Biogas as a potential renewable energy source: A Ghanaian case ...

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Author's Personal Copy Renewable Energy 36 (2011) 1510e1516

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Biogas as a potential renewable energy source: A Ghanaian case study Richard Arthur a, *, Martina Francisca Baidoo a, Edward Antwi b a b

Department of Energy Systems Engineering, Koforidua Polytechnic, Koforidua, Box KF 981, Koforidua, Ghana Department of Mechanical Engineering, Kumasi Polytechnic, Box 854, Kumasi, Ghana

a r t i c l e i n f o

a b s t r a c t

Article history: Received 26 May 2010 Accepted 8 November 2010 Available online 3 December 2010

The associated harmful environmental, health and social effects with the use of traditional biomass and fossil fuel has enhanced the growing interest in the search for alternate cleaner source of energy globally. Ghana, a developing country depends heavy on woodfuel as a source of fuel contributing about 72% of the primary energy supply with crude oil and hydro making up the rest. Biogas generation has simply been seen as a by-product of anaerobic digestion of organic waste. Having proven to be a practicable and promising technology, it has been very successful and a very reliable and clean source of energy when proper management programmes are followed. There are vast biomass resources including organic waste in Ghana that have the potential for use as feedstock for biogas production to reduce the over reliance of woodfuel and fossil fuel, and to help reduce the it would reduce greenhouse gas emissions which may be affecting climate change. Ghana having the technical potential of constructing about 278,000 biogas plants, only a little over 100 biogas plants has so far been established. This paper presents the energy situation and the status of the biogas technology and utilization in Ghana. It also presents the potential benefits, prospects and challenges of the biogas technology. Ó 2010 Elsevier Ltd. All rights reserved.

Keywords: Ghana Anaerobic digestion Biogas Climate change Woodfuel

1. Introduction Biogas is generated from organic materials under anaerobic conditions. Feedstocks for biogas generation include cow dung, poultry droppings, pig manure, kitchen waste, grass faecal matter and algae. Countries where agriculture sector is an important component to the growth of economy, have found biogas as a useful replacement for woodfuel and dung as fuel for cooking, and heating. Given increasing oil prices, high health risk associated with unsustainable woodfuel usage and its impact on the environment it is crucial for the government to consider other alternatives which are sustainable and affordable. Biogas technology even though is a well known technology is relatively new in some parts of the world and can be used as a potent tool to address issues of Indoor Air Pollution (IAP), deforestation and Climate Change. Biogas is a clean fuel because it burns without leaving soot or particulate matter and also since it is lighter in terms of carbon chain length, less amount of carbon dioxide is released into the atmosphere during combustion. Biogas technology has helped some countries in many ways through income generation, life-style improvements and cost saving. In this paper we present the status of Ghana’s energy consumption with

* Corresponding author. Tel.: þ233 244 748 252. E-mail address: [email protected] (R. Arthur). 0960-1481/$ e see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.renene.2010.11.012

emphasis laid on the over reliance on woodfuels as source of energy by majority of households. Particularly, the paper presents the historical background and current status of the biogas technology, and attempts to reveal the future potential and challenges in the dissemination of the technology. 1.1. Demography and geography Ghana is a small West African country with an economy traditionally oriented toward agriculture contributing immensely to its Gross Domestic Product (GDP), and small scale domestic trading. Today, Ghana has a thriving gold and timber industry. A former British colony, Ghana uses English as the language of commerce and government. It shares a common border with the Republic of Togo on the east, Burkina Faso on the north, la Cote d’Ivoire on the west and the Atlantic Ocean on the south. The 2000 Population and Housing Census put Ghana’s population at 18.9 m, an increase of 53.8% over the 1984 population of 12.3 m, translating into an intercensal population growth rate of 2.7%. Number of household has been estimated at 3.7 million with an average of 8.7 persons per household [1]. In 2007 Ghana population was estimated at 22.4 million with a female to male population ratio of 1.02. The total land of area of Ghana is 238,533 km2 which projected the population density at 94 persons/km2 in 2007. The country is divided into six agro-ecological zones on the basis of their climate, reflected by the natural

Author's Personal Copy R. Arthur et al. / Renewable Energy 36 (2011) 1510e1516

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Fig. 1. Percentage contribution of primary energy supply in Ghana for 2008 [7].

