MYP Physics Generation and Transmission of Electricity Notes

How Is Electrical Energy Produced From Energy Resources?

1. Electricity is not a primary source of energy, it is an energy carrier.
2. Before it reaches a phone charger or a light bulb, energy must be converted from some source (often chemical energy in fuels, or kinetic energy of wind and water) into electrical energy, then transmitted efficiently to where it is needed.

What energy resources are used to generate electricity?

1. Electricity can be generated using both non-renewable and renewable energy resources.
2. The choice of energy resource affects how sustainable the electricity supply is.
3. Regardless of the resource used, most systems are designed to make a turbine rotate.

Non-renewable energy resources

1. Fossil fuels such as coal, oil, and natural gas store chemical energy.
2. Nuclear fuel stores energy in the nucleus of atoms.
3. These resources exist in limited quantities and will eventually run out.
4. They can release large amounts of energy, making them useful for large power stations.

Renewable energy resources

1. Renewable resources are replenished naturally over short timescales.
2. They rely on natural processes such as wind movement, flowing water, or sunlight.
3. Many renewable systems still use turbines and generators.
4. Some renewable systems convert energy directly into electrical energy.

Electricity Comes From Energy Transformations

1. A central idea in physics is the conservation of energy: the electrical energy we use must come from transforming energy from somewhere else.
2. On Earth, many energy resources can ultimately be traced back to the Sun.
3. Sunlight drives photosynthesis, storing energy as chemical energy in plants. Burning wood releases that stored energy.
4. Over millions of years, buried plant and animal matter can be transformed (by pressure, temperature, and chemical change) into coal, oil, and natural gas.
5. These are fossil fuels, and burning them releases energy that originally came from sunlight long ago.
6. Sunlight also drives the water cycle. Evaporation and rainfall can place water at higher altitude, giving it gravitational potential energy.
7. As it flows back downhill, this can be converted to electrical energy in hydroelectric systems.

The common energy transfer pathway

1. Energy from a resource is first converted into thermal energy or kinetic energy.
2. This energy is used to turn a turbine.
3. The turbine transfers energy to a generator.
4. The generator converts mechanical energy into electrical energy.

How Is Electricity Generated Using Fossil Fuels?

1. Fossil fuel is burned in a boiler.
2. Burning releases chemical energy as thermal energy.
3. The thermal energy heats water stored in pipes.
4. The water turns into high-pressure steam.
5. The steam flows over turbine blades.
6. The turbine begins to rotate.
7. The rotating turbine drives a generator.
8. The generator produces electrical energy.

Energy transfers in a fossil fuel power station

1. Chemical energy in the fuel is transferred to thermal energy in the boiler.
2. Thermal energy is transferred to kinetic energy of moving steam.
3. Kinetic energy causes mechanical energy in the rotating turbine.
4. Mechanical energy is converted into electrical energy in the generator.

Limitations of fossil fuel electricity generation

1. Burning fossil fuels releases carbon dioxide.
2. Carbon dioxide contributes to the greenhouse effect.
3. Fossil fuels are finite and will eventually be depleted.
4. Waste heat is released to the surroundings during generation.

How Is Electricity Generated Using Nuclear Energy?

1. Nuclear reactions release large amounts of thermal energy.
2. This thermal energy is used to heat water.
3. Steam is produced at high pressure.
4. Steam turns a turbine.
5. The turbine drives a generator.