List of abbreviations
Chapter 1: Introduction
1.1 Brief history of fuel cell
The principle of the fuel cell was discovered by German scientist Christian Friedrich Schönbein in 1838 [Wand, 2008]. Based on his work, the first fuel cell was demonstrated by Welsh scientist and barrister Sir William Robert Grove in 1839 [O'Hayre et al., 2004].
In 1889, Ludwig Mond and Carl Langer developed a hydrogen-oxygen fuel cell, with thin perforated platinum electrode, which could produce current density of around 6.45 mA/cm2 at 0.73 V [Zhang, 2005]. They were the first to demonstrate the practical hardware to sustain the fuel cell reactions. In 1893, Friedrich Wilhelm Ostwald experimentally determined the interrelated roles of the electrodes, anions and cations, electrolyte, as well as oxidizing and reducing agents in the fuel cells [Andujar and Segura, 2009]. Ostwald explained the correlation of physical properties and chemical reactions at the point of contact among electrode, gas, and electrolyte. His exploration of the
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underlying chemistry of fuel cells laid the foundation for fuel cell researchers. Francis Thomas Bacon, a British engineer, began work on alkaline fuel cells in the late 1930s, and by 1939 a fuel cell was built using nickel electrodes operating under pressure as high as 3000 psi [Bacon, 1969; Demirbas, 2009]. During World War II, Bacon worked on developing a fuel cell that could be used in Royal Navy submarines, and in 1958 demonstrated an alkaline fuel cell stack of 10-inch diameter electrodes. Later, Pratt and Whitney licensed Bacon's work for the Apollo spacecraft fuel cells [Bacon, 1985].
Emil Baur of Switzerland and his group conducted extensive research on the electrolyte for high temperature fuel cell. They used molten silver and a solid electrolyte of clay and metal oxides [website1]. In 1955, W. Thomas Grubb, a chemist working for the General Electric Company (GE), further modified the original fuel cell design using a sulphonated polystyrene ion-exchange membrane as an electrolyte. Three years later another GE chemist, Leonard Niedrach, devised a way for depositing platinum onto the membrane, which served as catalyst for the necessary hydrogen electro-oxidation and oxygen electro- reduction reactions. GE went on to develop this technology with NASA and McDonnell Aircraft, leading to its use during Project Gemini. This was the first commercial use of a fuel cell. However, the sulphonated polystyrene ion-exchange membrane used as an electrolyte in these fuel cells exhibited brittleness in the dry state and were later replaced with crosslinked polystyrene-divinyl benzene sulphonic acid membranes [Zaidi, 2009].
This material also lacked stability and underwent degradation and suffered other problems. Also, the main problem encountered with these membranes was that proton conductivity was not sufficiently high to reach a power density even as low as 100 mW/cm2 .
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In 1959, Francis Thomas Bacon successfully developed a 5 kW stationary hydrogen fuel cell. A team led by Harry Ihrig built a 15 kW fuel cell stack, which used potassium hydroxide as the electrolyte and compressed hydrogen and oxygen as the reactants. This was used in a fuel cell tractor and demonstrated across the USA at state fair. Later, Bacon and his colleagues demonstrated a practical 5 kW fuel cell unit capable of powering a welding machine. In 1960s, Pratt and Whitney licensed Bacon's USA patents for use in the USA space program to supply electricity and drinking water [Gross, 2010].
In 1966, sulphonated polystyrene membranes were replaced by Nafion®, which proved to be superior in performance and durability to sulphonated polystyrene. At this early stage of development, the nafion membrane showed lifetimes of up to 3,000 h at low current densities and temperatures of 50 °C [Zaidi, 2009]. After Gemini program, NASA decided to operate the next space programme with alkaline fuel cell systems [Stone and Morrison, 2002]. However, GE continued working on its proton exchange membrane fuel cell (PEMFC) units and by the mid 1970s water electrolysis technology using polymer electrolyte membrane (PEM) was developed for USA Navy Oxygen Generating Plant [Appleby, 1996]. In 1980s, the British Navy adopted PEM electrolyzer for its submarine fleet and other companies also started to look at PEMFC systems for the commercial development and end-use applications. The PEMFC technology has evolved a lot since the first commercial development of the PEMFC unit in the 1960s. PEMFC units are considered to be the most prevalent alternative for automotive and stationary applications [Hogarth and Ralph, 2002]. In 1991, the first hydrogen fuel cell automobile was developed by Roger Billings. United Technologies Corporation's UTC Power subsidiary was the first company to manufacture and commercialize a large, stationary fuel cell system to use as a co-generation power plant in hospitals, universities, and large office
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buildings. UTC Power marketed their 200 kW fuel cell system, the PureCell 200, which is now replaced by a 400 kW version, the PureCell Model 400 [Fuel cell industry review, 2012].
In 1990, Jet Propulsion Laboratory in Pasadena, California, in collaboration with the University of Southern California, developed a Direct Methanol Fuel Cell (DMFC) as a variant of PEMFC [Surampudi et al., 1994]. It was designed to supply electricity for field troops in the armed forces and for applications in NASA. Currently, DMFC is the technology of choice for the majority of portable appliances. DMFC with liquid-feed (methanol solution) offers promising alternative to hydrogen gas consuming fuel cell (PEMFC) as they allow easy handling and storage of the liquid fuel for applications in portable and mobile electronic devices [Surampudi et al., 1994]. Many liquid fuels such as methanol [Wang et al., 2006], ethanol [Zhou et al., 2004; Lobato et al., 2011; Datta et al., 2012], formic acid [Ha et al., 2005], and ethylene glycol [Neto et al., 2005] are being tested as a fuel in PEM based fuel cells. Among all the investigated possible fuels, methanol [Rice et al., 2002; Difoe et al., 2008] is the most favorite due to various reasons.
A few of the reasons include, generation of 6 moles of electron per mole of methanol, comparatively easy electro-oxidation than higher alcohols, and very high energy density as compared to hydrogen gas. Moreover, methanol can be obtained through biomass, thus is sustainable and environment friendly in production and use [Basak et al., 2010].