DESIGN OF GEOTHERMAL POWER PLANTS holistic approach considering - - PowerPoint PPT Presentation

ENGINE Final Conference Vilnius, Lithuania 12-15 February 2008 Stephanie Frick, Ali Saadat, Stefan Kranz GeoForschungsZentrum Potsdam

DESIGN OF GEOTHERMAL POWER PLANTS holistic approach considering auxiliary power

ENGINE Final Conference, 12-15 February 2008

Power plants serve for net power production Net power = gross power - auxiliary power Auxiliary power

Introduction conversion cycle

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ENGINE Final Conference, 12-15 February 2008 source: http://www.erdwaerme-kraft.de/ source: http://www.refplus.com/

Power plants serve for net power production Net power = gross power - auxiliary power Auxiliary power

Introduction conversion cycle cooling cycle

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ENGINE Final Conference, 12-15 February 2008

Power plants serve for net power production Net power = gross power - auxiliary power Auxiliary power

Introduction conversion cycle cooling cycle thermal water cycle

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ENGINE Final Conference, 12-15 February 2008

Power plants serve for net power production Net power = gross power - auxiliary power Auxiliary power For geothermal power plants, a maximum net power

• utput can‘t be reached by maximising the gross power

Geothermal power plant design needs a holistic approach

Introduction conversion cycle cooling cycle thermal water cycle

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ENGINE Final Conference, 12-15 February 2008

Overview

Methodical approach to power plant design Gross power characteristics Auxiliary power characteristics Practical approach to power plant design Conclusions & Outlook

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ENGINE Final Conference, 12-15 February 2008

Methodical approach

site-specific reservoir

characteristics and ambient conditions ( boundary conditions)

PI = II = 30 m3/(h MPa) TTW = 150 ° C TW = 1,147 kg/m3 cp = 3,5 kJ/(kg K) depth = 4.500 m Ta = 20 ° C a = 65 %

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ENGINE Final Conference, 12-15 February 2008

Methodical approach

site-specific reservoir

characteristics and ambient conditions ( boundary conditions)

plant-specific parameters

( component quality)

T = 5 K p = 0,1 bar T = 5 K p = 0,1 bar i = 0,75 m = 0,95 = 0,8 Isobutane = 0,6 T, p, , …

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ENGINE Final Conference, 12-15 February 2008

site-specific reservoir

characteristics and ambient conditions ( boundary conditions)

plant-specific parameters

( component quality)

design parameters:

condensation temp. TKond injection temperature TTW,in thermal water mass flow mTW Methodical approach

TKond TTW,in mTW

.

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ENGINE Final Conference, 12-15 February 2008

site-specific reservoir

characteristics and ambient conditions ( boundary conditions)

plant-specific parameters

( component quality)

design parameters:

condensation temp. TKond injection temperature TTW,in thermal water mass flow mTW Methodical approach

TKond TTW,in mTW

.

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What influence have the design parameters on power plant performance?

ENGINE Final Conference, 12-15 February 2008

Methodical approach

TKond TTW,in mTW

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Exemplary power plant in the North German Basin: TTW = 150 ° C PI = 30 m3/(h MPa) ...

• ther parameters see slide 13

ENGINE Final Conference, 12-15 February 2008

Gross power characteristics

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1000 2000 3000 4000 20 40 60 80 100 thermal water mass flow in kg/s gross power in kW...

T_cond=30 ° C : T_TWin=60° C T_cond=40 ° C : T_TWin=80° C Plant-specific parameters, reservoir and ambient conditions = const. (see slide 13)

ENGINE Final Conference, 12-15 February 2008

Gross power characteristics gross power = ƒ (Tcond, TTW,in) • mTW .

1000 2000 3000 4000 20 40 60 80 100 thermal water mass flow in kg/s gross power in kW...

T_cond=30 ° C : T_TWin=60° C T_cond=40 ° C : T_TWin=80° C

400 500 600 700 800 60 65 70 75 80 thermal water injection temperature in ° C

T_cond=30 ° C T_cond=40 ° C thermal water mass flow 20 kg/s Plant-specific parameters, reservoir and ambient conditions = const. (see slide 13)

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ENGINE Final Conference, 12-15 February 2008

Auxiliary power characteristics

Conversion cycle

Plant-specific parameters, reservoir and ambient conditions = const. (see slide 13)

100 200 300 400 20 40 60 80 100 thermal water mass flow in kg/s

T_cond=30 ° C : T_TWin=60° C T_cond=40 ° C : T_TWin=80° C

power demand conversion cycle in kW ...

