1. Combustion

2. Energy Everything in the world runs on energy
The Earth needs the sun’s energy for light and warmth
We need energy from the food we eat
Cars and furnaces run on energy from burning fossil fuels

3. Fossil Fuels Plants use the sun for energy through photosynthesis
After these plants die, their remains accumulate on the Earth’s surface
In some areas, these remains accumulate in thick layers and are covered by rock and soil over time
Pressure over time converts these layers into fossil fuels (coal, petroleum, natural gas), or fuels made from fossilized organic material

4. Fossil Fuels (Cont)
The energy from the sun is still trapped in these fossil fuels
Through combustion (or burning) of these fossil fuels, we can release that energy
The fossil fuels we use in industrial combustion are called hydrocarbons

5. Types of Hydrocarbons

6. What is combustion Combustion = Burning
Combustion can either be complete or incomplete
Examples of combustion
Burning a candle
Burning wood in a fire place
Igniting a gas burner on a stove or grill
Burning coal in a power plant
Burning fuel in an automobile’s engine
Burning of glucose in the human body (cellular respiration)

7. Combustion in a fuel tank

8. Complete Combustion
Usually occurs when a hydrocarbon reacts with oxygen to produce carbon dioxide and water vapor
Combustion is EXOTHERMIC (releases heat)
Hydrocarbon + Oxygen  Carbon dioxide + water
Hydrocarbon + O2  CO2 + H2O

9. Examples of Combustion reactions
Methane
CH4 +2O2 -> CO2 +2H2O
Naphthalene
C10H4 +12O2 -> 10CO2 + 4H2O
Ethane
2C2H6 + 7O2 -> 4CO2 + 6H20

10. Incomplete combustion
Complete combustion needs ample amounts of oxygen
With insufficient oxygen present, the result is incomplete combustion
Complete combustion produces Carbon dioxide (CO2)
Incomplete combustion produces Carbon Monoxide (CO) – a very dangerous gas
Incomplete combustion can also produce solid Carbon

11. Example of Incomplete Combustion
CH4(g) O2(g) → CO(g) + 2 H2O(g)
The product of this example is Carbon Monoxide
CH4(g) + 1 O2(g) → C(s) + 2 H2O(g)
The product of this example is solid Carbon

12. Effects of incomplete combustion
In a perfect world, automobiles would completely combust their fuel, or hydrocarbons(a combinations of hydrogens and carbons).
Hydrocarbons would enter an engine, along with nitrogen and oxygen. The pressure in the engine’s internal combustion chamber would cause it to burn (or combust)
All the of the hydrogens would turn into water, all the carbons into carbon dioxide, and the nitrogens remain unchanged
FUEL (hydrocarbons) + AIR (oxygen and nitrogen) = CARBON DIOXIDE (CO2) + Water (H2O) + Nitrogen

13. Effects of incomplete combustion
The world is not perfect however, and automobile combustion is usually imcomplete
Some of the oxygen reacts with the nitrogen creating Nitrous Oxides (NOx), while the rest of the oxygen reacts with the carbon, forming Carbon Monoxide instead of Carbon dioxide, along with the unburned fuel, or volitile organic compounds (VOCs)
(see next slide for reaction)

14. Effects of Incomplete combustion
Incomplete auto combustion reaction
FUEL (hydrocarbons) + AIR (oxygen and nitrogen) = UNBURNED or PARTIALLY BURNED HYDROCARBONS (VOCs) + NITROGEN OXIDES (NOx) + CARBON MONOXIDE (CO) + CARBON DIOXIDE (CO2) + Water (H2O)
Sound familiar? Remember the products of smog? Incomplete auto combustion creates smog!!!

15. Solutions? Alternatives?
1970 – The Clean Air Act was passed
I975 – Catalysts were put into car engines to reduce hydrocarbon and carbon monoxide emissions
– More sophisticated Catalysts not only reduced emissions, but converted carbon monoxide and unburned hydrocarbons (VOCs )to carbon dioxide and water and also changed Nitrogen Oxides to elemental Nitrogen and Oxygen. Why it’s called a Catalytic Converter

16. Solutions? Alternatives?
1990 – The Clean Air Act now required manufacturers to further reduce vehicle emissions
2004 – EPA’s tier 2 emission standards require that all new vehicles receive a 96-99% in emissions, effectively eliminating almost all pollutants from today’s vehicles.
Now – hybrid cars that use less fuel are becoming more common and even fully electronic cars are being developed.