Fig. 2. Total energy consumption by energy type in Ghana from 2003 to 2008 [7].

vegetation and influenced by the soils. These agro-ecological zones from north to south are: Sudan Savannah Zone, Guinea Savannah Zone, Transition Zone, Semi-deciduous Forest zone, Rain Forest Zone and the Coastal Savannah Zone [2]. 1.2. Economy The agriculture sector drives the Ghanaian economy accounting for almost 86% of household heads involvement and 35% of export earnings since 2000 [2]. Meanwhile the 2000 Population and Housing Census (PHC) showed that about 80% of the economically active population work in the informal sector showing the important role household enterprises play in the economy [3]. The total government expenditures increased from GH¢5624.53 million (40.0% of GDP) in 2007 to GH¢8009.82 million (46.5% of GDP) in 2008 which was mainly the result of high energy-related expenses, infrastructural developments and the social mitigating expenditures [23]. In a United Nations Development Programme (UNDP) document on Human Development Report for 2009, Ghana’s Human Development Index (HDI) value in 2007 was 0.526 where it is placed under the medium human development section and ranked 152nd [30]. About 3.4 million households in Ghana own or operate a farm or keep livestock and more than half of households (1.8 million), which cultivate crops hire labour for their operations. The two most important crops, in terms of sales, are maize and cocoa [3]. 1.3. Status of energy consumption The total energy produced in Ghana in 2000 was 6.2 million tonnes of oil equivalent about eleven and half times the yearly average energy generated by the Akosombo and Kpong hydroelectric power plants1 which rose to 6.8 million tonnes of oil equivalent by 2004 [4]. The bulk of energy supply in Ghana is met from woodfuels, i.e. firewood and charcoal. Woodfuels account for about 71 1% of total primary energy supply and about 60% of the final energy demand [5]. In 2008 woodfuel contributed about 72% of the primary energy supply to the country with crude oil and hydro making up the rest as shown in Fig. 1. In terms of sector wise utilization, the residential or household sector of the economy takes up on the average almost 50% of Ghana’s energy consumption. The significant residential sector share of the Ghana’s energy demand is due to the high usage of woodfuels comprising mainly of firewood (almost 76%) and charcoal [6].

1 These are the only two operational hydroelectric power plants in Ghana; the third is under construction at Bui.

Should the Ghana Poverty Reduction Strategy (GPRS) targets to usher the country into a middle income range of US$1000 per capita in 2015 be realised, demand for woodfuels would grow from about 14 million tonnes in 2000 to 38-46 million tonnes by 2012, and 54e66 million tonnes by 2020 [4]. This increase in demand would put the nation’s dwindling forest under undue stress which could culminate into serious deforestation. The effect of this may subsequently have serious impact on climate change, agriculture and water resources, if no significant action is taken. Since a majority of households, about 80% in Ghana depend on woodfuels for cooking and water heating, the demand for woodfuel has for the past years been on the increase [5]. In addition to the domestic dependence of woodfuels, there is also commercial, industrial and institutional use. As indicated above about 18 million tonnes of fuelwood was used in year 2000. If this trend of consumption continues, Ghana is likely to consume more than 25 million tonnes of fuelwood by the year 2020. Woodfuel has been the predominant energy type that has been consumed in Ghana from 2003 to 2008 as shown in Fig. 2 contributing about 70%, 77.7% and 76.4% in 2000, 2004 and 2008 respectively [7] of the total energy consumed.Ghana’s forest cover has dwindled from 8.13 million hectares at the beginning of the last century to 1.6 million hectares today [2]. According to the UN Food and Agriculture Organisation (FAO), the rate of deforestation in Ghana is 3% per year. In 2000, the annual production or yield of wood was about 30 million tonnes of which about 18 million tonnes was available and accessible for woodfuels [5]. Table 1 shows the main sources of cooking fuels for households in all ten regions in Ghana. The table confirms the heavy