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ENGINE Final Conference, 12-15 February 2008

Auxiliary power characteristics

Conversion cycle Power demand conversion cycle = ƒ (Tcond, TTW,in) • mTW .

100 200 300 400 20 40 60 80 100 thermal water mass flow in kg/s

T_cond=30 ° C : T_TWin=60° C T_cond=40 ° C : T_TWin=80° C

power demand conversion cycle in kW ... 20 40 60 80 60 65 70 75 80 thermal water injection temperature in ° C

T_cond=30 ° C T_cond=40 ° C thermal water mass flow 20 kg/s Plant-specific parameters, reservoir and ambient conditions = const. (see slide 13)

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ENGINE Final Conference, 12-15 February 2008

Auxiliary power characteristics

Cooling cycle (wet cooling tower)

400 800 1200 1600 20 40 60 80 100 thermal water mass flow in kg/s power demand wet cooling in kW ...

T_cond=30° C : T_TWin=60° C T_cond=40° C : T_TWin=80° C

1 1 2 2 3

Plant-specific parameters, reservoir and ambient conditions = const. (see slide 13)

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ENGINE Final Conference, 12-15 February 2008

Auxiliary power characteristics

Cooling cycle (wet cooling tower) Power demand cooling cycle = ƒ (Tcond) • TTW,in • mTW .

400 800 1200 1600 20 40 60 80 100 thermal water mass flow in kg/s power demand wet cooling in kW ...

T_cond=30° C : T_TWin=60° C T_cond=40° C : T_TWin=80° C

50 100 150 200 250 300 30 35 40 45 condensation temperature in ° C

T_TWin=60° C T_TWin=70° C T_TWin=80° C

thermal water mass flow 20 kg/s

Plant-specific parameters, reservoir and ambient conditions = const. (see slide 13)

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ENGINE Final Conference, 12-15 February 2008

Auxiliary power characteristics

Thermal water cycle Power demand thermal water cycle = ƒ (mTW ) .

Plant-specific parameters, reservoir and ambient conditions = const. (see slide 13)

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1000 2000 3000 4000 20 40 60 80 100 themal water mass flow in kg/s power demand thermal water cycle in kW ...

ENGINE Final Conference, 12-15 February 2008

Practical approach site-specific reservoir and ambient conditions plant-specific parameters design parameters power plant design net power

• utput

gross power

• utput

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ENGINE Final Conference, 12-15 February 2008

Exemplary power plant design

TTW = 150 ° C, PI = 30 m3/(h MPa), depthreservoir = 4,500 m

reservoir conditions 1,8 MW gross power maximum net power (wet cooling) 30 ° C condensation temp. 460 kW net power 66 ° C

• th. water injection temp.

56 kg/s thermal water mass flow maximum gross power (wet cooling)

Plant-specific parameters, ambient conditions = const. (see slide 13) 9 site-specific reservoir and ambient conditions plant-specifc parameters design parameters power plant design net power

• utput

maximum gross power

ENGINE Final Conference, 12-15 February 2008

Exemplary power plant design

TTW = 150 ° C, PI = 30 m3/(h MPa), depthreservoir = 4,500 m

reservoir conditions 1,3 MW 1,8 MW gross power 600 kW 33 ° C 71 ° C 41 kg/s maximum net power (wet cooling) 30 ° C condensation temp. 460 kW net power 66 ° C

• th. water injection temp.

56 kg/s thermal water mass flow maximum gross power (wet cooling)

Plant-specific parameters, ambient conditions = const. (see slide 13) 9 site-specific reservoir and ambient conditions plant-specifc parameters design parameters power plant design maximum net power gross power

• utput

ENGINE Final Conference, 12-15 February 2008

400 800 1200 1600 2000 200 400 600 800 net power in kW gross power in kW….

Conclusions Choice of mTW, TTW,in and Tcond has a decisive impact

• n power plant performance

A maximum net power

• utput can‘t be reached by

maximising the gross power! Geothermal power plant design needs a holistic approach

maximum gross power maximum net power

.

