MICINN‐DST Joint Workshop on Renewable EnergyEnergy from Biomass Work Supported BY MNRE P. J. Paul Combustion, Gasication and Propulsion Laboratory, Department of Aerospace Engineering, Indian Institute of Science, Indian Institute of Science Bangalore 560012
Overview• Biomass and its potential for power g generation• Types of biomass• T h l Technology for biomass utilization f bi ili i – Biomass conversion technologies – Biomass gasification – Engines
Climate change Climate change• Increase in green house gases emission possibly leading to global warming and climate change• Fossil fuels play a very important role in the economies and lifestyles of people throughout economies and lifestyles of people throughout the world• C th l b l Can the global economy can be powered in ways b di that might have less impact on the environment because they discharge less carbon dioxide? b h di h l b di id ?
How do biofuels reduce green house gas emissions?• Bi Biomass fuels as well as fossil fuels release carbon dioxide to the f l ll f il f l l b di id t th atmosphere when burnt.• Fossil fuels produce CO2 from carbon which was stored in the earth over several millions of years l illi f• if the biomass is produced sustainably, the growing trees and other plants remove carbon dioxide from the atmosphere during photosynthesis and store the carbon in plant structures. h t th i d t th b i l t t t• When the biomass is burned, the carbon released back to the atmosphere will be recycled into the next generation of growing plants. l• When biomass is used as fuel instead of fossil fuel, the carbon contained in the fossil fuels remain in ground instead of being released to the atmosphere.• Fast‐growing trees can recycle carbon rapidly and will displace fossil‐fuel use with every cycle.
Can CO2 growth rate be arrested by afforestation alone?• Forests that are not harvested does not continue h h dd i to accumulate carbon indefinitely.• In mature forests photosynthesis nearly balances the carbon that is released to the atmosphere by respiration, oxidation of dead organic matter, and fires and pests.• If fossil fuels are to be used continuously, then ever expanding afforestation would be needed to prevent increasing levels of carbon dioxide in the atmosphere.
What is biomass? What is biomass?• Biomass is any residue from plant or animal i i id f l i l matter.• Sources – Agricultural residues – Energy plantation – Biofuels – Wastes from Argo industries – Domestic and urban wastes• Many of these will generate CO2 and other green house gases even if left unutilized. g
Types of biomass Types of biomassBiomass Components – Sugars – Oils – Starch – Cellulose – Hemi‐cellulose – LigninLeafy biomass – Mostly cellulosic + some starch + f b l ll l h some ligninWoody biomass – 50 % cellulose + 25 % hemi‐Woody biomass 50 % cellulose + 25 % hemi cellulose + 25 % ligninSeeds Starch and/or oilsSeeds – Starch and/or oils
Sources of biomass Sources of biomass• Kitchen wastes – fruits/vegetables/some starchy stuff • Market wastes – similar to the above ‐ Contain large amount of sugars/starch. amount of sugars/starch• Sewage – contains starch/more complex biodegradable matter • Urban solid wastes – contains some biodegradable b lid i bi d d bl matter and a larger amount of matter that can be converted only by thermo chemical means (lignaceous, plastics, etc) l ti t )• Agricultural wastes – contains a large amount of matter that can be converted by thermo‐chemical y means• Plantation residues – same as above• Energy plantation/ wild growth Energy plantation/ wild growth
Energy plantation Energy plantation• F t Fast‐growing trees can recycle carbon rapidly and will i t l b idl d ill displace fossil‐fuel use with every cycle.• There plantations, either managed or not managed, p , g g , existing in India.• Eucalyptus and casuarinas plantations for fuel wood and paper and pulp industries are examples of managed paper and pulp industries are examples of managed plantations.• Prosopis Juliflora is being utilized as biomass fuel in several p g parts of the country — an example of utilization of wild growth.• Bamboo under intensive cultivation can generate biomass Bamboo, under intensive cultivation, can generate biomass at a rate of more then 100 ton/ha/yr (Growmore Biotech, Hosur, Tamil Nadu)
Availability of Bioamass in India Availability of Bioamass in India• Agricultural residues i l l id – Total Area: 143 M ha – Crop production: 500 M T/ yr – Residue generation: > 500 MT/ yr g /y – Surplus residues: 150 MT /yr – Power potential: 20000 MW Power potential: 20000 MW• Other residues –FForest residues t id – Waste land
