SUMMARY
Rural population of India mostly depends on bio energy for cooking, space and water heating.Though most of the energy need is harvested from fossil fuels, 70% of the rural population depends on the bio energy for their domestic usage in the country. About 70% of the Indian population lives in rural area where 75% of the primary energy need is supplied by bio energy resources. Also, about 22% of the urban households depend on firewood, 22% on kerosene and 44% on LPG for cooking in the country. Bio energy resources are renewable in nature and combustion would not produce poisonous gases and ash with sufficient oxygen supply. A village levelstudy on the present scenario of domestic energy consumption will help to assess the demand and supply of bio energy in the country. Uttara Kannada district in Karnataka state, India is chosen for bio energy assessment which has evergreen as well as moist and dry deciduous forest. In the district majority of the people live in rural area or in semi urban area, mostly dependent on forest, agricultural and livestock residues for domestic energy need.

Bioresource availability is computed based on the compilation of data on the area and productivity of agriculture and horticulture crops, forests and plantations. Sector-wise energy demand is computed based on the National Sample Survey Organisation (NSSO study) data, primary survey data and from the literature. Using the data of bioresource availability and demand, bioresource status is computed for all the agroclimatic zones. The ratio of bioresource availability to demand gives the bioresource status. The ratio greater than one indicates bioresource surplus zones, while a ratio less than one indicates scarcity.  The supply/demand ratio in the district ranges from less than 0.5 to more the 2. If the ratio is less than 1 (demand > supply) then that place is fuel wood deficit place and where the ratio is more than 1 (supply > demand) then that place is referred as fuel wood surplus region. In Uttara Kannada, most of the Taluks with ever green forest cover (Sirsi, Siddapur, Yellapur, Supa and estern hilly ares of Kumta, Honnavar and Ankola) are fuel wood surplus regions where the supply/demand ratio is currently > 2 (compared to 8-9 in early 1990’s). Dwindling resource base could be attributed to the decline in forest cover in the district.

KEYWORDS: Total primary energy supply (TPES), Bio energy, BETs, Municipal solid waste (MSW), forest residues

1. INTRODUCTION

Energy is the fundamental need of human beings with air, water, shelter and food (energy). In ancient time energy used by human was about 2,500 kJ per day. After the invention of fire and other energy harvesting methods from sun, water and wind, energy usage has been increased to 30,000 kJ per day. In the present day, energy used by humans is more than 2 lakh kJ every day [1]. As the energy demand has increased, exploitation of resources to produce energy is also increased and the fossil fuels hold the major share in generating energy. In India, more than 70% of the total primary energy supply (TPES) is supplied from non-renewable energy sources (coal, crude oil or natural gas) and around 20% is from hydro resources. Only about 10% of the energy basket is supplied by renewable energy sources which include solar, wind, geothermal, tidal etc [2]. Though most of the energy need is harvested from fossil fuels, 70% of the rural population depends on the bio energy for their domestic usage in the country.

Bio energy refers to the energy released when organic carbon reacts with oxygen. This energy may be harvested from plants or animals which are also called as biomass. During the process of photosynthesis some energy will be trapped and stored in the form of organic carbon in plants from which energy can be extracted through burning. Bio mass is the most processed energy form of carbon and used as primary energy which can substitute the non renewable energy sources [3]. Bio energy resources combine fuel wood from forest, biogas, bagasse, agricultural residues, livestock residues, feedstock residues, solid waste etc.

Bioenergy plays a prominent role in country’s economy and an important component of TPES. Technical analysis of the bio energy technologies (BET) would help to understand the recent developments and the need for the further research in the respective area. Various advantages of BETs open the ways for numerous application and developments in the technology. Cost of energy harvesting technology and the energy source is an important factor of consideration for its feasibility to common man. Bio energy is an in-exhaustive source, freely available in most of the situations (or very inexpensive). BETs mainly use the residues (byproducts) of forest, agriculture, horticulture etc. and animal waste which are abundantly available in rural areas. Municipal Solid Waste (MSW) is a major source for bioenergy in urban areas, which will reduce the associated difficulties such as waste disposal, pollution etc. Biomass based power generation system requires less capital cost compare to other technologies since land, infrastructure and technology requirements are less expensive. However bio energy utilization is techno-economically feasible and contributes significantly to the economic growth of the country.

About 70% of the Indian population lives in rural area where 75% of the primary energy need is supplied by bio energy resources. About 75% of the rural households depend on firewood, 10% on dung cake and 5% on LPG for cooking and 22% of the urban households depend on firewood, 22% on kerosene and 44% on LPG for cooking in the country [4]. About 1,50,000 households in the country yet to be electrified and more than 400 million people do not have access to electricity [5]. In electrified villages also the electricity supply is not reliable and load shedding is often. About 50% of the rural households depend on kerosene and 48% of the households depend on electricity for lighting. Hence most of the Indian population is either dependent on fossil fuel or bio energy for their daily cooking, water heating and lighting. The above discussion is evident that bio energy can contribute significantly to the sustainable developmentand to the country’s economy [6].

1.1 Present Bio-energy status in India: India is the 4th most energy producing country in the world with a population share of 17.5% of the world’s population. As the population increased, the energy requirement also increased over the years which led to exploitation of resources at a higher rate. Per capita Total Primary Energy Supply (TPES) in India was about 540 kgoe (kilogram oil equivalent) in 2010 and World average was 1803 kgoe [7]. Coal and peat are the major contributors to the TPES with a share of 42.30% followed by crude oil (23.60%) and natural gas (7.20%). Combustible Renewable and waste (CRW) are the 2nd prominent source of TPES with a share of 25%. Figure 1 (a) gives the percentage shares of energy sources in total primary energy supply in India. Residential sector gets around 78% of the energy from CRW sources followed by Industries (17.40%) [8]. Figure 1 (b) gives the sector wise usage of CRW in the country.

