Performance analyses of a hybrid geothermal–fossil power generation system using low-enthalpy geothermal resources

Low-enthalpy geothermal heat can be efficiently utilized for feedwater preheating in coal-fired power plants by replacing some of the high-grade steam that can then be used to generate more power. This study analyzes a hybrid geothermal–fossil power generation system including a supercritical 1000MW power unit and a geothermal feedwater preheating system. This study models for parallel and serial geothermal preheating schemes and analyzes the thermodynamic performance of the hybrid geothermal–fossil power generation system for various geothermal resource temperatures. The models are used to analyze the effects of the temperature matching between the geothermal water and the feedwater, the heat losses and pumping power during the geothermal water transport and the resource distance and temperature on the power increase to improve the power generation. The serial geothermal preheating (SGP) scheme generally generates more additional power than the parallel geothermal preheating (PGP) scheme for geothermal resource temperatures of 100–130°C, but the SGP scheme generates slightly less additional power than the PGP scheme when the feedwater is preheated to as high a temperature as possible before entering the deaerator for geothermal resource temperatures higher than 140°C. The additional power decreases as the geothermal source distance increases since the pipeline pumping power increases and the geothermal water temperature decreases due to heat losses. More than 50% of the power decrease is due to geothermal water temperature decreases along the pipeline since less higher pressure extracted steam is replaced by the geothermal water. For geothermal resource temperatures of 140–160°C, the additional power generated by the hybrid geothermal–coal power generation system is about 90% (at a geothermal source distance of 0km) or 39–49% (at a distance of 20km) greater than the power generated by an optimized organic Rankine cycle system using isopentane (R601a), the hybrid power generation system has little benefit over the ORC system when the distance increases to 40km. However, the additional power generated by the hybrid power generation system is less than the power generated by the ORC system at distances over 20km for geothermal resource temperatures of 100°C.

[1]  Zvonimir Guzović,et al.  The comparision of a basic and a dual-pressure ORC (Organic Rankine Cycle): Geothermal Power Plant Velika Ciglena case study , 2014 .

[2]  Hongguang Jin,et al.  Evaluation criteria for enhanced solar–coal hybrid power plant performance , 2014 .

[3]  Zhen Yang,et al.  Effect of condensation temperature glide on the performance of organic Rankine cycles with zeotropic mixture working fluids , 2014 .

[4]  R. Bertani.  Geothermal power generation in the world 2010–2014 update report , 2016 .

[5]  J. Kestin,et al.  HYBRID GEOTHERMAL-FOSSIL POWER PLANTS. , 1978 .

[6]  Tao Guo,et al.  Fluids and parameters optimization for a novel cogeneration system driven by low-temperature geother , 2011 .

[7]  Leyla Ozgener,et al.  Investigation of the effect of different refrigerants on performances of binary geothermal power plants , 2013 .

[8]  Zhen Yang,et al.  Performance analyses of geothermal organic Rankine cycles with selected hydrocarbon working fluids , 2013 .

[9]  Janusz Buchta.  Green power from conventional steam power plant combined with geothermal well , 2009, 2009 IEEE International Conference on Industrial Technology.

[10]  G. C. Bakos,et al.  Solar aided power generation of a 300 MW lignite fired power plant combined with line-focus parabolic trough collectors field , 2013 .

[11]  Philipp Blum,et al.  Review on life cycle environmental effects of geothermal power generation , 2013 .

[12]  W. Worek,et al.  Optimum design criteria for an Organic Rankine cycle using low-temperature geothermal heat sources , 2007 .

[13]  X. Chen,et al.  Current status and potentials of enhanced geothermal system in China: A review , 2014 .

[14]  N. Lai,et al.  Working fluids for high-temperature organic Rankine cycles , 2007 .

[15]  Guo Tao,et al.  Performance comparison and parametric optimization of subcritical Organic Rankine Cycle (ORC) and transcritical power cycle system for low-temperature geothermal power generation , 2011 .

