2481023 Fuel Cells Jas

Fuel Cells and Their Marine Applications

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Fuel Cells and Their Marine Applications Working Principle of Fuel Cells Typical fuels used in fuel cells are hydrogen, methanol, natural gas, ethanol, ammonia, bio-fuels, carbon monoxide or even light diesel oil. The chemical energy bound up in the fuel molecule gets changed into electrical energy in the fuel cell. These electrochemical reactions require state-of-the-art material technology. The primary working principles are distinctly different for a range of fuel cells. Currently Phosphoric Acid, Molten Carbonate, Proton Exchange Membrane, Solid Oxide, Direct Methanol, Alkaline, Regenerative, Protonic Ceramic, Zinc Air, Microbial Fuel Cell are the most widely used models. (Fuel Cell Basics Types. Fuel Cells 2000) A fuel cell’s working is very similar to that of a battery. A battery has two electrodes separated by an electrolyte, usually a solution. At least one of these electrodes is in form of a solid metal. This metal gets converted in some other chemical compound during the process of electricity production in the battery. The maximum energy the battery can produce in one succession depends on the amount of conversion of this solid metal. In case of a fuel cell this solid metal is generally substituted by an electrode that does not get consumed and also a continuously self-renewable fuel. A reaction between this fuel and an oxidant like oxygen (from the other electrode) takes place. A fuel cell can continuously produce electricity provided that the fuel and the oxidant are pumped through it regularly.

An alkaline fuel cell as depicted in the above figure is probably one of the oldest and simplest variety of fuel cell. It has been in use in a number of important applications, most notably space missions, for some time. Hydrogen and Oxygen are frequently used as fuel and oxidant respectively. The electrodes are usually composed of porous carbon plates tied with some catalyst (a substance that promotes chemical reactions). The electrolyte often used is potassium hydroxide. Hydrogen gas reacts with hydroxide ions to generate water vapors, at the anode. As a repercussion of this reaction excess electrons are left over. These excess electrons are then propelled out of the anode to produce electric current. On the other hand, oxygen and water along with the returning electrons from this circuit combine to form hydroxide ions, at the cathode. These ions are then again recycled back towards the anode. The primary core of a fuel cell, comprising of the manifolds, cathode, anode and electrolyte, is normally termed as the stack.

(Developing fuel cell systems for ship use. 2006) The above presented model of a fuel cell is for description only. It is too basic to be used onboard. A close to reality model is presented by the following diagram of a Hybrid Fuel Cell Propulsion System.

(Zemships: Zero Emission Ships Powered by Fuel Cell to be Ready by 2010. 2008.) Fuel Cells’ Applications Onboard Ships In the past decade, the increasing demand for safety, efficiency and a lower environmental impact from shipping has dominated the development of the industry. The European Commission has been strategically and actively seeking solutions to meet the social and industrial requirements. This has prompted the infusion of fuel cell based applications in waterborne transportation. Although substantial research and development

has been performed on fuel cells for use in the automotive industry and stationary power generation, limited work has been carried out on marine applications. There is presently no large scale design and production of fuel cell systems for marine purposes, and the requirements for such systems in order to be competitive for marine applications have not been defined. Moreover, safety and operational requirements as well as industrial standards suitable for fuel cell design and application in ships are presently lacking. (FCSHIP. 2002) These presently represent major barriers towards commercial application of fuel cells in ships. Further R&D on Fuel Cell applications on ships taking into account safety, environment, operation, infrastructure, and market aspects is the need of the time. Introduction of new technology must be based on proven design, verified and approved by an independent verification body. For fuel cell application in ships, no such basic requirements currently exist, which are vital for the future implementation of this new technology. A cargo ship, named E/S Orcelle (E/S stands for Environmentally sound Ship), designed by the Scandinavian shipping company, Wallenius Wilhelmsen, was on display in the Nordic Pavilion at the World Expo 2005. This ship will run exclusively on renewable energy. It will harness the power of the sun, water and wind and will release zero emissions into the environment. Almost half of the energy used on the ship will be produced by fuel cells. The generated energy, as a consequence of the combination of hydrogen and oxygen, will be used in the pod propulsion systems and the fins. Electricity production for other onboard