Figure 1 (b) clearly shows that major part of the domestic energy consumption is supplied by the combustible renewable or bio energy. Hence bio energy plays a vital role in feeding domestic energy demand of India.

Energy demand is in direct relation with population, demand increases with the population. Total primary energy demand in India was 117.2 Mtoe in 1960-61 and around 5.2% of the total demand was imported. Per capita energy demand was 266.82 kgoe in 1961 while the total population was about 43.9 crores. Total primary energy demand increased to twice in 45 years which is 539 Mtoe in 2007. Population in 2007 was 112.9 crores and per capita energy demand is about 477.12 kgoe [9]. About 15.5% of the total energy is being imported in the present day where the total demand has crossed 715 Mtoe [10]. Table 1 gives the trends in demand and supply of primary energy in India from 1960-61 to 2011-12. It also shows the increase in population for the same duration.

Table 1: Trends in demand and supply of primary energy (Mtoe)

Year	Population (Million)	TPES (Mtoe)	Net Imports (Mtoe)	% Imports
1960-61	439.23	117.2	6.04	5.15
1970-71	547.90	147.05	12.66	8.61
1980-81	685.20	208.3	24.63	11.82
1990-91	843.93	303.15	31.07	10.25
2000-01	1027	432.75	89.03	20.57
2006-07	1130	539.09	131.97	24.48
2007-08	1158	617.52	154.38	25.00
2008-09	1174	656.27	164.07	25.00
2009-10	1190	673.84	168.46	25.00
2010-11	1220	715	111	15.52

Figure 1 (a): Share of energy sources in TPES

Figure 1 (b): Sector wise share of CRW

Energy generation in the country depends mostly on fossil fuels which are limited in nature. Since India has less fossil fuel resources and these resources should be conserved for the future generation, the country is importing significant amount of petroleum oil, nuclear energy resources, coal, natural gas etc. This trade is affecting the economical growth of the country and also more and more fossil fuel extraction has adverse effects on sustainable development [11]. Burning of fossil fuels emits enormous amount of carbon dioxide (CO2) and other gases (CO, SO2or nuclear waste) which arethe root cause for all global and ecological problems.However renewable energy applications have negligible carbon dioxide emission and eco-friendly. About 25% of the primary energy demand is supplied by combustible renewable and wastes in India, where most of the rural population depends on bio energy [12].

Rural population of India mostly depends on bio energy for cooking, space and water heating. About 75% of the energy demand is supplied by bio energy in rural areas of the country where 70% of the total population live. The bio energy use in the country is showing a decreasing trend over the years due to urbanization and rural electrification; nevertheless at present about 25% of the energy demand is met by bio energy. More than 50% of the primary energy demand was supplied by bio energy in 1983 which is about 25% in 2010 [13]. Table 1 gives the share of bio energy in total primary energy supplies (TPES) from 1983 to 2010.

Bio energy has a significant share in the TPES which effects the total energy generation of the country. Since energy independence or the per capita energy consumption is one of the prominent factor to decide country’s development, bio energy is also has a significant effect on developmental issues. Other important aspect associated with energy generation is regarding environmental pollution and waste disposal. Bio energy resources are renewable in nature and combustion would not produce poisonous gases and ash with sufficient oxygen supply. However the CO2 generated during combustion of bio energy will be used by plants in the process of photosynthesis. Hence the ecological balance is not disturbed by using bio energy [14]. This process leads to forestation which is the important part of ecological system to maintain the balance and to promote sustainability. Table 2 gives the share of Combustible Renewable and Waste (CRW) in TPES for the duration 1983 to 2010 in the country.

Table 2: Share of CRW in TPES for the duration of 1983-2010

Year	Share or CRW in TPES (%)	Year	Share or CRW in TPES (%)
1983	52.3	1997	34.6
1984	50.8	1998	34.2
1985	48.9	1999	32.7
1986	47.6	2000	32.6
1987	46.7	2001	32.5
1988	44.9	2002	32.0
1989	43.4	2003	31.5
1990	42.1	2004	30.2
1991	41.1	2005	29.5
1992	40.0	2006	28.4
1993	39.3	2007	27.3
1994	38.1	2008	26.5
1995	36.4	2009	24.9
1996	35.6	2010	24.6

A village levelstudy on the present scenario of domestic energy consumption will help to assess the demand and supply of bio energy in the country. For bio energy assessment Uttara Kannada district in Karnataka state, India is chosen which has evergreen as well as moist and dry deciduous forest. In the district majority of the people live in rural area or in semi urban area, mostly dependent on forest, agricultural and livestock residues for domestic energy need.

2. OBJECTIVES

The primary objective of the study is to assess the bio energy status in Uttara Kannada district across the agroclimatic zones. This includes:

1. Identifying the bioenergy surplus and deficit places in the district
2. Techno-economic analysis of bio energy applications and
3. The role of bio energy in sustainable development.

3. MATERIALS AND METHOD

3.1 Study Area: Uttara Kannada district is located between 13° 55´ and 15° 31´ latitudes and 74° 9´ and 75° 10´ longitudes (figure 3). It is the 4th biggest district of the state having population of 14,36,847, with more than 70% of the people live in rural area or in semi urban area. District is located in central Western Ghats with rich ecology. More than 75% of the total area is forest covered and has 140 km costal belt [14].

The geographical heterogeneity is responsible for the diverse growth of vegetation in the district. Taluks of the district are categorized under 4 different types of forests which are

• Ever green forests normally found in Sirsi, Siddapur and eastern hilly regions of Honnavar, Kumta and AnkolaTaluks.
• Semi Deciduous forest, found in slopes of Ankola, Kumta, Karwar, Honnavar, Siddapur and Sirsi.
• Deciduous forests are mostly found in Haliyal, Supa and Mundgod region.
• Forest in the coastal region, normally found in Kumta, Honnavar, Ankola, Karwar and Bhatkal region.

