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Distributed Heat and Power Distributed Heat and Power
Biomass SystemsBiomass Systems
Denver, Colorado USAAugust 29-September 3, 2004
Dr. Eric BibeauDr. Eric BibeauMechanical & Industrial Engineering DeptMechanical & Industrial Engineering Dept
Doug SmithDoug SmithInnovative Dynamics Ltd., Vancouver BCInnovative Dynamics Ltd., Vancouver BC
Martin TampierMartin TampierEnvirochem Services Inc., Vancouver BCEnvirochem Services Inc., Vancouver BC
OUTLINEOUTLINEBackground Distributed BioPower systemsHow do we compare systems? Efficiency comparison– Gasification– Bio-Oil– Small steam– ORC– ERC
50% MC CHP conversion chart Conclusions
Distributed BioPower BackgroundDistributed BioPower Background
Biomass Life Cycle Analysis (LCA)– Identifying environmentally preferable
uses for biomass resources–Life-cycle emission reduction benefits of
selected feedstock-to product treads–Reports CEC website
Commission for Environmental Cooperationwww.cec.org
Distributed BioPower BackgroundDistributed BioPower BackgroundBarriers to distributed BioPower– need large scale capital cost + low O&M costs– need CHP economics
Low Canadian power rates– Residential/Commercial/Industrial: 4.3 / 3.6 / 2.5 cents US
Industrial users– convert waste to power incentive
Biomass: poor fuel + distributed– transportation cost limitation – biopower considered to be 20 MW and up
Decentralized power– when will it come?
Distributed BioPower Distributed BioPower ApplicationsApplicationsforestry wasteOSB plantsdiesel communitiesgreenhouses forest thinning – fire control
agricultural wastes animal wastes municipal wastes
CHP Sawmill ExampleCHP Sawmill Example
How Does One Compare How Does One Compare Distributed Power Systems?Distributed Power Systems?
Common feedstock?Overall Conversion Efficiency?Account for small scale?Do this for–– BioBio--oiloil–– GasifierGasifier–– Steam cycle (no CHP)Steam cycle (no CHP)–– Organic Rankine Cycle (ORC)Organic Rankine Cycle (ORC)–– Entropic Rankine Cycle (ERC)Entropic Rankine Cycle (ERC)
FEEDSTOCKFEEDSTOCK
Volume
(dry) (wet) FractionCarbon, C 50.0% 25.0% 29.50%
Hydrogen, H2 6.0% 3.0% 21.20%Oxygen, O2 42.0% 21.0% 9.30%
Nitrogen, N2 2.0% 1.0% 0.60%Water, H2O 0.0% 50.0% 39.40%
Feed Analysis
Mass Fraction
Biomass feedstock = natures solar energy storage system
HHV = 20.5 MJ/BDkgfuel & 50% MC
Modeling ApproachModeling ApproachRealistic systems for small size– limit cycle improvement opportunities
cost effective for technology for small size– limit external heat/power to system– adapt component efficiencies to scale
Model system as if building system today– design actual conversion energy system – ignore parasitic power for bio-oil & gasifier– mass and energy balances
Account for every step in conversionExclude use of specialized materials
BioBio--OilOilLiquid: condense pyrolysis gases – add heat; no oxygen – organic vapor + pyrolysis gases + charcoal
Advantages for distributed BioPower– increases HHV – lessens cost of energy transport – produces “value-added” chemicals
Disadvantages for distributed BioPower– energy left in the char– fuel: dry + sized
BIOBIO--OILOIL
Rotating Cone (fast pyrolysis)
Travelling Bed (fast pyrolysis)
Bubbling Bed (fast pyrolysis)
Slow pyrolysis
BioBio--OilOilJF Bioenergy ROI Dynamotive Ensyn
