*5.1.1.3.Oilseed crops*

Production of various important oil seeds such as Simsim, groundnuts, sunflower, palm oil and soya for food and Jatropha for petroleum producing continued to be emphasized. Al‐ ready a policy on Jatropha production for biofuel is in place [4]. Table 3 gives production of oil seed crops for the past 5 years.

sugar is a potential feedstock for ethanol production. Figures 4-7 show some of the crops

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Oil palm plantations can be found in Kigoma Region, along the shore of Lake Tanganyika, Western Tanzania. There are three main residues from oil palm processing, namely: empty fruit bunches, shells (Figure 5) and fronds. Empty fruit, bunches are rich in potassium and they can be used as fertilizer. The shells can be used for production of carbon and heating.

Coffee production in the country is increasing. The husk (Figure 6), which is the main resi‐ due generated during processing, can be utilized as an organic fertilizer as well as a source of energy. When compressed it can be used in modern energy generation; at the moment

**Figure 3.** Selected agriculture residue potential in Tanzania (*Source: National Bureau of Statistics, 2006)*

and their corresponding residues available in the country at the moment

The fronds are usually used for mulching.

coffee husks are disposed by burning.

**Figure 4.** Rice husk (Crop residue)


#### **Table 3.** Production of oilseed crops

There are factors, which determine whether a crop is suitable for energy use. The main ma‐ terial of interest during processing as an energy source relate to moisture contents, calorific value, proportions of fixed carbon dioxide and volatiles, ash content, alkali metal content and cellulose-to-lignin ratio.

### *5.1.2.Agriculture crop residues*

A large amount of agricultural residues are produced in the country. These constitute a po‐ tential biomass feedstock for energy conversion. Generally agricultural residue is used to describe all organic materials which are produced as by-product from the harvesting or processing of agricultural crops. These residues can be further categorized into two groups. The first group consisting of the residues which are generated in the field at the time of har‐ vest or field based residues such as rice straw, sugar cane tops etc.

The second group is of those residues that are co-produced during processing or well known as processing based residues e.g. rice husk, cashewnut husk, coffee husk, bagasse, etc. the availability of the first category residue for energy conversion or application is usu‐ ally low since collection is difficult and they have other uses as fertilizer, animal feeds, etc. Experience has shown that most of the first category residues are left or burnt in the farms. However, the secondary category residues are usually available in relatively large quantities at the processing site or mill and may be used as captive energy source for the same process‐ ing mill involving no or little transportation and handling costs. Figure 3 gives selected agri‐ cultural residue estimated potential in the country.

These residues have a high potential for energy production and therefore contribute to the energy balance of the country. Major residues generated from harvesting and processing of maize/corn is potential biofuel feedstock. Similarly, the stalk of sorghum which is rich in sugar is a potential feedstock for ethanol production. Figures 4-7 show some of the crops and their corresponding residues available in the country at the moment

Oil palm plantations can be found in Kigoma Region, along the shore of Lake Tanganyika, Western Tanzania. There are three main residues from oil palm processing, namely: empty fruit bunches, shells (Figure 5) and fronds. Empty fruit, bunches are rich in potassium and they can be used as fertilizer. The shells can be used for production of carbon and heating. The fronds are usually used for mulching.

Coffee production in the country is increasing. The husk (Figure 6), which is the main resi‐ due generated during processing, can be utilized as an organic fertilizer as well as a source of energy. When compressed it can be used in modern energy generation; at the moment coffee husks are disposed by burning.

**Figure 3.** Selected agriculture residue potential in Tanzania (*Source: National Bureau of Statistics, 2006)*

**Figure 4.** Rice husk (Crop residue)

*5.1.1.3.Oilseed crops*

248 New Developments in Renewable Energy

**CROP**

oil seed crops for the past 5 years.

**Table 3.** Production of oilseed crops

and cellulose-to-lignin ratio.