Figure 3 (a) gives the location of the study and Figure 3 (b) gives the climatic zones and forest types of Uttara Kannada. Extent of the forest cover and type of forest has a major effect on bio energy supply. Evergreen forest found in most of the places in the central region followed by moist and dry deciduous forests [15].

3.2 Method and Data:Bioenergy status assessment is done based on the resource availability and bio energy requirement in the district. Having the knowledge of current bioenergy usage pattern in different agroclimatic zones, demand for bioenergy is computed. Bioresourse is mainly depends on the land use pattern, forest cover and yields of various crops. Using the earlier energy survey data and by spatio temporal land use dynamics analysis availability of resources and corresponding demands are calculated. All the estimations are done taluk wise and aggregated for each agroclimatic zone.

3.3 LULC dynamics of Uttara Kannada:Forest resources constitute the primary source of energy in the district. The analysis of land use dynamics during 1979 to 2013 shows that about 75.88% of area under evergreen forest (1979) hasdeclined 53% in 2013. Areas under agriculture land and forest plantations have increased from 10.22% and 7.79% to 14.13% and 18.64% respectively. Figure 4 gives the percentage change in LULC pattern in the district from 1979 to 2013.

Table 3 gives the land use variation and area under different land use category from 1979 to 2013.

Table 3: Land use variations from 1973 to 2010

Category		1979	%	1989	%	1999	%	2013	%
Built-up		9,738	0.95	12,982	1.26	21,635	2.1	31,559	3.07
Water		18,527	1.8	16,604	1.61	32,983	3.21	28,113	2.73
Agriculture land		1,03,163	10.02	1,21,167	11.77	1,38,458	13.45	1,45,395	14.13
Open land		15,988	1.55	34,783	3.38	21,945	2.13	37,660	3.66
Horticulture land		20,675	2.01	32,227	3.13	43,623	4.24	48,993	4.76
Forest Plantation	Teak / Bamboo / other Softwood	0	0	21,937	2.13	38,588	3.75	67,911	6.6
	Acacia / Eucalyptus / Other Hardwood	80,217	7.79	55,694	5.41	73,977	7.19	1,23,927	12.04
	Total	80,217	7.79	77,631	7.54	1,12,565	10.94	1,91,838	18.64
Forest	Moist deciduous forest	1,02,967	10.01	1,43,849	13.98	1,79,075	17.4	1,64,996	16.03
	Evergreen to semi evergreen forest	5,89,762	57.31	5,31,872	51.68	4,23,062	41.11	3,30,257	32.09
	Scrub/grass lands	58,936	5.73	44,123	4.29	47,366	4.6	40,402	3.93
	Dry deciduous Forest	29,113	2.83	13,848	1.35	8,374	0.81	9,873	0.96
	Total	7,80,778	75.88	7,33,692	71.3	6,57,877	63.92	5,45,528	53.01
Total		10,29,086	100	10,29,086	100	10,29,086	100	10,29,086	100

Figure 4: Spatio temporal land use dynamics

Change in forest cover and other land use classes are given in Figure 5. It is evident that forest cover decreased and built up area and crop lands have increased over the years.

Figure 5: Land use dynamics of Uttara Kannada

4. RESULTS AND DISCUSSION

Bio resources from various sources (forests, agriculture, horticulture) is used for domestic applications (cooking, water heating) in the district. Fuel wood is mainly used for domestic cooking and water heating supplemented by horticultural and agricultural residues, forest biomass and biogas production from livestock. Majority of the fuel requirement for cooking, water and space heating is supplied by agricultural residues, animal matter or by forest in the district. More than 80% of the people are dependent on bio energy for their requirements such as food, fuel wood for traditional stoves, timber for houses and cattle sheds, poles for fencing and shelter construction, leaves to prepare manure and covering to control weed, wood to prepare all housing structures, ropes, herbal medicines and decorative articles [16]. Study gives the village level details of supply and demand trend of bio energy in the district.

4.1 Supply and Demand trends of Bio energy in Uttara Kannada

4.1.1 Fuel wood: Fuel wood is one of the prominentforest by-products collected (normally by women and children)which is used for cooking and water heating through burning. Major domestic energy need is shared by fuel wood in the rural regions where the people collect it from nearby forest. The availability of the fuel wood for the consumers is depends on the closeness of the forest, type of the forest and methods of extraction. Figure 6 gives the availability of fuel wood in the districts annually. Since fuel wood is the cheapest primary energy source hence the demand will be high depending upon the availability. If the demand for the fuel wood increases then it may lead to deforestation or consumers may switch over to some other fuels such as LPG, electricity or kerosene due to the lack of availability.The annual fuel wood availability in the district ranges from less than 1,000 tonnes to 56.000 tonnes. In majority of the villages of Sirsi, Siddapur, Kumta and HonnavarTaluks, availability of fuel food ranges from 1,000 to 5,000 tonnes per annum. In northern villages of Haliyal and SupaTaluks availability of forest bio mass per annum is less than 1,000 tonnes to 5,000 tonnes. Availability of fuel wood is high in the central region of the district. In eastern part of Karwar and Ankola and southern part of Supa fuel wood availableness is 10,000 to 25,000 tonnes per annum. There are few villages Supa and YellapurTaluks where the bio-mass availability is 25,000 to 56,000 tonnes in a year.

Figure 7 gives the supply to demand ratio of available forest bio mass (fuel wood) in the district. The supply/demand ratio in the district ranges from less than 0.5 to more the 2. If the ratio is less than 1 (supply< demand) then that place is fuel wood deficit place and where the ratio is more than 1 (supply > demand) then that place is fuel wood surplus region. In Uttara Kannada, most of the Taluks with ever green forest cover (Sirsi, Siddapur, Yellapur, Supa and estern hilly ares of Kumta, Honnavar and Ankola) are fuel wood surplus regions where the supply/demand ratio is more than 2. The villages with semi and moist deciduous forests (Western parts of Mundgod and Haliyal, Eastern parts of Bhatkal and Karwar) are also forest bio mass surplus places where the availability ratio is more than 1. The coastal and the extreme eastern part of the district (coastal villages of Karwar, Ankola, Kumta, Honnavar and Bhatkal with eastern part of Mundgod and Haliyal) are the fuel wood deficit places. The bioresource supply is dwindling in the district evident from the reduced bioresource supply to demand ratio from 8-9 [15] to 2. This necessitates sustainable management approaches with augmentation of forest resources.

