1. Fuel cells An electrochemical conversion device Chemical reactions cause electrons (current) to flow Requires a fuel, an oxidant and an electrolyte ( a substance that contains free ions and acts as a conductor) Typical type of fuel cell is called a proton exchange membrane fuel cell (PEMFC)

3. Hydrogen Fuel Cells Clean-only emission is water Expensive to produce Highly efficient-in an automobile, efficiencies of converting fuel energy to mechanical energy of 60% could be achieved, almost double the current efficiencies Hydrogen itself has issues as a fuel source

4. Issues with Hydrogen Abundant in nature, but not a freely available fuel Must be unbound from compounds Currently obtained via steam reforming – Steam and a nickel catalyst react, producing H – Need steam at very high temperatures, 1600F In the future, H is anticipated to be produced by the electrolysis of water, requiring large amount of water and electricity

5. Electrolysis Pass an electrical current through water and obtain H Pass a direct current from a battery or other DC power supply through a cup of water (salt water solution increases the reaction intensity making it easier to observe). Using platinum electrodes, hydrogen gas will be seen to bubble up at the cathode, and oxygen will bubble at the anode. Choice of the electrode is critical, you do not want a metal that will react with oxygen

6. Issues with Hydrogen Storage-occurs in gas form at room temperature, hard to contain As a liquid, it can be stored, but needs temperatures of -253 C. – As a liquid, its energy density increases 1000 times – In principle, could replace gasoline as a liquid fuel, but not practical at this time One solution is to store it as a metallic hydride (the negative ion of Hydrogen in a compound with another element) at room T.

7. Issues with H Highly explosive – Forms a volatile mixture with air A mixture of 4-75% of H in air is explosive, compared with natural gas which is only explosive in a range of 5-15% concentration in air Ignition energy is small, needing only 2 x 10 -5 J (basically a spark of static electricity can ignite H) Only good news is its low density means if there is a H leak, it disperses quickly

8. Hydrogen Hindenburg disaster Hindenburg was a German passenger airship (zeppelins) built for transatlantic air flight. Filled with Hydrogen Something caused ignition of the Hydrogen- cause is debatable 36 fatalities out of 79 people onboard

9. Alchohol Use methanol or ethanol as a fuel – Already gone over ethanol Methanol is already in use at Indy 500 race – Proven that no significant loss of performance is experienced (though they are in the process of switching to ethanol) About ½ the energy content of gasoline Produces only CO 2 and water – Some nitrogen oxides produced in the engine Can be manufactured from re-newable sources (biomass for example) Technologies exist now.

10. Disadvantages Very dangerous – Burns with no visible flame-needs a colorant added – Fumes are toxic CO 2 is a greenhouse gas Currently made mostly from natural gas-a non-renewable fossil fuel Possibly more corrosive than ethanol to engine parts

11. Use in liquid fuel cells Another use is as a input to a liquid feed fuel cell In these cells, Methanol replaces hydrogen Methanol has a much higher energy density and is easier to store than H Current methanol fuel cells produce power too low for vehicles, but can be used in cell phones, laptops etc Advantage is that they store lots of power in a small space, which they over a long period of time

12. Environmental effects of energy production All of our energy producing mechanisms have some effect on the environment – Production of waste products pollutes air, water and ground – Disruptions to local ecosystems Our job is to understand and mitigate these effects to the best of our ability Philosophy : If it hurts (the environment) when you do that, don’t do that!

13. Air pollution If its in the air, its in your body Components of the Earth’s Atmosphere: – Nitrogen 78.08% – Oxygen 20.95% – Argon 0.93% – Also small amounts of Neon, Helium, Krypton,& Hydrogen In addition, there are compounds whose concentrations vary with height: water vapor, carbon dioxide, methane, carbon monoxide, ozone, ammonia These are naturally occurring concentrations, any additional influx or destruction of these compounds via human beings alters the system.

14. Profile of the Earth’s atmosphere