[16]  Adele Manzella,et al.  The web-oriented framework of the world geothermal production database: A business intelligence platform for wide data distribution and analysis , 2015 .

[17]  Ruggero Bertani,et al.  Geothermal power generation in the world 2005–2010 update report , 2012 .

[18]  Yang Yongping,et al.  Performance evaluation of solar aided feedwater heating of coal-fired power generation (SAFHCPG) system under different operating conditions , 2013 .

[19]  Hongguang Jin,et al.  A Typical Solar-coal Hybrid Power Plant in China , 2014 .

[20]  Yongping Yang,et al.  Evaluation of solar aided thermal power generation with various power plants , 2011 .

[21]  Andrea Toffolo,et al.  A multi-criteria approach for the optimal selection of working fluid and design parameters in Organic Rankine Cycle systems , 2014 .

[22]  R. Dipippo.  Geothermal power plants : principles, applications, case studies and environmental impact , 2008 .

[23]  Behdad Moghtaderi,et al.  Assessment of geothermal assisted coal-fired power generation using an Australian case study , 2014 .

[24]  Yang Yong-ping.  HEAT RATE TRANSFORMATION COEFFICIENT, EXTRACTION STEAM EFFICIENCY AND MAIN CYCLE EFFICIENCY , 2001 .

[25]  Basel I. Ismail.  Advanced Electrical Power Generation Technology Using Renewable & Clean Low-Enthalpy Geothermal Energy Sources , 2011 .

[26]  Guo Min.  Thermodynamic System Matrix Thermal Balance Equation of Power Plant and Its Application , 2002 .

[27]  Y. Duan,et al.  Parametric optimization and performance analyses of geothermal organic Rankine cycles using R600a/R601a mixtures as working fluids , 2015 .

[28]  Matthias Bruhn,et al.  Hybrid geothermal–fossil electricity generation from low enthalpy geothermal resources: geothermal feedwater preheating in conventional power plants , 2002 .

[29]  Alexander Mitsos,et al.  Modeling and optimization of a binary geothermal power plant , 2013 .

[30]  Ronald DiPippo,et al.  Geothermal preheating in fossil-fired steam power plants , 1978 .

[31]  Vincent Lemort,et al.  Systematic optimization of subcritical and transcritical organic Rankine cycles (ORCs) constrained by technical parameters in multiple applications , 2014 .

[32]  Eric Hu,et al.  A Modified Thermodynamic Model to Estimate the Performance of Geothermal Aided Power Generation Plant , 2011 .

[33]  Alessandro Franco,et al.  An integrated “Reservoir-Plant” strategy for a sustainable and efficient use of geothermal resources , 2012 .

[34]  Ennio Macchi,et al.  Binary ORC (Organic Rankine Cycles) power plants for the exploitation of medium–low temperature geothermal sources – Part B: Techno-economic optimization , 2014 .

[35]  Ronald DiPippo,et al.  Compound Hybrid Geothermal-Fossil Power Plants: Thermodynamic Analyses and Site-Specific Applications , 1981 .

[36]  Ronald DiPippo,et al.  Geothermal power plants: Evolution and performance assessments , 2015 .

[37]  Fredrik Haglind,et al.  Selection and optimization of pure and mixed working fluids for low grade heat utilization using organic Rankine cycles , 2014 .

[38]  Janusz Buchta,et al.  Economical and ecological aspects of renewable energy generation in coal fired power plant supported with geothermal heat , 2010, 2010 IEEE Electrical Power & Energy Conference.

[39]  T. J. Hammons,et al.  Geothermal Power Generation Worldwide: Global Perspective, Technology, Field Experience, and Research and Development , 2004 .

[40]  Maurizio Vaccaro,et al.  Numerical simulation of geothermal reservoirs for the sustainable design of energy plants: A review , 2014 .

[41]  Alessandro Franco,et al.  Optimal design of binary cycle power plants for water-dominated, medium-temperature geothermal fields , 2009 .

[42]  Yun Bai,et al.  Thermodynamic performance analysis of the coal‐fired power plant with solar thermal utilizations , 2014 .