Table 1 Household source of cooking fuel in the regions in Ghana [2]. Region

Fuel type (%) Non-woodfuels

Woodfuels

Electricity LPG Kerosene Agric Others Firewood Charcoal residue Ashanti Northern Upper East Upper West Western Central Gt. Accra Volta Eastern Brong-Ahafo Ghana

0.6 0.1 0.4 0 0.2 0.1 0.3 0.1 0.3 0.1 0.3

7.5 1.3 1.2 1.1 6.3 4.6 29.4 2.3 4.6 2.7 8.5

0.7 0.2 0 0.2 0.3 0.9 2.1 0.4 0.5 0.3 0.7

0.1 0.2 32.8 e 0 0.1 e 0.2 0.4 0.2 1.3

0.7 0.1 0.2 0.3 0.6 0.2 e 0.1 e 0.6 0.5

50.6 81.8 55 80.2 65.2 63.1 7.2 73.2 71.2 77.6 56.6

39.9 16.4 10.4 18.2 27.3 31.1 59.8 23.7 22.9 18.5 32

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Table 2 Profile of selected biogas service providers [2]. Company

Date established

Workforce (full time)

Type of biodigester installed

Number of digesters installed

Biogas Engineering Ltd Biogas Technologies West Africa Limited (BTWAL) RESDEM UNIRECO Beta Construction Engineers Ltd.a

2002 1994

6 148

CAMARTEC fixed dome type, and effluent treatment plants Fixed dome and effluent treatment plants

10 35

1996 2001 1975

Mostly bio-latrine digesters Mostly bio-latrine digesters Puxin biogas digesters

25

5 25

a

12

Although Beta Construction Engineers Ltd appears to be the oldest among the lot, it should be noted that the company only ventured into biogas construction in 2006.

dependence of households on traditional cooking fuels, revealing that an average of 87% of households in Ghana use fuelwood: firewood (56.6%) and charcoal (32%) as their main cooking fuels [2]. 2. Status of biogas technology 2.1. Historical background and current status of biogas in Ghana The conventional use of cow dung as source of fuel for cooking has been a common practice for many years in Ghana. This is predominant in the northern savannah regions where there are usually scarcity of firewood and charcoal for household cooking [2]. Interest in biogas technology in Ghana began in the late 1960s but it was not until the middle 1980s did biogas technology receive the needed attention from government [8]. The government’s intervention in the dissemination programmes before the mid 1980s focused on the provision of energy for domestic cooking [8]. The rapid depletion of the woodfuel resource base coupled with projected increase in the demand for woodfuels in future with its attendant social and environmental effects brought into sharp focus the need for alternative cooking fuels sources to be developed and exploited. The biogas technology was subsequently selected as one such option to curb the incidence deforestation. The first biogas demonstration plant e a 10 m3 Chinese fixed dome digester - was constructed in 1986 by the Ministry of Energy at the Shai Hills cattle ranch in the Greater Accra Region, with the support from the Chinese government. A year later in 1987 the United Nations Children Fund (UNICEF) supported the construction of a couple of domestic biogas demonstration plants at Jisonayilli and Kurugu in Northern region [2]. The Ministry of Energy established one of the first major comprehensive biogas demonstration projects in Ghana - the “Integrated Rural Energy and Environmental Project” at Apollonia, a village located some 46 km from Accra. The Apollonia Biogas Plant which used animal dung and human excreta had a 12.5 kW generator to provide electric power for street and home lighting as well as cooking, while the bio-slurry was used for agriculture [9]. A total of nineteen fixed-dome digesters comprising six 15 m3 and two 30 m3 Deenbandhu digesters, and eight 10 m3 and three 25 m3 Chinese dome digesters were constructed by engineers from the Ministry of Energy (MoE) and the Institute of Industrial Research (IIR) [8,10]. As part of a first step in the planning and development of a nationwide biogas programme, interviews were conducted in 2007 by Kumasi Institute of Technology and Environment (KITE)a local energy NGO. This was done in partnership with the entrepreneurs involved in the construction of biogas plants. During the study period it was observed that a little over 100 biogas plants have been installed in Ghana to date [2]. Majority of the biogas plants are bio-sanitation interventions such as waste/effluent treatment plants and biolatrines, which are largely, located in educational and health institutions in predominantly urban areas [2,8,9]. A survey of 50 biogas plants was conducted in order to ascertain the true state of biogas technology in Ghana. Field visits to

