PEM Fuel Cell REPORTERS Aliñabon, Louella Ann Delima, Venus Dizon, Clark Inot, Lysa Lamanilao, Juphil Tuquib, Percy
Contents What is PEMFC? OVERVIEW of FUEL CELL HISTORY of PEMFC
Contents Part II Basic Elements in a PEMFC How PEM Fuel Cell Works How PEM FC SYSTEM works PEM FUEL CELL Applications The Current PEM Market
Overview of a Fuel Cell A fuel cell consists of two electrodes sandwiched around an electrolyte. Oxygen passes over one electrode and hydrogen over the other, generating electricity, water and heat. A fuel cell system which includes a "fuel reformer" can utilize the hydrogen from any hydrocarbon fuel - from natural gas to methanol, and even gasoline.
Different Types of Fuel Cell Description: Molten Carbonate Alkali Fuel Cell Phosphoric Acid Solid Oxide PAFC - uses phosphoric acid as the electrolyte. (MCFC) uses high-temperature compounds of salt (like sodium or magnesium) carbonates (chemically, CO3) as the electrolyte. (AFC) operates on compressed hydrogen and oxygen. They generally use a solution of potassium hydroxide (chemically, KOH) in water as their electrolyte. (SOFC) uses a hard, ceramic compound of metal (like calcium or zirconium) oxides (chemically, O2) as electrolyte. (PEM) works with a polymer electrolyte in the form of a thin, permeable sheet. PROTON EXCHANGE MEMBRANE
History of PEM Fuel Cell PEM technology was invented at General Electric through the work of Thomas Grubb and Leonard Niedrach. GE developed a small fuel cell for a program with the U.S. Navy's Bureau of Ships (Electronics Division) and the U.S. Army Signal Corps. The unit was fueled by hydrogen generated by mixing water and lithium hydride. GE developed PEM water electrolysis technology for undersea life support, leading to the US Navy Oxygen Generating Plant. Los Alamos National Lab and Texas A&M University experimented with ways to reduce the amount of platinum required for PEM cells. The British Royal Navy adopted this technology in early 1980s for their submarine fleet. 1960 mid-1960s mid-1970s 1990s 1980s
What is PEM Fuel Cell? Polymer Electrolyte Membrane FC Description Concept - consists of an electrolyte membrane sandwiched between an anode (negative electrode) and a cathode (positive electrode). PEM fuel cells work with a polymer electrolyte in the form of a thin, permeable sheet and allow hydrogen protons to pass through but prohibit the passage of electrons and heavier gases. - a thin, solid, organic compound, typically the consistency of plastic wrap and about as thick as 2 to 7 sheets of paper. This membrane functions as an electrolyte: allows the solution to conduct electricity
PEM Fuel Cell Basics Fuel cells are operationally equivalent to a battery. For automotive applications hydrogen is the fuel choice. Low temperature; Polymer Electrolyte Membrane (PEM) type cells are the standard devices. The reactants or fuel in a fuel cell can be replaced unlike a standard disposable or rechargeable battery. 1 4 2 5 3 Electrochemical energy comes from the reaction: ½ H2 + ½ O2 -> H2O. 6 Theoretically the maximum voltage that this reaction can generate is 1.2 V. However, in practice the cell usually generates about 0.7 V to 0.9 V and about 1 W cm-2 of power.
ADVANTAGES Rapid load following capability Lower cost of fabrication Robust High power density The Proton Exchange Membrane (PEM) system allows compact designs and achieves a high energy to weight ratio. Efficient In comparison, the internal compaction motor has an efficiency of about 15% .
HIGH Manufacturing Cost Heavy Auxiliary Equipment Needs Pure Hydrogen Complex Heat and Water Management Start and stop conditions induce drying and wetting, which contributes to membrane stress. If run continuously, the stationary stack is estimated at 40,000 hours. Stack replacement is a major expense. Disadvantages
It conducts the electrons that are freed from the hydrogen molecules so that they can be used in an external circuit.
It has channels etched into it that disperse the hydrogen gas equally over the surface of the catalyst.
has channels etched into it that distribute the oxygen to the surface of the catalyst.
conducts the electrons back from the external circuit to the catalyst, where they can recombine with the hydrogen ions and oxygen to form water
Cathode Anode Reaction Cathode Reaction H 2 -> 2H+ + 2e- O 2 + 4H+ + 4e- -> 2H 2 O
Basic Elements of PEMFC [Image Info] www.wizdata.co.kr - Note to customers : This image has been licensed to be used within this PowerPoint template only. You may not extract the image for any other use. Electrolyte - This specially treated material, which looks something like ordinary kitchen plastic wrap, only conducts positively charged ions. - The membrane blocks electrons. Catalyst - It is usually made of platinum powder very thinly coated onto carbon paper or cloth. - The catalyst is rough and porous so that the maximum surface area of the platinum can be exposed to the hydrogen or oxygen. - The platinum-coated side of the catalyst faces the PEM.
PEM Fuel Cell Applications The first viable electric alternative to the internal combustion engine for vehicles, e.g. cars, motorbikes, buses, locomotives, forklifts, light aircraft and UAVs. Portable generation systems for domestic, industrial, military and maritime application Small scale power packs for remote, unattended and military application On board auxiliary power units (APUs) for land and air transportation Decentralized power generation for industrial and domestic applications General battery replacement/displacement .
The Current PEM Market 63% 6% 10% 2% Portable Niche Transportation Light Duty Devices Large Stationary 3% Buses 16% Small Stationary Total Number of PEM Units Installed Globally By Application
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