Chapter 23 – Fossil Fuels

1. Chapter 23 – Fossil Fuels

2. Energy Converters • Conversion of energy from one form to another involves ‘losses’, usually in the form of thermal energy.

3. Fossil Fuels • Non renewable resources are those that are used at a rate faster than they can be replaced. • Sustainability is all about meeting the long term ongoing needs of society, as well as immediate and short term demands.

4. Coal • As wood is converted into coal, the carbon content increases and the proportion of hydrogen and oxygen decreases. • The amount of water decreases as these changes occur. • When coal is burned, energy is used to vaporise the water, reducing the amount of heat released.

5. Coal Fired Power Stations • A number of energy transformations are involved in a coal-fired power station: • Coal is burnt: chemical energy in coal is converted to thermal energy • Heat from burning coal is used to boil water: thermal energy from burning coal becomes thermal energy in steam • Steam is passed through a turbine: thermal energy in the steam becomes mechanical energy as the turbine spins • Electricity is produced from a generator that is driven by the turbine: mechanical energy is converted to electrical energy

6. a b Coal Fired Power Stations

7. Oil • Crude oil is a mixture of hydrocarbon molecules that are members of the homologous series of alkanes. • Crude oil itself is of no use as a fuel, but many of the compounds in it are.

8. Fractional Distillation of Crude Oil • Separation of the components of crude oil occurs through fractional distillation.

10. Natural Gas • Natural gas is mainly methane with small amounts of other hydrocarbons such as ethane and propane. • Energy from a gas or oil-fired power station can be increased or decreased quickly to meet changing demands for electricity over a daily period.