biogas installations were conducted between June, 2008 and February, 2009. The sample size (50 plants) was determined from the population using stratified and convenience sampling techniques [8,10]. Out of 50 installations studied, 22 were in good condition, 10 were functioning even though some defects (including deteriorated gasholders, gas pipelines and appliance) were observed, and 14 were off-line. This was attributed to the following reasons; (i) the owners of the plants were reluctant to spend additional financial resources to maintain the plant, (ii) some service providers do not spend time to take users through the rudiments and the functions of the biogas systems [8]. Following the low involvement of biogas projects by government, a number of private biogas companies have marketed the technology on purely business grounds, and mainly based on the ability of biogas plants to improve sanitation [8]. There are at least 10 biogas service providers who have been actively involved in the design and construction of both domestic and institutional size biogas plants across the country. Table 2 shows the list of selected service providers and the number of plants they have constructed. Though there is no clear-cut strategy for the promotion of the biogas technologies in Ghana [9], a number of systems have been built since 1996 [2]. According to author [4], Ghana government will promote biogas-for-heating in institutional kitchens, laboratories, hospitals, boarding schools, barracks, etc. The Strategic National Energy Plant (SNEP) for Ghana- strategic target is to achieve 1% penetration of biogas for cooking in hotels, restaurants and institutional kitchens by 2015 and 2% by 2020. This document did not mention programs for domestic biogas systems. However, a number of individuals have had biogas digester size ranging between 8 m3 and 12 m3 installed in their homes as an effluent and kitchen waste treatment units [2]. 2.2. Biogas digester design Biogas yield from biodigestion depends on the substrate composition, type of substrate, retention time and biodigester conditions. The average composition of biogas is shown in Table 3. The composition of biogas generated should be determined before use as there is a consequence of the presence of traces of hydrogen sulphide especially when the biogas is used as fuel in internal combustion engines [14]. However, the situation where the biogas

Table 3 Average composition of biogas from different organic residues [14]. Gases

Percentage (%)

Methane (CH4) Carbon dioxide (CO2) Nitrogen (N) Oxygen (O) Hydrogen sulphide (H2S) Ammonia (NH3) Carbon monoxide (CO) Hydrogen (H)

40e75 25e40 0.5e2.5 0.1e1 0.1e0.5 0.1e0.5 0e0.1 1e3


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Fig. 3. Fixed dome digester 1. Mixing tank with inlet pipe. 2. Gasholder. 3. Digester. 4. Compensation tank. 5. Gas pipe.