4.1.2 Bio-energy from Agricultural residues:Agricultural crops grown in the district include rice, ragi, jowar, bajra, maize and wheat. Paddy is the major crop in the district followed by jowar and maize. Net sown area in the district is about 1,12,946 ha which includes cereals, commercial crops and oilseeds.

1. Paddy residues: Paddy (Oryza sativa) is the widely grown crop in the district (78,073 ha, 69.12%). Rice husk and stalk are major constituents of the residue from paddy cultivation. The average higher calorific value of rice husk ranges from 2937.5 to 3461.31 kcals and lower value is from 2637.2 9 to 3161.2 5 kcals. The stalk is mainly used as fodder and husk is the main energy component in the residue.

2. Maize residues: Maize is one of the prominent crops in the district with a share of 3.68% of net sown area. Maize cobs are major residues from the crop which constitute about 30% of maize gain (Zea mays). Cobs are used to feed cattle or as fuel.

3. Bagasse: Sugarcane is an important cash crop in the district which is mainly used to prepare jaggery. Area used to grow sugarcane in the district is about 1,232 ha (1.09% of total sown area). Bagasse is a major residue from sugarcane which is left after extracting juice from it. The fibrous content in the sugarcane is the major contributor to the bagasse which is normally in the range of 30-32%. Bagasse is used as a fuel with wood in the process of producing jaggery from sugarcane juice which has a calorific value of 3500 kcals. Bagasse is also used to generate methane gas;1 tonne of bagasse generates about 20 m3 of combustible methane gas.

4. Oil seed: Ground nut is the most important and widely grown oil seed crop in the district followed by cotton. Ground nut is grown in 2949 ha (2.61%) where the total oil seed growing area is 3177 ha (2.81%). Sun flower is the other oil seed crop which is grown in the district (228 ha). About 1,878 ha (1.66% of net sown area) of area is under cotton which produces oil seeds. About 30% of the ground nut pod consists of shell which is used as residue has an average higher calorific value of about 4532.15 kcal/kg and the lower calorific value of about 4248.5 8 kcal/kg [17,18].

Figure 8 gives the annual energy available from agricultural residues in the district, which ranges from 250 million kWh to 90,000 million kWhper year. In majority of the villages (895 villages) of Yellapur, Supa, Siddapur, Sirsi and KumtaTaluks energy availability from agricultural residues is less than 250 million kWh per year. Some villages in Ankola, Sirsi, Siddapur and HaliyalTaluks get the annual energy from agricultural residues about 250 to 500 millon kWh. Similarly, some villages in Karwar, Ankola and HaliyalTalukshave annual energy from agri-residues of 500 to 2,000 million kWh. In very few villages in the district (Mundgodtaluk),  energy from agricultural residues is more than 10,000 million kWh per year and the maximum availability is about 90,000 million kWh per annum.

4.1.3 Bio energy from Horticulture: Plantation crops (cash crops) such as areca (Areca catechu), coconut (Cocosnucifera), cashew (Anacardiumoccidentale), banana (Musa accuminata), cardamom (Elletariacardamomum), cocoa (Theobroma cacao), pepper and spices are the major crops (32,953 ha, 29%) next to paddy in the district. There is an increasing trend in growing these crops in the district due to their commercialvalue. Coastal belt takes the major share in growing coconut crop and areca is grown in almost all the taluks. Area under areca crop is increasing with a higher rate in recent years which has become the crop of major income in Kumta, Honnavar, Ankola,  Sirsi, Siddapur and part of Yellapurtaluks. Cashew is a seasonal bearing plant which is normally grown in hilly or in waste land in the district. Cardamom, cocoa tree and spices are grown with areca and coconut plantations (1,675 ha) in the district which have higher trade value in the market. Horticulture crops are also the important source of residues which mainly contains combustible bio mass.

Horticulture residues

1. Areca residues
   Areca is the most growing crop after paddy in the district. Fuel biomass extracted from areca is leaves, inflorescence, and husk and leaf sheath. Areca husk is the outer cover of areca fruit which accounts for 60-80% of the total volume (fresh weight consideration) [19]. It is normally used to cover the field or as mulch rather than used as fuel. It can be used in the manufacture of card boards, paper boards etc and properly composted husk can be good organic manure [20]. On average 5-6 leaves can be obtained from each areca tree per year. It is used to prepare manure, to cover edges of cannels agricultural land, as fuel bio mass and to feed cattle.  Used and throw (single use) plates and cups, hats and other decorative items manufactured by sheaths are getting attention of people in the district and state wide.
   Areca leaves are used as thatching materials and to cover areca gardens. These are the good source of manure and also combustible bio mass.Other residues such as inflorescence and trunk of the tree are used as fuel. Trunk is mainly used for construction and when it dries and become strength less it will be used as fuel.

2. Coconut residues
   Coconut residues are mainly used for combustion (fuel bio mass) which are leaves, inflorescence, shells, husk and leaf sheath. Coconut husk is widely used for making coir, mats, rope and also used to cover coconut plantations [21]. It is dried and used as main fuel for water heating during rainy season in the district. Shells are mainly used as fuel which has higher combustion value. Coconut shell charcoal production is gaining importance since it has a market value. Leave of coconut palms are used to cover houses and other plantation fields. Leaves are used to produce groom sticks which can be trade in the market [22].

