Biomass Gasification System for Rural Electrification

Prof. Dr. Krishna Raj Shrestha Research Centre for Applied Science and

Technology (RECAST)Tribhuvan University

Kathmandu, Nepal

Project Team• Prof.Dr.Krishna Raj Shrestha-TeamLeader• Uttara Bajracharya -Sociologist• Rajib Thakur- Energy Engineer• Bijay Raj Subedee- Biotechnologist• Roshan Kumar Amatya -Senior Mechanics• Sushil Karmacharya - Senior Mechanics• Dambar Bahadur Ale - Helper

Introduction • Biomass refers to all forms of organic matter produced

as products of photosynthesis. Biomass has long served as one of the primary energy forms utilized by human being for essential activities aside from nutrition. Different forms of biomass are

• Forest based products • Timber, fuel wood, wood chips/shavings, saw dust, a

milling residue, forest waste like leaves, twigs, shrubs, herbs herbal products, etc.

• Agriculture based products • Aquatic plants • Animal dung and human waste.

Energy Consumption Situation by fuel type

79.6%

2.8%

3.9%

12.3% 1.2% 0.1%

376.3 MGJ

BiomassGrid electricityCoalPetroleumRenewableOthers

Source :WECS Survey ,2011

Gasification

Biomass gasification is basically conversion of solid biomass (i.e. wood/ wood wastes, agro-residues and organic industrial wastes) into a combustible gas mixture. It is carried out in an enclosed reactor operating at about 900oC where in a part of the biomass is combusted by air to provide the heat. The resulting gas known as producer gas contains CO(15 -29 %), CO2 (5 -15 %), H2 (5 -12 %), N2 (50 –65 %) and small amounts of hydrocarbon gases. The calorific value of the gas ranges from 1200-1500 kcal/m3.

Gasification Reactions

Devolatilization C+heat CH4+ condensible -hydrocarbons+char

Steam-Carbon C + H2O + heat CO + H2

Reverse Boudouard C + CO2 + heat 2COOxidation C+O2 CO2 +heatHydrogasification C+2H2 CH4+ heatWater Gas shift H2O + CO CO2+ H2 + heatMethanation 3H2 + CO CH4 + H2O + heat

4H2 + CO2 CH4 + 2H2O + heat

Why Gasification?• Biomass covers 80 percent of the energy needs

of Nepal (WECS 2011).• The biomass mostly used for fuel is firewood (68

percent) followed by agricultural residue and animal dung, which are generally of low grade and burnt in traditional stoves. (WECS 2010)

• Due to smoke and particulate matters created by unscientific combustion, the indoor air in houses gets polluted causing respiratory and eye-related health problem to users, especially women and children.

Different waste biomass

Lantana camera Mugwort – Tite pati

Banmara Mikania Macrantha - Banmasa

Pine needles

Agro residuesCrop type Area

[Ha]Crop Prod[MT]

Residue type

RPR* Total Residue Prod [MT]

Paddy 1,531,493 5,072,248 Total residue

1.68 8,521,376

Husk 0.267 1,354,290Maize 871387 2179414 Total

residue5,389,691

stalk 2 4,358,828cob 0.273 594,980husk 0.2 435,883

Millet 278030 315067 stalk 1.08 340,272Wheat 765317 1846142 straw 1.75 3,230,748Buckwheat 10339 10021 Straw 1 10,021

Barley 27966 34829.8 straw 1.75 60,952

Agro residues (cont)Crop type Area

[Ha]Crop Prod[MT]

Residue type RPR Total Residue Prod [MT]

Oil Seed 214835 179145 Stalk 4.01 71,837Sugarcane 64472 2930047 Bagasse 0.29 849,714

tops/leaves 0.3 879,014Total 1,728,728

Jute 10540 14424 Stick 2 28,848Soybean 29281.8 28269.8 Total 98,944.3

Straw 2.5 70,674.5Pods 1 28,269.8

Black Gram 27496.2 22482.4 Straw/stick 1.66 37,320Cotton 135 133 Sticks 2.75 365.75Coconut Husk 0.419 NA