will be substitute for woodfuel for cooking such as in Ghana where woodfuel share of cooking fuels for urban household averaged about 90% since 2000 [4], the biogas will require no purification as the presence of trace gases will not have any effect on cooking appliances. The three main types of biogas that have been designed, tested and disseminated in Ghana are the fixed-domed, floating drum and Puxin digester [2]. A fixed dome2 plant comprises of a closed, dome-shaped digester with an immovable, rigid gasholder and a displacement pit, also named ‘compensation tank’. The gas is stored in the upper part of the digester. When gas production commences, the slurry is displaced into the compensating tank as shown in Fig. 3. Gas pressure increases with the volume of gas stored, i.e. with the height difference between the two slurry levels. If there is little gas in the gasholder, the gas pressure is low. When gas production starts, the slurry is displaced into the compensation tank. Gas pressure increases with the volume of gas stored and the height difference between the slurry level in the digester and the slurry level in the compensation tank [11]. Floating-drum3 plants consist of an underground digester and a moving gasholder as shown in Fig. 4. The gasholder floats either directly on the fermentation slurry or in a water jacket of its own. The gas is collected in the gas drum, which rises or moves down, according to the amount of gas stored. The gas drum is prevented from tilting by a guiding frame. If the drum floats in a water jacket, it cannot get stuck, even in substrate with high solid content [12]. The Puxin biogas4 digester is a hydraulic pressure biogas digester, composed of a fermentation tank built with concrete, a gasholder made with glass fibre reinforced plastic and a digester outlet cover made with glass fibre reinforced plastic or concrete. The gasholder is installed within the digester neck, fixed by a component; the gasholder and digester are sealed up with water [2] as shown in Fig. 5. The mesophilic temperature range5 for biogas production is 20e40 C [12] and with Ghana annual temperature of 25 C as stated by KITE [2], indicates that most biogas plants in Ghana operate well within mesophilic temperature conditions. 2.3. Biogas energy sources Biogas a clean and renewable form of energy could augment conventional energy sources. Produced through anaerobic degradation in a very complex process and requires certain environmental conditions as well as different bacteria populations

2 3 4 5

The fixed dome digester is a Chinese technology. Floating drum digester is an Indian Technology. Puxin digester is a Chinese technology. Mesophilic temperature range.

Fig. 4. Floating drum digester 1. Mixing tank with inlet pipe. 2. Digester. 3. Compensation tank. 4. Gasholder. 5. Water jacket. 6. Gas pipe.

[8,14,15]. The complete anaerobic fermentation process is briefly described below as shown in Table 4. Biogas energy has some advantages over other energy sources. Successful use of biogas technology can result not only in energy generation and bio-fertiliser production, but also other social and ecological benefits including sanitation, reforestation and reduction of imported fuel oil [16]. In Ghana, identified feedstock substrate for an economically feasible biogas programme includes water hyacinth, dung, cassava leaves, urban refuse, solid waste, agricultural residues and sewage. Cattle, sheep, goat, pigs and poultry are the main livestock produced in Ghana, with the poultry industry being the largest and most successful [2]. These animals produce large amounts of manure, which are suitable substrates for anaerobic digestion and they being the most common substrate for biogas production by anaerobic digestion. Table 5 shows the biogas potential of dung from the various livestock in Ghana for 2006. From Table 5 it can be seen that dung from the livestock produced in Ghana in 2006 could generate about 350 million m3 of biogas. A cursory analysis shows that using the calorific value of the biogas of 22.5 MJ/m3 [14], an equivalent of about 7875,000 GJ or 2,100 GWh6 of energy can be obtained. Due to lack of resources and ability to plan and implement sewage systems, liquid and solid waste management and other sanitation issues are difficult to manage in developing countries, where houses often are built before sewage systems and other infrastructural necessities [19]. According to Refs. [19,20] the problem of waste in Ghana is also a direct result of a growing urban population, the changing patterns of production and consumption, the inherently more urbanized life-style and industrialization. The use of biogas from Municipal Solid Waste (MSW) may not be seen as the only solution for the entire energy problems of the country, but it could improve the environment through the proper waste management, preservation of underground and surface water, creating jobs, poverty reduction and creation of sustainable development [14]. In Ghana it is estimated that the average daily solid waste produced is 0.45 kg per capita per day [20]. An estimated population of 22.9 million in 2007 as quoted by Human development Report for 2009 [30] puts the total generated MSW at 3.73 million tonnes every year. Every organic material can degrade to generate biogas [9,11]. In view of this, the process of degradation of organic material which

