DESIGN AND PERFORMANCE ANALYSIS OF CONTINUOUS HYDRAULIC - COMPRESSED AIR ENERGY STORAGE (CH-CAES) AS AIR STORAGE SYSTEM

• Main Author: Surya Rahmany, Rijal
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/62320
• Institution: Institut Teknologi Bandung

One characteristic of Renewable energy sources is its intermittency so, it cannot be utilized all the time. Energy storage systems can be used to overcome the intermittent nature of a system that utilizes renewable energy sources so that renewable energy sources can be used optimally. The compressed air energy storage system (CAES) is one of the energy storage systems that are commonly used today. In a large-scale implementation, CAES is built in areas that have large underground spaces, so CAES can only be installed in certain areas. Research on Small-Scale Compressed Air Energy Storage Systems (SS-CAES) with a capacity of less than 10 MW is currently being carried out. It is because SS-CAES has several advantages that address the shortcomings of the CAES system. Firstly, the SS-CAES system is more easily adapted to environmental conditions, so it can be installed in various regional conditions. Second, the components for building an SS-CAES system are still relatively easy to manufacture. However, SS-CAES still has its drawbacks. The use of air as a driving fluid for small-scale gas turbines is relatively inefficient. The use of hydraulic fluid combined with compressed air is one solution that can be applied to SSCAES. This concept is known as pump hydro-compressed air energy storage (PH-CAES). PH-CAES is an SS-CAES that utilizes an incompressible fluid at the output so that the use of a gas turbine at CAES can be replaced with an energy conversion machine that uses an incompressible fluid as the working fluid. However, to apply this concept, a relatively large incompressible fluid storage is needed and must be filled repeatedly, making it difficult to apply. Therefore, in this study, a physical model of the PH-CAES design was created which can be built with an incompressible fluid reservoir that is relatively more compact and can run continuously without the need for repeated filling on the hydraulic tank. The design that has been made is Continuous Hydraulic-Compressed Air Energy Storage (CH-CAES). In the CH-CAES system, two hydraulic tanks are used whose flow direction is regulated by a solenoid valve. The solenoid valve arrangement in the CH-CAES system can produce a one-way rotation of the hydraulic motor. The method used in this research is designing CH-CAES physical model, experiments on the physical model that has been created and simulating the power output using the CH-CAES mathematical model on hydraulic motors and generators. CH-CAES performance analysis was carried out by measuring the pressure changes in each tank and the rotational speed of the hydraulic motor and generator on the physical model that was made. The output power of the generator is simulated using the CH-CAES mathematical model. The results of the analysis of the parameters on the CH-CAES test and simulation results are used to design prototype scale of CH-CAES. The results of the experiment and simulations on the CH-CAES model are, the pressure on the hydraulic tank affects the rotational speed of the hydraulic motor and generator. The increase in the rotation speed of the generator has a positive effect on the value of the terminal voltage output of the generator. Overall, the pressure on the hydraulic tank side influences the output power of the CH-CAES. Another parameter that has been simulated is the influence of inertia and coefficient of friction using the equation model of the hydraulic motor and generator. Changes in the inertia value of the hydraulic motor and generator do not affect the rotation and maximum power. While the coefficient of friction on the generator and hydraulic motor influences the value of rotation and maximum power. The greater the value of the coefficient of friction in the equation model of the hydraulic motor and generator, the smaller the rotational speed and maximum power of the CH-CAES system. In the prototype scale of CH-CAES, a pneumatic tank with a volume of 9 m3 and a pressure of 80 bar can produce a system output power of 3.5 kW for 2 hours.