3. Other residues
   Other residues generated from horticulture crops are due to cashew cocoa and banana plantation. Cashew is one of widely grown cash crop in Uttara Kannada. Cashew shell husk is the major residue from the crop followed by the fuel wood from tree branches. Cocoa tree is sparsely grown in the district from which fuel wood and leaves are extracted as residues. Main Residue of banana plantation is leaves which are used instead of plates for serving the food and in cooking; also leaves are used to cover the plantation. However the banana tree will not produce any combustible residues.

Figure 9 gives the annual energy availability from horticultural residues in the district. In many taluks in the district namely Sirsi, Siddapur, Yellaour, Haliyal, Mundgod and Supa the annual availability of energy from horticultural residues is less than 250 million kWh per annum. Few villages(126) in the eastern part of Ankolataluk have 250 to 500 million kWh. In some villages of Honnavar and Karwartaluks, annual energy availability from horticultural residues ranges from 500 to 2,000 million kWh. Very few villages in the district have availability of energy from horticultural residues more than 10,000 million kWh.

Figure 10 gives the combined annual energy availability from agriculture and horticulture residues. In majority of the villages annual energy availability is less than 250 million kWh per annum. There are some villages in the district where energy availability rages from 250 to 500 million kWh (155 villages) and 500 to 2,000 million kWh (225 villages). In 159 villages of eastern part of Ankola, Mondgod and Haliyal energy from horticulture and agri residues in the range 2,000 to 10,000 million kWh. In nine villages, available energy is more than 10,000 million kWh which extends up to 90,000 million kWh.

4.1.4 Biogas resource status: Livestock a vital component of agrarian ecosystem, provides milk and manure. Other uses of livestock are for wool, for meat, transportation and for ploughing (or sowing). Animal residue from livestock aid in recharging the essential nutrients of soil. It also boosts the quality of the organic manure which increases the soil fertility.

Figure 6: Availability of forest biomass (fuel wood) in tonnes/annum

Figure 7: Fuel wood resource status (Supply to demand ratio)

Figure 8: energy from agricultural residues

Figure 9: energy from horticultural residues

Figure 10: Annual energy availability from agricultural and horticultural residues

Figure 11: Annual biogas production from livestock residues in Uttara Kannada

Figure 12: Biogas resource status (supply to demand ratio)

Farmers in Uttara Kannada are very much dependent on livestock for their agriculture and horticulture practices. Animal residue is the main feedstock for the production of biogas as well as manure. There are about 3,66,949 cattle, 1,18,669 Buffaloes, 2,702 Sheep,  11,994 Goats in Uttara Kannada. Other members of livestock are Pigs (900), Dogs (93,403) and Rabbits (277). Total livestock population in the district is about 5,94,929 and poultry population is 3,61,351. Dung available from each cattle varies from 3-4 kg to 8-10 kg (from coastal to hilly region). Similarly average dung produced from a buffalo is 12-15 kg and from a hybrid one is 15-18 kg. By considering 3 kg dung production from a cattle in coastal area and 8 kg in hilly area, total dung production from cattle is about 6,32,058.46 tonnes per year. Similarly by considering the dung production per buffalo as 12 kg/day, total dung obtained is 5,19,770.22tonnes per year. Assuming gas production of 0.036 m3 per kg of dung, total biogas generated will be 41,465 thousand m3 per year [23, 24]. National per capita natural gas consumption is about 54 m3 per annum; then the biogas produced from livestock residue could meet the 50% of the gas demand in Uttara Kannada district [25]. (100% dung produced is considered to generate biogas). Table 4 gives the Taluk wise livestock population with annual dung and biogas production in the district.

Table 4: Taluk wise dung and biogas production in Uttara Kannada

Taluk	Cattle population	Dung Prod./day (kg)	Dung Prod./yr (tonnes)	Buffalo population	Dung Prod./day (kg)	Dung Prod./yr (tonnes)	Total biogas production (*1000 m3)
Ankola	28570	85710	31284.15	5967	71604	26135.46	2067.11
Bhatkal	24619	73857	26957.81	6094	73128	26691.72	1931.38
Haliyal	41485	124455	45426.08	20820	249840	91191.60	4918.24
Honnavar	47828	143484	52371.66	8849	106188	38758.62	3280.69
Karwar	11218	33654	12283.71	5460	65520	23914.80	1303.15
Kumta	35891	107673	39300.65	5820	69840	25491.60	2332.52
Mundgod	32122	96366	35173.59	8686	104232	38044.68	2635.86
Siddhapur	43881	351048	128132.52	18897	226764	82768.86	7592.45
Sirsi	52230	417840	152511.60	18845	226140	82541.10	8461.90
Supa	19052	57156	20861.94	8224	98688	36021.12	2047.79
Yellapur	30053	240424	87754.76	11007	132084	48210.66	4894.76
Total	366949	1731667	632058.46	118669	1424028	519770.22	41465.83

Figure 11 gives the annual biogas production from livestock residues in Uttara Kannada. It is evident that in majority of the villages in the district, annual biogas energy generated from biogas ranges from 0.1 to 0.5 million kWh. In 340 villages of Mundgod, Haliyal, Karwar and Siddapurtaluks biogas energy generation is 0.5 to 1 million kWh. Few villages in Bhatkal, Honnavar and Mundgod taluk have biogas based energy production of 1-12 million kWh per annum.

Figure 12 gives the availability to demand ratio of biogas resource in the district. In more than 50% of the villages (625 villages) the availability is less than demand; which are called biogas energy deficit regions. In 334 villages of Siddapur, Yellapur and Supataluks supply to demand ratio is between 1 and 2. There are 275 villages in Ankola, Mundgod and eastern Yellapurtaluk, availability is more than twice of biogas demand.About 40% of the villages have adequate biogas potential to meet the domestic needs. These villages are to be considered for dissemination of biogas technology in the district.