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ENGINE Final Conference, 12-15 February 2008

Outlook

Successful geothermal project development needs a

detailed and site-specific analysis

Further technical constraints need to be considered Possible combination with other energy carriers to hybrid-

plants (…please have a look at the poster “The combined use of geothermal

and biomass for power generation - drawbacks and opportunities –“)

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ENGINE Final Conference, 12-15 February 2008

turbine feed pump condensator heat transfer thermal water waste heat (Biogas CHP) heat recuperation

turbine feed pump condensator heat transfer thermal water waste heat I (Biogas CHP) heat recuperation waste heat II (Biogas CHP)

BMKW ORC Kalina I Kalina II A B A B C A B C A reference cases 200 400 600 800 1000 1200 1400 1600 1800 200 400 600 800 1000 1200 1400 1600 1800 Electric power in kW

The combined use of geothermal and biomass for power generation

• drawbacks and opportunities -

Jan Wrobel a, Martin Kaltschmitt a,b

a Institute for Environmental Technology and Energy

Economics, Hamburg University of Technology

b Institute for Energy and Environment

• ENGINE Final Conference

poster session

ENGINE Final Conference, 12-15 February 2008

Outlook

Successful geothermal project development needs a

detailed and site-specific analysis

Further technical constraints need to be considered Possible combination with other energy carriers to hybrid-

plants (…please have a look at the poster “The combined use of geothermal

and biomass for power generation - drawbacks and opportunities –“)

Non-technical aspects can be further limiting factors Successful geothermal development needs integrating,

holistic planning tools

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ENGINE Final Conference, 12-15 February 2008

Thank you very much for your attention!

Contact: Stephanie Frick GeoForschungsZentrum Potsdam Telegrafenberg 14473 Potsdam e-mail: frick@gfz-potsdam.de http://www.gfz-potsdam.de/pb52 12

ENGINE Final Conference, 12-15 February 2008

Plant-specific parameters & site-specifc conditions

thermal water temperature 150° C reservoir depth 4,500 m thermal water heat capacity 3,5 kJ/(kg K) thermal water density 1,147 kg/m3 productivity-/injectivity index 30 m3/(h MPa) ambient temperature 20° C relative humidity 60%

reservoir and ambient conditions

down-hole pump efficiency 60%

• misc. parameter see [Legarth, 2005]

thermal water cycle

wet cooling: water-sided pressure losses 1 bar air-sided pressure losses 0,002 bar cooling range 6K approach 3K cooling tower constant 0,8 cooling pump efficiency 80% fan efficiency 80% dry cooling: air-sided pressure losses 0,002 bar fan efficiency 80%

cooling cycle

turbine isentropic efficiency 75% turbine mechanical efficiency 95% heat exchanger temp. gradients 5K heat exchanger pressure losses 0,1 bar working fluid Isobutane

conversion cycle plant-specific parameters 13

ENGINE Final Conference, 12-15 February 2008

Exemplary run of power output against thermal water injection temperature

50 60 70 80 90 100 thermal water injection temperature conversion efficiency transferred heat power output

Power output = transferred heat x conversion efficiency

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ENGINE Final Conference, 12-15 February 2008

Auxiliary power characteristics

Cooling cycle (dry condensation)

400 800 1200 1600 20 40 60 80 100 thermal water mass flow in kg/s power demand dry cooling in kW ...

T_cond=30° C : T_TWin=60° C T_cond=30° C : T_TWin=80° C T_cond=40° C : T_TWin=60° C T_cond=40° C : T_TWin=80° C

50 100 150 200 250 300 30 35 40 45 condensation temperature in ° C

T_TWin=60° C T_TWin=70° C T_TWin=80° C

thermal water mass flow 20 kg/s

a f Plant-specific parameter, reservoir and ambient conditions = const. (see slide 13)

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Power demand cooling cycle = ƒ (Tcond) • TTW,in • mTW .

ENGINE Final Conference, 12-15 February 2008

Exemplary power plant design

TTW = 150 ° C, PI = 30 m3/(h MPa), depthreservoir = 4,500 m

reservoir conditions 485 kW 1,1 MW 36 ° C 73 ° C 37 kg/s maximum net power (dry cooling) 100 kW 1,8 MW 30 ° C 66 ° C 56 kg/s maximum gross power (dry cooling) 600 kW 1,3 MW 33 ° C 71 ° C 41 kg/s maximum net power (wet cooling) 460 kW 1,8 MW 30 ° C 66 ° C 56 kg/s maximum gross power (wet cooling) gross power condensation temp. net power

• th. water injection temp.

thermal water mass flow

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