Bio-oil (% by weight) 25% 60% 60% – 75% 60% – 80%Non-cond. gas (% by weight) 42% 15% 10% – 20% 8% – 17%Char (% by weight) 33% 25% 15% – 25% 12% – 28%Fuel feed moisture Not published
BioBio--oil Overall Energy Balanceoil Overall Energy Balance
Biomass Feed 50% moisture
Drying/Sizing to 10% / 2 mm Pyrolysis
21.5% energy loss 32% energy
Char 45.6%
energy loss
Engine/ Generator
6.4% Electricity
60% energy Bio-oil
8% energy loss
18.5%
3%
3%
5%
N2 Sand
Electricity: 363 kWhr/BDtonne
Pyrolysis heat: non-condensable gas + some char (no NG)Pyrolysis power: 220 – 450 kWhr/BDtonne (335 or 5%)Engine efficiency: 28% (lower HHV fuel; larger engine; water in oil lowers LHV)Other parasitic power neglected (conservative)Limited useable cogeneration heat
PowerPower
Gasifier Gasifier -- Producer GasProducer GasSub-stoichiometric combustion – syngas: CO, CH4, H2, H2O– contains particles, ash, tars
Advantages for distributed BioPower– engines and turbines (Brayton Cycle)– less particulate emission
Disadvantages for distributed BioPower– flue gas cleaning– cool syngas – fuel: dry + sized – quality of gas fluctuates with feed
GasifierGasifier
Assume require 25% MC and no sizing requirements (conservative)Ignore parasitic loads: dryer, gas cooler, gas cleaning, tar removal, fans (conservative)Heat to dry fuel comes from process (3.8 MJ/BDkgfuel)100% conversion of char to gas (conservative)HHV of syngas = 5.5 MJ/m3 dry gas
Syngas Vol Dry vol Dry wgtfraction fraction kg/kgfeed
CO 0.1907 0.2994 0.461CO2 0.0365 0.0573 0.139CH4 0.0143 0.0224 0.02H2O 0.363 0 0
H2 0.1043 0.1638 0.018N2 0.2911 0.457 0.703
5.5 MJ/m3 dry gasHHV (dry gas)
Gasification Overall Energy BalanceGasification Overall Energy Balance
Biomass Feed 50% moisture
Drying to 25%
40% energy Producer Gas
7.75% Electricity
Engine/ Generator Gasification
15%
15% energy loss
60% energy loss
17.25% energy loss
Electricity: 440 kWhr/BDtonne
Low HHV of gas affects efficiency of engineAssume ICE operates at 75% of design efficiency15% heat from producer gas dries fuelNo heat lost across gasifier boundaryLimited useable cogeneration heat
Small Steam CycleSmall Steam Cycle(no CHP)(no CHP)
Steam Rankine Cycle– common approach – water boiled, superheated, expanded, condensed and
compressed
Advantages distributed BioPower– well known technology – commercially available equipment
Disadvantages distributed BioPower – costly in small power sizes – large equipment and particulate removal from flue gas
Deaerator
BoilerTube Bank
& Wet Wall
Super Heater
Economizer
Attemporator
Feed Pump
Condenser
Ejector
8%steam
makeup
Turbine
1
23
4
67
8
9
2% blowdown
Small Steam Overall Energy BalanceSmall Steam Overall Energy Balance
Biomass Feed 50% moisture Heat Recovery Steam Cycle
9.9% Electricity
40.5% energy loss
49.6% energy loss
Electricity: 563 kWhr/BDtonne
Limit steam to 4.6 MPa and 400oC (keep material costs low)Use available turbines for that size: low efficiency (50%)No economizer4% parasitic loadFlue gas temperature limited to 1000oC for NOxAll major heat losses and parasitic loads accounted
4% power
ORCORCAdvantages distributed BioPower– smaller condenser and turbine as high
turbine exhaust pressure– higher conversion efficiency– no chemical treatment or vacuum– no government certified operators– CHP – Dry air cooling can reject unused heat
