Physics 470 Lecture Hydrogen Fuel Cells May 9,

The hydrogen fuel cell 2

The PEM fuel cell 3

Features of a fuel cell Sir William Grove invented the fuel cell in 1839 Hydrogen gas is fed to the negative terminal (the anode) A catalyst helps the hydrogen to split, sending its electrons through an external circuit and the protons through an electrolyte 4

Features of a fuel cell Oxygen combines with the electrons at the positive terminal (the cathode) and protons to form water The overall reaction combines hydrogen and oxygen to produce electricity and water. 5

The proton exchange membrane fuel cell Has a high power density and low operating temperature The electrolyte is a specially treated polymer (chemically related to Teflon) that conducts only positive ions The membrane must be hydrated (7 water molecules for every proton conducted!) The membrane is “poisoned” by carbon monoxide 6

The proton exchange membrane fuel cell The anode-membrane-cathode assemblies are stacked for higher voltage 7

The PEM fuel cell 8

PEM Fuel Cell Stack 10 kW Fuel Cell Power Supply GENEPAC by PSA Puegot Citroën, France 9

Other types of fuel cells Phosphoric Acid Molten Carbonate Solid Oxide Alkali See comparison chart from the Department of Energycomparison chart Department of Energy 10

Compare Fuel Cell Types 11

Fuel cell problems PEM cells: Hydration of the membrane requires careful water control and/or pressurization (adds weight, complexity). New membranes such as PBI may require less water.PBI For all fuel cells, drawing large currents reduces performance 12

Fuel cell losses Ohm’s Law Applet 13

Which of the following statements is FALSE? A. Catalysts help fuel cells increase the gas transport rate to the electrodes. B. Fuel cells operate on the chemical reaction that combines hydrogen and oxygen. C. Fuel cells are like a battery with a continuous supply of chemical reactants. D. The only outputs of a fuel cell are water and electrical energy. 14

Which of the following statements is FALSE? A. Catalysts help fuel cells increase the gas transport rate to the electrodes. B. Fuel cells operate on the chemical reaction that combines hydrogen and oxygen. C. Fuel cells are like a battery with a continuous supply of chemical reactants. D. The only outputs of a fuel cell are water and electrical energy. 15

Suppose a fuel cell has an internal resis- tance of . What is the output voltage when the ideal voltage is 12.0 V and the current is 30 A ? A.0.30 V B.0.75 V C.9.00 V D V 16

Suppose a fuel cell has an internal resis- tance of . What is the output voltage when the ideal voltage is 12.0 V and the current is 30 A ? A.0.30 V B.0.75 V C.9.00 V D V 17

Suppose a fuel cell has an internal resis- tance of . What fraction of the power is lost when the ideal voltage is 12.0 V and the current is 30 A ? A.2.5% B.3.6% C.6.25% D.12.0% 18

Suppose a fuel cell has an internal resis- tance of . What fraction of the power is lost when the ideal voltage is 12.0 V and the current is 30 A ? A.2.5% B.3.6% C.6.25% D.12.0% 19

Stationary Power Fuel Cells Fuel Cell power plant, Santa Rita Jail, Dublin, CA Biogas-powered fuel cell power plant, Sierra Nevada Brewing Co, Chico, CA 200 kW fuel cell, Central Park, NY police station 20

Fuel Cell-Powered Zero Emission Vehicles Ford Focus FC5 Fuel Cell Car Hyundai FC Tucson Honda FCX Clarity Thor UTC Bus 21 Several other fuel cell cars in this 2008 article. More links at fueleconomy.gov.this 2008 articlefueleconomy.gov

Fuel cell airplane 22 Boeing fuel cell aircraft first flight: April 3, It used a battery to assist the takeoff.first flight DLR Antares, the world’s first fuel-cell-only aircraft, takes off July 7, 2009 in Hamburg, Germany.fuel-cell-only aircraft