Е-Публикации
Технически университет - София

Abstract: In recent years, a growing global effort has been underway to reduce the Earth’s carbon footprint. One of the main strategies to achieve this goal is the utilization of available renewable energy resources. Among the largest and most inexhaustible is hydro-power. This paper presents an experimental study of three hydrokinetic turbines tested under real river conditions, aiming to evaluate their effectiveness in harnessing the kinetic energy of flowing water. The experiment is described in detail, including velocity field measurements conducted within the river section used for testing. Based on the experimental data, the main performance characteristics of the three turbines are presented, specifically their power output and efficiency. The importance of selecting an optimal riverbed site and customizing turbine runners to local flow conditions is highlighted, as even slight velocity fluctuations can significantly impact performance. Among the tested designs, the K1–6 turbine runner showed the highest power and efficiency, while the K2–4 runner provided superior rotational stability, making it promising for consistent energy output in variable flow environments

References

1. Kim S. Cho K. Assessing International Technological Competitiveness in Renewable Energy: An IPC-Based Analysis of Granted Patents Sustainability 2025 17 5479 10.3390/su17125479
2. Castro Hernandez C.D. Montuori L. Alcázar-Ortega M. Olczak P. Extreme Climate Events and Energy Market Vulnerability: A Systematic Global Review Appl. Sci. 2025 15 6210 10.3390/app15116210
3. Zyśk J. Wyrwa A. Raczyński M. Pluta M. Suwała W. Regional-Scale Energy Modelling for Developing Strategies to Achieve Climate Neutrality Energies 2025 18 1787 10.3390/en18071787
4. Ahmed S. Ali A. Ciocia A. D’Angola A. Technological Elements behind the Renewable Energy Community: Current Status, Existing Gap, Necessity, and Future Perspective—Overview Energies 2024 17 3100 10.3390/en17133100
5. Available online: https://www.hydro.org (accessed on 1 June 2025)
6. Smil V. Energy and Civilization: A History MIT Press Cambridge, MA, USA 2017
7. Spirov M. Georgiev A. Tsonev M. History of Electrification in Bulgaria Heron Press Sofia, Bulgaria 1998 (In Bulgarian)
8. Available online: https://hidro-energia.org/ (accessed on 24 May 2025)
9. Witkowski K. The Development of the Use of Water Energy in the Mountain Catchment from a Sociohydrological Perspective Energies 2022 15 7770 10.3390/en15207770
10. International Renewable Energy Agency (IRENA) Global Energy Transformation, a Roadmap to 2050 Available online: https://www.irena.org/-/media/Files/IRENA/Agency/Publication/2019/Apr/IRENA_Global_Energy_Transformation_2019.pdf (accessed on 20 June 2025)
11. Todorov G.D. Kamberov K.H. Zlatev B.N. Research and Development of a Large-Scale Axial-Flux Generator for Hydrokinetic Power System Appl. Sci. 2024 14 10564 10.3390/app142210564
12. Şişman A. Dragomirescu A. Ciocănea A. Dancă P.A. Bunea F. Babuţanu C.A. Experimental Study of a Small-Scale Axial Hydrokinetic Turbine with Adjustable Blade Pitch Proceedings of the 11th International Conference on ENERGY and ENVIRONMENT (CIEM) Bucharest, Romania 26–27 October 2023 1 5 10.1109/CIEM58573.2023.10349709
13. Kirke B. Hydrokinetic and ultra-low head turbines in rivers: A reality check Energy Sustain. Dev. 2019 52 1 10 10.1016/j.esd.2019.06.002
14. Zhou D. Deng Z. Ultra-low-head hydroelectric technology: A review Renew. Sustain. Energy Rev. 2017 78 23 30 10.1016/j.rser.2017.04.086
15. Velichkova R. Pushkarov M. Simova I. Stanilov A. Ivanov V. Pavlova Y. Alexandrov A. Harnessing the Energy of Moving Water to Generate Electricity in Bulgaria Green Energy and Technology Springer Science + Business Media New York, NY, USA 2023 129 164
16. Kumar D. Sarkar S. A review on the technology, performance, design optimization, reliability, techno-economics and environ-mental impacts of hydrokinetic energy conversion systems Renew. Sustain. Energy Rev. 2016 58 796 813 10.1016/j.rser.2015.12.247
17. Vermaak H.J. Kusakana K. Koko S.P. Status of micro-hydrokinetic river technology in rural applications: A review of literature Renew. Sustain. Energy Rev. 2014 29 625 633 10.1016/j.rser.2013.08.066
18. Chica E. Velásquez L. Rubio-Clemente A. Full-Scale Experimental Assessment of a Horizontal-Axis Hydrokinetic Turbine for River Applications: A Challenge for Developing Countries Energies 2025 18 1657 10.3390/en18071657
19. Ramadan A. Nawar M.A.A. Mohamed M.H. Performance evaluation of a drag hydro kinetic turbine for river current energy extraction-A case study Ocean. Eng. 2020 195 106699 10.1016/j.oceaneng.2019.106699
20. Nago V.G. dos Santos I.F.S. Gbedjinou M.J. Mensah J.H.R. Tiago Filho G.L. Camacho R.G.R. Barros R.M. A literature review on wake dissipation length of hydrokinetic turbines as a guide for turbine array configuration Ocean Eng. 2022 259 111863 10.1016/j.oceaneng.2022.111863
21. Laws N.D. Epps B.P. Hydrokinetic energy conversion: Technology, research, and outlook Renew. Sustain. Energy Rev. 2016 57 1245 1259 10.1016/j.rser.2015.12.189
22. Güney M.S. Kaygusuz K. Hydrokinetic energy conversion systems: A technology status review Renew. Sustain. Energy Rev. 2010 14 2996 3004 10.1016/j.rser.2010.06.016
23. Pankaj K.Y. Ankit K. Satyanand J. A critical review of technologies for harnessing the power from flowing water using a hydrokinetic turbine to fulfill the energy need Energy Rep. 2023 9 2102 2117 10.1016/j.egyr.2023.01.033
24. Ibrahim W.I. Mohamed M.R. Ismail R.M.T.R. Leung P.K. Xing W.W. Shah A.A. Hydrokinetic Energy Harnessing Technologies: A Review Energy Rep. 2021 7 2021 2042 10.1016/j.egyr.2021.04.003
25. Khan J. Bhuyan G. Iqbal M.T. Quaicoe J.E. Hydrokinetic energy conversion systems and assessment of horizontal and vertical axis turbines for river and tidal applications: A technology status review Appl. Energy 2009 86 1823 1835 10.1016/j.apenergy.2009.02.017
26. Aristizábal-Tique V. Villegas-Quiceno A.P. Arbeláez-Pérez O.F. Colmenares-Quintero R.F. Vélez-Hoyos F.J. Development of riverine hydrokinetic energy systems in Colombia and other world regions: A review of case studies Dyna 2021 88 256 264
27. Mancilla C.C. Río J.S. Arrieta E.C. Zuluaga D.H. Horizontal axis hydrokinetic turbines: A literature review Tecnol. Cienc. Agua 2018 9 180 197 10.24850/j-tyca-2018-03-08
28. Tan K.W. Kirke B. Anyi M. Small-scale hydrokinetic turbines for remote community electrification Energy Sustain. Dev. 2021 63 41 50 10.1016/j.esd.2021.05.005
29. Karakaya D. Elci S. Numerical Assessment of Vertical Axis Hydrokinetic Turbine Efficiencies with Different Grate Protections IET Renew. Power Gener. 2025 19 e70060 10.1049/rpg2.70060
30. Ramadan A. Hemida M. Abdel-Fadeel W.A. Aissa W.A. Mohamed M.H. Comprehensive experimental and numerical assessment of a drag turbine for river hydrokinetic energy conversion Ocean. Eng. 2021 227 108587 10.1016/j.oceaneng.2021.108587
31. Churchfield M.J. Li Y. Moriarty P.J. A large-eddy simulation study of wake propagation and power production in an array of tidal-current turbines Philos. Trans. A Math. Phys. Eng. Sci. 2013 371 20120421 10.1098/rsta.2012.0421 23319713
32. Zaidi M. Uddin N. Adeel A. Numerical Simulations of Hydrokinetic Turbine for Power Generation Proceedings of the International Conference on Energy and Sustainability Karachi, Pakistan 27 April 2013 Volume 1 10.13140/RG.2.1.3714.6484
33. Lyubenov S. Hydropower Systems Technika Sofia, Bulgaria 1990
34. Obretenov V. Water Turbines Ecoprogress Sofia, Bulgaria 2008
35. Available online: https://en.wikipedia.org/wiki/List_of_rivers_of_Bulgaria (accessed on 21 June 2025)

Issue