6 Calorific value of biogas: 6 kWh/m3 [17] and this corresponds to about half a litre of diesel oil [12].



3.2. Health

Fig. 5. Puxin digester 1. Mixing tank with inlet pipe. 2. Digester. 3. Compensation tank. 4. Gasholder. 5. Gas pipe.

can be found in a landfill is the same as the process in a biogas reactor. The difference is that biogas production from anaerobic digestion takes place in a controlled reactor and at a faster rate due to optimized conditions in the biogas reactor [19]. In addition to that, a study conducted by Netherlands Development Organisation (SNV) also showed Ghana has the technical potential of constructing about 278,000 biogas plants [21] across the country. 3. Potential benefits of biogas in Ghana 3.1. Agricultural In Ghana the agricultural sector has contributed immensely to the growth of the economy. The sector contributed about 33.5% GDP with an annual growth of 5.1% in 2008 [22] with majority of households in Ghana are reliant on agriculture, most of these use manure as their major source of fertilizer. In the 2008 Bank of Ghana Annual Report, real GDP grew by 7.3% in 2008, above both the targeted level of 7.0% and 6.3% achieved in 2007. The growth was driven by improved performance in the Agricultural and Industrial sectors. The growth rate in the agricultural sector jumped from 3.1% to 4.9% in 2007 below the target level of 5% [23]. According to authors [21], farmers in developing countries are in dire need of fertilizer for maintaining cropland productivity. At the same time, the amount of technically available Nitrogen (N), potassium (K) and phosphorous (P) in the form of organic materials is around eight times as high as the quantity of chemical fertilizers actually consumed in developing countries. The effluent from the digester has been proven to be the best fertilizer for farms which provides farmers with an improved organic fertilizer [25] and in addition it can be used on farms as an alternative to chemical fertilizers [24]. The cumulative effect of the use of biogas effluent as organic fertilizer will lead to increased crop production yields. It could eventually reduce the importation of chemical fertilizer hence providing some savings for other economic activities which will improve the Ghanaian economy.

As mentioned earlier about 87% of Ghanaian households use woodfuel as their source of fuel for cooking. There is smoke exposure in the indoor environment as a consequence of using woodfuel as a source fuel in households. It can cause acute respiratory and eye infections on population of all ages and increase infant mortality rates as a result of incomplete combustion. Biogas used as cooking fuel drastically reduces smoke in the kitchen. The burning of biogas therefore noticeably reduces the number of smoke borne diseases for the concerned women or children. Cooking with biogas is a lot easier as it not necessary keep the fire burning, by adding woodfuel constantly. Where human excreta is used as a fertilizer, it should be digested with the other organic substrate before application to the land, as direct handling can spread faecal-borne diseases. The majority of faecal pathogens cause gastrointestinal symptoms such as diarrhoea, vomiting and stomach cramps, while some also cause symptoms involving other organs and severe consequences [26]. 3.3. Employment generation Ghana, having the technical potential of establishing about 278,000 biogas plant as stated earlier, provides enormous opportunities for creating both skilled and unskilled employment. A typical Biogas service provider; Biogas Technologies West Africa Limited (BTWAL) has 148 full time workers as shown Table 2. In addition, the areas of design and manufacture of biogas construction equipments and appliance also provides a relevant opportunity for employment. Areas of research and development to improved biogas systems suitable for the Ghanaian environment and research can be taken on by academic institutions. Not only does biogas technology open market niches for masons, plumbers, civil engineers and agronomists, they are often the most effective promoters of biogas technology [12]. The activities of the over ten biogas service providers have contributed enormously to the creation of employment. 3.4. Environmental Metropolis, municipalities and district assemblies can use biogas technology to solve public waste disposal and wastewater treatment problems. The energy output of biogas digestion is usually not a priority, but may respond to public energy demands such as street lighting, water pumping and cooking in hospitals or schools [12]. Besides, a public convenience visited by about 2000 persons per day would produce approximately 60 m3 of biogas which can run a 10 KVA generator for 8 h a day, producing 65 units of power [27]. The over-dependence and utilization of woodfuels is also known to have contributed partly to deforestation and emission of some greenhouse gases in Ghana. According to authors [2], smoke from cooking fires will release about 7 billion tons of carbon in the form of greenhouse gases to the environment by 2050 in Africa alone.

