An experimental study of kit fuel cell car to supply power

Transcription

1 An experimental study of kit fuel cell car to supply power Mustafa I. Fadhel Faculty of Engineering and Technology, Multimedia University, Jalan Ayer Keroh Lama, 75450, Melaka, Malaysia. Abstract Fuel cell is one of energy source that has potential to replace petroleum in the future especially in transportation sector. In this paper the experimental of kit fuel cell car has been conducted in order to study the performance of hydrogen fuel cell car to supply power under Malaysian conditions. The photovoltaic panel (PV) was used to supply current to electrolyzer in order to break the water molecule into hydrogen and oxygen gas, and then, the hydrogen and oxygen gas remix in the fuel cell to generate electricity and also water as product. The efficiency of (PV, electrolyzer, and fuel cell) has been determined were found (17%, 95%, and 47%, respectively), while the total efficiency of the fuel cell car was 8%. The polarization curves for (PV, electrolyzer, and fuel cell) have been studied which have been shown the same pattern as the standard polarization curves of them. Even though the total efficiency of laboratory fuel cell car is very low, it shows the potentiality and reliability of using fuel cell as the power supply especially in the car. However there are still a lot of works for improvement and more effort should be contributed in this area. Keywords Photovoltaic, electrolyzer, fuel cell, fuel cell car efficiency I. INTRODUCTION Petroleum and fossil fuel are the main energy in this world nowadays. Whether for the domestic purposes or the transportation, we depend too much on them. However, petroleum and fossil fuel are not the renewable energy. It means, once is being used, we never get them back. According to Hubert peak oil theory, the oil reservation will at peak at [1]. Renewable energy like solar, wind, hydro and etc seems like the solution to encounter the problem. However, not all of them are suitable to use in both transportation and domestic purposes like petroleum and fossil fuel except fuel cell. It has been grown rapidly after the successful practical application in space program by NASA in After that, more researches have been done to make it practical to use in transportation and also to supply energy for domestic purposes and portable application. This because fuel cell has several advantages compare to fossil fuel and other alternative source; environmental friendly, renewable energy, and high efficiency. The first fuel cell vehicle called electrovan was built in 1967 by General Motor (GM) [2]. After that invention, the rapid development fuel cell car was show by participant of other car company like DaimlerChrysler, Ford, Mazda, BMW, Mercedes and etcetera. U.S Department of Energy (DOE) estimated that state of the initial validation of fuel cell is in year 2009 and will reach stability in customer acceptance in 2015[3]. TABLE I ESTIMATION OF FUEL CELL BY DEPARTMENT OF ENERGY (DOE) [3] Performance Measure Fuel Cell Durability Vehicle Range Untaxed Fueling Cost At Station ,000 hours 5,000 hours 402km (250 miles) $3/gallon gasoline equivalent 483 km (300 miles) $2-3/gallongasoline equivalent The number development of fuel cell in transportation sector has shown larger increase in Many car manufacturers have already begun their research in fuel cell to power their vehicle. This is because fuel cell has proved that they can replace ICE s car in the future. However, until now, there is no fuel cell car has been commercialize in the market. This because there are several problems like the price are too expensive and also the durability still unknown makes the car manufacture think twice before make it in the mass production. Some estimate that the fuel cell vehicle only can meet customer acceptance in only at [3-4]. The first fuel cell is invented by Sir William Grove in 1839 [5]. By using electrolysis principle, he invented the gas battery which can generate about 1 volt by experimenting with current flow during the electrolysis experiment. After that, Grove invents the gas chain by combining the series of gas battery in years later, the term of fuel cell was used. Ludwig Mond and Carl Langer have developed a new kind of gas battery that is a prototype of fuel cell [5-6]. Their research has encountered the problem about the flooding electrode due to the liquid electrolyte. It also used platinum black as the catalyst in their experiment. The results, it generates 0.97V fuel cell. After that, there is significant of the fuel cell development. One of the achievements is the research by Francis T. Tom Bacon. Inspired by the Grove s work, he successfully developed an alkaline fuel cell that can generate 6-kW [7]. There are many types of fuel cell. All of it have there are own advantages and disadvantages, in this study PEM (Proton ISBN:

