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 CO2 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 CO2 is a greenhouse gas
Burns with no visible flame-needs a colorant added
Fumes are toxic
CO2 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 %
Oxygen %
Argon %
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

15. Atmospheric profile Exosphere
From 500–1,000 km (310–620 mi; 1,600,000–3,300,000 ft) up to 10,000 km (6,200 mi; 33,000,000 ft), contain free-moving particles that may migrate into and out of the magnetosphere or the solar wind.
Exobase
Also known as the 'critical level', it is the lower boundary of the exosphere.
Ionosphere
The part of the atmosphere that is ionized by solar radiation stretches from 50 to 1,000 km (31 to 620 mi; 160,000 to 3,300,000 ft) and typically overlaps both the exosphere and the thermosphere. It plays an important part in atmospheric electricity and forms the inner edge of the magnetosphere. Because of its charged particles, it has practical importance because it influences, for example, radio propagation on the Earth. It is responsible for auroras.
Thermopause
The boundary above the thermosphere, it varies in height from 500–1,000 km (310–620 mi; 1,600,000–3,300,000 ft).

16. Atmospheric profile Thermosphere
From 80–85 km (50–53 mi; 260,000–280,000 ft) to over 640 km (400 mi; 2,100,000 ft), temperature increasing with height. Although the temperature can rise to 1,500 °C (2,730 °F), a person would not feel warm because of the extremely low pressure. The International Space Station orbits in this layer, between 320 and 380 km (200 and 240 mi).
Mesopause
The temperature minimum at the boundary between the thermosphere and the mesosphere. It is the coldest place on Earth, with a temperature of −100 °C (−148.0 °F; K).
Mesosphere
From the Greek word meaning middle. The mesosphere extends from about 50 km (31 mi; 160,000 ft) to the range of 80–85 km (50–53 mi; 260,000–280,000 ft). Temperature decreases with height, reaching −100 °C (−148.0 °F; K) in the upper mesosphere. This is also where most meteors burn up when entering the atmosphere.

17. Atmospheric profile
Stratopause The boundary between the mesosphere and the stratosphere, typically 50 to 55
Stratosphere
From the Latin word "stratus" meaning spreading out. The stratosphere extends from the troposphere's 7–17 km (4.3–11 mi; 23,000–56,000 ft) range to about 51 km (32 mi; 170,000 ft). Temperature increases with height. The stratosphere contains the ozone layer, the part of the Earth's atmosphere which contains relatively high concentrations of ozone. It is mainly located in the lower portion of the stratosphere from approximately 15–35 km above Earth's surface, though the thickness varies seasonally and geographically.
Ozone Layer
Though part of the Stratosphere, the ozone layer is considered as a layer of the Earth's atmosphere in itself because its physical and chemical composition is far different from the Stratosphere. Ozone (O3) in the Earth's stratosphere is created by ultraviolet light striking oxygen molecules containing two oxygen atoms (O2), splitting them into individual oxygen atoms (atomic oxygen); the atomic oxygen then combines with unbroken O2 to create O3. O3 is unstable (although, in the stratosphere, long-lived) and when ultraviolet light hits ozone it splits into a molecule of O2 and an atom of atomic oxygen, a continuing process called the ozone-oxygen cycle. This occurs in the ozone layer, the region from about 10 to 50 km (33,000 to 160,000 ft) above Earth's surface. About 90% of the ozone in our atmosphere is contained in the stratosphere.

18. Atmospheric profile Tropopause
The boundary between the stratosphere and troposphere.
Troposphere
From the Greek word meaning to turn or change. The troposphere is the lowest layer of the atmosphere; it begins at the surface and extends to between 7 km (23,000 ft) at the poles and 17 km (56,000 ft) at the equator, with some variation due to weather factors. The troposphere contains roughly 80% of the total mass of the atmosphere. Fifty percent of the total mass of the atmosphere is located in the lower 5.6 km (18,000 ft) of the troposphere.
The average temperature of the atmosphere at the surface of Earth is 20 °C (68 °F; 293 K).[1][2]