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

DESIGN OF GEOTHERMAL POWER PLANTS holistic approach considering auxiliary power Stephanie Frick, Ali Saadat, Stefan Kranz GeoForschungsZentrum Potsdam ENGINE Final Conference Vilnius, Lithuania 12-15 February 2008

Introduction � Power plants serve for net power production � Net power = gross power - auxiliary power conversion cycle � Auxiliary power 1 ENGINE Final Conference, 12-15 February 2008

Introduction � Power plants serve for net power production � Net power = gross power - auxiliary power conversion cycle � Auxiliary power cooling cycle source: http://www.erdwaerme-kraft.de/ source: http://www.refplus.com/ 1 ENGINE Final Conference, 12-15 February 2008

Introduction � Power plants serve for net power production � Net power = gross power - auxiliary power conversion cycle � Auxiliary power cooling cycle thermal water cycle 1 ENGINE Final Conference, 12-15 February 2008

Introduction � Power plants serve for net power production � Net power = gross power - auxiliary power conversion cycle � Auxiliary power cooling cycle thermal water cycle � For geothermal power plants, a maximum net power output can‘t be reached by maximising the gross power � Geothermal power plant design needs a holistic approach 1 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 2 ENGINE Final Conference, 12-15 February 2008

Methodical approach � site-specific reservoir characteristics and ambient T a = 20 ° C � a = 65 % conditions ( � boundary conditions) PI = II = 30 m 3 /(h MPa) � TW = 1,147 kg/m 3 T TW = 150 ° C c p = 3,5 kJ/(kg K) depth = 4.500 m 3 ENGINE Final Conference, 12-15 February 2008

Methodical approach � i = 0,75 � site-specific reservoir Isobutane � m = 0,95 characteristics and ambient conditions ( � boundary conditions) � T, � p, � T = 5 K � , … � p = 0,1 bar � plant-specific parameters � T = 5 K ( � component quality) � p = 0,1 bar � = 0,8 � = 0,6 3 ENGINE Final Conference, 12-15 February 2008

Methodical approach � site-specific reservoir characteristics and ambient conditions ( � boundary conditions) � plant-specific parameters ( � component quality) T Kond � design parameters : condensation temp. T Kond injection temperature T TW,in . thermal water mass flow m TW T TW,in m TW 3 ENGINE Final Conference, 12-15 February 2008

Methodical approach � site-specific reservoir characteristics and ambient conditions ( � boundary conditions) � plant-specific parameters ( � component quality) T Kond � design parameters : condensation temp. T Kond What influence have the injection temperature T TW,in . design parameters on thermal water mass flow m TW power plant performance? T TW,in m TW 3 ENGINE Final Conference, 12-15 February 2008

Methodical approach Exemplary power plant in the North German Basin: T TW = 150 ° C PI = 30 m 3 /(h MPa) T Kond ... other parameters see slide 13 T TW,in m TW 3 ENGINE Final Conference, 12-15 February 2008

Gross power characteristics Plant-specific parameters, reservoir and ambient conditions = const. (see slide 13) 4000 T_cond=30 ° C : T_TWin=60° C T_cond=40 ° C : T_TWin=80° C 3000 gross power in kW... 2000 1000 0 20 40 60 80 100 thermal water mass flow in kg/s 4 ENGINE Final Conference, 12-15 February 2008

Gross power characteristics Plant-specific parameters, reservoir and ambient conditions = const. (see slide 13) 4000 800 T_cond=30 ° C : T_TWin=60° C T_cond=30 ° C T_cond=40 ° C : T_TWin=80° C T_cond=40 ° C 3000 700 gross power in kW... 2000 600 1000 500 thermal water mass flow 20 kg/s 0 400 20 40 60 80 100 60 65 70 75 80 thermal water mass flow in kg/s thermal water injection temperature in ° C . gross power = ƒ ( T cond , T TW,in ) • m TW 4 ENGINE Final Conference, 12-15 February 2008

Auxiliary power characteristics Conversion cycle Plant-specific parameters, reservoir and ambient conditions = const. (see slide 13) 400 ... power demand conversion cycle in kW T_cond=30 ° C : T_TWin=60° C T_cond=40 ° C : T_TWin=80° C 300 200 100 0 20 40 60 80 100 thermal water mass flow in kg/s 5 ENGINE Final Conference, 12-15 February 2008

