Comparative analysis of geothermal-solar hybrid heat pump systems for residential applications in Afyonkarahisar, Türkiye

Öz

Afyonkarahisar is located in the inner regions of Türkiye and exhibits pronounced continental climate characteristics. The long and cold winters and the hot and dry summers make electricity, space heating, and domestic hot water (DHW) requirements a significant energy burden for residential buildings. Therefore, meeting these energy demands through renewable energy sources is of great importance.

This study presents a performance analysis of a geothermal solar assisted hybrid energy system designed to meet the electricity, space heating, and domestic hot water demands of a residential building located in Afyonkarahisar. Three different system configurations with identical photovoltaic (PV) and solar collector layouts namely, a ground-coupled collector system, a geothermal probe system, and a groundwater-source heat pump system were compared through simulations under regional climatic conditions.

The results indicate that the groundwater-source system achieved the highest performance due to the stable temperature of the groundwater and the effective integration of the PV system. This system emerged as the most efficient configuration, with an SPF of 4.38 and a VDI-SPF of 7.51, while also achieving the lowest annual electricity consumption (944 kWh) and the highest self-sufficiency ratio (67.7%). The geothermal probe system ranked second with an SPF value of 3.83, whereas the ground-coupled collector system provided a balanced alternative in terms of performance and cost. Overall, it was concluded that the groundwater-source system represents the most efficient and sustainable solution for electricity generation, space heating, and domestic hot water production in residential buildings located in Türkiye’s regions with high geothermal potential.

Anahtar Kelimeler

• Geothermal energy
• Groundwater heat pump
• Solar hybrid system
• Seasonal performance factor
• Renewable energy

Kaynakça

1. [1] Islam M, Hasanuzzaman M. Introduction to energy and sustainable development. Energy for Sustainable Development 2020; 1: 1–18.
2. [2] Leonard MD, Michaelides EE, Michaelides DN. Energy storage needs for the substitution of fossil fuel power plants with renewables. Renewable Energy 2020; 145: 951–962.
3. [3] Colonna P, et al. Organic Rankine cycle power systems: From the concept to current technology, applications, and an outlook to the future. Progress in Energy and Combustion Science 2015; 137: 100801.
4. [4] Cetin TH, Kanoglu M, Yanikomer N. Cryogenic energy storage powered by geothermal energy. Geothermics 2019; 77: 34–40.
5. [5] International Energy Agency. Global energy review 2020. Energy Policy 2020; 810.
6. [6] Güler ÖF. Working fluid selection and performance analysis for the Afyon geothermal energy plant. Energy Policy 2025; 4: 1–8.
7. [7] Moya D, Aldás C, Kaparaju P. Geothermal energy: Power plant technology and direct heat applications. Renewable and Sustainable Energy Reviews 2018; 94: 889–901.
8. [8] Aryanfar Y, Mohtaram S, Garcia CH, Tag-Eldin EM, Arslan B, Deifalla A, Sun H. Energy, exergy and exergoeconomic analysis of a trans-critical CO₂ cycle powered by a single flash geothermal cycle in with/without economizer working modes. Thermal Science 2024; 28: 1701–1716.