*5.1.2.Agriculture crop residues*

Production of various important oil seeds such as Simsim, groundnuts, sunflower, palm oil and soya for food and Jatropha for petroleum producing continued to be emphasized. Al‐ ready a policy on Jatropha production for biofuel is in place [4]. Table 3 gives production of

Sunflower 373,391,000 369,803,000 418,317,000 466,831,000 Groundnuts 783,775,000 408,058,000 396,769,000 385,480,000 Simsim 221,421,000 155,794,000 46,767,000 115,895,000 Soya 5,000,000 3,000,000 3,450,000 3,900,000

There are factors, which determine whether a crop is suitable for energy use. The main ma‐ terial of interest during processing as an energy source relate to moisture contents, calorific value, proportions of fixed carbon dioxide and volatiles, ash content, alkali metal content

A large amount of agricultural residues are produced in the country. These constitute a po‐ tential biomass feedstock for energy conversion. Generally agricultural residue is used to describe all organic materials which are produced as by-product from the harvesting or processing of agricultural crops. These residues can be further categorized into two groups. The first group consisting of the residues which are generated in the field at the time of har‐

The second group is of those residues that are co-produced during processing or well known as processing based residues e.g. rice husk, cashewnut husk, coffee husk, bagasse, etc. the availability of the first category residue for energy conversion or application is usu‐ ally low since collection is difficult and they have other uses as fertilizer, animal feeds, etc. Experience has shown that most of the first category residues are left or burnt in the farms. However, the secondary category residues are usually available in relatively large quantities at the processing site or mill and may be used as captive energy source for the same process‐ ing mill involving no or little transportation and handling costs. Figure 3 gives selected agri‐

These residues have a high potential for energy production and therefore contribute to the energy balance of the country. Major residues generated from harvesting and processing of maize/corn is potential biofuel feedstock. Similarly, the stalk of sorghum which is rich in

vest or field based residues such as rice straw, sugar cane tops etc.

cultural residue estimated potential in the country.

**YEARS 2006 2007 2008 2009**

The residue from coconut harvestings are mainly the husk and shells. These residues (Figure 7) are a potential source of energy generation. Large plantation of coconut tree can be seen

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The main residues generated from harvesting and processing sugarcane namely, the tops, baggase and molasses are also sources of energy. However, only bagasse is utilized in cogeneration of electricity. The tops and molasses are underutilized even though they are po‐ tential source of energy. Biomass contains sugars that are deemed uneconomical to remove. The recent and development in technology can assist in reducing sugar concentrate and

Rice husk is underutilized, efforts are underway to use rice husk in briquette production. At the moment rice husk are used by brick markers to burn their bricks. Moving across the country in particularly in rice growing areas, large amount of rice husk are seen unutilized. Rice straws

During harvesting period, most of agricultural residues are burnt on the farms to facilitate the harvesting process or as pest a control measure e.g. cotton some of the residues are also used as a substitute for firewood. However, at the moment there is no adequate information

Residue chemical composition of some of the agriculture residue was analysed, and the aim of the analysis was to establish if these residues have the characteristics as feedstock for con‐ version to usable energy using gasification method. The chemical compositions used in the analysis were: proximate analysis (%) dry basis, ultimate analysis (%) dry basis and heating value. Tables 4, 5 and 6 give the proximate, ultimate analyses and higher heating values.

Other agro-residues: Cotton stalks, cassava stalks and straws are mainly used as local fuels in rural areas. Besides, the residues can be used in production of ethanol. Table 7 gives cellu‐ lose, Hemicelluloses, lignin and theatrical yield (litres/tones) from some of agro-residue.

Experience gained from agriculture sector, particularly agricultural activities show that the agricultural crops generate considerable amount of residue which can be harnessed for modern energy generation. Annual evaluation of total amount of residue that originates from agricultural activities (Figure 3) is about 13 million tonnes; residues with higher poten‐

are virtually unutilized and could serve as major source of energy in the country.

about the share of the agricultural residue in modern energy generation.

in the coastal area of Tanzania and in Zanzibar

*5.1.3.Residue chemical composition*

tial for modern energy generation are:

**•** Wheat straw about 232,400 tonnes

**•** Sisal tole and flume 46,080 tonnes

**•** Bagasse is 447,030 tonnes

**•** Maize stalk and straw about 8 million tones

**•** Rice husk and straw about 4.1 million tones

hence the residue can be potential source of energy generation.