4.1 Techno-Economic analysis of Bio-energy technologies (BETs)

The major applications of bio-energy in the country are

1. Domestic use i.e. for cooking, space heating (during winter),  water heating (for bathing and livestock) and lighting;
2. In rural industries (or home industries), for agricultural and horticultural crops processing, bricks and tiles manufacturing;
3. Biogas production; and
4. Electricity production (community level, at few locations)

Biomass and agro-horticultural residues are the main sources of bio-energy applications in the country followed by biogas, since most of the bio-energy based application requires combustion and heat transfer. Normally the fresh biomass contains about 20-60% of moisture (which cannot be burnt effectively), needs to be dried so that they are suitable for combustion. In Uttara Kannada, solar drying is adopted to remove moisture content in the biomass. However the energy obtained from biomass is depends on the content of the fuel as well as the efficiency of the stoves or combustion method used, analysis of fuel efficient BET would contribute to the improvement of the technologies.

4.2.1 Cook stoves: The most commonly used stoves in the rural households are either made from mud or from stones (or both). These traditional stoves (TCs) are constructed by local people and have efficiency less than 10%. Also, in traditional stoves oxygen supply is not sufficient which may lead to the generation of CO (carbon monoxide). It is estimated that 826 million Indians depend on TCs that burn fuel wood or coal which causes pollution and the maximum temperature obtained is limited to lower values [26]. In order to overcome these barriers, CST (formerly ASTRA of IISc) has designed an Improved Cookstove (ICs) to give maximum heat transfer with improved efficiency (20-35%) which allows the complete combustion of fuel [27]. There are many ICs are available in market which give better efficiency than TCs and give complete combustion of fuel without CO gas emission. National Biomass Cookstoves Initiatives (NBCI) launched by MNRE (Ministry of New and Renewable Energy) on 2nd December 2009, has the primary aim to enhance the use of biomass ICs. MNRE perused the BIS on solid biomass cookstoves – portable that was brought out by BIS in 1991 to examine the applicability of the standard and test protocols in view of the newer designs of cookstoves.  This standard has been revised and draft is forwarded to BIS in November 2011 for further action. The ministry has suggested some standard performance factors for the cook stoves which are given in Table 5 [28].

Table 5: Performance parameters for improved cook stoves

Type of biomass cookstove	Standard performance parameters
	Thermal efficiency (%)	CO (g/MJd)	PM (mg/MJd)
Natural draft type	>25	<= 5	<= 350
Forced draft type	>35	<= 5	<= 150

Life span of traditional stoves built in rural areas is limited due to the usage of mud and stones. But ICs are constructed with modern technology and science which gives longer lifetime. Due to thermal stress, cracks develop in the walls of a mud stove where as ICs can withstand in higher temperature [29]. However the ICs are recommended due to higher efficiency, durability and less GHG (Green House Gas) emission over traditional stoves (TCs).

4.2.2 Biomass fueled steam generation: Steam is generated through direct combustion of bio mass which is a viable energy carrier in many applications. Bio mass fired power systems produce both heat as well as electrical energy mainly used in CHP (Combined Heat and Power) plants. These systems have found application is many industries such as paper and pulp, sugar, steel and plywood industries. In many applications, steam of high pressure and temperature generated from bio mass combustion is used to run the turbine which is coupled with alternator [30]. Steam of low pressure and temperature is collected from the outlets of turbine and used for other applications such as heating, drying or primary heating of water.Co-firing of biomass in modern large scale coal power plants is efficient and cost effective. Efficiency of co-fired plants is more (35-45%) compare to the biomass dedicated plants. Using low cost bio mass from solid waste, crop residues etc, investment may have shorter payback period of 2-3 years [31].

4.2.3 Biogas Technology: The district has significant livestock population which is main source of dung production. Cattle dung offers a very high potential of biogas production which can meet the ever increasing domestic fuel demand. The slurry generated in the biogas production process is good manure which can be used to prepare compost or directly fed to agricultural or horticultural plantations. Biogas mainly comprises of methane (60-65%) and carbon dioxide (35-40%). Hydrogen sulphide and water vapor accounts a small fraction in biogas mixture. Biogas is about 20% lighter than air which cannot be converted into liquid like LPG (Liquefied Petroleum Gas) under normal temperature and pressure (NTP) [32]. Biogas generation from dung or agro-horticultural residues is dependent on temperature, carbon:nitrogen ratio, pH and retention days. Temperature is the most prominent factor that affects the biogas generation; generation stops below the temperature of 10°C. The optimum conditions for biogas generation are: temperature 30-35°C, pH 6.8-7.5, carbon:nitrogen ratio (C:N) 20-30, solid contents 7-9%, retention time 20-40 days. The retention time decides the rate of digestion, longer the retention time more the gas generated for a given amount of waste. There are many technologies are available for biogas generation depending upon the availability of waste. The most widely used technologies are [33]:

1. Fixed Dome model (40 and 55 days retention period)
   1. Deenabandhu brick masonry
   2. Deenabandhuferro-cement in-situ construction
2. Floating Dome model (30,40 and 55 days retention period)
1. KVIC (Kadhi and Village Industries Commission) floating metal drum
2. KVIC reinforced cement concrete (RCC) digester
3. Prefabricated Model for limited field trial (40 days retention period)
1. Sintex - HDPE prefabricated Deenbandhu
4. Optimized design developed by Application of Science and Technology to Rural Areas (ASTRA) of IISc [34].
5. Fixed dome type designed by University of Agricultural Sciences - Bhagyalaxmi design.
6. Raitabandu Biogas Plant - designed by a farmer from SagarTaluk, Shimoga district to suit the needs of the Malnad region.

4.2.4 Applications of Biogas: Biogas is mainly used for cooking as it can be directly burned which is more efficient and produces negligible fumes. Biogas can substitute fuel wood for cooking and water heating. Biogas produced in the district can meet 50% of the total gas demand (Table 3). The other applications of biogas are for lighting and electricity generation. Biogas has better illumination ability; it can be used for lighting instead of kerosene lamps.

