CHEMISTRY 1000 Topics of Interest #5: Fuel Cells

Fuel Cells: An Alternative to Fossil Fuels For many years, scientists have been working on how to make cars run on fuels other than fossil fuels. After all, the planet is going to run out of accessible fossil fuels at some point. The ideal alternative to fossil fuels would be a fuel that was efficient and did not pollute the atmosphere. There has been much interest in the idea of using hydrogen as a fuel source for several reasons: Reaction of hydrogen with oxygen is a *very* spontaneous reaction, releasing a large amount of energy. The product of the reaction of hydrogen with oxygen is water, an environmentally benign substance. Hydrogen is light so it would not add much mass to the vehicle and would therefore not require much extra energy simply to ‘carry’ the extra weight.

Fuel Cells: An Alternative to Fossil Fuels The simplest approach to using hydrogen as a fuel might be to combust it: however, that raises safety concerns since the hydrogen/oxygen reaction is *very* exothermic. Also, much of the energy generated would be lost as heat, making combustion of hydrogen as inefficient as combustion of fossil fuels. A safer and more efficient approach would be to develop an electrochemical cell in which the hydrogen and oxygen gases are kept separate. Since an electrochemical potential would be generated (rather than as heat), this would be a more efficient method as well as a safer one. Several research groups at the University of Calgary are studying chemistry with the goal of developing practical fuel cells. 2 H 2(g) + O 2(g)  2 H 2 O (g)

Fuel Cells: An Alternative to Fossil Fuels One type of fuel cell is the proton exchange membrane (PEM) fuel cell: Issues that need work: Pt is expensive! Temperature-sensitive Need to stack many fuel cells together to get enough energy to power a vehicle for image for animation

Fuel Cells: An Alternative to Fossil Fuels Chemists in an inorganic chemistry lab at the University of Calgary just published research demonstrating that a PEM fuel cell can be made more efficient as well as cheaper: Instead of platinum, their fuel cell uses a complex salt called Na 3 (2,4,6- trihydroxy-1,3,5-benzenetrisulfonate) as the catalyst. Their fuel cell works up to 150  C (rather than 90  C that is typical for platinum-based fuel cells). At higher temperature, the reaction goes faster, producing more power (energy/second). Professors working on fuel cell research at Calgary: Prof. Viola Birss (analytical chemist) Prof. George Shimizu (inorganic chemist)