Geothermal Energy Systems (PDF)

Faculty of Engineering and Applied Science MECE3260U-Introduction to Energy Systems Geothermal Energy Dr. Ibrahim Dincer Professor of Mechanical Engineering Outline  Introduction  Resources  Applications  Power generation ...

Faculty of Engineering and Applied Science MECE3260U-Introduction to Energy Systems Geothermal Energy Dr. Ibrahim Dincer Professor of Mechanical Engineering Outline  Introduction  Resources  Applications  Power generation  Flashing process  Examples  Efficiencies  Geothermal heat pumps  Geothermal district heating  Economic aspects  Geothermal maps  Integrated geothermal systems  Conclusions 2 Introduction Geo means earth, and thermal means heat; so geothermal represents Earth heat. Some advantages: renewable, reliable, efficient and potential use directly and indirectly. Current prices range 5-8 cents/kWh. For every 100 m below ground, the temperature of the rock increases about 3ºC. Deep beneath the surface, water sometimes makes its way close to the hot rock and turns into boiling water or steam. The hot water can reach temperatures of more than 150ºC. Hot springs and spas are very popular around the world and are utilized when the sulfur content is relatively low. Other applications involve use of the reservoirs for agricultural production, aquacultures, industrial applications, and heating. 3 Geothermal Resources and Applications 4  https://www.bgs.ac.uk/geology-projects/geothermal-energy/ https://arstechnica.com/science/2019/06/report- geothermal-could-power-up-to-16-of-us-grid-by-2050/ 5 6 Geothermal Maps of Canada 7 Geothermal Power Generation Five common methods of power generation: direct steam (dry steam) power generation flash-steam power generation binary cycle power generation flash binary power generation combined geothermal power generation geothermalresourcescouncil.blogspot.com 8 Enel Green Power has completed its 25-MW Cove Fort