5. Methodology

Bioresource status assessment is based on compilation and computation of bioresource supply and sector wise bioenergy requirement. Bioresource supply is based primarily on land use statistics and yield of various crops (agriculture and horticulture), plantation and forest biomass productivities. Sector wise bioenergy requirement is computed based on the statistics of earlier energy surveys in Karnataka. This is done talukwise and aggregated for each agro-climatic zone in Karnataka.

Agriculture

Since the area under cultivation was not highly varying, the latest area (2000) was taken for the major crop production computation. The ratio of the main product to the by-product for each crop grown under local conditions along with their energy equivalents used in the computation is given in table 30. These were used to compute the agro residues production. The energy equivalent of these residues was taken based on what would be obtained if they were subjected to the most energy efficient transformation processes. Portion of the residues available are used as fuel, while some is used as fodder and the rest is left behind in the field for nutrient recycling. Apart from this, the actual availability of residues as energy supplements would also depend on other factors like efficiency of collection, mode of transportation and storage. Considering these, in the computation of bioresidues from agriculture only 50% is accounted for fuel. Bioenergy from agriculture residues (Bio₁) is computed by:

Bio₁ =Bioenergy from agriculture (kcal)= (Productivity of waste * Crop area* Energy equivalent)

Computation of bioenergy from agricultural crops requires inputs such as crop type (i.e. Cotton, Green grams, etc.), spatial extent, crop yield or productivity, residue to crop ratio, energy equivalent (kcal/tonne), while outputs are annual energy--crop wise, regionwise, etc.

Table 30: Ratio of the main product to the by-product of each crop grown and their energy equivalents

(Ramachandra et al, 2000)

Horticulture

The area under the horticulture plantations of coconut, areca and cashew at the taluk level were obtained from the State horticulture department for the previous four years. The average yield figures of the district were used to compute the production at the taluk level. The fuel biomass from coconut and areca nut plantations along with the energy equivalent of the husk, shells, leaves and inflorescence are given in tables 31 and 32. For the computation of the number of trees in the given area, tree count of 50/acre and 400/acre were assumed for Coconut and Arecanut plantations. Energy from horticulture (Bio₂) is computed by:

Bio₂ = Bioenergy from horticulture (kcal) = Area * Productivity * (Energy equivalent)

Computation requires input data such as crop type (i.e. Coconut, Arecanut etc.), spatial extent, number of trees per hectare, residues (leaf, shell, husk) actual count, anticipated use percent, conversion to weight (kg) and energy equivalent (kcal/kg), while output is annual energy--horticulture crop wise, regionwise, etc.

Table 31: Biomass from Coconut palm/ year

Table 32: Biomass from Arecanut tree/year

Forests

Data on the land use pattern was collected from the Directorate of Economics and Statistics. The major source of information on forest lands is the forest department, which maintains a variety of records like the annual administration reports, working plans, forest inventory reports, which gave information on the growing stock, current status of these forests, the management practices adopted, plantations maintained and their prescribed felling cycle. The inventory of forest resources published by the FSI was also utilized in this study. The forest area by types, given division wise in the forest records was used to compute the forest type at the taluk level. The biomass potential of the forests is dependent on the type of forest and its distribution cover. The biomass production varies with the type of the forest. The biomass productivity of the different types of forests is given in table 33. Total bioenergy from forests (Bio₃) is computed by

Bio₃ = Bioenergy from forests (kcal) = Forest area * Productivity * (Energy equivalent)

Computation requires inputs such as forest types (i.e. Deciduous, Evergreen, etc.); respective spatial extent, annual productivity (tonne/hectare) and energy equivalent (kcal/tonne) and outputs would be annual bioenergy--forest type wise, regionwise, etc.

Table 33: Biomass Productivity of Different Forest Types

(Ramachandra et al, 2001)

Using the low, high and average productivity values given above, the annual biomass production from each forest type was computed at the taluk level. Energy equivalent of 4000 kcal/kg was taken for evergreen, semi-evergreen and moist-deciduous forest types, while for the dry deciduous and scrub type vegetation 4800 kcal/kg and 3400 kcal/kg were taken respectively.