National Biomass Resource Atlas of India National Biomass Resource Atlas of India• A l t i tl An electronic atlas of India for excess biomass to enable f I di f bi t bl obtain local power potential• Partners: – Ministry of Agriculture (MoA, GOI) – their data base – RRSSC (Regional Remote Sensing Centers of ISRO) RRSSC (Regional Remote Sensing Centers of ISRO) – Consultants and Apex Institutions appointed by MNRE, GOI – Other institutions like Coir Board, Agricultural Universities, etc •IISc – National Focal Point for acquiring assessing and processing National Focal Point for acquiring, assessing and processing the data from various sources into digital maps on a GIS format to be used by industrialists, planners and others
Remote Sensing Data Taluka and l k d (ISRO-RRSSC) District Level MOA, Other Project Partners Gov. Sources SurveysThe Schemeof the Work Statistical NFP, Database CGPL, IISc Census, Other Boards & Discussion, Ageences g Interactive Meetings with AIs, Consultants GIS B Based d Interactive Package
The Key-Aspects of the Work: Key- Work:1. The Statistical Data Analysis and Compilation. y Compilation. p2. Graphical vectorisation for the base GIS layers. layers.3. Integration of remote sensing d t i t GIS l3 I t ti f t i data into layers. layers.4. Strategies for crop identification – use of NDVI (Vegetation Index) and AI (Artificial Intelligence) techniques. techniques.5. Create a strategy for stand alone use for a variety of users6. Provide options for dynamic queries with graphical or tabular outputs
The Main Features of the Package g• Statistical Data on crops, residues and estimate of surplus residues taking account of the socially essential usage are embedded as dynamic data. data.• About 40 crops all over the country, several of them having p y, g multiple residues are accounted for. for.• In a quick summary, 540 million tons/year of residue leading to an excess of 120 to 140 million tons/year with power potential of 15,000±1000 MWe is estimated having a 15,000± scope of distributed generation in 1–6 MWe range. range.• Users can obtain the data from the Atlas, the nature of , crops, residues, power potential of each district over the country and also the estimate for the talukas. talukas.
Main Achievements of the Project• A method of seamless integration of the data from all essential sources to generate a single electronic document to essential sources to generate a single electronic document to be used as biomass resource atlas is developed and demonstrated.• Methods for Crop Identification from land‐use data and remote sensing data for deriving coefficients from survey data and obtaining assessment of biomass resource spatially are and obtaining assessment of biomass resource spatially are developed and used. • The atlas available at http://lab.cgpl.iisc.ernet.in/Atlas/• Also at MNRE web site
Biomass conversion technologies Biomass conversion technologies• Efficient utilization of biomass for energy• Conversion of biomass to suitable forms of Conversion of biomass to suitable forms of fuel• Di Direct Combustion to generate thermal energy C b i h l• Advanced energy conversion devices gy
Technology Routes for Biomass Conversion Technology Routes for Biomass ConversionBiomass characteristics are relevant for conversionBiomass characteristics are relevant for conversion• Biomethanation – Biogas• Gasification Producer gas Gasification ‐ Producer gas• Direct combustion• Liquid Fuels – Non edible oil from trees Liquid Fuels – Non‐edible oil from trees Alcohols from sugarcane and biomass Pyrolitic oil through fast pyrolisis oil through fast pyrolisis. Liquid fuels through FT synthesis from PG• Reciprocating engines and gas turbines with Reciprocating engines and gas turbines with liquid fuels, biogas and producer gas
Biomethanation•Sugars + starch easily digested by bacteria (without orwith air)• Vegetable and leafy wastes digested by bacteriaeven though not so completely or easily (timerequirement) again, without or with air.•Woody wastes difficult to be digested by bacteria • Lignin requires fungi for digestion
Biomethanation route is well known for cattle dung and both China a d d a a e a y a ge u be o p a ts o do est c a d and India have vary large number of plants for domestic and community applications, The design is simple - a feed system and a extraction system – hydraulic residence time of 30 to 40 days at ambient temperature. This functions well at tropical conditions with liquid temperatures ~ 25 to 35 C C.Biomethanation plants for liquid residues, such as sewage and agro- industrial effluents are well established At lower temperatures, performance goes down. High rate Biomethanation techniques (35 and 55 C operations) can improve the performance These have not been attempted with performance. bovine dung since the market cannot sustain the capital investment costs. In the above cases the solids content is about 10 %. Other processes with lower content of water is also available.
