PREAPRED BY:ABHINAV KUMAR0901213308CHEMICAL ENGINEERING DEPARTMENT
Contents History of fuel cell Fuel cell introduction Different types of Fuel cell Overview of PEMFC PEMFC basis
Contents Basic Elements in a PEMFC How PEM Fuel Cell Works Comparison with IC engine and battery PEM FUEL CELL Applications The Current PEM Market Part II
History of PEM Fuel Cell PEM technology was invented at General Electric through the 1960 work of Thomas Grubb and Leonard Niedrach. GE developed a small fuel cell for a program with the U.S. Navys Bureau of Ships (Electronics Division) and the U.S. Army Signal mid-1960s Corps. The unit was fueled by hydrogen generated by mixing water and lithium hydride. GE developed PEM water electrolysis technology for mid-1970s undersea life support, leading to the US Navy Oxygen Generating Plant. 1980s The British Royal Navy adopted this technology in early 1980s for their submarine fleet. 1990s Los Alamos National Lab and Texas A&M University experimented with ways to reduce the amount of platinum required for PEM cells.
Fuel cell introduction A fuel cell is an They are being electrochemical publicized as a source ofconversion device. energy of tommorow.
Different Types of Fuel Cell Description: PAFC - uses phosphoric acid as the electrolyte. (MCFC) uses high-temperature compounds of salt (like sodium or magnesium) carbonates (chemically, CO3) as the electrolyte. PROTON EXCHANGE (AFC) operates on compressed hydrogen and oxygen. They generally use a solution MEMBRANE 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 Proton Exchange Membrane in the form of a thin, permeable sheet.
Proton Exchange Membrane FC - consists of an membrane sandwiched between an anode (negative electrode) and a cathode (positive electrode). Description- a thin, solid, organic compound, typically the consistency of plasticwrap and about as thick as 2 to 7 sheets of paper. This membranefunctions as an electrolyte: allows the solution to conduct electricity ConceptPEM fuel cells work with a polymer electrolyte in the form of a thin,permeable sheet and allow hydrogen protons to pass through butprohibit the passage of electrons and heavier gases.
A PEM fuel cell uses hydrogen and oxygen to produce electricity .
-A thin, solid, organic compound knownas Nafion.-the consistency of plastic wrap andabout as thick as 2 to 7 sheets of paper.-This membrane functions as angateway, allowing only +ive ions(protons) to pass through it.
1 Fuel cells are operationally equivalent to a battery. 42 Polymer Electrolyte Membrane The reactants or fuel in a fuel cell (PEM) type cells are the standard can be replaced unlike a standard devices. disposable or rechargeable battery. 5 For automotive applications3 hydrogen is the fuel choice. Theoretically the maximum voltage that this reaction can generate is 1.2 V. However, in practice the cell 6 usually generates about 0.7 V to Electrochemical energy comes 0.9 V of power. from the reaction: ½ H2 + ½ O2 → H2O.
Basic Elements of PEMFC -It conducts the electrons that are freed from the Anode hydrogen molecules so that they can be used in an external circuit. -has channels etched into it that distribute the oxygen to the surface of the catalyst. Cathode -conducts the electrons back from the external circuit to the catalyst, where they can recombine with the hydrogen ions and oxygen to form water Anode Reaction Cathode Reaction H2 → 2H+ + 2e- O2 + 4H+ + 4e- → 2H2O
Basic Elements of PEMFC -This specially treated material, which looks something like ordinary kitchen plastic wrap, only conducts Electrolyte positively charged ions. - The membrane blocks electrons. - 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 Catalyst surface area of the platinum can be exposed to the hydrogen or oxygen. - The platinum-coated side of the catalyst faces the PEM.
Energy Efficient Rapid load Zero following emission capability ADVANTAGESHigh power No Internal density combustion The Proton Exchange Membrane (PEM) system allows compact designs and achieves a high energy to weight ratio. In comparison, the internal compaction motor has an efficiency of about 15%. More then internal combustion engines.
HIGH Needs Pure Manufacturing Hydrogen Cost Disadvantages Complex Heat Heavy Auxiliary and Water Equipment ManagementStart 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.
The first viable Decentralized electric alternative power generation On board to the internal for industrial and auxiliary powercombustion engine domestic units (APUs) forfor vehicles aircraft applications. land and air and UAVs. transportation. PEM Fuel Cell.Applications Portable generation systems for Small scale power packs for domestic, industrial application remote, unattended and military application