Plantation

The area of plantations raised by the forest department under various schemes was obtained from the State forest department. Some of the commonly planted species are Casuarina equisetifolia , Acacia auriculiformis , Pongamia pinnata , Hardwickia binnata, Azadirachta indica, Leuceana leucocephala etc. Species wise extent and age of these plantations was not available even at the division level. However, the details of plantations raised on different sites, like canal side, roadside, in institutional premises etc available at forest department was used for computation. The biomass that could be obtained was calculated assuming that 30% were adult plantations. The yield of eucalyptus plantations in Uttara Kannada, Bangalore, Tumkur and Kolar districts were estimated to be 5 tonnes/ha. The yield of Acacia auriculiformis plantations is known to be 10-34 m³/ha (KFRI, 1991). Based on these productivity figures, the biomass production of plantations was calculated using an average productivity of 5 tonnes/ha/year. Total bioenergy from forest plantation (Bio₄) is computed as:

Bio₄ = Bioenergy from plantations (kcal) = Area * Productivity * (Energy equivalent)

Requires inputs such as forest plantation types, respective spatial extent, annual productivity (tonne/hectare) and energy equivalent (kcal/tonne). Outputs are annual bioenergy--forest type wise, regionwise, etc.

Livestock

The livestock population of cattle, buffalo, sheep and goat were collected from the State veterinary department. The quantity of dung yield varies from region to region. It was taken as 12- 15 kg/animal/day for buffalo, 3-7.5 kg/animal/day for cattle, 0.1 kg/animal/day for sheep and goat. The total dung produced annually was calculated by multiplication of the animal dung production per year and the number of head of different animals (Food and Agriculture Organisation-FAO) taking the lower and higher dung yield. Assuming 0.036 m 3 –0.042 m³ of biogas yield per kg of cattle/buffalo dung, the total quantity of gas available was estimated. The dung yield, biogas yield and the energy equivalents for each animal are given in table 34. Total bioenergy from livestock (Bio₅) is computed by:

Bio₅= Bioenergy from livestock (kcal)= (Biogas * Energy Equivalent)  

Where, Biogas (m³)= Biogas yield * Dung * 1000 and

Dung (tonnes)= Dung yield * Population * 365 (for annual energy computation).

Data input to compute energy from livestock are livestock type (i.e. Buffalo, Cattle, Goat, etc.); population, dung yield (kg/animal/day), biogas yield (m³/kg) and energy equivalent (kcal/m³), and output would be biogas (m³) and annual energy.

Table 34: Dung Yield, Biogas Yield and Energy Equivalents for Livestock

The per capita biogas demand varies across the agro-climatic zones. A per capita requirement of 0.34 m³/person/day (zones 1-8), 0.43 m³/person/day (zone 9) and 0.23 m³/person/day (zone10) was taken for the computation of the biogas demand across the agro-climatic zones.

Total bioresource available from various sectors is computed by aggregating the energy computed from individual sectors (forestry, plantation, horticulture, agriculture, livestock) and is given by,

Bioresource availability = Σ⁵_i=1 ( Bio_i)

Where i=1, 2…5 and Bio₁ : Bioenergy from agriculture, Bio₂ : horticulture, Bio₃ : forest, Bio₄ : plantation and Bio₅ : livestock.

Bioresource demand

Most of the bio-fuels consumed in rural areas (nearly 75%) are for domestic purposes mainly for cooking and water heating. The remaining is consumed by indigenous rural industries. Estimation of rural energy demand for domestic purposes was based on the State rural population, which was obtained from the provisional population total, census of India 2001-Karnataka. Since nearly 80% of the rural population is dependent on bioenergy, the demand was projected taking into account the entire rural population. Domestic fuel consumption depends on the size of the family. Energy consumption patterns are seen to vary across geographical, agro climatic zones, seasons and the different economic strata of the society. The study on the domestic energy patterns in Uttara Kannada by Ramachandra et.al. estimates the per capita fuel wood requirement across various agro-climatic zones. The above-referred study computed the per capita fuel consumption as

PCFC=FC/P

Where FC is the fuel consumed in kg/day and P is the number of adult equivalents, for whom the food was cooked. Standard adult equivalents of 1, 0.85 and 0.35 for male, female and children (below 6 years) respectively were used. The per capita values used for cooking and water heating across the agro-climatic zones are listed in table 35.

Table 35: Per Capita Fuelwood for Cooking and Water Heating across Agroclimatic Zones

In urban areas too fuel wood is used for domestic purposes by a smaller fragment of the population. The urban fuel demand was computed by taking a per capita value of 1.65 kg/capita/day for cooking and 1.07 kg/capita/day for water heating.