Shell 0.12 NACoffee 1780 425000 Husk 2.1 892,500Ground nut 2736 3869 Husk 0.477 1,845

Straw 2.30 8,899

Saw Dust

Twigs and branches

Different Forest waste• Banmara - 1.78 kg/m2 (17 tons/ha) • Pine needles - 4.5 million tons (382,944.80

ha pine forest area)• Besarmi jhar - 5-6 kgs/m2• Saal leaves - 2,019,600 tons of leaf litter per

year- 5 tons of waste materials/month

• Mikania micrantha - ~ 600,000 tons of dried Mikania (20 districts)

Besarmi jhar, Saal leaves and leaf litter

Estimates of Mikania as raw materials

Municipal Solid wasteNo. Type of waste 1976 1981 1985 1988 1995 1999 2000 2004 2008

1 Organic 67.8 60.0 67.5 58.1 65.0 67.5 69.84 67 68.0

2 Paper 6.5 19.3 6.0 6.2 4.0 8.8 8.5 10 10.0

3 Rubber 0.0 0.0 0.0 0.4 1.0 0.3 0.54 0.24 mix1

4 Leather - - - - - - 0.12 - -

5 Wood 2.7 1.6 0.0 0.5 3.0 0.6 0.73 - -

6 Plastic 0.3 3.6 2.6 2.0 5.0 11.4 9.17 16 13.0

7 Bone - - - - - - 0.23 - -

8 Textile 6.5 5.3 2.7 2.0 3.0 3.6 3.02 4 2.0

9 Ferrous metal 4.9 3.4 2.2 0.4 1.0 0.9 0.87 1 -

10 Aluminium - - - - - - 0.05 - -

11 Metal - - - - - - - - 1.0

12 Sand dust - - - - - - - - 1.0

12 Glass 1.3 3.4 4.0 1.6 1.0 1.6 2.5 1 4.0

13 Construction debris/Others

10.0 3.4 15.0 28.9 17.0 5.3 4.33 1.24 1.0

From simple calculations, this gives about 181 tons of plastics, 186 tons of paper, 36 tons of textiles and 15 tons of woody matter on a daily basis

58 municipalities in Nepal and the amount of waste generated by these municipalities per day comes to 2813.13 tons. Out of this amount of generated waste, 2164.49 tons are collected.

Industrial waste• Waste from veneer industries

• Furniture, handicraft (wooden frames), etc.– Bira Furniture in Patan - 10-15 tons of wood waste per

month – Lalitkaltmak Kastha Udyog - (~0.5 tons) of Saw dust and

1-1.5 tons of wooden strips are generated per week

Subject Amount in Cu.ft. processed per day

Waste per day (taking 50%)

Density of soft wood

Total Amount waste per day

Waste from Sri Om Veneer

400 cft. (300-500cft)

200 cft. = 5.66 m3

53lb/cft* (670kg/m3)

3792kg or 3.8 tons

Total Amount of waste generated from 200 industries from all over Nepal 758.440 tonsCurrent use by local people and boilers and tea drying = 25% 189.610 tonsUnutilized waste that can be used for briquetting = 75% 568.830 tons

RECAST’s involvement in Gasification (1985)

Biomass Gasification for Electricity Generation (1999)

Biomass Gasification for Electricity Generation(2011)

Schematic Diagram of biomass gasifier and its measuring points during testing

T1 Ambient temperature T4 Temperature at orifice meterT2 Temperature at outlet of cyclone separator T5 Temperature inside the gasifierT3 Temperature at outlet of cooler Pd Pressure difference at orifice

meter

Gasifier

Flaring of Producer gas

Design of

Design of Biomass gasifier

Cyclone separator

Filter Tank

Air Heater (9 kW capacity) to test the real output of the plant

Measuring Instruments used during the testing

Multi channel temperature scannerK type thermo coupleOrifice flow meterTrue RMS clamp on meterBalance up to 100 kg.Portable gas analyzer ( For Co measurement of producer gas)Stop watchburette 1000 ml

Test results

`Load (kW)

Ambient Temperature T1 (oC)

