Lesson 2. Biomass resource assessment management techniques/supply chains

2.1. Introduction

Biomass can be categorized broadly as woody, non-woody and animal wastes. Woody biomass comprises of forests, agro industrial plantations, bush trees, urban trees and farm trees. Wood, bark, branches and leaves constitute the above ground woody biomass. Woody biomass is generally a high valued commodity and has diverse use such as timber, raw material for pulp and paper, pencil and matchstick industries, and cooking fuel. Non-woody biomass comprises of crop residues like straw, leaves and plant stems (agro wastes), processing residues like saw dust, bagasse, nutshells and husks, and domestic wastes such as food, rubbish, sewage. They are harvested at the village level and are essentially used either as fodder or cooking fuel. Animal wastes constitute the wastes from the animal husbandry.

2.2. Biomass resource assessment

Assessment of available biomass resources is helpful in revealing its status and helps in taking conservation measures and ensures a sustained supply to meet the energy demand. Assessment of bioenergy potential can be theoretical, technical or economic. Natural conditions that favor the growth of biomass determine the theoretical potential. Technical potential depends on the available technologies that can be exploited for the conversion of biomass to more flexible forms and so is subjected to change with time. Of all the three potential estimates, the economic potential is subjected to high variability, as economic conditions fluctuate drastically over space and time.

2.3. Elements of an Assessment or Feasibility Study

End-Use Market

  • Energy requirements (type of energy/fuel, quantities, projections...)
  • Utilization pattern
  • Distribution system
  • By-products of bio-energy
  • Competing energy sources (type, cost…)

Resources

  • Biomass feedstock (nature, characteristics, production schedules, cost,)
  • Land
  • Water
  • Others
  • Present resources utilization

Conversion Technologies

  • Selection of technology(s)
  • State of development
  • Availability and cost of equipment
  • Maintenance and repair requirements
  • Labor requirements

Environmental Factors

  • Land and water impacts
  • Air pollution
  • Health hazards
  • Safety hazards

Social Factors

  • Regulatory aspects
  • Employment (regional, national...)
  • Training and skills
  • Relation to development plans

Financing

  • Options
  • Financial analysis
  • Comparison between bio-energy alternatives and competing sources of energy
  • Risk and sensitivity

Economic Analysis

  • Cost/benefits to region/nation
  • Comparison of alternatives and
  • Sensitivity to external factors

Recommendations

  • Selection of a technology plan for implementation

2.4. Objectives of biomass resource assessment

  • To identify the surplus biomass availability for power generation through the availability (biomass resource status) and consumption
  • To analyze available technologies that can be exploited for the conversion of biomass
  • Techno-economic analysis of feasible bio-energy technologies

2.5. Methodology

Data pertaining to the biomass availability in a particular village has to be collected by personal interaction with the local farmers and households.

2.5.1. Village Information

Information including the name of the village, list of the families in a village, geographical area, land details, agricultural activities, biomass generation and consumption, forest land details and livestock resources available are to be collected through village level survey. 

2.5.2. Biomass resource status

Biomass resource status assessment is based on compilation and computation of biomass resource supply and sector wise bio-energy requirement. Bio-resource supply is based primarily on land use/ cropping pattern (agriculture and horticulture), plantation and forest biomass collection / productivities, live stock availability and the animal waste available. Sector wise biomass consumption/ requirement is computed based on the availability and the needs of the villagers.

2.5.2.1. Biomass resource from agricultural and residues

The cultivated area and the biomass yield of each crop for biomass potential from agriculture residues was collected from village. The yield of a crop and agro residues production across an area was obtained by averaging the yields of the previous years. 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.

Bio-energy from agriculture residues (kcal) = Total agro residue production – consumption

2.5.2.2. Biomass resource from forestry

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 forest. The forest wood fuel collected annually by the household from the adjoining forest area was taken with the energy equivalent.

 Bio-energy from forest = Annual wood collected – consumption of wood in household activities

2.5.2.3. Biomass resource from live stock (animals)

The livestock population of cattle, buffalo, sheep and goat were collected from the personal interaction with the respondent. 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. Assuming 0.036 m3 – 0.042 m3 of average 0.30 m3 biogas yields per kg of cattle/buffalo dung, the total quantity of gas available was estimated.

Total bio-energy from livestock = Total cow dung collection- direct dung consumption through cake

2.5.2.4. Total biomass / bio-resources availability (surplus)

Total bio-resources available from various sector is computed by aggregating the energy computed from individual sectors.

Bio resources availability = Σ All above Bio-resources

2.5.3. Energy Consumption

The energy consumption pattern of the village such as use of energy in houses, irrigation pumping system, village lighting system, use of diesel tractor and allied machineries and use of petrol for two wheelers are to be computed using the village information study.

2.6. Technologies available for the conversion of biomass

Many technologies and options are available for generation of power from biomass. The options can be mainly classified as:

  1. Combustion route, where there is direct combustion of biomass fuel such as wood wastes, bagasse, briquettes etc. in a boiler and power generation by expanding the steam in a steam turbine. For fuel particles of below 6mm in size, bubbling fluid bed combustion and circulating fluid bed combustion are some of the technologies used in the combustion route systems.
  2. Gasification route, where biomass is gasified and power generated in a gas turbine or internal combustion engine. Fixed bed gasifiers like updraft, downdraft and cross draft gasifiers are available for power generation, each with its own advantages over the other technology.
  3. Biochemical conversion routes viz., anaerobic digestion and fermentation, where microorganisms convert chemical energy in solid biomass material into an energy carrier, often with high efficiency relative to thermochemical conversion.

To help the entrepreneurs, TamilNadu Energy Development Agency (TEDA) has completed Biomass Resource Assessment Studies in 49 Taluks which assessed the potential of surplus biomass waste/materials to serve as a guide to private entrepreneurs willing to set up biomass based power projects, biomass gasifiers etc. Proposals were sent to MNRE, Government of India for sanction of financial assistance to conduct Biomass assessment studies in all the Districts of Tamil Nadu. Further to assist the entrepreneurs, TEDA forwards their application received after necessary scrutiny to MNRE, Government of India for the sanction and release of Government of India’s financial assistance. The present installed Capacity of Biomass based Power Projects in Tamil Nadu is 116.15MW.

2.7. Techno-economic feasibility of suitable renewable energy generation system

The surplus biomass available in the particular village shall be utilized for the successful diffusion of the renewable energy technology in that village. Total crop residue and forest wood surplus in the village shall be utilized for the generation of electrical energy through gasification. The wood gasification mode of power generation is quite feasible and offers immense scope for rural development.  Biogas has been promoted as an appropriate rural technology for utilization of local resources like cattle dung etc. Cooking energy accounts for about 80 percent of the total energy consumption, mainly derived from crop residue and forest wood. Fuel consumption can be reduced by employing improved stoves (20-25 percent efficient) instead of traditional wood based cooking stoves (8-10 percent efficient).

 

 

References

  1. Khambalkar.V.P, D.S.Karale, S.R.Gadge and S.B.Dahatonda.2008, “Energy Self-sufficient village”, BioResources, Vol. 3(2), pp: 566-575
  2. GCEP Energy Assessment Analysis Spring, 2005
Last modified: Monday, 28 April 2014, 10:37 AM