biomass combined heat & power th ltechnology– stirling engine – fuel cell 6. rankine cycle...

BiomassCombined Heat & Power

T h lTechnology

1Morris A. PierceNovember 5, 2009

Why CHP/Cogeneration?• Typical thermal electric plants have a

thermal efficiency of 25 to 30%thermal efficiency of 25 to 30%• 70 to 75% of the energy input into an

l t i l t i j t d i t thelectric plant is rejected into the atmosphere as waste heat

• Wasted heat = wasted money, higher emissions

• Biomass CHP plants can achieve efficiencies above 90%

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US Electric System Energy Flow

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US Electric System Energy Flow

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Biomass Fuel & Technology

CHP 5 000 MBH

Heating 1,000 – 20,000 MBH

CHP >5,000 MBH Green Wood Chips>30% moisture

180 4 000 MBHDry Wood Chips 180-4,000 MBH<30% moisture

50 - 300 MBHPellets

5MBH 100 1,000 10,000 100,000Sq Ft 4,000 40,000 400,000 4,000,000

CHP Technologies• Rankine Cycle

Steam turbine– Steam turbine– Organic Rankine Cycle

• Brayton CycleBrayton Cycle– Gas turbine

• Otto CycleOtto Cycle– Reciprocating engine

• OtherOther– Stirling engine– Fuel cell

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Rankine Cycle

Heat SourceHeat Source

WorkingFluid

Turbine orEngine Power

Heat SinkHeat Sink

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Steam Turbine CHP

Boiler

900 psig875°F

SteamSteam CondensingTurbine

ElectricGenerator

13 psiaSteam

Condenser 200°FCondenserHot Water

Very efficient above 5 MW less efficient at smaller sizes

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Very efficient above 5 MW, less efficient at smaller sizes

Steam Turbines

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Organic Rankine Cycle CHP

Currently available for 300 kW to 2,200 kW

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ySmaller units down to 10 kW are being tested

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Organic Rankine Cycle CHP Module

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Brayton & Otto Cycles• Gas turbines & reciprocating engines

require a liquid or gaseous fuelrequire a liquid or gaseous fuel• Biomass gasification technology to support

t bi & i i t t t b tturbines & engines is not yet mature, but continued development could make it

i ll i bl i th f tcommercially viable in the near future.• Gasification usually requires a consistent,

dry feedstock

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CHP/Cogeneration• More complicated than a heat-only or

electric only projectelectric-only project• Significant stimulus incentives available• Use of standardized, modular technology

will help reduce costs

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For more information:

Morris A Pierce, PhDUniversity of RochesterUniversity of Rochester

585 275-4331mapi@mail rochester edumapi@mail.rochester.edu

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