Electrical energy generation is an important application of biogas where it is used to produce steam or used with diesel in co-generation units. Biogas has higher calorific value (4700 kcal) which can be effectively utilized for electricity generation. Biogas is used with conventional fuels such as diesel or coal in CHP (Combined Heat and Power) generation which improves the efficiency of the plant. The system capacityranges from 3 to 250 kW which is a decentralized system. This can meet the rural domestic electricity demand and enables hybridization with other renewable energy based generating systems on micro/smart grid platform. A community level plant which is fueled by biogas and diesel can supply the irrigation pump sets during day time and lighting load during night. In the same manner if it is hybridized with solar, wind or pico hydro plants (depending on the potential), then a micro grid can meet the energy demand in decentralised manner. The standalone generating mechanism leads to sustainable development by ensuring the reliable and pollution free power generation. Upgradation to smart grid infrastructure is possible through integrationof  communication and automatic control networks.

MNRE has initiated “Biogas based Distributed/Grid Power Generation Programme” (4th January 2006) to promote biogas based power generation especially in rural areas in a decentralized way. It also helps in utilizing the waste generated in that region and produces valuable manure as a byproduct. There are about 98 installed plants with cumulative capacity of 793.25 kW in the country (as of March 2011). There are 250 plants that are under installation adding 5824 kW in future. Karnataka has 5 installed plants with total capacity of 66 kW and 36 plants are being installed (695 kW). The ministry is also providing the financial aid for biogas based power generation plants depending upon the ratings, maximum up to 40% of the plant cost [35].Cost of the biogas plant depends upon the size gas storage area and retention duration. For a fixed dome Deenabandhu modelwith retention period of 40 days, cost ranges from INR 12,000 to INR 24,000 (depending on the size of 1 m3 to 4 m3). Similarly if retention period is 55 days then cost ranges from INR 16,000 to 31,000. For a KVIC masonry digester and steel gas holder which has retention period of 30 days, plant cost varies from INR 19,000 to 28,000 (1 m3 to 4 m3). If retention period is increased to 40 days the cost also increases, i.e. INR 24,000 for 1 m3 and INR 39,000 for 4 m3 plant. The average payback period of biogas plant decreases with increase in size of the plant which ranges from 4.07 years (1 m3) to 2.45 years (4 m3) [33].The cost of electrical energy produced from biogas is about INR 5.5 per kWh and the capital cost ranges from INR 1,50,000 to 2,00,000 depending upon the capacity of the plant (CHP plant). In case of direct combustion of fuel wood, operating cost is about INR 2.5 per kWh and capital cost varies from INR 60,000 to 1,00,000 [36].

4.2.5 Biomass gasification: Fuel wood can be converted into gas using thermo-chemical processes with only 2-4% of ash. Gasification is carried out in oxygen starved environment so as to generate Carbon monoxide and Hydrogen which are combustible. The reactions are carried out in elevated temperature of 500-1400°C and pressure of 33 bar (480 psi). The main difference between biomass gasification and biogas generation is that, wet organic feed stocks such as animal dung and sewage waste are used in biogas production. Mostly fuel wood, forest residues, agricultural and horticultural residues are the main sources for gasification. Air based gasifiers normally produce a gas with high nitrogen content, whose calorific value varies between 4 and 6 MJ/Nm3 (100-1200 kilocalories/Nm3). Oxygen and steam based gasifiers produce a gas with relatively high calorific value of 10 to 20 MJ/Nm3. Gas generated from bio mass is also called as Producer gas which is highly combustible [37].

Pyrolysis is the primary step of converting biomass into gas in which the biomass decomposition takes place, producing volatile materials (75-90%) in the form of gas and liquid, and char which is non-volatile. In the later steps (gasification), volatile hydrocarbons and char are converted to combustible gas. Figure 13 shows the biomass gasification process and byproducts generated in the process.

Figure 13: Process of gasification

Many types of biomass gasifiers[Table 5] have been developed depending upon the flow of fuel and oxidants and means of supporting structures [38]:

Table 5: Types of gasifier

Gasifies type	Flow direction		Type of support
	Fuel	Oxidant
Updraft fixed bed	Down	Up	Grate
Downdraft fixed bed	Down	Down	Grate
Bubbling fluidized bed	Up	Up	None
Circulating fluidized bed	Up	Up	None

4.2.6 Electricity generation from biomass gasification: End product in gasification process is combustible gas which may either be used for cooking or in steam power plants. Gas is burnt and steam high pressure steam is obtained at very high temperature. Steam is used to run turbines which are mechanically coupled with alternators. Alternators generate electrical power depending on the capacity which may be fed to consumers or supplied to grid. The combustible gas may be directly fed to external combustion engines which are connected to alternators. However the output of the alternator is same but the efficiency in latter method is marginally higher. Normally the producer gas is used in dual fueled generating stations in order to reduce the stress on fossil fuel demand.

The capacity of the biomass based electricity generation ranges from few kilowatts to hundreds of kilowatt. Fuel requirement for gasifier is around 1.2kg in order to generate 1 kWh of electricity which works for 4 to 5 hours/day. These type of systems are best suited for distributed generation, have the capacity to meet the demand of domestic electricity consumption. Remote area electrification in absence of conventional grid supply has been successfully implemented [39]. Producer gas can be used with conventional fuels such as diesel or natural gas which allows 60-80% savings in fossil fuel consumption.MNRE is encouraging gasifier projects for both in community level and for individual household. Central Financial Assistance (CFA) will be given for various components of gasifier plants from 15,000 per kW to 5 lakhs (one time) depending upon the application and benefitting population. Also the ministry organizes technical courses for technicians in order to understand the technology and for effective implementation [40]. At present, few number of biomass gasifier plants are working in the country accounting cumulative capacity of less than 125MW. Though the operating cost of the plant is marginally higher than the present grid electricity cost, due to lack of public interest and limited shared knowledge of technology, bio energy technologies are sparsely used.

