Lecture 66 – Lecture 67 Fossil Fuels Ozgur Unal NIS – PHYSICAL SCIENCE Lecture 66 – Lecture 67 Fossil Fuels Ozgur Unal

Fossil Fuels Remember how generators work.. Generators transform mechanical energy into electrical energy. Energy transformation always conserves energy  law of conservation of energy Check out Figure 2!! What are the main sources of energies used in the US? Fuels such as petroleum, or oil, natural gas and coal are called fossil fuels because they are formed from the decaying remains of ancient plants and animals. Fossil fuels take millions of years to form. Fossil fuels are concentrated energy sources  Figure 3!!

How Do Fossil Fuels Form? Oil and natural gas form when organic matter on the ocean floor gradually buried under additional layers of sediment, is chemically changed by heat and crushing pressure. Coal forms when peat – partially decomposed vegetation – is compressed by overlying sediments and transformed first into lignite and then into harder bituminous coal. Check out Figure 4!! http://www.grantowngrammar.highland.sch.uk/subjects/Peak%20Oil%20web%20site/Formation%20of%20Fossil%20Fuels.html

Petroleum Millions of gallons of petroleum are pumped every day from wells deep in Earth’s crust. Petroleum is a highly flammable liquid formed by decayed ancient organisms. Petroleum is a mixture of thousands of chemical compounds. These compounds are separated in a process called fractional distillation.

Natural Gas The chemical processes that produce petroleum as ancient organisms decay also gaseous compounds called natural gas. Natural gas is composed of CH4, C3H8 and C4H10. Natural gas contains more energy per kg than petroleum or coal does.

Coal Coal is a solid fossil fuel that is found in mines underground. Coal mines were once the sites of ancient swamps. Coal formed from the organic material that was deposited as the plants that lived in these swamps died. Compared to natural gas and petroleum, coal contains more impurities, such as sulfur and nitrogen compounds. As a result, more pollutants, such as sulfur dioxide and nitrogen oxides are produced when coal is burned.

Generating Electricity

Efficiency of Power Plants When fossil fuels are burned in power plants, not all of the chemical energy stored in the fuels is converted into electrical energy. In each energy transformation, some energy is converted into thermal energy that cannot be used. Efficiency is the percentage of energy that can be used after each transformation. Check out Table 1!!

Fossil Fuels The Cost of Using Fossil Fuels: What are the disadvantages of using fossil fuels? Nonrenewable Resources: How long does it take to form fossil fuels? How long does it take to consume fossil fuels? How does it compare to the time it takes to form them? Nonrenewable resources cannot be replaced by natural processes as quickly as they are used.