• 1 kg of solids with 4 to 9 times the water will produce about 50 to 120 g (30 to 70 liters) of gas.• The composition of the gas is: 50 to 55 % Methane, ~ 1000 to 5000 ppm Hydrogen sulfide and the remaining amount ~ 47 % carbondioxide• For distillery effluents one uses anaerobic digestion technique to reduce the BOD/COD of the effluent. These q / plants use generally high rate biomethanation processes.• The composition of the gas is 60 to 65 % Methane, 2 to 5 %H d Hydrogen sulfide and remaining ~ 33 % CO2. lfid d i i• The gas has a calorific value of 18 to 22 MJ/m3.• A number of institutions are involved in research in this area (eg. Agharkar Research Institute, IISc
Liquid Fuels from biomass Liquid Fuels from biomass• N Non-edible oil f dibl il from t trees• Alcohols from sugarcane and other biomass containing largely cellulose/ sugar• Pyrolitic oil through thermal degradation process• A large number of trees store in their seeds, starch or oils. Some of these are non-edible. They can be used for power generation.• Th These are R Rape seed oil, J d il Jatropha, J j b M h h Jojoba, Mohua, S l Sal, Pongemia, Cashew, Neem, Anderouba, Soumarouba.• Indian government in collaboration with public sector government, undertaking and private partners, is taking initiative in increasing the bio-oil production.
Biomass utilization for energy (Thermal root) B iom ass U tilisation for Energy Therm al Pow er Am b. Pr. High Pr. Boiler Steam turbine Gasifier R/c engine Gas turbine Mecha nica l Electricity W a ter pum ping Stoves Large Gasifier Com bustors Dom estic Industrial Gas Burner
Thermochemical conversion Technologies Solids (Combustion)• Use combustion process – on a grate/ fluidized bed – to provide hot gases to be used to raise high pressure steam and then extract power from steam turbine – generator route (standard) (standard).• The calorific value of dry biomass is 16 MJ/kg.• The air-to-biomass ratio at stoichiometry is about 6. air to biomass (note for reference, the calorific value of fossil fuels is about 42 MJ/kg and the stoichiometric air-to-fuel ratio is 15)• Several projects have been implemented with mixed results – L k of mechanism f collection and di t ib ti Lack f h i for ll ti d distribution of bi f biomass residues• Cost of energy critically depends on the biomass price.
Cogeneration potential in India Cogeneration potential in IndiaIndia has several industries which has potential g ( p ) for cogeneration. (ref: Teri report) Industry Cogeneration potential (MW) Sugar 5000 Paper 600 Cotton 500 Non‐agro‐industries 1400Sugar industry is one large potential for cogeneration.
Cogeneration in Sugar Industries in India• Sugar industry is one of the industries having g p g large potential for cogeneration.• The fuel for power generation is generated in‐ house. house• The potential for power generation in sugar industries in India is about 5000 MW• The achieved potential is about 1000 MW The achieved potential is about 1000 MW
Gasification• For power levels less than 2 MWe, the cost can be cut down by using gasification t h l i i ifi ti technologies and using th gas i reciprocating d i the in i ti engines.• Gasification of solid biomass occurs because of thermo-chemical reactions at sub-stoichiometric conditions.• Gas composition: CO = 20 %, H2 = 18 %,CH4 = 2 %, CO2 = 12 %, H2O = 2 %, Rest =N2• This gasification process captures between 78 to 82 % of the energy in Biomass. Every kg of dry biomass generates 2.6 m3 of gas. The gas has a calorific value of 4.5 to 5 MJ/m3. The stoichiometric air-to- g fuel ratio is 1.3 [note: 1 kg biomass needs 6 kg of air for combustion. This is the same as the above calculation as follows: Biomass requires 1.8 kg air for gasification. 2.8 kg of gas requires 2.8 times 1.4 kg air = 3.92 kg air – thus the total air required for combustion is 1.8 + 3.92 = 5.72, a value close to 6.0]
Gasification – contd. Gasification contd• When used in dual fuel mode in diesel engines, the dry biomass and diesel required are about 0.9 to kg d 0 9 t 1 k and 60 t 75 ml per kWh to l kWh.• When used in producer gas engines, the dry biomass required i about 0 8 t 1 3 k /kWh bi i d is b t 0.8 to 1.3 kg/kWh.