T2 (oC) T3 (oC)

T4 (oC) T5 (oC)

Pressure difference ( cm of water)

Gas quantity (m3/second

Gas quantity (m3/Hour

Time taken to consume 100 ml

Diesel consumption per hour (liter) Mode

Diesel/ Producre gas ratio

Charcole consumption (Kg)

12.30 6.00 24.00 2.53 2.37 Diesel 100.00 0.001.00 6.00 24.00 79.00 19.00 84.00 457.00 8.00 0.00 14.15 4.23 1.42 Duel 59.811.30 6.00 27.00 156.00 62.00 164.00 525.00 7.00 0.00 13.00 3.19 1.88 Duel 79.31

2.00 6.00 30.00 203.00 84.00 208.00 530.00 8.50 0.00 14.58 5.06 1.19 Duel 50.002.30 6.00 33.00 265.00 112.00 247.00 560.00 7.00 0.00 13.00 5.13 1.17 Duel 49.32

3.00 6.00 33.00 192.00 84.00 196.00 459.00 8.50 0.00 14.20 5.06 1.19 Duel 50.00Average 6.00 30.75 204.00 85.50 203.75 518.50 8.00 0.00 13.70 4.53 1.32 57.69 2.80

7.00

TimeLoad (kW)

Ambient Temperature T1 (oC)

T2 (oC) T3 (oC)

T4 (oC) T5 (oC)

Pressure difference (cm of water)

Gas quantity (m3/second

Gas quantity (m3/Hour)

Time taken to consume 100 ml(minut

Diesel consumption per hour (liter) Mode

Diesel/Producre gas ratio

Char cole consumption (Kg)

12.30 3.00 28.00 28.00 28.00 28.00 28.00 3.96 1.52 Diesel 100.00 0.001.00 3.00 28.00 142.00 94.00 140.00 1052.00 3.00 0.00 8.92 5.05 1.19 Duel 78.421.30 3.00 29.00 168.00 94.00 178.00 1293.00 4.00 0.00 10.10 5.93 1.01 Duel 66.782.00 3.00 32.00 253.00 127.00 269.00 1440.00 3.00 0.00 8.92 4.40 1.36 Duel 90.002.30 3.00 34.00 238.00 119.00 215.00 1440.00 3.00 0.00 8.92 5.08 1.18 Duel 77.91

Average 3.00 30.75 200.25 108.50 200.50 1306.25 3.25 0.00 9.21 5.12 1.17 78.28 2 kg/hour

4.00

Efficiency Calculation

Mass flow rate of producer gas (m3/hour) (mg)

Calorific value of producer gas (Kcal/m3)(cg)

Out put (mg*cg) (Kcal/hour)

Mass flow rate of Solid fule (Kg/hour) (ms)

Calorific value of Solid fuel (Kcal/Kg) (cs)

Input (ms*cs) (Kcal/hour)

Efficiency (%)

9.21 1167.15 10752.37 2.00 6794.00 13588.00 79.1313.70 1167.15 15984.94 2.80 6794.00 19023.20 84.03

Efficiency of Biomasss gasifier at diffferent load condition

Power produce from generator (KW)

Tharmal energy required(Kcal/hour)

Diesel consumed (liter/hour)

Calorific value of diesel(Kcal/lit)

Thermel energy imputs from diesel (Kcal/hour)

Producer Gas consumption (m3/h)

Calorific value of producer gas (Kcal/m3)

Thermel energy imputs from producer

Total Energy imputs Efficiency

3.00 2580.00 1.17 9281.00 10858.77 9.21 1167.15 10752.37 21611.14 11.946.00 5160.00 1.32 9281.00 12250.92 13.70 1167.15 15984.94 28235.86 18.27

Efficiency Dual Mode

Power (kW)Efficiency of Gasifier

Efficiency of CI engin and

Overall efficiency

3.00 79.13 11.94 9.456.00 84.03 18.27 15.36

Overall efficiency of the Gasification

Power produce from generator (KW)

Tharmal energy required (Kcal/hour)

Diesel consumed (liter/hour)

Calorific value of diesel(Kcal/lit)

Thermel energy imputs from diesel (Kcal/hour) Efficiency

3.00 2580.00 1.52 9281.00 14107.12 18.296.00 5160.00 2.27 9281.00 21067.87 24.499.00 7740.00 2.57 9281.00 23852.17 32.45

Efficieny Diesel mode

Gasification Plant at Sarlahi

• Capacity 11 kW• Equipment cost Rs 20 Lacs• Power supplied to 100 houses• Funded by RERL, through AEPC• Biomass used- Dhaincha (Sesbania sp.)