geothermal power plant in Utah. KENYA Naivasha, 140 MW power plant 9 Dry Steam Power Plants without/with Condenser Steam turbine Source: EIA Production to atmosphere well http://www.digtheheat.com/geothermal/dry_steam_plant.html 10 Flash-Steam Power Plant technologystudent.com 11  Single-Flash Steam Power Plant 4 3 turbine separator 5 Balance Equations: 2 condenser Flash Chamber: Separator 7 MBE: ṁ 1 = ṁ 2 MBE: ṁ 2 = ṁ 3 + ṁ 7 flashing 6 EBE: ṁ 1 h1 = ṁ 2 h2 EBE: ṁ 2 h2 = ṁ 3 h3 + ṁ 7 h7 EnBE: ṁ 1 s1 + Ṡ gen,FC = ṁ 2 s2 EnBE: ṁ 2 s2 + Ṡ gen,Sep = ṁ 3 s3 + ṁ 7 s7 1 ̇ dest,FC ̇ dest,Sep Reinjection ExBE: ṁ 1 ex1 = ṁ 2 ex2 + Ex ExBE: ṁ 2 ex2 = ṁ 3 ex3 + ṁ 7 ex7 + Ex Production well 8 well Turbine: Condenser: MBE: ṁ 4 = ṁ 5 MBE: ṁ 5 = ṁ 6 EBE: ṁ 4 h4 = ṁ 5 h5 + Ẇ T1 EBE: ṁ 5 h5 = ṁ 6 h6 + Q̇ con EnBE: ṁ 4 s4 + Ṡ gen,T1 = ṁ 5 s5 EnBE: ṁ 5 s5 + Ṡ gen,con = ṁ 6 s6 + Q̇ con ⁄Tb ExBE: ṁ 4 ex4 = ṁ 5 ex5 + Ẇ T1 + Ex ̇ dest,T1 ExBE: ṁ 5 ex5 = ṁ 6 ex6 + Q̇ con (1 − T0 ⁄Ts ) + Ex ̇ dest,con Energy and Exergy Efficiencies: Without re-injection: With re-injection: Note: Most common steam plant is the single-flash steam plant 𝑊𝑊̇ 𝑇𝑇 𝑊𝑊̇ 𝑇𝑇 where it produces electricity from hot and high-pressure liquid- 𝜼𝜼𝒆𝒆𝒆𝒆 = 𝜼𝜼𝒆𝒆𝒆𝒆 = dominated reservoirs by flashing the entering liquid into steam by 𝑚𝑚̇ 1 ℎ1 𝑚𝑚̇ 1 ℎ1 − 𝑚𝑚̇ 8 ℎ8 reducing the pressure. The steam is then piped directly to a steam and and turbine. 𝑊𝑊̇ 𝑇𝑇 𝑊𝑊̇ 𝑇𝑇 𝜼𝜼𝒆𝒆𝒆𝒆 = 𝜼𝜼𝒆𝒆𝒆𝒆 = 𝑚𝑚̇ 1 𝑒𝑒𝑒𝑒1 𝑚𝑚̇ 1 𝑒𝑒𝑒𝑒1 − 𝑚𝑚̇ 8 𝑒𝑒𝑒𝑒8 12 Flashing Process 105 104 m1 = m2 103 1 h1 = h2 P [kPa] x1 = 0 102 2 0 < x2 < 1 101 ex1 = ex 2 +exdest 100 0 500 1000 1500 2000 2500 3000 h [kJ/kg] 13 (Cengel, 2019). 14  separator turbine Double-Flash Steam Power Plant separator Note: The remaining hot fluid from the first flashing stage is flashed again to make steam with a lower pressure than the primary steam. It produces 10-20% more power than the single one. flashing condenser Production Reinjection