advantages and economical feasibility of combined heat and...

BIOS BIOENERGIESYSTEME GmbHBIOS BIOENERGIESYSTEME GmbHInffeldgasseInffeldgasse 21b, A21b, A--8010 Graz, Austria8010 Graz, Austria

TEL.: +43 (316) 481300; FAX: +43 (316) 4813004TEL.: +43 (316) 481300; FAX: +43 (316) 4813004EE--MAIL: MAIL: office@[email protected]

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Advantages and economical feasibility of combined Advantages and economical feasibility of combined heat and power production based on biomass with a heat and power production based on biomass with a

special focus on ORC special focus on ORC technologytechnologyDipl.-Ing. Norbert Wildbacher

2

BIOENERGIESYSTEME GmbHInffeldgasse 21b, A-8010 Graz

Presentation Presentation --overviewoverview

Technologies and constraints for the application of small-scale biomass CHP plants

The ORC process – technology and application

Conclusions and recommendations

3


Definitions and constraintsDefinitions and constraints

Decentralised biomass CHP technologies

Nominal electric capacity: 0.01 – 20 MWel

Nominal fuel power: 0.02 – 70 MW (based on NCV)

Size of CHP plant limited by

Low energy density of the biomass fuel(storage, logistics)

Availability of heat consumers

4


Constraints for the application of Constraints for the application of smallsmall--scale biomass CHP plantsscale biomass CHP plants

Nominal electric capacity of small-scale biomass CHP plants: < 2.0 MW(el)

Relatively low electric efficiency only heat controlled operation economically meaningful

Biomass CHP plants in wood manufacturing and wood processing industries(high process heat demand)

Biomass CHP plants for base load coveragein district heating systems

Biomass CHP plants in non-wood and non-agricultural industrieswith high process heat or process cooling demand

5


Criteria for decentralisedCriteria for decentralisedbiomass CHP technologies (I)biomass CHP technologies (I)

Biomass should be used locally

Thermal biomass utilisation for “heat only” production is an exegetically not optimal solution.

Electricity production increases the plant utilisation rate(in comparison to “heat only” applications).

The electricity demand of the plant can be covered from the own production (if this is of interest).

Nearly all electricity production technologies show comparably low electric efficiencies for small-scale applications at present.

6


Criteria for decentralisedCriteria for decentralisedbiomass CHP technologies (II)biomass CHP technologies (II)

The specific capital costs (per kWel installed) increase with decreasing plant capacity (”economy of scale”).

Biomass CHP plants only seem to be reasonable if acceptable feed-in rates are secured for long terms.

A basic requirement for the technologies used is their robustness and their operational safety(especially of relevance for decentralised applications)

For the operator of a steam boiler or a turbine a higher educational level is affordable than for the operator of a hot water boiler => personal costs increase

7


Criteria for decentralisedCriteria for decentralisedbiomass CHP technologies (III)biomass CHP technologies (III)

Ecologically and in most cases also economically seen, decentralised CHP systems should be operated in heat and not in electricity controlled mode.

In correctly dimensioned plants a minimum of 5,000 full load operating hours per year should be achieved from the CHP unit (target value: >6,000 full load hours per year).

For the evaluation of the realisability of a biomass CHP project a comprehensive technological and economic assessment should be made (including a heat only application as a reference unit).

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Assessment factorsAssessment factorsfor CHP technologiesfor CHP technologies

plant parameters ηel-plant

ηtot

P el

complexity of the plantoperation behaviour start up

partial load operationprocess control demand and education of operation personnel

level of automationmaintenance usual maintenance

personnel demand for maintenancefrequency of malfunctions

ecology hazardous operational supplementsnoise

state of development maturity of technologyshort term potential for further development

cost structure capital costsconsumption costs

operation costs and maintenance costsother costs

9


SmallSmall--scale scale biomass CHP biomass CHP technologies technologies -- overviewoverview

CHP plants based on biomass combustion

Steam turbine process

Steam piston engine process

Screw-type engine process

ORC process

Stirling engine process

CHP plants based on biomass gasification

Gasification systems combined with gas engines or turbines

10


Steam turbineSteam turbine process process --schemescheme

boilergeneratorbiomass

air

G

flue gas

feedpump

steamturbine

pressure reducingvalve

throttle valve

heat consumers

condenser

condensatetankcondensate

pumpfeed water supply

feed watertreatment

feed watertank

11


Steam turbineSteam turbine processprocess--thermodynamic cyclethermodynamic cycle

T

s

p =konst.o

p =konst.u1

23

4

12


Steam turbineSteam turbine process process --technological evaluationtechnological evaluation