Auxiliary power characteristics Conversion cycle Plant-specific parameters, reservoir and ambient conditions = const. (see slide 13) 80 400 ... power demand conversion cycle in kW T_cond=30 ° C : T_TWin=60° C T_cond=30 ° C T_cond=40 ° C : T_TWin=80° C 300 T_cond=40 ° C 60 200 40 100 thermal water mass flow 20 kg/s 0 20 20 40 60 80 100 60 65 70 75 80 thermal water mass flow in kg/s thermal water injection temperature in ° C . Power demand conversion cycle = ƒ ( T cond , T TW,in ) • m TW 5 ENGINE Final Conference, 12-15 February 2008

Auxiliary power characteristics Cooling cycle (wet cooling tower) Plant-specific parameters, reservoir and ambient conditions = const. (see slide 13) 1600 3 T_cond=30° C : T_TWin=60° C ... power demand wet cooling in kW 2 T_cond=40° C : T_TWin=80° C 1200 2 800 1 1 400 0 20 40 60 80 100 thermal water mass flow in kg/s 6 ENGINE Final Conference, 12-15 February 2008

Auxiliary power characteristics Cooling cycle (wet cooling tower) Plant-specific parameters, reservoir and ambient conditions = const. (see slide 13) 1600 300 T_TWin=60° C T_cond=30° C : T_TWin=60° C ... power demand wet cooling in kW 250 T_TWin=70° C T_cond=40° C : T_TWin=80° C 1200 200 T_TWin=80° C 800 150 100 400 50 thermal water mass flow 20 kg/s 0 0 20 40 60 80 100 30 35 40 45 thermal water mass flow in kg/s condensation temperature in ° C . Power demand cooling cycle = ƒ ( T cond ) • T TW,in • m TW 6 ENGINE Final Conference, 12-15 February 2008

Auxiliary power characteristics Thermal water cycle Plant-specific parameters, reservoir and ambient conditions = const. (see slide 13) 4000 ... power demand thermal water cycle in kW 3000 2000 1000 0 20 40 60 80 100 themal water mass flow in kg/s . Power demand thermal water cycle = ƒ ( m TW ) 7 ENGINE Final Conference, 12-15 February 2008

Practical approach site-specific reservoir and ambient conditions plant-specific design parameters parameters power plant design gross power net power output output 8 ENGINE Final Conference, 12-15 February 2008

Exemplary power plant design site-specific reservoir and ambient conditions plant-specifc design parameters parameters power plant design maximum net power gross power output maximum gross power maximum net power (wet cooling) (wet cooling) C, PI = 30 m 3 /(h MPa), depth reservoir = 4,500 m reservoir conditions T TW = 150 ° thermal water mass flow 56 kg/s th. water injection temp. 66 ° C condensation temp. 30 ° C gross power 1,8 MW net power 460 kW Plant-specific parameters, ambient conditions = const. (see slide 13) 9 ENGINE Final Conference, 12-15 February 2008

Exemplary power plant design site-specific reservoir and ambient conditions plant-specifc design parameters parameters power plant design gross power maximum output net power maximum gross power maximum net power (wet cooling) (wet cooling) C, PI = 30 m 3 /(h MPa), depth reservoir = 4,500 m reservoir conditions T TW = 150 ° thermal water mass flow 56 kg/s 41 kg/s th. water injection temp. 66 ° C 71 ° C condensation temp. 30 ° C 33 ° C gross power 1,8 MW 1,3 MW net power 460 kW 600 kW Plant-specific parameters, ambient conditions = const. (see slide 13) 9 ENGINE Final Conference, 12-15 February 2008

Conclusions . � Choice of m TW , T TW,in and 2000 T cond has a decisive impact 1600 maximum on power plant performance gross power in kW…. gross power 1200 � A maximum net power maximum output can‘t be reached by net power 800 maximising the gross power! 400 � Geothermal power plant 0 0 200 400 600 800 design needs a holistic net power in kW approach 10 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 –“) 11 ENGINE Final Conference, 12-15 February 2008