9. [9] Chitgar N, Hemmati A, Sadrzadeh M. A comparative performance analysis, working fluid selection, and machine learning optimization of ORC systems driven by geothermal energy. Energy Conversion and Management 2023; 286: 117072.
10. [10] Li X, Chen Y, Zhang Y, Liu Y. Thermoeconomic modelling and multi-objective optimisation of ORC systems for low-temperature waste heat recovery. Applied Thermal Engineering 2025; 127603.
11. [11] Behnam P, Arefi A, Shafii MB. Exergetic and thermoeconomic analysis of a trigeneration system producing electricity, hot water, and fresh water driven by low-temperature geothermal sources. Energy Conversion and Management 2018; 157: 266–276.
12. [12] Feng J, Yan Y, Wang L, Zhao L, Dong H. Research on thermal economic performance of HP-ORC pumped thermal energy storage system coupled with low-temperature waste heat. Energy Storage Science and Technology 2025; 14: 2130.
13. [13] Bina SM, Jalilinasrabady S, Fujii H. Exergoeconomic analysis and optimization of single and double flash cycles for Sabalan geothermal power plant. Geothermics 2018; 72: 74–82.
14. [14] El-Emam RS, Dincer I. Exergy and exergoeconomic analyses and optimization of geothermal organic Rankine cycle. Applied Thermal Engineering 2013; 59: 435–444.
15. [15] Arpa İ, Şahin AŞ. Jeotermal enerji kaynaklı organik Rankine güç santralinin termodinamik analizi. Sürdürülebilir Mühendislik Uygulamaları ve Teknolojik Gelişmeler Dergisi 2023; 7(1): 1–15.
16. [16] Erbaş O. Effect of different fluid types on cycle performance in electricity generation with geothermal energy. Kırklareli University Journal of Engineering and Science 10(2): 282–293.
17. [17] Yilmaz C, Arslan M, Tokgoz N, Ozdemir SN. Thermoeconomic optimization of a geothermal-assisted hybrid LNG and power generation system: Simulation, performance assessment, and sustainability insights. Case Studies in Thermal Engineering 2025; 106426.
18. [18] Borunda M, Jaramillo O, Dorantes R, Reyes A. Organic Rankine cycle coupling with a parabolic trough solar power plant for cogeneration and industrial processes. Renewable Energy 2016; 86: 651–663.
19. [19] Valenzuela C, Mata-Torres C, Cardemil JM, Escobar RA. CSP+PV hybrid solar plants for power and water cogeneration in northern Chile. Solar Energy 2017; 157: 713–726.
20. [20] Vittorini D, Antonini A, Cipollone R, Carapellucci R, Villante C. Solar thermal-based ORC power plant for micro cogeneration – performance analysis and control strategy. Energy Procedia 2018; 148: 774–781.
21. [21] Pina EA, Serra LM, Lozano MA, Hernández A, Lázaro A. Comparative analysis and design of a solar-based parabolic trough–ORC cogeneration plant for a commercial center. Energies 2020; 13: 4807.
22. [22] Mana A, Kaitouni S, Kousksou T, Jamil A. Enhancing sustainable energy conversion: Comparative study of superheated and recuperative ORC systems for waste heat recovery and geothermal applications, with focus on 4E performance. Energy 2023; 284: 128654.
23. [23] Inayat A, Raza MJ. District cooling system via renewable energy sources: A review. Renewable and Sustainable Energy Reviews 2019; 107: 360–373.
24. [24] DeLovato N, Sundarnath K, Cvijovic L, Kota K, Kuravi SJ. A review of heat recovery applications for solar and geothermal power plants. Renewable and Sustainable Energy Reviews 2019; 114: 109329.
25. [25] Başoğul Y. Environmental assessment of a binary geothermal sourced power plant accompanied by exergy analysis. Energy Conversion and Management 2019; 195: 492–501.
26. [26] Borunda M, Jaramillo O, Dorantes R, Reyes A. Organic Rankine cycle coupling with a parabolic trough solar power plant for cogeneration and industrial processes. Renewable Energy 2016; 86: 651–663.
27. [27] Karapekmez A, Dincer I. Thermodynamic analysis of a novel solar and geothermal based combined energy system for hydrogen production. International Journal of Hydrogen Energy 2020; 45: 5608–5628.
28. [28] Canton H. International Energy Agency – IEA. The Europa Directory of International Organizations 2021; 684–686.
29. [29] Şen O, Yılmaz C. Thermodynamic analysis of geothermal and solar assisted power generation and heating system. Journal of the Faculty of Engineering 2022; 37: 1625–1637.
30. [30] Güldürek M. Sustainable energy and Turkey: The role of geothermal energy and energy planning. Çukurova Üniversitesi Mühendislik Fakültesi Dergisi 2025; 40(1): 239–249.
31. [31] Kaya F, Akar O. Geothermal energy based hydrogen energy storage and charging station system. İstanbul Ticaret Üniversitesi Fen Bilimleri Dergisi 2024; 23(45): 156–168.
32. [32] Şirikçi BS, Çetinkaya G. Economic structure of tomato production in geothermal energy-heated greenhouses: Simav district case of Kütahya province. Turkish Journal of Agricultural and Natural Sciences 2025; 12(4): 1139–1152.
33. [33] Alacalı M. Environmental effects of geothermal energy utilizations: A case study of the Seferihisar geothermal system, İzmir, Türkiye. Gümüşhane Üniversitesi Fen Bilimleri Dergisi 2024; 14(2): 592–607.
34. [34] Girgin B, Balcı K, Solmaz M, Durmaz Y. Living in geothermal energy plant emergency pond: Isolation and cultivation of Arthrospira platensis to stressful high temperature in the geothermal ponds. Journal of Anatolian Environmental and Animal Sciences 2024; 9(3): 299–306.
35. [35] Kendirci EN, Tunçez FD. Dünya çapında jeotermal enerjinin karbon ayak izi üzerindeki etkisi: Bölgesel analiz ve sürdürülebilirlik boyutu. Ulusal Çevre Bilimleri Araştırma Dergisi 2025; 8(1): 44–50.
36. [36] Spitler JD, Gehlin S. Measured performance of a mixed-use commercial-building ground source heat pump system in Sweden. Energies 2019; 12(10): 2020.
37. [37] Valentin Software GmbH. GeoT*SOL 2026: Solar thermal and photovoltaic system simulation software. Available from: https://valentin-software.com/en/. Accessed: 2025. [Online].
38. [38] Republic of Türkiye Ministry of National Defense, General Directorate of Mapping. Map of Turkey. Available from: https://www.harita.gov.tr/il-ve-ilce-yuzolcumleri. Accessed: 2025. [Online].