Biomass sources
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Biomass for fuel use may be derived from fuelwood and other sources in India. This was a by-product of other primary activities like agriculture, forestry, trees outside forests and food processing. ...

Biomass for fuel use may be derived from fuelwood and other sources in India. This was a by-product of other primary activities like agriculture, forestry, trees outside forests and food processing. Barriers need to be overcome to develop a sustainable bioenergy system.

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Biomass sources Biomass sources Document Transcript

  • Sources of biomass for fuel applications The material of plants and animals is called biomass. Bio-energy is energy derived from biomass. Before the development of technology based on coal, lignite, crude oil and natural gas (fossil fuels) bio-fuels were the sources of heat energy. Primary activities of raising food crops, trees, animal husbandry and degradable waste collection for disposal are the sources of biomass used as fuels for energy recovery. Agriculture, forestry, plantations, dairies etc., produce agro-residues, woody biomass and animal waste respectively which are processed to produce fuels. Biofuels are mostly produced in rural areas and utilized for such applications as domestic cooking, village industries and the technology for conversion and end use devices are often primitive. In rural India, biomass and human and animal energy continue to contribute 80 % of the energy consumption. Cooking energy constitutes about 85 percent of our rural energy demand and has traditionally been met by biomass fuels such as firewood, agricultural residues and animal wastes. Under the National Programme on Improved Cookstoves, about 30 million cookstoves have so far been installed, which are helping to cut back and conserve fuelwood use. Energy plantations using appropriate fast-growing tree species have also been established on marginal lands to provide fuelwood for use in efficient cookstoves and biomass gasifiers. Patterns of energy use are changing in urban areas, with greater use of LPG and kerosene. It is, however, unlikely that fuelwood will be completely replaced, as poorer sections of the community may continue to lack the cash resources to purchase even minimal amounts of kerosene or LPG, or the appliances to make use of these fuels. It is now increasingly realised that there is considerable potential for the modernisation of biomass fuels to produce convenient energy carriers such as 1
  • electricity, gases and transportation fuels whilst continuing to provide for traditional uses of biomass. The modernisation of biomass and the necessary industrial investment is already happening in many countries. However, it is important to emphasise that the future use of bioenergy must be strongly linked to high energy efficiency, and environmentally sustainable production and use. Woody biomass is product of forestry and trees from different agroforestry activities of smaller intensity. Timber (used for commercial purpose) and fuel wood are obtained from the forests besides minor forest produce. Commercial plantations like rubber and plants/trees that yield hydrocarbon can be a source of byproduct fuel. Non -edible vegetable oils from tree borne oil seeds can be used as liquid fuels. By trans-esterification reaction between the oil and an alcohol in presence of an alkaline catalyst, esters can be produced that are potential substitute for diesel as engine fuel. Agriculture yields by annual harvest a large crop residue biomass part of which can be a source of rural biofuels. Sugar cane yields bagasse as a byproduct of agro-industry. Plants that grow in wastelands are also potential energy crops. Animal manures and wastewaters containing organic putrefiable matter can be treated by anaerobic digestion or biomethanation to produce biogas as a fuel. Starchy and sugar wastewaters can be substrates for fermentation processes that yield ethanol which is a potential liquid fuel. Biomass that is used for producing bio-fuel may be divided into woody, nonwoody and wet organic waste categories. The sources of each are indicated in Table 1. 2
