Challenges and future developments in proton exchange membrane fuel cells
Introduction
The first working fuel cell was invented by Sir William Grove in 1843 by reacting oxygen and hydrogen on separate platinum electrodes that were immersed in dilute sulfuric acid inside five cells of a gas voltaic battery and using the current produced to electrolyze water in another similar cell. Fuel cell technology was too crude and inefficient then and could not compete with the dynamo invented by von Siemen. Since then, there have been several attempts to apply it for more than 100 years but none was very successful. In the 1920s, early German fuel cell research developed primitive carbonate and solid oxide fuel cells and from 1932 to 1959, Francis T. Bacon developed a fuel cell that used alkaline electrolyte and nickel electrodes [1].
It was only after a more efficient design of the fuel cell was made in the 1960s for the Gemini and Apollo space missions that fuel cell technology came of age. General Electric produced the fuel cell powered electrical power system for NASA's Gemini and Apollo space capsules that also provides drinking water for the crew. In developing the fuel cell technology, NASA funded more than 200 research contracts that finally brought the technology to a level now more viable for commercial application.
Fossil fuel reserves are finite and will be depleted in 70–150 years time. By the year 2015, the world fossil fluid fuel demand will outstrip the world fossil fluid fuel production (Fig. 1) and will precipitate an energy shortage crisis unless a sustainable alternative fuel will be available by then and will also face an energy shortage crisis in 2015 [2]. In addition, continued use of fossil fuels will generate green house gases that will cause global warming and climate change. The Kyoto protocol that regulates the reduction of green house gases has now become a binding international law when its ratification was approved by the Russian Republic. Solar and hydrogen energy could also be used but at a much lower total capacity. The contribution from both solar and hydrogen energy will grow in the future as the shortfall between the demand and the production of energy resources grow. While hydrogen powered internal combustion engines will continue to be used in the near term, the fuel cell will slowly be introduced first in hybrid power systems but ultimately in the long term in hydrogen energy systems at the advent of the so called hydrogen economy.
Section snippets
The fuel cell
The fuel cell as shown in Fig. 2 is an electrochemical energy conversion device that converts chemical energy of hydrogen and oxygen into electricity and heat by electrochemical redox reactions at the anode and the cathode of the cell, respectively, that produces water as the only byproduct. It is the chemical engineering way of producing energy.
The fuel cell has a high-energy conversion efficiency of more than 40–50% that is higher than a coal fired power station or an internal combustion
Research trends in PEMFC
The proton exchange membrane fuel cell (PEMFC) is a rugged, quite, clean and efficient energy conversion means for transportation application [3], [4]. The capital cost of PEMFC originally used in space, at USD2000/kW is too expensive for terrestrial application and must be reduced in order to make it more competitive. Cost reduction is directed in order of priority, on polymer electrolyte membrane and catalyst electrodes (membrane electrode assemblies, MEA), fuel cell stack, fuel cell
Fuel cell system demonstration and commercialization
The PAFC has reached commercialization stage mainly for central stationary power of up to 11 MW. The MCFC and SOFC have been demonstrated for stationary central power of up to 250 and 100 kW, respectively, since late 1990s. Both are now entering commercial markets in the next 5 years. Although PEMFC has been demonstrated in buses, cars, motorcycles and portable power units of up to 250 kW all over the world since the early 1990s, there are still many unresolved commercialization issues especially
Conclusions
Fuel cell will be the technology of choice of the future hydrogen economy that will certainly be a reality when our fossil fuel runs out. The first three older fuel cells (AFC, PAFC and MCFC) were well developed and there are no more research and development issues to address. The developments of both fuel cell technologies have already reached the top plateau of the S-curve of technological development. In contrast, the technologies for the last three types of fuel cells (SOFC, PEMFC and DMFC)
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