Investigation of Electricity and Hydrogen Production Using Hybrid Renewable Energy Systems
Thesis Type: Doctorate
Institution Of The Thesis: Balikesir University, Fen Bilimleri Enstitüsü, Mechanical Engineering, Turkey
Approval Date: 2010
Thesis Language: Turkish
Student: ERSİN AKYÜZ
Supervisor: Zuhal Oktay Coşkun
Abstract:
In recent years, the implementation of sustainable energy strategies has become crucial for creating sustainable living environments and for combating climate change and global warming. Hydrogen energy and hydrogen production from renewable energy sources play an important role in addressing these challenges. In this study, the production of electricity and hydrogen using renewable energy sources, specifically solar and wind energy, is investigated.
Initially, system sizing was carried out using the HOMER software, and a hybrid energy system consisting of a 1 kWp photovoltaic system and a 10 kW wind turbine, together with 48 kW battery storage and a 5 kW inverter, was installed at the Kınalı Keklik production facility in Bigadiç, Balıkesir. The system components were optimally sized based on the annual energy demand of the facility and regional meteorological data.
For hydrogen production, a proton exchange membrane (PEM) electrolyzer with a hydrogen production capacity of 150 ml/min was utilized. Energy and exergy analyses, as well as life cycle cost analyses and economic evaluations, were performed for the Photovoltaic–Electrolysis, Wind–Electrolysis, and Photovoltaic–Wind hybrid systems. To evaluate the performance of the electrolyzer under variable operating conditions, the effects of current density and temperature on energy efficiency and exergy efficiency were examined.
All system components were modeled using MATLAB–Simulink, and the simulation results were compared with experimental data. The energy efficiency of the photovoltaic system was found to vary between 10.7–14%, while the exergy efficiency ranged between 9.5–12%. For a 1 m² photovoltaic panel with 14% efficiency, coupled with the 150 ml/min electrolyzer, the annual hydrogen production was calculated as 2.97 kg, with an annual hydrogen production cost of 46 USD/kg. In addition, hydrogen production rate, cost, and panel temperature were expressed using mathematical equations.
The energy efficiency of the electrolyzer system operating at 25°C and within a current range of 10–40 A was calculated to be between 69–65%, while the exergy efficiency ranged between 68–63%. The energy efficiency of the wind turbine was determined to be 34.6%, with an exergy efficiency of 28.5%. Furthermore, the economic feasibility of hydrogen production using a wind turbine–electrolysis system in the Balıkesir region was investigated. It was found that 20.3 kg of hydrogen per year could be produced using a 1 kW wind turbine and a 0.56 kW electrolyzer, with a hydrogen production cost of 30.8 USD/kg.
Based on measurements conducted at the facility installed in Bigadiç, the capacity utilization factors between March and July were found to range between 4.7–14.2% for the wind turbine and 1.7–2.3% for the photovoltaic system. The state of charge of the batteries varied between 56.6–84.2%.