well well Balance Equations: Turbine: Flash Chamber 1: Separator 2: MBE: ṁ 3 + ṁ 8 = ṁ 4 MBE: ṁ 1 = ṁ 2 MBE: ṁ 7 = ṁ 8 + ṁ 9 EBE: ṁ 3 h3 + ṁ 8 h8 = ṁ 4 h4 + Ẇ T1 EBE: ṁ 1 h1 = ṁ 2 h2 EBE: ṁ 7 h7 = ṁ 8 h8 + ṁ 9 h9 EnBE: ṁ 3 s3 + ṁ 8 s8 + Ṡ gen,T1 = ṁ 4 s4 EnBE: ṁ 1 s1 + Ṡ gen,FC = ṁ 2 s2 EnBE: ṁ 7 s7 + Ṡ gen,Sep2 = ṁ 8 s8 + ṁ 9 s9 ExBE: ṁ 3 ex3 + ṁ 8 ex8 = ṁ 4 ex4 + Ẇ T1 + Ex ̇ dest,T1 ExBE: ṁ 1 ex1 = ṁ 2 ex2 + Ex ̇ dest,FC ExBE: ṁ 7 ex7 = ṁ 8 ex8 + ṁ 6 ex6 + Ex ̇ dest,Sep2 Separator 1: Flash Chamber 2: Condenser: MBE: ṁ 2 = ṁ 3 + ṁ 6 MBE: ṁ 6 = ṁ 7 MBE: ṁ 4 = ṁ 5 EBE: ṁ 2 h2 = ṁ 3 h3 + ṁ 6 h6 EBE: ṁ 6 h6 = ṁ 7 h7 EBE: ṁ 4 h4 = ṁ 5 h5 + Q̇ con EnBE: ṁ 2 s2 + Ṡ gen,Sep = ṁ 3 s3 + ṁ 6 s6 EnBE: ṁ 6 s6 + Ṡ gen,FC = ṁ 7 s7 EnBE: ṁ 4 s4 + Ṡ gen,con = ṁ 5 s5 + Q̇ con⁄Tb ExBE: ṁ 2 ex2 = ṁ 3 ex3 + ṁ 6 ex6 + Ex ̇ dest,Sep ExBE: ṁ 6 ex6 = ṁ 7 ex7 + Ex ̇ dest,FC ExBE: ṁ 4 ex4 = ṁ 5 ex5 + Q̇ con (1 − T0 ⁄Ts ) + Ex ̇ d,con Energy and Exergy Efficiencies: Without re-injection: With re-injection: 𝑊𝑊̇ 𝑇𝑇 𝑊𝑊̇ 𝑇𝑇 𝜂𝜂𝑒𝑒𝑒𝑒 = 𝜂𝜂𝑒𝑒𝑒𝑒 = 𝑚𝑚̇ 1 ℎ1 𝑚𝑚̇ 1 ℎ1 − 𝑚𝑚̇ 10ℎ10 𝑊𝑊̇ 𝑇𝑇 𝑊𝑊̇ 𝑇𝑇 𝜂𝜂𝑒𝑒𝑒𝑒 = 𝜂𝜂𝑒𝑒𝑒𝑒 = 𝑚𝑚̇ 1 𝑒𝑒𝑒𝑒1 𝑚𝑚̇ 1 𝑒𝑒𝑒𝑒1 − 𝑚𝑚̇ 10𝑒𝑒𝑒𝑒10 15 Schematic layout of Tuzla geothermal power plant (Coskun-Oktay-Dincer, 2011) 16 (Cengel, 2019). 17 Binary Power Plant technologystudent.com 18 Binary Power Plant Balance Equations: Condenser: Turbine: MBE: 𝑚𝑚̇ 4 = 𝑚𝑚̇ 5 MBE: 𝑚𝑚̇ 3 = 𝑚𝑚̇ 4 EBE: 𝑚𝑚̇ 4 ℎ4 + 𝑚𝑚̇ 8 ℎ8 = 𝑚𝑚̇ 5 ℎ5 + 𝑚𝑚̇ 9 ℎ9 EBE: 𝑚𝑚̇ 3 ℎ3 = 𝑚𝑚̇ 4 ℎ4 + 𝑊𝑊̇ 𝑇𝑇𝑇 ̇ EnBE: 𝑚𝑚̇ 4 𝑠𝑠4 + 𝑚𝑚̇ 8 𝑠𝑠8 + 𝑆𝑆𝑔𝑔𝑔𝑔𝑔𝑔,𝑐𝑐𝑐𝑐𝑐𝑐 = 𝑚𝑚̇ 5 𝑠𝑠5 + 𝑚𝑚̇ 9 𝑠𝑠9 ̇ EnBE: 𝑚𝑚̇ 3 𝑠𝑠3 + 𝑆𝑆𝑔𝑔𝑔𝑔𝑔𝑔,𝑇𝑇𝑇 = 𝑚𝑚̇ 4 𝑠𝑠4 ExBE: 𝑚𝑚̇ 4 𝑒𝑒𝑒𝑒4 + 𝑚𝑚̇ 8 𝑒𝑒𝑒𝑒8 = 𝑚𝑚̇ 5 𝑒𝑒𝑒𝑒5 + 𝑚𝑚̇ 9 𝑒𝑒𝑒𝑒9 + 𝐸𝐸𝑥𝑥 ̇ 𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑,𝑐𝑐𝑐𝑐𝑐𝑐 ExBE: 𝑚𝑚̇ 3 𝑒𝑒𝑒𝑒3 = 𝑚𝑚̇ 4 𝑒𝑒𝑒𝑒4 + 𝑊𝑊̇ 𝑇𝑇𝑇 + 𝐸𝐸𝑥𝑥 ̇ 𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑,𝑇𝑇𝑇 Production Pump: Circulation Pump: MBE: ṁ 5 = ṁ 6 MBE: ṁ 1 = ṁ 2 EBE: ṁ 5 h5 + Ẇ PP = ṁ 6 h6 EBE: ṁ 1 h1 + Ẇ CP = ṁ 2 h2 EnBE: ṁ 5 s5 + Ṡ gen,P = ṁ 6 s6 EnBE: ṁ 1 s1 + Ṡ gen,P = ṁ 2 s2 ExBE: ṁ 5 ex 5 + Ẇ P1 = ṁ 6 ex6 + Ex ̇ dest,FC ExBE: ṁ 1 ex1 + Ẇ P1 = ṁ 2 ex 2 + Ex ̇ dest,FC (Cengel, 2019). Heat Exchanger: MBE: ṁ 2 = ṁ 3 , ṁ 6 = ṁ 7 EBE: ṁ 2 h2 + ṁ 6 h6 = ṁ 3 h3 + ṁ 7 h7 EnBE: ṁ 2 s2 + ṁ 6 s6 + Ṡ gen,Sep = ṁ 3 s3 + ṁ 7 s7 ExBE: ṁ 2 ex 2 + ṁ 6 ex6 = ṁ 3 ex 3 + ṁ 7 ex 7 + Eẋ d,Sep Energy and Exergy Efficiencies: Without re-injection: With re-injection: 𝑊𝑊̇ 𝑇𝑇 − 𝑊𝑊̇ 𝑃𝑃𝑃𝑃 − 𝑊𝑊̇ 𝐶𝐶𝐶𝐶 𝑊𝑊̇ 𝑇𝑇 − 𝑊𝑊̇ 𝑃𝑃𝑃𝑃 − 𝑊𝑊̇ 𝐶𝐶𝐶𝐶 𝜼𝜼𝒆𝒆𝒆𝒆 = 𝜼𝜼𝒆𝒆𝒆𝒆 = 𝑚𝑚̇ 1 ℎ1 𝑚𝑚̇ 1 ℎ1 − 𝑚𝑚̇ 7 ℎ7 𝑊𝑊̇ 𝑇𝑇 − 𝑊𝑊̇ 𝑃𝑃𝑃𝑃 − 𝑊𝑊̇ 𝐶𝐶𝐶𝐶 𝑊𝑊̇ 𝑇𝑇 − 𝑊𝑊̇ 𝑃𝑃𝑃𝑃 − 𝑊𝑊̇ 𝐶𝐶𝐶𝐶 𝜼𝜼𝒆𝒆𝒆𝒆 = 𝜼𝜼𝒆𝒆𝒆𝒆 = 𝑚𝑚̇ 1 𝑒𝑒𝑒𝑒1 𝑚𝑚̇ 1 𝑒𝑒𝑒𝑒1 − 𝑚𝑚̇ 7 𝑒𝑒𝑒𝑒7 19 Flash-Binary Power Plant condenser Steam turbine separator condenser turbine BINARY CYCLE pump Heat exchanger flashing Production Reinjection well well 20 Geothermal Combined Power Plant Geothermal Energy Association 21  Geothermal Energy Use https://www.geothermal-energy.org/pdf/IGAstandard/WGC/2020/01017.pdf 22  Geothermal/Ground Source Heat Pumps A geothermal or ground source heat pump system can use the constant temperature under the ground to heat or cool a building or drying crops. cullenconstructioninc.com Source: EPA 23 Edremit geothermal district heating system (Coskun-Oktay-Dincer, 2009 24 Husavik Energy. Multiuse of geothermal energy in Iceland (VEKS, 2010). 25 Global Geothermal Energy Use 26 Geothermal Map Geothermal Power Plants’ Geothermal power plants and solar intensity map 27 Case Study-1: 28 Case Study-2: 29 Closing Remarks A renewable and environmentally friendly energy source. Multiple systems options are available for power production. Geothermal systems are cost effective. There are application possibilities for many applications, including heating, cooling, power generation, district energy, drying, etc. There are integrated energy systems using geothermal sources for hydrogen production. Ground source heat pumps are widely deployed. 30