Rice Husk Gasification Plant• 32 K.W Plant at Suhapur sohari, Parsa Dist.• Husk Power System (P) Ltd., Bihar• Plant Cost Rs 52 Lacs.• Funded by Poverty Alleviation Fund and DDC Parsa• Fuel consumption- 50 kg RH per hour• Power supplied to 209 houses in the community• Run by community-earns Rs 70,000/- by supplying

power and Rice milling• Charges Rs 80/- per family per months per CFL bulb• Rice Sheller mill- 12 Quintal Paddy produces 350 kg

of Rice Husk.

Further developments in this area…..• Alternative Energy Promotion Centre(AEPC) has conducted

feasibility study in the Terai region of Nepal to install Biomass Gasification Plant for Rural Electrification. Such a unit has been tested in Sarlahi district aiming to pilot a site in the district.

• There are more than 40 gasification plants that are successfully operating in India and overseas for heat and power applications. (TERI 2010)

• Renewable Nepal Program of Kathmandu University (KU) is also working on a Project namely “Design, fabrication and testing of a biomass gasifier for small size petrol and diesel engines” since August, 2010.(KU 2010)

• China is expected to achieve the most rapid growth in gasification worldwide. Since 2004, 29 new gasification plants have been licensed or built in China.

Biomass Power Plant• Narayani –Shanker Biomass Power Plant to be established in Lumbini, Rupandehi District• Technology & equipments is based on Indian

Institute of Science specifications• Installed capacity of the BPP is 700 Kwe which

will be fed to the NEA sub-station at Lumbini. PPA already done with NEA.

• undertaken by TMB-ENERGIETECHNIKChhetrapati, Kathmandu, Nepal.Tel# 4256056/ 4257627Email: cbari@info.com.npURL:http://reeep.org/groups/TMB.energie

• Biomass contributes nearly 80 % of the total energy demand in Nepal. Its efficient utilization coupled with co-generation of value added products can provide a dependable and economic route.

• Use of partially pyrolyzed biomass materials eliminates the problem relating to tar formation.

• The performance evaluation of the gasification plant showed that this unit is capable of generating producer gas of 1167 kcal/Nm3 energy to power 20 H.P engine generator on dual fuel mode with 51% replacement of diesel oil. This shows that the gasification plant could be used for generating electricity in the rural areas as a decentralized power unit after carrying out some field tests.

• Biomass gasification can offer an attractive alternative renewable energy system especially in rural areas where biomass fuel is available. Thus can provide community based small-scale independent power plants.

Conclusion and recommendation

Recommendation• Proper training on the Fabrication and use of the

biomass gasification plant for electricity generation should be given to the rural communities before the technology is disseminated in the field.

• There should be Policy support from the government like providing subsidies for the promotion and development of this technology.

• The technology of the gasification system is simple in construction and requires negligible maintenance during its operation.

• Field trials and demonstrations should be done in order to convince the rural communities for generating electricity through biomass gasification.

• Elaborate testing of the gasification plant on various partially pyrolyzed biomass materials should be done.

• Various biomass residues should be characterized to establish their suitability for gasification.

• Different biomass material such as forest residues like pine needles, agricultural waste, briquettes, etc. should also be tried as feeding materials in the gasifier in order to save forest.

• Scope for other industrial application should be ventured.

Scope for Further Studies

Acknowledgements

• University Grant Commission

• Executive Director, RECAST, T.U.

• Kathmandu University

• TERI and IIT-Delhi, India.

• AEPC