MYP Physics Energy Sources and Resources, Fuels and Environmental Impact Notes

How Do Different Energy Resources Generate Electricity? Why Do Energy Choices Affect The Environment?

1. Modern life depends on a continuous flow of energy for lighting, heating, transport, communication, and industry.
2. Physics helps us track where that energy comes from, how it is converted into useful forms (especially electrical energy), and what trade-offs exist between different energy resources.

What Is an Energy Resource?

1. An energy resource is something that can be used to provide energy.
2. Energy resources are used to generate electricity, heat buildings, and power transport.
3. Most electricity is produced by converting energy from one form into electrical energy.

Most Usable Energy On Earth Ultimately Comes From The Sun

1. A powerful way to organize energy sources is to ask: "What is the original source of the energy we are using?"
2. For almost everything humans use at Earth's surface, the answer is the Sun.
3. Sunlight warms the Earth directly.
4. Sunlight drives photosynthesis, storing energy in plant matter as chemical energy.
5. Sunlight drives the water cycle: evaporation, rainfall, and rivers, which create gravitational potential energy that can become electricity in hydroelectric systems.

Why do some energy resources eventually run out?

Fossil Fuels

1. Fossil fuels include coal, oil, and natural gas.
2. They were formed from dead plants and animals over millions of years.
3. The energy stored in fossil fuels originally came from the Sun through photosynthesis.

Coal-Fired Power Stations

1. Coal is burned to release chemical energy.
2. The energy heats water to produce steam.
3. Steam turns a turbine.
4. The turbine drives a generator to produce electricity.
5. Large amounts of energy are lost as thermal energy to the surroundings.

Power and Efficiency in Power Stations

1. Power stations convert input power from fuel into useful electrical power.
2. Not all input power becomes useful output.
3. Efficiency shows how effective this conversion is.

$$\text{Efficiency} = \frac{\text{useful power output}}{\text{total input power}} \times 100\%$$

The Typical Thermal Power Station Energy Chain

1. A simplified conversion chain is: chemical (or nuclear) energy → thermal energy → kinetic energy → electrical energy
2. Each arrow represents a conversion, and each conversion loses some energy to less useful forms (mainly heating the surroundings).
3. That is why the overall efficiency is well below 100%.

Environmental Impact of Fossil Fuels

1. Burning fossil fuels releases carbon dioxide.
2. Carbon dioxide is a greenhouse gas that traps thermal energy in the atmosphere.
3. This contributes to global temperature increase and climate change.

Why Are Renewable Resources Considered More Sustainable?

1. Renewable resources can be replaced naturally in a short time.
2. They rely on continuous natural processes.
3. Most renewable resources ultimately depend on the Sun.

1. Hydroelectric Power

1. Uses falling or flowing water to turn turbines.
2. Water gains gravitational energy when stored at height.