**5.1 Biogas technology**

58 Renewable Energy – Trends and Applications

Renewable energy exploitation in the country is still at an initial stage with a limited number of project developers, promoter's finance providers; services contribute less than 1% of the energy balance. Biomass within the renewable energy section accounts for more than 89% of the cooking resource in rural Tanzania, but the budget allocated by the Government for renewable energy services including biomass is limited to less than 1% of the annual

Nevertheless, renewable energy applications in the country have a good potential for powering development goals considering their local availability potential, the limited

Renewable energy will be a catalyst of rural development in the near future. It will play a major role in generation of electricity to spur quick rural electrication. However this, will be accomplished if the existing technologies are improved and new affordable technologies are developed. The following technologies are result of the assessment process conducted in the country from 2006 to 2010 by the author. Some of the technologies are old but need improvement to increase their efficiencies. New technologies need testing and commissioning.

**[m3/sec]** 

**Capacity [kW]** 

energy development budget of the Ministry of energy and Minerals (MEM).

energy per capital consumption and ever-hiking prices of imported fossil-fuel.

**S/No Site River Load Centre Head[m] Discharge** 

Table 12. Identified Potential River sites [Source REA-March 2010]

1 Sunda Falls Ruvuma Tunduru 13.5 26 2x3,000 2 Kiboigizi Kitanga Karagwe 90 3.8 3,200 3 Kenge Ngono Bukoba 10 24 2,400 4 Luamfi Luamfi Namanyere 40 9 1,200 5 Mkuti Mkumti Kigoma Rural 23 3.3 650 6 Nakatuta Ruvuma Songea 67.8 50.3 1,500 7 Mtambo Mtambo Mpanda 17 13.5 2,000 8 Lumeme Lumeme Mbinga 301.2 1.31 4,200 9 Ngongi Ngongi Ruvuma 270.7 1.09 3,100 10 Luwika Luwika Mbamba bay 359.5 1.5 5,800 11 Mngaka Mngaka Paradiso 15 7.64 900 12 Songwe Songwe Idunda 75 1.5 720 13 Mngaka Mngaka lipumba 25 4.424 870 14 Kiwira Kiwira Ibililo 20 10 1,350 15 Prison kiwira Natural Bridge 30 12 3,000 16 Kitewaka Kitewaka Ludewa Township 50 9.884 4,200 17 litumba Ruhuhu Litumbaku Hamba 8 59 4,000 18 Mtigalala Falla Lukose Kitonga 70 10 5,000 19 Kawa Kawa Kasanga/Ngorotwa 65 0.3 130 20 Ijangala Ijangala Tandala 80 6 500

Recent studies show that, more than 6,000 domestic biogas plants have been built countrywide for domestic and commercial applications. However, as these new technologies get rolled out to more remote areas, especially biogas they invariably encounter more isolated local cultures. For example in predominantly Muslim households it is difficult to convince the community to use pig dung to generate energy. Studies have revealed that pig dung is more efficient fuel than cow dung.

Hundred of tones of livestock dung across the country generated by cattle went unused every year, adding to that for example, The National Ranching Company Ltd (NARCO), has 10 ranches with about 33,000 animal units and proximity to around 55 Villages with a total population of around 156,900 individuals, who are also engaged in the livestock industry. With new innovations in more effective way bio-mass and bio-fuels, the hundreds of tones of cow-dung left over on the grazing land is a resource which could make a difference in the livelihood of the communities close to the ranches as a source of energy and fuel.

The use of bio-gas will reduce deforestation which contributes to global warming, leads to reduction in rains thus leading to low crops and vegetation growth and eventually reduction in crop and livestock production.

Biogas is a cheap [source of energy] when compared to other sources because it uses organic matter such as vegetables and animal waste. Bio gas turned into electricity will improve the quality of life for communities within and around the ranches. Biogas project helps to reduce waste, bacteria and waste odour and clean up the environment. Bio gas based electricity could be linked with solar powered electricity as a hybrid system in order to promote decentralized power systems and consequently enhance energy security.

Dar es Salaam Institute of Technology (DIT) has developed a portable biogas plant made from plastic containers which can be used by rural households. The scheme is shown in Figure 4 and is cheap and affordable. Besides DIT, Small Industries Development Organisation (SIDO), GAMARTEC, VETA, and private enterprises are researching and developing biogas plants for domestic and institution applications.

