Biomass and Bioenergy:  Developments and Potentials

 

B. K. Bala 

Department of Farm Power & Machinery Bangladesh Agricultural University Mymensingh -2202, Bangladesh 

Introduction

 

l       Biomass is renewable fuel 

l       Biomass energy systems offer an opportunity for sustainable, self-reliant and equitable development 

l       Modern biomass is projected to account for 45% of new contributions of renewables by 2020 

l       Bioenergy is now reality 

 

 

Biomass is defined as:

 

•           materials of plants and animals

•           (i) terrestrial biomass and

  (ii) aquatic biomass

 

Major sources of biomass:

•           fuelwood

•           agricultural wastes

•           animal wastes

Biomass

 

 

 

Bioenergy

 

Energy derived from biomass:

 

l         Solid fuel ®  fuelwood

l         Gaseous fuel ® biogas

l         Liquid ®  biofuel (ethanol)

 

  

 

 

 

Category of Landuse	Source	Area in "000"ha	Percentage Area
Agriculture Land	SYB, 1997	8773.7	59.12
Public Forest Land	Forest Dept. 1999	2213.6	14..92
Village Forests	FMP, 1992	270.0	1.82
Rivers and lakes	SYB,1997	940.5	6.34
Urban Settlement	SYB,1997	79.1	0.53
Other	SYB, 1997& Forest Dept. 1999	1748.0	11.78
Total land (Area of the country)	䦋㌌㏒㧀좈໱琰茞ᓀ㵂Ü	14839.6	100.00

 

Note: Bangladesh has an area of 1,084,750 ha. under homesteads and tanks,

940,520ha. under Rivers and beels, and about 79,130 ha under urban settlements

etc (SYB, 1997). The FMP, 1992 reports about 270,000 ha area under village

forests, which are mainly, homesteads. Assuming the area under figure of 270,000

valid for 1996 leads to an estimate of 814,750 ha. area under tanks.)

(Source: SYB, 1997 and FMP, 1992)

 

Solid Fuels: 

• Sources of fuelwood are village forests and

• public forests 

•  Fuelwood is the main forest product (61%)

•  Annual requirement is 9.4 million m3

•  Annual supply is 6.18 million m3

 

Fuelwood

 

 Forest land 

• Share of forest land:

• remained 15% during 1970

• fell to 14% during 1980

• slipped further to 13% during

• 1990

• slight increase in 1996 

 

 Fuelwood Production

 

Fuelwood Production and Consumption

 

l       expected to rise to 11.9 million M3 by 2015 

l       the fuelwood consumption in Bangladesh   has an income and a regional pattern 

l       per capita consumption of fuelwood in Bangladesh increases with income 

l       0.035 M3 for low income to 0.072 M3 for high income families

  

Share of Fuelwood Use

 

l       presents the share of domestic      (like cooking) 

l        industrial (like brick burning) 

l        commercial (like bakeries and

    restaurants)

 

 Fuelwood Use

 

 The Sundarbans

 

 

Photo : The Sundarbans 

 

 

Solid fuel

 

l       Biomass is the main fuel for cooking

 

l       Used most inefficiently (efficiency less than 10%)

 

l       Improved stoves can be used for efficient utilization of biomass (3000000)

 

l        rice husk briquettes are becoming popular

 

 

Improved stoves

  

Improved stoves

 

 

Agricultural Wastes

  

l       Shortage of fuelwood has forced the households to shift to agricultural wastes for cooking fuel

l       Agricultural wastes are mainly derived:

l       Crop residues such as rice straw

l       Sugar cane bagasse

l       Estimated crop residues 25.16 million tonnes

  

 

 Animal wastes 

 

l       Cowdung cake use is dominant feature in Bangladesh

l       Animal dung 

l       Poultry wastes 

l       Estimated dung supply: 19.02 million tonnes

 

Energy demand by fuel types

  

 

 

Rice husk briquettes

 

 

  

Gaseous Fuels

 

• There is potential of production of biogas

• animal wastes

• crop residues

• olid wastes

•       depends  on  technology,  economic  and

•       social factors

•          Biogas digesters in the field are not as expected

  

 

Biogas digester

  

l       There are 10,000 biogas digesters in  Bangladesh 

l       17.5 kWp are produced

 

 Animal Manure

 

 

Kinetics of biogas production

 

 

 

    

 

Economics of biogas production

 

 

 

 

 

Biofuels

  

•          Ethanol production from energy crops such as sugarcane is a mature technlgy

•          Ethanol production from crop residues is not yet at commercial scale

•          Lignocellulosic biomass composed of

•          the compounds cellulose, hemicellulose and lignin

 

 

Plant cell wall 

 

 

 

Biofuel

 

 

.

 

 

 

Electricity from bagasse

 

 

Steps:

 

•          Bagasse → burning of bagasse

           to raise super heated steam

•          Steam → drives steam turbine

•          Steam turbine rotates the rotor

•          Electricity generated

 

Electricity from solid wastes

 

• Steps:

• •          Solid wastes burnt

• •          Steam generated

• •          Turbine rotates the rotor

• •          Electricity generated

 

Solid wastes 

 

 

 

Open dumping outside the Dhaka City

 

 

Population- 4,375000 to 12.1e+6

           Solid waste- 1,026800 to 4,257000 tons

           Collection capacity- 483000 to 2,412000 tons

           Electricity- 456,900 to 1,894,400 MWh

 

   

Concluding Remarks 

 

l       Biomass is the major of energy and it contributes about 70% of the total energy 

l       Mainly used for cooking in rural areas 

l       Used most inefficiently 

l       Improved stoves would improve the situation 

l       Briquetting of rice husk is a better way to utilize the rice husk 

l       Ethanol from energy crop is mature technology 

l       Ethanol production from crop residue is at development stage 

l       There is a potential of ethanol production from sugarcane and electricity from bagasse

l       Solid waste generation, collection capacity and electrical energy generation are increasing with time

l       Adoption of policy for electricity generation should be dictated by economy of electricity generation and environmental implication

l       Finally bioenergy is more environmental friendly and it is reality