AdvantagesNo upper limit regarding plant size

Technologically mature

Low specific investment costs

Well applicable for large-scale installations (>2 MWel)

Weak pointsLow electric plant efficiency for small-scale systems

Partial load operation requires special control systems

Educated steam boiler operator necessary

High operating costs (maintenance, feed water treatment)

13


ORC process ORC process --description of technologydescription of technology

Utilisation of an organic working medium instead of waterOrganic Rankine Cycle (ORC)

The necessary energy is transferred from the biomass boiler to the evaporator of the ORC by a thermal oil cycle under atmospheric conditions

no pressurised boiler necessary (decreased personal cost)no water treatment necessary

An ORC process especially adapted for biomass CHP plants was developed in Italy (working medium: silicon oil)

The implementation of ORC modules in existing biomass combustion plants is relatively easy

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ORC process ORC process --optimised schemeoptimised scheme

G

ORC-process

Biomass

Combustionair

Flue gas

Thermal oil cycleGenerator(directly coupled)

Turbine

Evaporator

Condenser

Regenerator

Economiser

Silicon oilpump

Thermal oilboiler

Furnace

Combustionair pre-heater

DistrictHeating

Thermal oil ECO

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BIOENERGIESYSTEME GmbHInffeldgasse 21b, A-8010 Graz ORCORC--ProcessProcess –– componentscomponents

911

10

1 Regenerator2 Condenser3 Turbine4 Electric Generator

5 Circulation pump6 Pre-heater7 Evaporator8 Hot water inlet

9 Hot water outlet10 Thermal oil inlet11 Thermal oil outlet

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EU Demonstration Project EU Demonstration Project LienzLienz (A) (A) ORCORC--ProcessProcess –– evaporatorevaporator, ,

regeneratorregenerator and and turbineturbine

17


ORC process ORC process --description of technology IIdescription of technology II

Turbine with high efficiency and low speed of rotation,optimised for small-scale applications

No danger of droplet erosion on turbine blades due to the favourable thermodynamic properties of the silicon oil

ORC plants show an excellent partial load behaviour,are suitable for rapid load changes and can be operatedbetween 10% and 100% of their nominal load

The operation of the ORC plant is fully automatic,no additional personal is required(just some man hours per week for regular checks)

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ORC process ORC process --thermodynamic cyclethermodynamic cycle

T

s

p =konst.o

p =konst.u1

2 3

4

19


ORC process ORC process --partial load behaviourpartial load behaviour

0

20

40

60

80

100

0 10 20 30 40 50 60 70 80 90 100

[%] of the nominal electric efficiency

η el/η

el-fu

ll lo

ad[%

]

ORC process

According to measured operating data

According to data of the supplier

20


ORC process ORC process --relevant maintenance issuesrelevant maintenance issues

High reliability (long experiences available from geothermal applications)

The working medium does not age and is not corrosive

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ORC process ORC process --ecological aspectsecological aspects

ORC plants are relatively silent (the highest noise emissions occur at the encapsulated generator and amount to 75 dBA in a distance of 1 m)

Silicone oil is not toxic, not depleting the ozone layer, not explosive but is flammable with a flame point of 34°C

The ORC cycle is completely closed(no losses of the working medium occur)

The thermal oil cycle demands higher security measures regarding leakage than water or steam cycles

22


EU Demonstration Project EU Demonstration Project LienzLienz (A) (A) integration of the ORC processintegration of the ORC process

into the overall plantinto the overall plant

0

5,000

10,000

15,000

20,000

25,000

0 1,200 2,400 3,600 4,800 6,000 7,200 8,400operating hours per year [h]

Ther

mal

and

ele

ctri

c ou

tput

of t

he C

HP

plan

t [kW

]

Solar thermal collectorPeak load boilerHeat recoveryHot water boilerCHP unitElectricity production

0

5,000

10,000

15,000

20,000

25,000

0 1,200 2,400 3,600 4,8000

5,000

10,000

15,000

20,000

25,000

0 1,200 2,400 3,600 4,800 6,000 7,200 8,400operating hours per year [h]

Ther

mal

and

ele

ctri

c ou

tput

of t

he C

HP

plan

t [kW

]

Solar thermal collectorPeak load boilerHeat recoveryHot water boilerCHP unitElectricity production

23


EU Demonstration Project EU Demonstration Project LienzLienz (A) (A) ORC ORC processprocess -- technicaltechnical datadata

