Plasma Energy Conversion System for Electric Power Generation A.O Ayeleso, M.T.E Kahn and A.K. Raji Abstract-In the conventional conversion system, a large amount that would convert plasma energy into electric power. The of energy (about 60%) is required to generate electric power for electric power generated from the plasma can be used in industrial applications and commercial usage. As a result, there is a need for more energy conversion systems which can be used to vehicles, houses, satellites and industries. Fig. 1 depicts the produce reliable and efficient electrical power. In this paper, the stages of the direct energy conversion system. present study focuses on the direct energy conversion systems such as magnetohydrodynamics (MHD) and plasmadynamic (PDC). In these systems, a plasma source is directly converted into electrical energy without the use of any mechanical energy. Furthennore, the Energy Convers�n Exolhermic electrical power generated from these systems is very efficient and Syslem Thermal Energy large loss of energy is greatly minimised. The objective of the PrimaryE nergy -+ Chemical Reaclion f-+ -+ present study is to develop an improved MHD energy conversion (MHD/PDe) system based on the principle of Faraday's Law of electromagnet­ ism and plasma physics. The testing of this system will be explored using the available plasma sources in the Western Cape, South � Africa. These sources may include gas discharge fluorescent light, flames, gas laser, solar wind, aurora and earth's ionosphere. Another objective of the study is to use numerical simulations (1- dimensional and 2-dirnensional MHD models) to study the Electrical Energy dynamics of plasma fluid flowing through a rectangular MHD generator channel and a conducting magnetic field. Index Terms- Conventional conversion systems, electric Fig. The stages of the direct energy conversion system power, Faraday's Law of electromagnetism, plasma sources I. Magnetohydrodynamics, Plasmadynamic, plasma physics. 2 DIRECT ENERGY CONVERSION SYSTEM The direct energy conversion system can be grouped into two categories: The PDC and MHD conversion systems. 1 INTRODUCTION Power consumption is becoming one of the major challenges affecting many industrial and commercial users. 2.1 Plasmadynamic conversion system The fossil fuel and other conventional resources that are The PDC conversion system is a method of converting currently being used for power generation are not sufficient thermal energy of plasma into electric power without plasma for industrial applications and commercial usage [1],[2],[3]. flow. This method begins when two floating conducting Furthermore, in the conventional energy conversion system electrodes are immersed into high temperature plasma. One (hydroelectric and thermodynamics), a large amount of of the electrodes is magnetised while the other is energy (about 60%) is required when converting thermal unmagnetised. By measuring the potential difference energy into mechanical energy. Therefore, there is a need between the two electrodes, the output voltage can be for more research to discover new technologies which can measured. In addition, the potential difference between the be used for converting different forms of energy into magnetised and unmagnetised electrodes drive a current to electrical power. One of the new technologies is the direct an extemal load where electric power is measured [4]. energy conversion system (the magnetohydrodynamics (MHD) and plasmadynamic (PDC». The MHD and PDC 2.2 Magnetohydrodynamics conversion system systems uses plasma energy to generate efficient electric The MHD conversion system is a distinctive method used power [1],[4]. These systems convert plasma energy for the generation of electric power based on the principle of (primary energy) directly into electrical energy without Faraday's Law of electromagnetism and plasma physics, as passing through any mechanical energy stage [1],[5]. The shown in Fig. 2. In this method, a plasma (ionised gas) focus of the present study is to develop an efficient system flowing with high velocity is required [3],[5],[6],[7]. Mr. A. O. Ayeleso, Electrical, Electronic & Computer Engineering, Cape Peninsula University of Technology, PO Box 1906, Bellville 7535, Cape Town , South Africa (e-mail: [email protected]). Prof. M.T.E. Kahn, director, Energy Research Centre, Electrical, Electronic & Computer Engineering, Cape Peninsula University of Technology, Bellville campus, (e-mail: [email protected]). Dr. A. K. Raji, Electrical, Electronic & Computer Engineering, Cape Peninsula University of Technology, Bellville campus, (e-mail: [email protected]). Authorized licensed use limited to: Cape Peninsula University of Technology. Downloaded on July 17,2020 at 12:47:36 UTC from IEEE Xplore. Restrictions apply. From Fig. 3, in order to obtain good output voltage, the electrical conductivity, (J, of the plasma must be above the temperature range of 2000 K [2],[8]. This temperature is usually maintained in the Faraday's generator walls. Furthermore, when the plasma is in motion with velocity, v, a magnetic