2 Exchange Membrane also known as Polymer Electrolyte Membrane) fuel cell was used due to compact and lightweight of the cell and it can operate at very low temperature about 80 o C that make it suitable for the transportation industry [4]. Other types like Alkaline Fuel Cell (AFC) and Solid Oxide Fuel Cell (SOFC) have their own uniqueness that has been used in different purposes. The aim of this paper to determine the performance of the hydrogen fuel cell car under Malaysian conditions, and to verify the relation of current and voltage in the fuel cell car (The polarization curves have to be plotted in order to see the relationship between the current and voltage in the fuel cell, electrolyzer and also solar panel). II. METHODOLOGY A. Kit Fuel Cell Car Description The kit fuel cell car consists of three main components (photovoltaic panel (PV), electrolyzer and fuel cell). The car experiments set up shown in Figure 1. The photovoltaic panel (PV) was used to supply current to electrolyzer in order to break the water molecule into hydrogen and oxygen gas, and then, the hydrogen and oxygen gas remix in the fuel cell to generate electricity and also water as product. Later, water that has been produced can be use back to electrolyzer. The process can go on as long as the water produce is enough for the reaction. This process is called reversible process. of water with the help of catalyst in anode will separate the molecule into hydrogen proton (H + ), oxygen gas and electron. Hydrogen proton (H + ) will go through the PEM because PEM only allows the positive charge to go through it. At the cathode side this hydrogen proton (H + ) will combine with electron with the help of catalyst and produce hydrogen gas. The gasses will be store for the fuel cell process later. However, this process needs electricity for the reaction in anode and cathode. So, PV panel is use to supply the electricity for the electrolyzer. The reactions in PEM electrolyzer are: Anode reaction: 2 H 2 O(l) O 2 (g) + 4 H + (aq) + 4e (1) Cathode reaction: 4 H + (aq) + 4e 2H 2 (g) (2) Overall reaction: 2H 2 O 2H 2 (g) + O 2 (g) (3) The hydrogen and oxygen gasses will be used in order to generate electricity in fuel cell process. Hydrogen gasses will be supply to anode that later will be transform into hydrogen ion (H + ) and electron with the help of catalyst. The hydrogen ion (H + ) will cross the PEM to go to cathode side while, the electron have to cross the wire to go to cathode side. Once reaching the cathode, the ions are reunited with the electrons and the two react with oxygen, to create water and generate the energy. The reactions in PEM fuel cell are: Anode equation: 2H 2 4H + + 4e - (4) Cathode equation: O 2 + 4e - + 4H + 2H 2 O (5) Overall equation: 2H 2 + O 2 2H 2 O (6) B. Photovoltaic (PV) Efficiency The PV efficiency calculated by: (7) η PV PV efficiency Pm Maximum Power (voltage*current) E Light irradiance (1000 W/m 2 at STP) Ac Surface area of PV Fig.1 Kit fuel cell car experimental set up In the electrolyzer, water has been used to produce hydrogen and oxygen gasses. Water will be supply in anode. The reaction ISBN:

3 C. Electrolyzer Efficiency The electrolyzer efficiency could be: (8) η E Electrolyzer efficiency V cell Cell potential (V) i Input current density (A/cm 2 ) i loss Internal current density (A/cm 2 ) η DC The efficiency of voltage regulator ξ The ratio between parasitic power and fuel cell gross power output D. Fuel Cell Efficiency The fuel cell efficiency can be computed as: (9) η E Electrolyzer efficiency V cell Cell potential (V) i Input current density (A/cm 2 ) i loss Internal current density (A/cm 2 ) η DC The efficiency of voltage regulator ξ The ratio between parasitic power and fuel cell gross power output E. Fuel Cell Car Efficiency The total efficiency of fuel cell car is: III. RESULTS AND DISCUSSION The Table 2 shows the results between voltage and current of PV at different times of the day. TABLE 2 VOLTAGE AND CURRENT RESULTS OF PV Time 10.00am am am am pm pm pm pm pm pm pm pm An important design consideration in electrolyzer is the match between the current-voltage (I-U) characteristics of the PV array and the electrolyzer. If the electroyzer is connected directly to the array, it must operate near the maximum power point of the array or power will be lost. However, it is important that the electrolyzer voltage not be much larger than the Maximum Power Point (MPP) voltage or array output will drop precipitously. The relationship between voltage and current (I-U) of PV is shown in Figure 2. The maximum power of a PV depends on solar radiation and cell temperature, for fix cell temperature if the solar radiation increase the PV power increase. The relationship between voltage and current of electrolyzer is shown in Figure 3. As seen from the Figure 3 that high voltage produced which is necessary to split water as the 1.23 V enough to split the water. The amount of power (energy per time) that goes into the splitting of water is the product of the voltage and current. (10) ISBN:

4 potential power output at different load conditions. Many polarization curve-fitting strategies are available [8-9]. Figure 4 shows the relation of voltage against the current for the Fuel cell. A typical cell voltage versus current illustrates the performance of a fuel cell that operates at low temperature. As seen from the figure there are variations in the cell voltage due to an increasing current. The output power from the fuel cell is independent on the fluctuations in the solar insulation Fig. 2 voltage and current relationship of PV panel Fig. 3 voltage and current relationship of electrolyzer One typical feature in fuel cell is the cell current voltage relation referred to as the polarization curve. Such polarization curve is a plot of the measured cell voltage as function of the average current/current density, and therefore shows the Fig. 4 voltage and current relationship of fuel cell The photovoltaic efficiency calculated by equation (7), which is equal 17%. The PV panel efficiency is very small. However, compare with other PV panel efficiency, the efficiency is acceptable. The electrolyzer and fuel cell efficiency determined using equations (8) and (9), respectively. These efficiencies equations is based on the higher heating value (HHV), the efficiency of voltage regulator is fixed (η DC = 0.95), no internal current loss (i loss = 0) and no parasitic losses. The magnitude of the electrolyzer efficiency in this study was high which is equal 95%, however the value is still acceptable comparing with others. The fuel cell efficiency is 47%. The value of the efficiency of fuel cell is acceptable when it compare to other fuel cell. The total car fuel cell efficiency calculated by equation (10) which is equal 8%. Even though the total efficiency of laboratory fuel cell car is very low, it shows the potentiality and reliability of using fuel cell as the power supply especially in the car. ISBN:

5 IV. CONCLUSION The experiments of kit fuel cell car (Laboratory fuel cell car) have been conducted to show the reliability of using fuel cell car in Malaysia. The polarization curves for (PV, electrolyzer, and fuel cell) have been studied which have been shown the same pattern as the standard polarization curves of them. The efficiency of (PV, electrolyzer, and fuel cell) has been determined were found (17%, 95%, and 47%, respectively), while the total efficiency of the fuel cell car was 8%. Even though the total efficiency of laboratory fuel cell car is very low, it shows the potentiality and reliability of using fuel cell as the power supply especially in the car. However there are still a lot of works for improvement and more effort should be contributed in this area. REFERENCES 1. Wikipedia. Hubbert Peak Theory. [Online]. [2009, April 27] 2. Hoogers G. Introduction. Fuel Cell Technology Handbook. CRC Press, National Renewable Energy Laboratory (NREL), Validation of Hydrogen Fuel Cell Vehicle and Infrastructure Technology, October Crawley, G., 2006, Opening doors to fuel cell commercialisation: Proton Exchange Membrane Fuel Cells (PEMFC). Fuel Cell Today, March G. Hoogers (eds.), Fuel Cell Technology Handbook. ISBN , CRC Press, Nice K., Strickland J. How Fuel Cell Works? [Online]. [2009, April 2] 7. Cook B. Introduction To Fuel Cells and Hydrogen Technology. Engineering Science and Education Journal, 11(6); 2002: Amphlett JC, Baumert RM, Mann RF, Peppley BA, Roberge PR, Rodrigues A. Parametric modeling of the performance of a 5-kW proton-exchange membrane fuel cell stack. Journal of Power Sources 1994; 49: Larminie J, Dicks A. Fuel Cell Systems Explained. England: John Wiley and Sons; ISBN: