An oscillating water column wave energy system consists of a barrier (front wall), a wave turbine, an electric generator and an air chamber (air column). The parts of a system must be improved to increase efficiency of the system in general. The dimensions of the air chamber affect directly the efficiency of the system because the conversion of the wave power into the air movement is realized here, thus the wave parameters are important. One of the characteristic parameters for waves is their amplitude. In this study, the system is simulated in 2D and solved numerically to see the effect of water wave amplitude on the efficiency of energy system. In the design of this system the barrier length is constant. The numerical modelling involves computational fluid dynamics analysis and optimization of the oscillating water column. The Navier-Stokes equations and the continuity equation are numerically solved based on the finite volume method using the commercial ANSYS Fluent code. In the numerical model the flow is assumed to be inviscid, unsteady, and incompressible. The efficiency of oscillating water column system is first increased up to 67% and then decreases to 50% with the increase of the wave amplitude.

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Wind energy, which is enormously important to protect the environment, can be converted into electricity by wind turbines. Wind turbines consist of a base, a tower, a generator, a gearbox, a hub and rotor blades. Horizontal wind turbines are designed with three blades to have higher efficiency. Wind turbine blade can be made of wood, steel, aluminum, carbon fiber-reinforced plastics and glass fiber-reinforced plastics. In this work it is aimed to study the effect of blade material on the wind turbine efficiency using numerical method. The commercial software ANSYS Fluent is used to calculate and compare the efficiencies of wind turbines with different blade materials. In the numerical analysis the flow is modelled as viscous, laminar and incompressible. Results show that the frictional effect on the hub bearing is bigger if a denser material is used. This effect reduces the efficiency of wind turbines.

Environmental physics deals with energy demand problems and investigates the possible contributions of renewables to energy supply. Wave energy is one of the renewable, environmentally friendly types of energy sources. To convert the wave energy into the electrical energy, wave energy converters are used, such as the oscillating water column systems. Oscillating water column consists of air chamber, air turbine and generator. Air turbine is the main component of such system. It is a special type of turbine, called Wells turbine, which differs from others by its surface geometry. In the Wells turbine, blade surface geometry affects the efficiency enormously. An increased turbine efficiency with optimized turbine blade surface will contribute to environmental protection. In this study, it is aimed to increase the efficiency of an oscillating water column type wave turbine by using the dimpled blade surface instead of a flat blade surface. Numerical optimization is performed under Spalart Allmaras turbulence model in the commercial code ANSYS Fluent. Numerical results show that surface with dimples has higher efficiency when compared to flat blade surface.