4.3 Energy Plantation

Basically, energy plantation refers to the plantation or forest which is exclusively cultivated for fuel wood extraction. The species selected for plantation should grow in shorter period of time and give maximum biomass and litter. The fuel wood harvested from energy plantations should have higher calorific value and produce less ash. Casuarina is one such species suitable along coast has the heat value of 280.6*106 kcals/year/ha (about 3,83,364.6 ha of area needed to install 1,000 MW thermal power plant with energy plantation). By selecting suitable native species for plantation valuable byproducts can be harvested such as fruits, oil (oil seeds), feedstock for cattle, organic compounds, fibre, leaves for manure and other forest products. Data collected from Forest Department reveals that annual woody biomass available is in the range 11.9 to 21 t/ha/yr.  An energy forest raised at Hosallivillage inTumkur district to support a wood gasifier plant has annual yield of 6 t/ha/year [41]. The energy plantation is an everlasting energy source (with periodic maintenance) which are independent and decentralized. The prominent uses of these plantations are

1. Energy obtained is similar to Indian coal
2. Wood contains less sulphur and does not pollute while burning with sufficient oxygen
3. Ash after burning wood can be used as good fertilizer
4. Plantations reduce soil erosion by water and wind, also absorbs GHG which slows down global warming
5. Since plantation and the power plants associated with it require constant attention and periodic maintenance, it will produce employment. On an average, 1 ha f energy plantation could give employment for 7 people.

4.4 Scope for energy plantations in Uttara Kannada

District has about 22,800 ha of barren land which can be used for energy plantation. These energy forests have the potential to yield 1,36,800 t/yr of biomass. If 80% of these biomass are used for power generation using gasifies, 91.2 GWh of electric energy can be generated. The electricity generated will be in a decentralized manner which is more reliable and has lesser T&D losses. This system can be further hybridized and grid connected with smart grid platform. The gasifier expansion in rural area with energy plantation would reduce the fossil fuel dependency. This approach has prominent advantages such as energy independence, barren land utilization, employment generation in rural area, switching over from fossil fuel consumption, implementation of next generation RETs (Renewable Energy Technologies), etc.

4.5 Economic analysis

Bio energy is in-exhaustive source, freely available in most of the situations (or very inexpensive). BETs mainly use the residues (byproducts) of forest, agriculture, horticulture etc and animal waste which are abundantly available in rural areas. Municipal Solid Waste (MSW) is the source for bioenergy (biogas) in urban area with massive supply. Hence the availability of resource for bioenergy generation is plenty and has negligible cost compare to fossil fuels. Table 6 shows the comparison of different power plants under capital cost requirements. Biomass based power generation system requires less capital cost compare to other technologies since land, infrastructure and technology requirements are less expensive. Table 7 gives the comparison of overnight capital cost and O&M costs of different power plants.The generation cost of electricity from bio energy is marginally high compare to conventional method. Nevertheless cost/kWh is less in case of direct biomass combustion since fuel wood is freely available. Table 8 gives the cost/MWh energy generation from different technologies.

Table 6: Capital cost comparison of power plants

Type of technology	Capital cost (million rupees/MW)
Solar photovoltaic	300-400
Micro-hydel	40-60
Wind	40-50
Biomass	20-40

Table 7: comparison of overnight capital cost and O&M costs

Power plant	Overnight Capital Cost ($/kW)
Coal	2844-5348
Natural gas	665-2060
Nuclear	5339
Fuel cell	6835
Geothermal	4141
Hydropower	3078
Wind	2438
Wind offshore	5975
Solar thermal	4692
Solar PV	4755
Biomass	3860
MSW-Landfill gas	8232

Table 8: Electrical energy generation cost comparison of different power plants

Type of Power Plant	Rs/MWh (at 5% Discount rate)	Rs/MWh (at 10% Discount rate)
Nuclear	2440.8	4217.24
Coal	3400.2	4643.17
Gas	3877.65	4339.85
Hydro – Small hydro	4743	8501.27
Large hydro	4557.15	8841.65
Wind – Onshore	4887	8346.17
Offshore	6276.15	8999.03
Geothermal	4438.35	7244.28
Solar – PV	12600.45	19058.99
PV (rooftop)1	15854	23273.48
Solar thermal2	9503.1	14809.73
Biomass3	Rs. 4.55 to 6.75

(Source: International Energy Agency (IEA) Nuclear Energy Agency (NEA), Organization for Economic Co-operation and Development, 2010, MNRE, Case Studies of Selected Biomass Power Projects in India)
¹ Solar PV (rooftop) system in Germany,
² Solar thermal systems in United States
³ MNRE, Case Studies of Selected Biomass Power Projects in India

5. CONCLUSION

In Uttara Kannada district, bio energy meets the household energy demand.The supply/demand ratio of bioresources in the district ranges from less than 0.5 (Bioresource deficit) to more the 2. The coastal and the extreme eastern part of the district (coastal villages of Karwar, Ankola, Kumta, Honnavar and Bhatkal with eastern part of Mundgod and Haliyal) are the fuel wood deficit places. The bioresource supply is dwindling in the district evident from the reduced bioresource supply to demand ratio from 8-9 [15] to 2. This necessitates sustainable management approaches with augmentation of forest resources.

In coastal regions (Kumta, Honnavar, Ankola, Bhatkal, Karwar), availability of agro-horticultural residues is more than the current demand which has the potential to meet the rural household energy demand. Similarly in Sirsi, Siddapur and Yellapurtaluks, forest biomass potential could meet the energy demand. In Mundagod, Haliyal and in coastal villages, availability of animal residues provides the scope for biogas production. About 40% of the villages have adequate biogas potential to meet the domestic needs. These villages are to be considered for dissemination of biogas technology in the district. Biogas can also be used for electricity generation and the byproduct, i.e. slurry is used for organic manure production which is a very good fertilizer. Advanced BETs will encourage the bio energy use and make the application simpler.Improved cook stoves, biomass gasification and other new bioenergy technologies are yet to available in rural areas which could change the older energy conversion pattern with higher efficiency. BETs are economically feasible and environmental friendly apart from ensuring sustenance of resources.

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