uses is also under consideration. The sole by-products of this process are water vapor and heat. (Environment News Service. 2005) Future Development Trends Scandinavian ship manufacturers think that this technology has the potential to replace all the other currently used technologies in the market. The amount of investment from their side is also a reflection of this belief. What makes a fuel cell a darling to every engineer is its potential efficiency. Fuel cell powered ship is anticipated to have an efficiency level of almost 50 per cent about two times that of the current diesel-electric propulsion system used in our ships. (Zemships: Zero Emission Ships Powered by Fuel Cell to be Ready by 2010. 2008.)

The above diagram depicts the higher Efficiency of Solid State Fuel Cells compared to conventional gas turbines. (Steinfeld, G.; Sanderson, R.; Ghezel-Ayagh H.; Abens, S. n.d.) Ships with responsibilities like operations at part load will be particularly ideal for installation of these fuel cells. In these vessels, a fuel cell plant will result in dramatic

reduction in fuel consumption as compared to traditional technology (diesel engines, gas/steam turbines). (Developing fuel cell systems for ship use. 2006) A small constraint is the number of passengers onboard a fuel cell powered ship which is in the range of 100 passengers for a 300 to 600 kW fuel cell. (Zemships: Zero Emission Ships Powered by Fuel Cell to be Ready by 2010. 2008.) Presently fuel cells have an installation cost of nearly six times that of diesel engines. But the most interesting fact is that the diesel engines’ higher fuel consumption over the lifetime of a diesel engine and today’s price of LNG and marine diesel oil, FC reduces fuel cost by about half of the extra investment cost. (Developing fuel cell systems for ship use. 2006) Iceland has committed to converting its vast fishing fleet to use fuel cells to provide auxiliary power by 2015 and, eventually, to provide primary power in its boats. (Fuel Cell Basics Applications. Fuel Cells 2000.) Besides high level of efficiency another of the reason why fuel cells will be everyone’s choice in the future is their lower level of emissions.

(Fuel Cell Basics Benefits. Fuel Cells 2000) Bibliography

Developing fuel cell systems for ship use. 2006. Scandinavian Shipping Gazette. [Online]. Available at: http://www.shipgaz.com/magazine/issues/2006/18/1806_article.php [Accessed December 4, 2008] Environment News Service. (2005). Sun, Wind, Fuel Cells Power Cargo Ship of the Future. [Online]. Available at: http://www.ens-newswire.com/ens/apr2005/2005-04-0603.asp [Accessed December 4, 2008] FCSHIP. (2002). Marine application of fuel cells. P.84-85. [Online]. Available at: ec.europa.eu/research/energy/pdf/efchp_fuelcell39.pdf [Accessed December 4, 2008] Fuel Cell Basics Applications. Fuel Cells 2000. [Online]. Available at: www.fuelcells.org/basics/apps.html [Accessed December 4, 2008] Fuel Cell Basics Benefits. Fuel Cells 2000. [Online]. Available at: www.fuelcells.org/basics/benefits.html [Accessed December 4, 2008] Fuel Cell Basics Types. Fuel Cells 2000. [Online]. Available at: www.fuelcells.org/basics/types.html [Accessed December 4, 2008] Steinfeld, G.; Sanderson, R.; Ghezel-Ayagh H.; Abens, S. n.d. Direct Carbonate Fuel Cell for Ship Service Application. Energy Research Corporation. Steinfeld, G.; Sanderson, R.; Ghezel-Ayagh, H.; Abens, S. Concept Development of a Ship Service Fuel Cell. (November 16-19, 1998). 1998 Fuel Cell Seminar Abstracts, Palm Springs, CA. Zemships: Zero Emission Ships Powered by Fuel Cell to be Ready by 2010. 2008. MarineBuzz. [Online]. Available at: http://www.marinebuzz.com/2008/08/05/zemshipszero-emission-ships-powered-by-fuel-cell-to-be-ready-by-2010/ [Accessed December 4, 2008]