  • Table-1. Sources of three categories of biomass WOODY NON-WOODY (cultivated) FORESTS FOOD CROPS WOODLANDS CROP RESIDUES PLANTATIONS PROCESSING (MULTIPURPOSE RESIDUES TREES) HYDROCARBON NONEDIBLE OIL PLANTS SEEDS WET ORGANIC WASTE ANIMAL WASTES MANURE, SLUDGE MUNICIPAL SOLID WASTE TREES FROM VILLAGE COMMON LANDS OTHER INDUSTRIAL EFFLUENTS (B O D) ENERGY CROPS: (SUGAR CANE BAMBOO) WASTE STARCH & SUGAR SOLUTIONS Sources of Woody Biomass: India has low forest cover which is under high pressure. With only around one percent of the world’s forests, India has to sustain nearly 16 percent of the world’s human population and almost 15 percent of the world’s livestock. India has 63.3 million hectares of forest land – 19.27 percent of its total land area. According to estimates, some 80 percent of the country’s energy requirement is met from non-commercial energy sources, of which firewood is a major component. Within a total land area of nearly 3 million km2, India’s forest land covers some 640 000 km2, or 21.6%. Biomass fuels contributed 41% of total inland primary energy supplies in 1998; in India’s rural areas, the percentage supplied by biomass (wood, animal dung and agricultural residues) rises to about 95. Whereas the use of dried dung and waste as fuel is widespread in agriculturally prosperous regions, wood is still the principal domestic fuel in poorer and less well-endowed regions. Overall, fuelwood is estimated to provide almost 60% of energy in rural areas and around 35% in urban areas. 3
  • Current annual consumption of fuelwood is estimated at 217 million tonnes, of which only about 18 million tonnes constitutes sustainable availability from forests: approximately half of fuelwood supplies is derived from TOF (trees outside forests) sources, such as farms, village woodlots, small plantations on private or government land, and trees or shrubs alongside roads, railways, canals, ponds etc. The balance of fuelwood supply represents non-sustainable drawings from forest areas plus miscellaneous gathering of woody material. Besides its primary use as the almost universal rural fuel for domestic cooking and heating, fuelwood is also used in bakeries, hotels, brick and tile manufacture, and numerous small cottage industries. It is to be noted that estimates of Indian fuelwood production/consumption, and especially of the breakdown by source or sector, are extremely conjectural, varying widely from agency to agency and from one estimate to another. Consequently any levels quoted above should be regarded as, at best, indicative. Energy Plantation: Growing trees for their fuel value on ‘Wasteland’ or land that is not usable for agriculture and cash crops is social forestry activity. A plantation that is designed or managed and operated to provide substantial amounts of usable fuel continuously throughout the year at a reasonable cost may be called as ‘energy plantation’ Suitable tree species and land with favorable climate and soil conditions of sufficient area are the minimum resource required. Depending on the type of trees, the tree life cycle, the geometry of leaf bearing branches that determines the surface area facing the sun, the area required for growing number of would be evaluated. Combination of harvest cycles and planting densities that will optimize the harvest of fuel and the operating cost, are worked out. Typical calorie crops include 12000 to 24000 trees per hectare. Raising multipurpose tree species on marginal lands is necessary for making fuel wood available as well as for improving soil condition. Trees for fuel wood plantations are those that are capable of growing in deforested areas with degraded soils, and withstand exposure to wind and drought. Rapid growing 4
  • legumes that fix atmospheric nitrogen to enrich soil are preferred. Species that can be found in similar ecological zones, and have ability to produce wood of high calorific value that burn without sparks or smoke, besides having other uses in addition to providing fuel are the multipurpose tree species most suited for bioenergy plantations or social forestry programs. AZADIRACTA INDICA (NEEM), LEUCAENA LEUCOCEPHALA (SUBABUL), DERRIS INDICA (PONGAM), AND ACACIA NILOTICA (BABOOL) are examples of tree species for the above plantations. Sources of Crop and agro-industry residues: Agriculture yields by annual harvest a large crop residue biomass part of which can be a source of rural biofuels. There are other or alternative uses of residues e.g. feed, their role in reducing erosion, stabilisation of soil structure, enhance moisture content, use as animal bedding or use as fertilisers (dung). Availability for fuel use also depends on variation in the amount of residue assumed necessary for maintaining soil organic, soil erosion control, efficiency in harvesting, losses, non- energy uses, etc. Hall et al (1993) have estimated that using the world's major crops only (e.g. wheat, rice, maize, barley, and sugarcane), a 25% residue recovery rate could generate 38 EJ and offset between 350 to 460 Tg C/yr. 5