Table 4 Anaerobic degradation of organic matter [13]. Stage

Substance

Molecules

Bacteria

Initial Intermediate

Manure, vegetable, wastes Acids, gases, oxidized, inorganic salts

Cellulose, proteins CH3COOH, CHOOH, SO4, CO2, H2, NO

Final

Biogas, reduced inorganic compounds

CH4, CO2, H2S, NH3, NH4

Cellulolytic, proteolytic Acidogenic, hydrogenic, sulphate reducing Methane formers


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Table 5 Biogas potential of waste from livestock production in Ghana in 2006. Species

Population (values in 1,000s) [2]

Dry dung output (kg head1 day1) [17]

Total annual dung output (tonnes)

Biogas potential (m3/kg of dung)

Annual Biogas potential ( 103 m3)

Cattle Sheep & goat Pigs Poultry Total

2750 13,297 1463 22,984 40,494

8 1 2 0.08

8,030,000 4,853,405 1,067,990 671,133

0.023 [18] 0.016 [17] 0.04 [18] 0.065 [18]

184,690 77,654 42,720 43,624 348,688

That is about 6% of the total expected greenhouse gases from the continent. By using the biogas generated as fuel, harmful effects of methane7 on the atmosphere reduced. Surface and ground water are significantly protected by confiding waste material which also reduces the exposure of Ghanaians to toxins. By conversion of waste material and dung into a more convenient and high-value fertilizer (’biogas slurry’), organic matter is more readily available for agricultural purposes, thus protecting soils from depletion and erosion [21]. 3.5. Women empowerment and workload reduction Looking at gender issues from both the demand-side and supply-side of energy, men and women have different demands on energy due to the existing socio-cultural and traditional roles. Women mostly do the cooking. They are also heavily involved in fuelwood collection and charcoal production. More time required for firewood collection is another problem associated with the use of firewood. Gender division of labour and environmental degradation are increasing women’s time burdens [4]. Tractors employed on farms are in most cases operated by men and tends to replace the hard task of hand or bullock ploughing. Weeding and harvesting which forms majority of the farms work are done by women. Thus, although, the tractor may improve the family’s overall income, the new balance in the work leaves the women still with their heavy burden. It is estimated that a minimum of two to three mornings a week is spent by many rural women collecting woodfuel. Although the time spent collecting woodfuel may not cost them money in real terms, it has been established that this perpetual toil casts a long shadow over their lives [2]. On a daily basis one just needs to condition the feedstock into a homogeneous form before charging into digester. This involves thorough mixing of animal manure, chopping of kitchen or agricultural residue. The weekly commitment for domestic biogas plants include; cleaning the gas burners and other appliances and manual opening of moisture trap to drain off moisture condensed in the biogas pipeline. To ensure optimum performance of the plant, some monthly recommended maintenance activities must be adhered to, this includes; mixing of swimming and sinking layers in the expansion chamber, checking and filling up of the water in the water jacket of a floating drum digester [11]. Most of these activities occur on the premises of the biogas plant hence the operators do not need to travel unless it involves the replacement of major equipment such as stove, desulphurizer, etc. At the household level, time saved while not fetching firewood could also be used for educational or other productive activities. This consequently will improve the standard of living, provide additional income and enhance the nutritional and health status of the household. Currently in Ghana, male literacy for adults is 20% higher than females’, with a much wider gap of 30% in the Northern regions [29]. Installation of biogas plants

