2 Energy Everything in the world runs on energy The Earth needs the sun’s energy for light and warmthWe need energy from the food we eatCars 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 surfaceIn some areas, these remains accumulate in thick layers and are covered by rock and soil over timePressure 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 fuelsThrough combustion (or burning) of these fossil fuels, we can release that energyThe fossil fuels we use in industrial combustion are called hydrocarbons
6 What is combustion Combustion = Burning Combustion can either be complete or incompleteExamples of combustionBurning a candleBurning wood in a fire placeIgniting a gas burner on a stove or grillBurning coal in a power plantBurning fuel in an automobile’s engineBurning of glucose in the human body (cellular respiration)
8 Complete CombustionUsually occurs when a hydrocarbon reacts with oxygen to produce carbon dioxide and water vaporCombustion is EXOTHERMIC (releases heat)Hydrocarbon + Oxygen Carbon dioxide + waterHydrocarbon + O2 CO2 + H2O
10 Incomplete combustion Complete combustion needs ample amounts of oxygenWith insufficient oxygen present, the result is incomplete combustionComplete combustion produces Carbon dioxide (CO2)Incomplete combustion produces Carbon Monoxide (CO) – a very dangerous gasIncomplete 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 MonoxideCH4(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 unchangedFUEL (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 imcompleteSome 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 reactionFUEL (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 passedI975 – 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 emissions2004 – 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.