Replacing Gasoline In Vehicles With Hydrogen Fuel Cell Engineering Essay
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Case study: As we know, gasoline is limited energy source in the world and it is getting lesser and lesser. Hence, the price of the fuel keeps on increasing in recent years. Energy produced by burning fuel (gasoline) in vehicles has causes serious pollution to our environment. In order to be eco-friendly and to solve the increasing price of the fuel, hydrogen fuel cell vehicles are in its development to be used as a replacement for gasoline vehicles. Discuss.
Hydrogen fuel cell as an alternative source of energy in vehicles
First of all, in order to make hydrogen fuel cell to be applicable for vehicles, we have to find out the ways to produce hydrogen. Hydrogen is the simplest element which consist one proton and one electron. Although it is the simplest element and can be found elsewhere, it does not occur individually and naturally as a gas on the world. Hydrogen always combined with other element for example oxygen to become water (H2O).There are several processes that can be used to produce hydrogen which include thermochemical processes [1, 2], electrochemical processes [3], photochemical processes [4], photocatalytic processes [5] and photo-electrochemical process [6]. In thermochemical process, hydrogen is released by involving thermal assisted chemical reactions for example hydrocarbons or water [7]. It has the advantage of higher overall efficiency (η ~ 52%) and lower production costs [8].
In a fuel cell, the produced hydrogen (gaseous) is electrochemically combined with oxygen from the air (oxidant gas) through electrodes and across an ion conducting electrolyte which generates electricity and heat [9]. As in battery, fuel cell does have two electrodes while the electrodes in fuel cell are sandwiched around an electrolyte [9]. Under the action of the catalyst, the hydrogen is being splits into protons and electrons, and both will be taking different paths towards the cathode [9]. The electrons flow out of the cell creating separate current which will be used as electrical energy. Meanwhile, the hydrogen ions (protons) pass through the electrolyte to the cathode electrode. The protons and electrons that reach cathode will be combined with oxygen from the air to form pure water molecule and heat [9, 10]. Unlike battery, fuel cell never run out but will generate electrical power continuously.
Hydrogen fuel cell vehicles bring us several advantages. First, hydrogen fuel cell vehicles can achieve higher efficiency and with lower emission. Electricity in internal combustion engines is generated by using a dynamo driven by the stored energy extracted through a controlled explosive reaction [11]. In contrast, fuel cell only needs one step which is using electrochemical reaction to convert the fuel directly into energy. Therefore, the conversion efficiency is higher. For the applications in vehicles, the efficiency of fuel cell vehicles will be 2-3 times higher than current gasoline vehicles. Such vehicles can reduce the demand for gasoline to almost zero by year 2050 and reduce CO2 emissions by 80% according to National Academies of Science and NHA's Energy Evolution Study. The emission is reduced mainly due to the higher efficiency in fuel cell which means lesser amount of fuel is required to generate the same amount of energy and there are negligible of NOx and SOx emissions since there is no combustion in the fuel cell [11]. The only waste from the hydrogen fuel cell is water vapor. Second, hydrogen vehicles will have higher reliability with lower maintenance. Compared to internal combustion engines, fuel cell vehicles have lesser moving parts and hence required lesser maintenance for example changes of lubricant. In another words, lesser maintenance means higher reliability. Furthermore, moving parts in internal combustion engines such as pistons, timing belt, and crankshaft will produce a lot of noises and vibrations. While in fuel cell, there are fewer moving parts which will remarkably reduce the noises and the vibrations [11].
Fuel cell vehicles do have several disadvantages although they are beneficial in a few ways. For example, the electrolysis process which is using water to produce hydrogen by separating them from oxygen is very costly and is rarely used [12]. Besides, hydrogen is hardly stored and distributed unlike oxygen which comes from the air [9]. Hydrogen can easily evaporate and it needs a tank with perfect insulation to store it safely while the tank will be much larger than the ordinary tank in gasoline vehicles.
Concerning about the future of hydrogen fuel cell vehicles, there are several developments in fuel cell technology and marketing. Germany, Japan and Korea have anticipated that they will have over 30 fueling stations operating by the timeframe of 2015-2017. Besides, there are a few car manufacturers have announced that they will unveil their Fuel Cell Electric Vehicles (FCEV) soon for example Mercedes Benz B-class F-cell and Mazda Premacy Hydrogen RE Hybrid. In United States, 2.8 million miles of real-world driving has been achieved after 152 FCEVs and 24 hydrogen stations have been demonstrated by the industry [13].
In short, hydrogen fuel cell vehicles have great potential to replace the current gasoline vehicles. In order to achieve these objective, reformers need to work hard to overcome all the limitations and disadvantages step by step and we are expecting that there will be more hydrogen fuel cell vehicles on the market starting from year 2015 onwards.
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