Thermal power (thermal oil) input - ORC at nominal load 5.560 kWNet electric power output - ORC at nominal load 1.000 kWThermal power output - ORC at nominal load 4.440 kWNet electric efficiency - ORC at nominal load 18 %Thermal efficiency at nominal load 80 %Electric and thermal losses 2 %Heating medium Thermal oilInlet temperature 300 °COutlet temperature 250 °CWorking medium Silicon oilCooling medium WaterInlet temperature 80 °COutlet temperature 60 °C

24


EU Demonstration Project EU Demonstration Project LienzLienz (A) (A) EnergyEnergy FlowFlow SheetSheet

thermal oil ECO

combustion airpre-heater

biomass primaryenergy input (NCV)

= 100%

thermal oil boiler

ORC-process

hot water ECO

radiation and heat losses 8%

thermal output 75%

electricity output15%

heat and electricity losses

ORC 2 %

25


CompositionComposition of of electricityelectricityproductionproduction costscosts ––

ORC ORC processprocess (1,000 (1,000 kWkWelel))

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

spec

ific

elec

tric

ity p

rodu

ctio

n co

sts

[Eur

o/kW

h el]

other costs

operation based costs

consumption basedcostscapital costs

tFL = 5,000 h/apfuel = 1.5 Cent/kWhfunding 0%utilisation time 10ainterest rate 6% p.a.

26


ElectricityElectricity productionproduction costscosts of aof a1,000 kW(el) ORC 1,000 kW(el) ORC processprocess

vs. vs. fullfull loadload hourshours and and fuelfuel priceprice

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0 2,000 4,000 6,000 8,000electric full load operating hours [h/a]

spec

ific

elec

tric

ity p

rodu

ctio

n co

sts

[Eur

o/kW

h el]

pfuel = 1.5 Cent/kWhfunding 0%utilisation time 10ainterest rate 6%

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0 0.5 1 1.5 2 2.5fuel price [Cent/kWhNCV]

spec

ific

elec

tric

ity p

rodu

ctio

n co

sts

[Eur

o/kW

h el] tFL = 6,000 h/a

funding 0%utilisation time 10ainterest rate 6%

27


ORC process ORC process --state of developmentstate of development

Thermal oil as well as ORC cycles are applied in industries for many years

ORC modules for biomass CHP plants with nominal electric capacities between 200 kWel and 1,500 kWel are available

Biomass CHP plants based on an ORC process are now entering the market

First EU Demo unit: 400 kW(el) (STIA Admont, A), more than 40,000 operating hoursSecond EU Demo unit: 1,000 kW(el) (Lienz, A), Third plant: 1,100 kW(el) (Fussach, A)Combined heat, cold and power production(combination of ORC – absorption chiller)

About 20 ORC units with nominal electric capacities between 200 and 1,500 kW are in operation in Austria, Italy, Switzerland and Germany

28


ORC process ORC process --technological evaluationtechnological evaluation

AdvantagesExcellent partial load behaviourMature technologyAtmospherically operated boiler reduces personal costs High degree of automationLow operation and maintenance costs

Weak pointsRelatively high investment costs (no serial production yet)Thermal oil cycle necessary

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Conclusions and recommendationsConclusions and recommendationsfor smallfor small--scale biomassscale biomass

CHP plants (I)CHP plants (I)

Relevant technical side constraints for small-scale

biomass CHP systems (Pel < 2.0 MW):

Highly robust technology (high availability)

High degree of process control and automation(unmanned operation)

Good partial load behaviour andsuitability for quick load changes

Overall electric efficiency (=electricity generated /fuel input based on NCV) between 12 and 20%

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Conclusions and recommendationsConclusions and recommendationsfor smallfor small--scale biomassscale biomass

CHP plants (II)CHP plants (II)

Relevant economic side constraints for small-scale

biomass CHP systems (Pel < 2.0 MW):

High number of full load operation hours (> 5,000 h/a)

High overall efficiency (heat controlled operation)

Utilisation of „economy-of-scale“ and „learning curve“effects regarding a reduction of investment costs

Appropriate feed-in tariffs for electricity from biomass guaranteed over a time period of at least 10 years

Typical electricity production costs vary between70 and 150 Euro / MWh(el) at present

BIOS BIOENERGIESYSTEME GmbHBIOS BIOENERGIESYSTEME GmbHInffeldgasseInffeldgasse 21b, A21b, A--8010 Graz, Austria8010 Graz, Austria

TEL.: +43 (316) 481300; FAX: +43 (316) 4813004TEL.: +43 (316) 481300; FAX: +43 (316) 4813004EE--MAIL: MAIL: office@[email protected]

HOMEPAGE: HOMEPAGE: http://http://wwwwww..biosbios--bioenergy.atbioenergy.at

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