**Figure 5.** Palm Oil Shell

**Figure 6.** Coffee husk (Source of energy)

**Figure 7.** Coconut shells

The residue from coconut harvestings are mainly the husk and shells. These residues (Figure 7) are a potential source of energy generation. Large plantation of coconut tree can be seen in the coastal area of Tanzania and in Zanzibar

The main residues generated from harvesting and processing sugarcane namely, the tops, baggase and molasses are also sources of energy. However, only bagasse is utilized in cogeneration of electricity. The tops and molasses are underutilized even though they are po‐ tential source of energy. Biomass contains sugars that are deemed uneconomical to remove. The recent and development in technology can assist in reducing sugar concentrate and hence the residue can be potential source of energy generation.

Rice husk is underutilized, efforts are underway to use rice husk in briquette production. At the moment rice husk are used by brick markers to burn their bricks. Moving across the country in particularly in rice growing areas, large amount of rice husk are seen unutilized. Rice straws are virtually unutilized and could serve as major source of energy in the country.

During harvesting period, most of agricultural residues are burnt on the farms to facilitate the harvesting process or as pest a control measure e.g. cotton some of the residues are also used as a substitute for firewood. However, at the moment there is no adequate information about the share of the agricultural residue in modern energy generation.

### *5.1.3.Residue chemical composition*

**Figure 5.** Palm Oil Shell

250 New Developments in Renewable Energy

**Figure 6.** Coffee husk (Source of energy)

**Figure 7.** Coconut shells

Residue chemical composition of some of the agriculture residue was analysed, and the aim of the analysis was to establish if these residues have the characteristics as feedstock for con‐ version to usable energy using gasification method. The chemical compositions used in the analysis were: proximate analysis (%) dry basis, ultimate analysis (%) dry basis and heating value. Tables 4, 5 and 6 give the proximate, ultimate analyses and higher heating values.

Other agro-residues: Cotton stalks, cassava stalks and straws are mainly used as local fuels in rural areas. Besides, the residues can be used in production of ethanol. Table 7 gives cellu‐ lose, Hemicelluloses, lignin and theatrical yield (litres/tones) from some of agro-residue.

Experience gained from agriculture sector, particularly agricultural activities show that the agricultural crops generate considerable amount of residue which can be harnessed for modern energy generation. Annual evaluation of total amount of residue that originates from agricultural activities (Figure 3) is about 13 million tonnes; residues with higher poten‐ tial for modern energy generation are:



*5.1.4. Economic and environmental implications of biomass*

boost local/village economies by providing jobs and services.

and human and environmental health

Hence, more studies are needed

distributed.

*5.1.6. Agriculture waste*

gy generation in the country.

*5.1.5. Challenges with agricultural residues are*

Advantages of using crop residues as energy source are twofold: economic and environmental.

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*Economic:* For the farmer, agricultural residues can be a cash crop. Traditionally, farmers burnt agricultural residue or left them in the field. The market ability of crop residues will

*Environment:* the burning of agricultural residues causes air pollution, soil erosion and a de‐ crease in soil biological activity, which eventually leads to low yields. Burning of agricultur‐ al residues yield smoke and other pollutants, which adversely affect air quantity, visibility

**•** Agricultural resources in the country are largely un- organized, scattered and not evenly

**•** Collection, storage, pre-processing and distribution are a big challenge because of low

**•** Exact data on consumption of agriculture- residues in the country is not well known.

Apart from agricultural residue from the farms, in Urban and semi-urban areas certain other residues and waste water also constitute a potential source of energy. The agro-processing industries such as fruit processing and vegetable, urban vegetable market places (Figure 8 and 9), road sweepings and road side are areas, which generates significant biomass waste. The management of these wastes are in hands of poor farmers, un-organized sector, rural and semi-urban households. Hence, large amount of these wastes are left to rot in open space resulting into air pollution. Good management of these wastes can contribute to ener‐

land holdings and low level of mechanization in complete value chain.

**•** Overall agro-residue conversion is low through existing technology;

**•** Agriculture-residue is marginalized in the country;

**Table 4.** Proximate analysis (%), dry basis –Source CEET (2008)


**Table 5.** Ultimate analysis (%), dry basis- Source CEET (2008)


#### **Table 6.** Heating values


**Table 7.** Other chemical component