  • AGRO-RESIDUE IN INDIA (POTENTIAL AVAILABILITY - 1995-96) MT = Million tons Agro-residue Wheat Straw Rice Husk Maize Cobs Pearl Millet straw Sugar Cane Bagasse Coconut shell Coconut pith Groundnut shells Cotton Stalks Jute Stalks India, MT 83.3 39.8 2.8 9 93.4 3.4 3.4 2.6 27.3 2.7 T.Nadu, MT 9.2 3.3 0.6 0.4 0.6 0.8 Bioenergy Technologies: Biomass energy technologies can be roughly divided into three main groups e.g. direct combustion processes, thermochemical processes and biochemical processes. The first process is in principle directly concerned with primary fuels e.g. the fuels are used as they are found or after some form of processing such as size reduction, drying, compaction through briquetting, carbonization, etc. The latter two are basically processes in which the primary fuel is converted into a secondary fuel. In thermochemical and biochemical conversion processes the biomass is converted from a solid form into either a gas or a liquid through pyrolysis, gasification or catalytic liquefaction or through fermentation and other related processes such as hydrolysis with acids or enzymes, etc. There is no single best way to use biomass for energy, and environmental acceptability will depend on sensitive and well informed approaches to new developments in each location. It is clear that biomass for energy can be environmentally friendly, and steps must be taken to ensure that it is, if biomass is to be accepted as an important fuel of the future, and the implications for the agricultural sector thoroughly assessed. 6
  • BIOMASS CONVERSION METHODS FOR PRODUCING HEAT OR FUELS: Controlled decomposition of low value biomass to derive its energy content in a useful form is the purpose of the bio-energy programs. Biomass energy conversion may give a mixture of bio-fuel and. by product. Examples are given below. Bio-fuels derived from biomass can be solid, liquid and gas fuels that can be used for combustion in specially designed furnace, kiln and burners. PRIMARY BIOMASS SECONDARY CO-PRODUCT PRODUCT WOOD CHAR (PYROLYSIS) PYROLYSIS OIL WOOD CHAR (GASIFICATION) PRODUCER GAS ANIMAL MANURE BIOGAS (ANEROBIC DIGESTION) FERTILIZER 7
  • Table-2. : Estimated potential for biomass energy :1015 J y-1 (1015 J y-1 = 320MW) Estimated total potential bio-fuel resources harvested per year for various countries (1978): Source Sudan Brazil India Sweden U.S.A. Animal Manure 93 640 890 18 110 Sugar Cane 660 1000 430 --- 420 Fuelwood 290 3200 420 160 510 Urban Refuse 5 94 320 23 170 Municipal 2 11 66 1 5 Other --- --- --- ---- 630 Total Potential 1000 4800 2100 200 1800 Present 180 2700 5800 1500 72000 1.8 0.4 0.13 0.03 Sewage national energy consumption Ratio potential 5.5 to consumption 8
  • Ref: Vergara,W. and Pimental, D.(1978)’Fuels from biomass’, in Auer, P.,(ed.), Advances in Energy Systems and Technology, vol.1, Academic Press, New York,pp125-73 Bio-fuel production from primary biomass may utilize thermo-chemical, biochemical and catalytic conversion processes. Conversion process chosen depends on the properties of the primary biomass available. THERMOCHEMICAL BIOCHEMICAL ▼ ▼ CATALYTIC CONVERSION ▼ PYROLYSIS ANAEROBIC DIGESTION HYDROGENATION GASIFICATION FERMENTATION TRANS-ESTERIFICATION COMBUSTION HYDROLYTIC ENZYMES SYN.GAS PROCESS PREPARATION OF BIOMASS FOR FUEL USE: Preliminary treatment of biomass can improve its handling characteristics, increase the volumetric calorific value, and fuel properties for thermo-chemical processing. It can increase ease of transport and storage. Examples: CHIPPING, CHOPPING, DRYING, GRINDING, BRIQUETTING ETC. Fuel wood requires drying in air and chopping for best result in cook stoves. Saw dust requires drying and briquetting to increase its bulk density. Industrial boilers require uniformly smaller sizes of wood for feeding their furnaces. Predrying of 9
  • biomass to moisture levels of below 20% (oven dry basis) enhances efficiency of combustion in cook stoves and industrial boilers. Estimated quantity of waste generated in India (1999): Waste Quantity Municipal solid Waste 27.4 million tones/year Municipal Liquid Waste 12145 million liters/day (121 Class1 and 2 cities) Distillary (243 nos) 8057 kilolitres/day Press-mud 9 million tones/year Food and Fruit processing waste 4.5 million tones /year Dairy industry Waste 50 to 60 million litres / day 3 (C O D level2 Kg/m ) Paper and Pulp industry Waste 1600m3 waste water/day (300 mills) Tannery (2000 nos) 52500 m3 waste water/day Source:IREDA News, 10(3):11-12, 1999, V.Bhakthavatsalam For production of high or medium pressure steam by using biomass the best choice of equipment is the water tube boiler. It has a large combustion area surrounded by banks of vertical water tubes, which makes it suitable for biomass fuels. Biomass fuels have a high content of volatile matter and lower density and bulk density compared to solid fossil fuels; as a result , biomass fuels need a large space (relatively ) above the fuel bed to prevent flaring volatile material from impinging upon the chamber wall and causing damage to it over a period of time. Shell boilers are unsuitable for biomass fuels because of the restricted diameter of the furnace tube and high risk of damage to the tube wall by flame impingement. Additionally demand for uniform fuel quality and size by shell boilers are relatively stricter. 10