field, jj, is applied transverse to its motion. Consequently, the charged particles inside the plasma Righthand ruleof experience an induced electric field, current and retarding force [1 ],[3],[5], E=vxjj, (1) generator where E is the induced electric field, v is the particle Fig. 2. Principle of Magneto hydrodynamics velocity and jj is the induced magnetic field. From Fig. 2, when plasma flows through a strong magnetic The induced current is given by, field, jj, placed between two conducting electrodes (cathode and anode), an electric current, 7, is generated 1= (JXE, (2) from the voltage, Vo, measured between the electrodes, as shown in Fig. 3 [3],[5],[6],[8]. Furthermore, the conducting where is the electrical conductivity of the plasma. electrodes must be placed on the sides at 9Cfto the induced (J magnetic field in order to create a retarding force (Lorentz The retarding force on the conducting electrodes is given by, force) which is perpendicular to the direction of the field and the measured current. The MHD conversion system can be categorised into different groups: Faraday's generator F=IxB, (3) with continuous electrodes, Faraday's generator with segmented electrodes, Hull generator, disc generator and series connected generator with discontinuous electrodes. where J is the induced current. Each group varies according to the way the electrodes are connected with the load. 2.2.2 Faraday's generator with segmented electrodes The Faraday's generator can also be used with segmented electrodes, as shown in Fig. 4. In this generator, the 2.2.1 Faraday's generator with continuous electrodes The Faraday's generator can be used with continuous electrodes and other materials such as insulators, loads and electrodes, as shown in Fig. 3. In this generator, the magnet are simple to construct. Furthermore, since each conducting electrodes and other materials such as load (R) segmented electrode is connected to an external load, large and magnet are simple to construct. However, because the losses are greatly minimised. Hence, the potential difference electrodes have the same potential, the fluid circuit is of each of the circuit is differently separated [3],[6],[9:41- vertical to the flow of plasma. Consequently, the circuit 43]. components experience more long direction which causes large output losses. In addition, the transverse component of 1 the circuit is reduced as well [3],[6],[9:41-43]. <;J-y x B 1 V ....�\ x Output Voltage B v @ l<--- '---_ Plasma ____ I + (ionized 9as)_ Cathode wall Plasma (ionized gas l- Magnetic field coil Fig. 4. Faraday's generator with segmented electrodes Fig. 3. Faraday's generator with continuous electrodes 2 Authorized licensed use limited to: Cape Peninsula University of Technology. Downloaded on July 17,2020 at 12:47:36 UTC from IEEE Xplore. Restrictions apply. 2.2.3 Hull generator 2.2.5 Disc generator The Hull generator design is shown in Fig. 5. In this In this generator, the plasma flows between the centre and generator, the electrode's edges are shortly connected edge of the disc. Also, a circular Helmholtz coil is placed together and the load is connected to the first and the last above and under the disc to create magnetic excitations, electrodes [6],[9:41-43]. If an electric potential (loads) is which produce Faraday's current around the edge of the connected at different electrode points in the channel, an disc. The benefit of this generator is that it is compact and equipotential will flow diagonally across the insulator walls. the size of the magnet is very small [3]. The advantage of Consequently, the electrodes might wait for some period of the above mentioned MHD conversion systems over other time before it matches the equipotential. The output power energy conversion systems is that they have high efficiency, that can be obtained from a hall generator is driven by the full power generation and cost effectiveness. In the present electric field circuit. Furthermore, this generator produces study, a MHD generator and plasma with high temperature fewer losses than the Faraday's generator because the will be investigated in order to produce reliable and efficient resulting output voltage is very high and shorting of the electric power. Furthermore, this research will help to induced current is significantly reduced. However, due to improve on the existing MHD conversion systems. the high velocity of plasma, the hull generator is less efficient in terms of capturing the output current unlike the 3 PLASMA ENERGY SOURCE Faraday's generator, which is very sensitive to plasma flow Plasma energy can be used in the MHD power generator to [3]. produce a reliable and efficient power. This type of energy are obtained from electrically conducting ionised gas i y (plasma) [10:3],[11:3],[12],[13],[14]. The electrons inside �x the ionised gas display collective behaviour when they are B v Load separated from their atoms, [15:1],[16],[17]. In addition, the plasma sources that are used in Faraday's generators (MHD) are mostly created by thermal ionisation, where high gas Plasma temperatures are required.