2000	60,000
Gas storage bags	6	20,000	120,000
feedstocks and water for 3  months			200,000
Casual Labour for  2  months	2	100,000	400,000
Gas meters	6	30,000	90,000
Communication for 3 months		30,000	30,000
Stationary (paper, printing, pens etc)		50,000	50,000
Transport for 3 months		50,000	50,000
Liquid soap	10 L	3,000	30,000
Hand towels	10	2000	20,000
Gloves	1 box	50,000	50,000
Heat resistant rubber tubes	6	10,000	60,000
Shredder	1	50,000	50,000
Apron	3	3000	9000
Miscellaneous		100,000	100,000
Grand Total			UGX

Project plan

It is estimated that the project will take about 16 weeks. A detailed schedule is provided below.

Project plan
Activity/Time in week	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16
Purchasing materials
Identifying feed stock
Designing of a prototype digester
Designing a shredding method
Feedstock Fermentation
Measuring Quantities of Biogas produced
Measuring quality of Biogas produced
Data Analysisi
Report Writing, printing and Handling in