Proton Exchange Membrane Fuel Cells - Essay Example

Proton Exchange Membrane Fuel Cells This paper focuses on Proton Exchange Membrane Fuel Cells (PEMFCs) because this is the type of fuel cell the government is supporting as the most promising fuel cell technology. It is believed to soon power vehicles and even our homes. This paper will shed light on what is needed for this type of fuel cell to work, how they are made, advantages and disadvantages of this type of fuel cell, and developments in this field. This paper will focus on the applications of PEMFCs in the automotive industry. Fuel cells use the chemical energy stored within the fuel and convert it into electrical energy. Different types of fuel used are hydrogen, methane, and gasoline. The polymer exchange membrane fuel cell (PEMFC) is a type of fuel cell that uses hydrogen as fuel. Using hydrogen, PEMFCs follow the chemical reaction below to make electricity. 2H2 (g) +O2 (g) 2H2O (l) + Energy For PEMFCs to create electricity, it must have the following parts: The anode, or the negative post of the fuel cell, which conducts electrons separated from hydrogen molecules. These electrons will then be used in an electric circuit. The electrolyte, which is the proton exchange membrane, conducts positively charged ions and blocks electrons. The catalyst, which facilitates the reaction of hydrogen and oxygen. The figure below shows how these different components make the fuel cell work. Figure 1: Proton exchange membrane fuel cell diagram First, hydrogen gets into the fuel cell via the anode. The catalyst then split the H2 molecule into H+ ions and electrons. The electrons then pass through the external circuit that lights the lamp as shown in the figure. During this process, oxygen, usually from the air, enters at the cathode. The oxygen combines with the electrons, which have completed their circuit. The oxygen then combines with H+, which leads to the formation of water (H2O) (a waste product in the fuel cell). This is how all fuel cells work, and they differ mostly in the type of electrolyte they use. At the anode: oxidation reaction 2H2 4H++ 4e- At the Cathode: Reduction reaction O2 + 4H+ + 4e- 2H2O Overall cell reaction (redox reaction) 2H2 + O2 2H2O Unlike other fuel cell types, PEMFCs are excellent for transportation applications. They generate electricity at relatively low operating temperatures compared with other fuel cell types and, therefore, can be easily started up. Other fuel cells are best for stationary power generation because of extremely high operating temperature between 600 and 1000 degrees Celsius. With all the available technology for vehicles, fuel cell electric vehicles are seen as promising because of their fuel efficiency. Traditional gasoline vehicles have a fuel efficiency of about 20%. Battery-powered electric vehicles are much higher up in fuel efficiency. Batteries in themselves have an efficiency of 90%. From electrical energy, the car still has to convert it to mechanical energy, which is also at around 80% efficient. While electric vehicles are efficient, the means of producing electricity, if generated by the power plant, only has an efficiency of 40%. Charging the car also has an efficiency of 90% when converting alternating current to direct current. Considering everything, the overall efficiency of electric vehicles is only at about 26%. Fuel cells, when powered by pure hydrogen, are potentially 80% efficient. Like for the electric vehicle, the motor has an efficiency of 80%. This brings the overall efficiency of the fuel cell vehicle to 64%. This value, however, goes down when the fuel source is not pure hydrogen. The U.S. Department of Energy thus decided to concentrate on pure hydrogen fuel cell vehicles. Fuel cell vehicles, therefore, are expected to supersede their rival technologies in terms of fuel efficiency (Nice and Strickland). However, free hydrogen does not exist on planet earth. Consequently, it is produced from sources such as natural gas, gasified coal, and water electrolysis among others. The production of hydrogen involves energy losses, but this remains insignificant against the efficiency of electric vehicles. While very promising, fuel cell technology is not without its challenges. For applications in the automotive industry, a lot of factors must be considered. First consideration is the cost. The electrolyte (made of proton exchange membrane (PEM)), only permits the exchange of the right ions between the anode and cathode, catalysts (usually made of platinum), and other components of fuel cells are still very expensive. Currently, the price is twice the competitive prices compared to gasoline vehicles. Next is the technology’s durability. Cars are subjected to all kinds of weather depending on where they are located and what time of the year it is. This is problematic for fuel cells because the proton exchange membrane must be hydrated at all times for it to work. In hot and dry climates, fuel cells may not function properly. Cars are also frequently started up and turned off, which means the ability of the membrane to remain stable under these cycling conditions is important. To make PEMFC vehicles more attractive to consumers, a hydrogen generation and delivery system must be put up by the government, among other infrastructure needed. The government is just waiting for a marketable vehicle model to drive the development of this infrastructure. Finally, and most importantly, PEMFCs are still too large and heavy for standard-sized vehicle use (U.S. Department of Energy). Aside from the technology, one of its major problems is the difficulty in obtaining the hydrogen. Ina study by Ulf Bossel in 2006, he claims that a hydrogen economy – or the sourcing, packaging, delivery, and distribution or hydrogen – is wasteful. This is due to the large amount of energy needed to isolate hydrogen from its source (i.e. water, natural gas, and biomass), package the gas through compression, and deliver this to the user. Also, the energy lost upon conversion to electricity with fuel cells is significant. This whole process leaves 25% for practical use. This value would not be acceptable in terms of sustainability (Zyga). Recently, however, a study in Virginia Tech showed that researches discovered a new biological way of producing hydrogen that takes less time and is less expensive. The most common way of producing hydrogen now uses high processed sugars. The method in this study uses dirty biomass instead. These are husks, cobs, and stalks of corn plants. Thus, through this method, producing the fuel would be much cheaper, and production plants with corn-based products can make the fuel from their waste (Russon). In July 2014, Toyota announced that its new hydrogen car Mirai will start arriving at dealers this year. The Mirai has since then been in auto shows and is priced at almost $6,000.However, a recent article claims that there is reason to believe that fuel cell vehicles will never beat electric vehicles in terms of cost of the car and fueling, limited fuel stations, and problems in cost-efficient emission reductions (Romm). In conclusion, proton exchange membrane fuel cells have long been proved to be scientifically feasible. There is no doubt that the technology works and that this is a step towards emission reduction. However, in automotive applications, there are still a lot of hurdles to overcome. The fuel itself, the methods of its extraction, and packaging for transportation, are not efficient and costly. There is still a long way to go for fuel cell vehicles, but seeing the government’s initiative for research on this type of technology, and more private companies vying for entry in the fuel cell vehicle market, it may take less time to make fuel cell vehicles technically feasible and competitive with other types of cars. Works Cited Nice, Karim and Jonathan Strickland. How Fuel Cells Work. 18 September 2000. Print. Romm, Joe. Tesla Trumps Toyota: The Seven Reasons Hydrogen Fuel Cell Cars Are Stalled. 8 April 2015. Web. 10 April 2015. . Russon, Mary-Ann. Hydrogen fuel made from corn husks could be renewable energy breakthrough for cars. 7 April 2015. Web. 9 April 2015. . U.S. Department of Energy. Fuel Cells. n.d. 8 April 2015. Web. 9 April 2015. . —. Type of Fuel Cells. n.d. Web. 8 April 2015. . Zyga, Lisa. Why a hydrogen economy doesn't make sense. 11 December 2006. Web. 9 April 2015. . Read More