Browsing by Subject "Hybrid energy systems"

Now showing 1 - 3 of 3

Open Access
Optimization of hybrid energy systems with pumped hydro storage: a case study for Turkey
(Gazi Üniversitesi Mühendislik-Mimarlık, 2019) Kocaman, Ayşe Selin
There is a need for energy models that include renewable energy sources to reduce the role of fossil fuels in electricity generation. However, renewable energy sources are intermittent and cannot be predicted precisely. Designing hybrid systems that combine alternative resources and energy storage helps reduce the intermittency of renewable sources and result in cost effective and reliable solutions. The most widely used energy storage form in the World is to store the potential energy of water in the pumped hydroelectricity systems (PHES). Pumped hydroelectricity systems can be designed in two types: mixed systems, if there is a natural water inflow to the system and pure systems, if the system is closed to water inflow. In this study, we present two-stage stochastic programming models for both types of PHES, which take into account the uncertainty of resources and electricity demand. For the first time in the literature, we consider the sizing problem of hybrid systems that include solar generation supported by pure and mixed PHES systems separately and present the results for Turkey, which currently does not have any PHES system and highly depends on fossil fuels for electricity generation, despite of the rich renewable energy potential.
Open Access
Renewable energy system design and operational planning for demand fulfillment
(2024-08) Yurter, Gülin
Renewable energy sources have gained prominence in reducing the dependency on fossil fuels and minimizing their negative environmental impacts. Considering renewables' uncertain and variable nature, an effective design and operational planning of hybrid energy systems is key to success in clean energy transition. We study the optimal design and operational planning problem of hybrid energy systems involving a renewable energy source and a storage unit. We first develop two-stage stochastic mixed-integer programming models to determine the optimal sizing and investment decisions for solar/wind farms co-operated with pumped hydro energy storage facilities in decentralized areas. We then utilize a Markov decision process to find the optimal energy generation and storage decisions for decentralized grid-connected wind farm-battery systems with demand-fulfillment obligations. This is a novel study that compares several pumped hydro energy storage configurations with respect to optimal sizing decisions for system components and allows for uncertainties in electricity price, wind speed, and electricity demand for optimal operational planning. Using real-life data and considering economic benefits, we demonstrate how the renewable energy systems should be designed and managed to mitigate the adverse effects of uncertainties in matching supply with demand.
Embargo
The impact of pumped hydro energy storage configurations on investment planning of hybrid systems with renewables
(Elsevier Ltd, 2024-02) Yurter, Gülin; Nadar, Emre; Kocaman, Ayşe Selin
The pumped hydro energy storage (PHES) systems can be installed in various configurations depending on the specific geographical and hydrological conditions. Closed-loop PHES systems are off-stream and have no natural inflow to the system. However, open-loop systems are on-stream and have natural inflows to the upper and/or lower reservoirs. In this study, we develop two-stage stochastic programming models for various PHES configurations to investigate how the choice of PHES configuration impacts the sizing decisions and costs of a hybrid system that includes a renewable power generator co-operated with PHES. Our numerical results show that using a PHES facility instead of a conventional hydropower system reduces the expected system cost and mismatched demand significantly. Open-loop PHES facilities perform better than closed-loop PHES and seawater-PHES facilities, dramatically lowering the need for fossil fuels in demand fulfillment. The most cost-efficient PHES configuration is when there is natural inflow to the upper reservoir. Using solar energy instead of wind as the renewable source significantly increases the requirement for larger upper reservoirs in on-stream open-loop PHES facilities, while reducing the expected system cost for all configurations.