The Gasification Process The Gasification ProcessBiomass when heated looses volatiles leaving fixed Biomass when heated looses volatiles leaving fixedcarbon (about 20–25 %)The volatile matter reacts with air providing energy for p g gybiomass heating and to raise the temperature of gases b h d h fto about 1200–1400°C.The hot gases thus produced, which contains CO2 and The hot gases thus produced, which contains CO2 andH2O react further with the fixed carbon to generate CO and H2.These are endothermic reduction reactions and brings These are endothermic reduction reactions and bringsdown the temperature to about 600–700°C.The IISc open top reactor has a second stage of oxidation‐reduction process to minimize the tar in the id ti d ti t i i i th t i thproduct gases and to improve the carbon conversion.
Work at IISc Work at IIScNovel reactor designN l t d i Air is drawn from the top and from the air nozzles – • Uniform distribution Air (~ 50-70%) Biomass A Broader high temperature zone Broader than in Stratific ation (upward closed-top. Enough residence time propagation of flame front) B A Air B Grate o Hot gases 1200 - 1400 C o (700 - 800 C) • Consistent high quality gas over the turn down ratio • Varying biomass quality – can accept a variety of agro residues The ratio of air flow rate from the nozzle to the top depends on the fuel properties – size, density; the char consumption rate, etc
Gas cleaning ‐ Gas cleaning process• Gas has to be cooled and cleaned for end use application Gas has to be cooled and cleaned for end use application T and P levels of 100 ppm and 1000 ppm respectively in the raw gas at 350 T and P levels of 100 ppm and 1000 ppm – 650°C 650° – Cooling and cleaning is achieved by using a number of components – These are cyclones and cooling devices by spraying water in scrubbers – Further cleaning is achieved using chilled scrubbers Further cleaning is achieved using chilled scrubbers With this gas cleaning process it is possible to restrict the contaminants to ppb levels contaminants to ppb levels• Water is the only medium used for cooling and cleaning process. Water treatment process cleaning process Water treatment process enables reusing of water
Gasification Elements Gasification Elements 1 5 4 6 2 3 1 0 8 7 9 11 12Components• The reactor• N Necessary cooling and cleaning system li d l i t - to meet the end use requirements
Comparison of steam and gasification root for electricity generation Steam GasificationElements Boiler, steam turbine Boiler steam turbine Gasifier, IC engine Gasifier IC engineTechnology Well established Reasonably maturedSkills required for Low to medium MediumoperationInstallation cost 4 – 4.5 crores/ MWe 5 ‐ 6 crores/ MWeEfficiency Reasonably high at High efficiency can be several 100 MW level, achieved at low power but low at lower power but low at lower power levels levels
Research on gasification process Research on gasification process• Single particle behaviour in various p atmospheres• Behaviour of packed beds• G ifi modeling Gasifier d li• Gas cleaning processes gp• Water treatment
Research on Gasification process – Single particle Reactants : (a) CO2 (b) H 2O (c) air (d) O2 Kinetic and CO2 diffusion t b ~ d 1.03 1 0 dependence CO 2tc/ρ(s m3/kg) Kinetic and H2 O -1 H 2O diffusion 10 t b ~ d1.2 -1.3 0 dependence air t b ~ d 1 .9 air diffusion limited -2 0 10 O2 T = 1273 K tb ~ d 2 O2 diffusion limited 0 10 -3 1 10 Conversion time for char reaction with d 0 (mm) 1. CO2 is 3-4 times that of H 2O 2. H2O is comparable to air at dp > 8 mm
Basic Research packed bed Basic Research – packed bedWith increase in mass flux the front velocity initially increases and then reduces ‐ This fixes the turn down ratio of the gasification system ‐ Superficial mass flux and ash properties are used as design parameters
Power generation using producer gas Using R/C engines Dual – Fuel Engine 80% gas & 20% diesel Gas Engine 100% gas
Research on Engines Research on Engines• Basic Research – Experimental & Modeling• Development of gas carburetion system p g y• Reliability tests - Long duration trails• Collaborative work with Cummins India – Adaptation of Natural gas engines – Laboratory trails & Field monitoring• Collaborative work with engine manufacturers
How is PG different from NG in engine?• Th air-to-fuel ratio of PG is 1.3:1, whereas for The i t f l ti f i 131 h f NG it is 17:1 – this calls for a different carburetor• PG has higher octane rating, therefore can be used rating sed in engines with higher Compression ratio• The flame speed of PG is higher ~ 20%; calls for a different ignition timing setting• The energy density of PG is lower ~ 20%, this 20% causes de-rating of the engine power• The flame temperature is lower by about 300 K, K implies different operating condition in the engine cylinder and turbocharger y g