Fig. 4. A biogas plant using plastic containers (Source DIT R&PGS-2011)

Biogas is a feasible option for the domestic energy needs of Tanzania's rural population and offers the following socio-economic and environmental advantages


### **5.1.1 Improved stove technology**

Tanzania has about 35 million hectares of forests; of which about 38 percent of total land areas (13 million hectares) are protected forest reserves and the remaining 62 percent are forests on public land in village areas that are under pressure from human activities including harvesting for energy. Forest and trees in farmlands contribute to wood fuel supply. However, supply of wood fuel is declining rapidly in the country causing scarcity of energy to rural and semi-urban low-income families and environmental degradation in areas where harvesting of wood fuel exceeds the growing stock potential.

Much of the research and development work carried out on biomass technologies to serve the rural areas has been based on improvement of available traditional stoves. This was initially in response to the threat of deforestation but has been focused on the needs of women to reduce fuel collection time and improve the kitchen environment by smoke removal.

There have been many approaches to stoves improvement, some carried out by local institutions, individuals and others as part of wider programmes run by international organisations.

Some of the features considered in improving the stoves include:

An enclosed fire to retain the heat

60 Renewable Energy – Trends and Applications

Organisation (SIDO), GAMARTEC, VETA, and private enterprises are researching and

developing biogas plants for domestic and institution applications.

Fig. 4. A biogas plant using plastic containers (Source DIT R&PGS-2011)

 improves sanitation in the home, farmyard and surrounding environment eliminate respiratory and eye diseases caused by indoor air pollution

save time for women and children because they don't need to collect firewood

produces an effluent called bio-slurry which is an excellent organic fertilizer

areas where harvesting of wood fuel exceeds the growing stock potential.

offers the following socio-economic and environmental advantages provides a low cost energy sources for cooking and lighting

create rural employment

reduce deforestation

reduces greenhouse gas emission

**5.1.1 Improved stove technology** 

Biogas is a feasible option for the domestic energy needs of Tanzania's rural population and

Tanzania has about 35 million hectares of forests; of which about 38 percent of total land areas (13 million hectares) are protected forest reserves and the remaining 62 percent are forests on public land in village areas that are under pressure from human activities including harvesting for energy. Forest and trees in farmlands contribute to wood fuel supply. However, supply of wood fuel is declining rapidly in the country causing scarcity of energy to rural and semi-urban low-income families and environmental degradation in


Designs of stoves depend on the form of biomass providing energy. Improving a stove design is a complex procedure which needs a broad understanding of many issues. Involving users in the design is essential for a thorough understanding of the user's needs and requirements of the stove. The stove is not merely an appliance of heating food, but in rural context is often acts as a social focus; a means of lighting and space heating. Tar from the fire can help to protect a thatched roof, and the smoke can keep out insects and other pets. Hence, cooking habits need to be considered as well as the lifestyle of the users.

Fuels with improved designs of stoves include firewood, charcoal and sawdust. Based on the assessment conducted, it has been established that there are difference between stoves used in rural, urban and institutions or commercial ventures. Use of firewood is predominant in the rural areas and as one travels into the urban areas there is a shift to charcoal.

It was established during the assessment that stoves in use in rural areas are normally adaptable to using more than one form of biomass such as wood and agricultural wastes. Firewood is used widely in the rural areas. The traditional firewood stoves used in rural areas is normally at no cost to the user and these stoves have a lot of inefficiencies. One stove fits any size of pot and the intensity of fire is controlled by adding or removing fuel from the stove. The fuel i.e. firewood is not bought but collected free of charge from the forest or farms. Urban stoves are normally single fuel devices. Charcoal is a very important fuel for urban areas and is usually purchased rather than collected.

Improved stoves designs in the country to date are usually targeted to urban dwellers. This has been probably been due to the higher income levels of this group of people. Hence, improved charcoal stoves are widely disseminated stoves technology. Improved charcoal stoves are highly efficient stoves that save fuel and money because the heat to be lost is minimized by some insulation included in the design. These stoves can save about 35%-40% charcoal over traditional stoves.