7

Methane has a Global Warming Potential of 21 [28].

will also allow children to attend school who formerly have been too busy looking for firewood. This will therefore bridge the illiteracy gab between males and females. 4. Prospects and challenges Even though there are several opportunities in the biogas sector, there are however challenges that cannot be ignored. An enterprise-centred approach to the large scale deployment of domestic biogas plants in rural Ghana with emphasis on the three northern regions, and the Ashanti Region makes it technically possible for about 80,000 households in the four regions to install at least one 6 m3 fixed dome digesters in their homes to take care of their daily cooking energy needs [2]. There are national programs that can promote its infusion into homes and institutions. The government through the National Community Water and Sanitation Programme (NCWSP) has a medium to long term national strategy to extend safe water and improved sanitation facilities to rural communities and small towns in Ghana. The NCWSP indirectly provides a platform for biogas production through the Community Water and Sanitation Agency (CWSA).The CWSA is committed to delivering close to 1,100,000 latrines in households, communities and institutions as part of ‘its strategy for breaking the cycle of transmission of excreta-related disease’. However, the Energy for Poverty Reduction Action Plan for Ghana (EPRAP) document by KITE [31], proposed that up to 50% of institutional latrines (approximately 800) and 20% of the communal latrines (1670) should be constructed as biolatrines and the associated benefits include the use of the digested waste as a fertilizer. In Africa, biogas technology dissemination has been relatively unsuccessful. This is attributed to failure of African governments to support biogas technology through a focused energy policy, poor design and construction of digesters, wrong operation and lack of maintenance by users. In addition, poor dissemination strategies, lack of project monitoring and follow ups by promoters, and poor ownership responsibility by users [8] have also lead to the dissemination challenges. Even though biogas is capable of solving some of the energy and environmental problems of the poor rural populations, urban communities and industrial estates, there is usually a high investment requirement. The major problem of rural cattle farmers face lies with the inability to afford the full cost of biogas plants. For example in 2009, the average investment cost of a 10 m3 biogas plant ranged from $2800.00 and $4200.00. These figures are far above the financial capability of the rural farmer [8]. Other social and cultural convictions such as ethnical barriers, poor monitoring and maintenance culture and stigmatization in the use of digested human excreta as fertilizer can potentially affect the dissemination and should not be overlooked. 5. Conclusion The penetration of biogas technology into the Ghanaian economy though will contribute immensely; there are however, potential technical, economic and socio-cultural challenges that must not be



overlooked. The benefits it provides to the country are environmental sustainability, improved health and increase in agricultural productivity inter alia. It goes further to reduce the workload of women in households providing avenues for other social and economic benefits when proper programmes are followed. Implementation of biogas technology will support the global climate change mitigation interventions through methane capture. Some of the recommendations suggested to overcome the financial component of biogas technology dissemination programme are the introduction of financial incentives such as soft loans and subsidies at the initial stage. The government can also provide support to local energy Non-governmental Organizations (NGOs) such as KITE and Centre for Energy, Environment and Sustainable Development (CEESD) who will then provide periodic technical and financial support to domestic biogas owners. Though Ghana has no national biogas technology dissemination programme, global challenges such as Climate Change, dwindling oil reserves rapid increase in oil price, poor waste disposal practices occurrence of extremely poor sanitation in rural and urban areas, rapid loss of vegetation cover, and effect of conventional approach in using woodfuel for domestic activities, would encourage the development and promotion of such interventions. The targeted groups for biogas technology dissemination should be stratified into three levels; the national, regional and community level. These levels play a role in the dissemination of the technology but they should be approached differently. In addition intensive educational and campaign programmes, and a well developed institutional framework will be required for the overall success of a biogas technology programme in the country.

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