Disadvantage for distributed BioPower– organic fluid ¼ of water enthalpy– binary system– systems are expensive – particulate removal from flue gas
ORCORC
Biomass Feed50% moisture Turboden CycleHeat Recovery
80°C liquidcogeneration
10.2% Electricity
40.1%energy loss
49.7%energy loss
Electricity: 580 kWhr/BDtonneHeat: 2713 kWhr/BDtonne
Flue gas temperature limited to 1000oC for NOxCool flue gas down to 310oCCHP heat at 80oCAll major heat losses and parasitic loads accounted
ERCERCAdvantages for small BioPower– pre-vaporized non-steam fluid – small turbine and equipment – no chemical treatment, de-aeration or vacuums – no government certified operators– ideal for CHP: 90°C to 115°C – dry air cooling can reject unused heat
Disadvantages for small BioPower– restricted to small power sizes (< 5 MW)– system has not been demonstrated commercially– special design of turbine– particulate removal from flue gas
ERCERC
Biomass Feed 50% moisture Entropic CycleHeat Recovery
90°C liquidcogeneration
12.0% Electricity
56.2%energy loss
31.8%energy loss
Electricity: 682 kWhr/BDtonneHeat: 3066 kWhr/BDtonne
Flue gas temperature limited to 1000oC for NOx
Cool flue gas down to 215°CCHP heat at 90oC
Fluid limited to 400°CAll major heat losses and parasitic loads accounted
NonNon--Steam Base SystemsSteam Base SystemsORC & ERCORC & ERC
Thermal Oil Heat Transfer
TURBODEN srl
synthetic oil ORC
Conversion
1000°C 310°C
250°C 300°C
60°C
80°C Liquid Coolant
Air heat dump
17%
Input Heater 59.9% recovery
Entropic Fluid Heat
Transfer
ENTROPICpower cycleConversion
1000°C 215°C
170°C400°C
60°C
90°C Liquid Coolant
Air heat dump
17.6%
Input Heater 68.2% recovery
1
Distributed BioPowerDistributed BioPowerCHP Conversion ChartCHP Conversion Chart
Note: Results are for 50% moistures content
Bio-oil GasificationSyngas
AirBrayton
Large Steam
Overall Power Efficiency 6.6% 7.8% 7.4% 15.9%Electricity (kWhr/Bdtonne) 363 440 420 903Heat (kWhr/Bdtonne) - - - -Overall Cogen Efficiency 6.4% 7.8% 7.4% 15.9%
SmallSteam
SmallSteam CHP
OrganicRankine Entropic
Overall Power Efficiency 9.9% 5.7% 10.2% 12.0%Electricity (kWhr/Bdtonne) 563 324 580 682Heat (kWhr/Bdtonne) - 2,936 2,713 3,066Overall Cogen Efficiency 9.9% 53.9% 54.5% 67.5%
1
Distributed BioPowerDistributed BioPowerCHP Conversion ChartCHP Conversion Chart
Note: Results are for 50% moistures content
$0.038 per kWhr$0.014 per kWhr
USDPower (85% use) Heat (40% use) Total
Bio-Oil $11.8 n/a $11.8Gasification $14.3 n/a $14.3Air Brayton $13.6 n/a $13.6
Large Steam (simple) $29.3 n/a $29.3Small Steam $18.3 n/a $18.3
Small Steam CHP $10.5 $16.1 $26.6ORC $18.8 $14.9 $33.7ERC $22.1 $16.9 $39.0
Revenue (per BDTon)
Electrical Power (USD)Natural gas (USD)
ConclusionConclusionConversion: losses at many points Comparison: energy captured from original fuel– moisture content – scaling effect
Technologies: drying and sizing – disadvantage for small distributed systems
High parasitic loads at further disadvantage Power and heat produced for base fuel
30662713NoneNoneNoneUseful heat (kWhr/Bdtonne)
682580563440363Electrical (kWhr/Bdtonne)ERCORCSmall steamGasificationBio-oilSystem
Natural Resources CanadaCommission for Environmental CooperationNational Research CouncilManitoba Hydro: Chair in Alternative Energy
ACKNOWLEDGEMENTACKNOWLEDGEMENT