  • Other types of end use equipment that are suitable for size reduced biomass include cyclone furnaces, fluidized bed systems and the controlled combustion incinerator. Cyclones furnaces are adaptable to use of wood waste s fuel. Briquetting technologies: Reference: ’Biomass feed processing for energy conversion’ P. D. Grover, in Biomass Energy Systems, Ed. P. Venkata Ramana and S. N. Srinivas , T E R I and British Council, N. Delhi(1996) pp 187-192 The proven high pressure technologies presently employed for the briquetting of biomass are by the piston or the ram type press and the screw or the extruder type machines. 11
  • Both the machines give briquettes with a density of 1-1.2 gm/cc and are suitable as industrial solid fuels. The screw type machines provide briquettes with a concentric hole that gives better combustibility and is a preferred fuel. These briquettes can also be more conveniently deployed in small furnaces and even cook-stoves than solid briquettes generated by a ram press. Biomass densification-A solid(fuel) solution. N.Yuvraj, Dinesh Babu, TERI, New Delhi. TERI Newswire, 1-15 December, 2001, page 3. In India, briquettes are mostly made from groundnut shell, cotton stalk, saw dust, coffee husk, bagasse, mustard stalk and press mud. While the Southern region of India produces briquettes mostly from groundnut shell and saw dust, Western and Northern regions produce bagasse, groundnut shell, cotton stalk, mustard stalk and press mud briquettes. As a recent addition municipal solid waste is also densified for use as fuel in process industries (tea, tobacco, textile, chemical, paper, starch, tyre re-treading, tiles, etc) for thermal applications. Biomass & Bio-energy 14, no5-6, pp 479-488, 1998 ‘A techno-economic evaluation of biomass briquetteing in India’ A.K.Tripathi, P.V.R.Iyer and Tarachand Khandapal (I I T, N.Delhi) tarak@ces.iitd.ernet.in Various types of raw materials used for briquetteing are: ground-nut shells, cotton stalks, bagasse, wood chips, saw dust, and forest residues. Pyrolysed biomass can also be used. Materials can be fine granulated, coarse granulated or stalky. Material may be dry or wet with various moisture content. After a material is dried and crushed the pellets may be formed under pressure with effect of heat. 12
  • Biomass & Bio-energy 18(3):223-228(2000) ‘Characteristics of some biomass briquettes prepared under modest die pressures’ Chin,O.C and Siddiqui, K.M Universiti Sains Malaysia,31750,Perak, Malaysia kmust@hotmail.com Properties of Biomass Physical, chemical and thermal properties of solid, liquid and gaseous bio-fuels for required for energy conversion methods like combustion are determined experimentally and data are used in design calculations. Physical Properties: Moisture Content, Particle Size and Size distribution Bulk Density & Specific gravity Proximate Analysis: Moisture Content Volatile Matter Fixed Carbon Ash or mineral content Elemental Analysis: Carbon Hydrogen Oxygen Nitrogen Sulphur 13
  • Types Wood Oak(dry) Pine(dry) Peat Lignite Coal (Range TABLE 3.TYPICAL COMPOSITIONS OF SOLID FUELS Proximate Analysis Ultimate Analysis Moisture Volatile Fixed Ash C H O N S carbon ------ 85.6 13.0 1.4 58.2 6.0 43.3 0.1 - 4622 -----56.8 34.8 3-20 87.0 26.0 28.2 16-40 12.8 11.2 30.8 4080 0.7 6.0 6.2 3.040 52.2 23.1 42.4 6050 7.0 9.6 6.7 3.0-6 40.2 59.6 43.3 3.06 0.2 1.3 0.7 11.5 0.4 0.7 0.34.3 ----0.8 12.0 80.5 1.4 1.9 17.0 87.1 83.1 2.5 10.7 3.0 48 85 84 6.0 0.8 2.3 43.2 1.2 10.7 0.3 1.3 -- 0.1 1.0 -- 5338 4625 6110 4000 to 8000 4430 7105 7130 Of property) Bagasse Coke Charcoal Heating Value, dry basis, kcal/kg Higher Heating value: Gross calorific value or higher heating value of a fuel containing C, H and O is given by the expression: Cg =[C x 8137 + (H--O/8) x 34500]/100 where C, H and O are in % and Cg is in calories. Net calorific value is the difference between GCV and latent heat of condensation of water vapor present in the products Chemical composition Chemical Composition: Total Ash %, Solvent soluble %, Water Soluble %, Lignin %, Cellulose % Hemi-cellulose % 14
  • Table: x. Chemical composition of some biomass material Species Soft wood Hard wood Wheat Straw Rice Straw Bagasse Total ash % 0.5 0.3 6.0 16.1 2.2 Solvent Soluble % 2.0 3.1 3.1 Water Soluble % 7.1 Lignin % Cellulose 27.9 19.5 16.0 Hemicellulose % 24.0 35.0 28.1 4.6 8.3 13.1 10.0 11.9 18.4 24.1 28.0 30.2 33.1 Properties of Wet and biodegradable biomass: C O D value & B O D value, Total dissolved solids & Volatile solids 15 40.8 39 39.7