Sawdust stove designs are also finding their way into the market especially in small business enterprises called "*Nyama Choma*" or meat roasting in the urban areas. There are some few problems that would need to be addressed in order to make the technology popular in the country.

Improved stove technology focuses on improving firewood consumption. In the long run it aims at reducing carbon dioxide emission and indoor air pollution, reducing workload to women and children and conserving forest resources. The overall aim of the project is to improve thermal performance of the woodfuel stoves in rural areas

 Other benefits are income generation opportunities especially to village technicians. Stove improvement technology adds value on indigenous technology that uses indigenous fuel resources and material. Improved stove technology project is designed to start with small models that can be replicated in the whole country. The project will relate to construction of the efficient stoves and imparting knowledge on proper management of woodfuels. Amongst of the improved stove is "*Jiko Mbono"* shown in Figure 5. The stove is a Top-Lit-UpDraft (TLUP) gasification stove with natural draft air supply. The stove can use Jatropha seeds directly instead of Jatropha oil.

#### Fig. 5. Jiko Mbono Underdevelopment (Source DIT R&PGS-2011)

Timber and manufacturing industries in the country generate a lot of sawdust (shown in Figure 6). The sawdust can be used as a renewable source of technology. Sawdust stoves have been developed as can be seen in Figure 7. The stoves are cheap and affordable and can be used in both semi-urban and urban areas. The sawdust stoves are expected to be popular in future.

Fig. 6. Sawdust accumulation at one of Timber Processing Industry in Tanzania

### **5.2 Solar Technology**

62 Renewable Energy – Trends and Applications

some few problems that would need to be addressed in order to make the technology

Improved stove technology focuses on improving firewood consumption. In the long run it aims at reducing carbon dioxide emission and indoor air pollution, reducing workload to women and children and conserving forest resources. The overall aim of the project is to

 Other benefits are income generation opportunities especially to village technicians. Stove improvement technology adds value on indigenous technology that uses indigenous fuel resources and material. Improved stove technology project is designed to start with small models that can be replicated in the whole country. The project will relate to construction of the efficient stoves and imparting knowledge on proper management of woodfuels. Amongst of the improved stove is "*Jiko Mbono"* shown in Figure 5. The stove is a Top-Lit-UpDraft (TLUP) gasification stove with natural draft air supply. The stove can use Jatropha

improve thermal performance of the woodfuel stoves in rural areas

Fig. 5. Jiko Mbono Underdevelopment (Source DIT R&PGS-2011)

popular in future.

Timber and manufacturing industries in the country generate a lot of sawdust (shown in Figure 6). The sawdust can be used as a renewable source of technology. Sawdust stoves have been developed as can be seen in Figure 7. The stoves are cheap and affordable and can be used in both semi-urban and urban areas. The sawdust stoves are expected to be

popular in the country.

seeds directly instead of Jatropha oil.

Over several past decades, new commercial industries have been established for an assortment of solar energy technologies, demonstrating schemes with wide variations of success. The SHSs system components are usually imported through various private sector initiatives. The common PV applications in the country are household lighting, telecommunication, vaccine refrigeration in rural and semi-urban areas, powering electronic accessories e.g. radios, TVs, computers etc, etc. water pumping, powering schools and health centres and rural dispensaries.

Dar es Salaam Institute of Technology (DIT) has developed a high power solar thermal system based on parabolic concentrator Heliostat. The scheme is cheap to construct and can be used by institutions in the country. The system is capable of concentrating 20 kW per unit Heliostat. The unit can be cascaded to a very high power station. A parabolic concentrator is given in Figure 8

#### **5.3 Wind Technology**

Based on Mmasi, Lujara and Mfinanga [Mmasi *et al*, 2001] on wind energy potential in Tanzania, wind resources are expressed in wind power classes ranging from class 1 to class 7, with each class representing a range of mean wind power density or equivalent speed at specified height above the ground. In this aspect, Mtwara, Dar es Salaam, Pwani, Tanga, Kigoma, Kagera, Singida, Dodoma, Tabora, Shinyanga, Morogoro, and part of Southern Arusha are suitable areas for future generation of electricity using wind as the source of energy.

Fig. 7. Sawdust stove in Rural Tanzania

Fig. 8. A Parabolic Concentrator Heliostat (Source DIT-R&PGS-2011)