Analysis of Producer Gas Engine y g Reasons for de-rating with PGEnergy density gy y Sub-optimal – p Reactant:Product R t tP d t PG < NG Turbocharger < 12% by 20 - 23% Properties of Gaseous Fuel p Fuel Fuel Air/Fuel Mixture, Φ, Limit SL (Limit), SL Peak Product/ + LCV, @ (Φ =1) MJ/kg cm/s Φ =1, Flame Reactant Air MJ/kg Lean Rich Lean Rich cm/s Temp, K Mole Ratio H2 121 34.4 34 4 3.41 3 41 0.01 0 01 7.17 7 17 65 75 270 2400 0.67 0 67 CO 10.2 2.46 2.92 0.34 6.80 12 23 45 2400 0.67 CH4 50.2 17.2 2.76 0.54 1.69 2.5 14 35 2210 1.00 C3H8 46.5 15.6 2.80 0.52 2.26 - - 44 2250 1.17 C4H10 45.5 15.4 2.77 0.59 2.63 - - 44 2250 1.20 PG 5.00 1.35 2.12 0.47 1.60 10.3 12 50 1800 0.87 a b c d
Typical Applications Application Requirement Rural Electrification •Short duration ~ 4 – 6 hour/day, low PLF •High plant availability > 95% i h l il bili •Load reasonably constant Industrial - Captive p •Continuous operation – 24 hr x 6/7 day a week p y •High plant availability > 90% •Large load fluctuations Independent Power •Continuous operation – 24 hr x 7 day a week Producer – grid lined •High plant availability > 90% •Ability to take fluctuations in the grid (in India) y g ( )Producer gas engine can meet each of the above applications
Emission 1 Load ~ 80-90% 2 0.8 1.6 CONO, g/MJ CO, g/MJ 0.6 1.2 g g 0.4 NO 0.8 0.2 0.4 0 0 0 4 8 12 16 20 24 Time Cycle, Hour
Some Case Studies Some Case Studies• Gasification technology is commercially deployed in India with mixed performance in the field• A few manufacturers in India provides gasifiers for industrial use for industrial use• While it has been proved in the field on commercial operations, optimal use still to be i l ti ti l till t b achieved• Biomass collection and distribution still to be p developed
Grid connected 100 kWe biomass gasification power plant in Karnataka• 08 0.8 MWe of gasification power plant connected f ifi i l d to the grid in Karnataka as a part of Biomass Energy for Rural India a program under E f R l I di d GoK/UNDP/MNRE• The project is being implemented in five village clusters with a total of 26 villages in the state of Karnataka, India K k I di• The project had six gasifier based power plants composed of two 100 kWe and one 200 kWe in different villages
Performance• In the last 12 months the system has operated for 14500 hours (~ 7250 each) of operation generating about 4.0 million units of electricity b ll f l using about 5500 tons of biomass.
Heat treatment –Tahafet, Hosur Heat treatment Tahafet Hosur• Eight furnaces and temperatures vary from 600 C to 1000 C • Each furnace is fitted with two burners having air to fuel ratio control and also a PID air to fuel ratio control and also a PID controller to oversee the operations. The industry operates on three shifts for about 6 h hf f b days in a week• Typical LDO consumption per day = 1500‐2000
Heat treatment .. contd Heat treatment contd• 300 k /h 300‐kg/hr capacity installed it i t ll d• All the eight furnaces are connected to the gasifier connected to the gasifier using WESMAN make dual‐ fuel burner. The temperatures in the individual furnaces are i th i di id l f maintained independently.• With 8 furnaces connected With 8 furnaces connected presently to gasifier saving is about 2000 litres/day.• Average fuel consumed per day 5.2 ton of coconut shells, woodchips• Total operating hours ~35000
5 MW th for heat application5 MW th for heat application
Performance using briquetted fuelsPerformance using briquetted fuels• Agro residue briquettes tested at 20 % ash – Same gasification system can handle 1 to 20 % ash g y – Gas quality acceptable for engine – SFC consumption similar on ash free basis SFC consumption similar on ash free basis• Fuel quality requirement – Thermal stability of the briquette important – Density and binding an important property Density and binding an important property
Future Directions and possible areas of cooperation• Fuel cells for increased efficiency l ll f i d ffi i – High temperature fuel cells operating directly on producer gas. d• Liquid fuel generation (FT process) for generation transportation fuels. i f l – Work in progress at IISc and IIT Guahati• Hydrogen from biomass – Generation of hydrogen rich syngas and hydrogen separation. – Work in progress at IISc