Energy and Society SS3 Physics Lesson Note

In human society, the term energy is used as a synonym of energy resources and most often refers to substances like fuel, petroleum products and electricity in general.        

Sources of energy

There are many energy resources now available to society. These are.

1. Petroleum and natural gas (Fossil Fuel)
2. Nuclear energy
3. Solar energy
4. Wind energy
5. Hydroelectric energy
6. Geothermal energy
7. Energy from the coal wood
8. Tidal and Ocean
9. Biomass

Renewable and Non-Renewable Energy

Renewable Energy Resources are those that can be replaced as they are used up. They can be continually replenished as they are exploited and utilised.

Examples are

1. Solar energy 
2. Wind energy
3. Biomass 
4. Tidal Power
5. Water or hydroelectric power
6. Biofuel

Non-renewable energy Resources are those that cannot be replaced as they are used up. They cannot be replenished as they are used up.

Examples are

• Nuclear energy from radioactive material
• Petroleum and Natural gas 
• Coal and wood 
• Such other fuels are classified as fossil fuels.

Uses of Energy

The use of energy has been key in the development of human society by helping it to control and adapt to the environment. In most countries, the development of energy resources has become essential in these vital areas of use such as

1. Agricultural- irrigation etc  
2. All forms of transportation 
3. Waste collection and recycling
4. Information technology
5. Communication
6. Electricity supply to homes and running industrial machinery
7. For heating or cooling of homes 

Hydroelectric power, also called hydropower, is electricity produced from generators driven by turbines that convert the potential energy of falling or fast-flowing water into mechanical energy. In the early 21st century, hydroelectric power was the most widely utilised form of renewable energy; in 2019 it accounted for more than 18 per cent of the world’s total power generation capacity.

In the generation of hydroelectric power, water is collected or stored at a higher elevation and led downward through large pipes or tunnels (penstocks) to a lower elevation; the difference in these two elevations is known as the head. At the end of its passage down the pipes, the falling water causes turbines to rotate. The turbines in turn drive generators, which convert the turbines’ mechanical energy into electricity. 

Transformers are then used to convert the alternating voltage suitable for the generators to a higher voltage suitable for long-distance transmission. The structure that houses the turbines and generators, and into which the pipes or penstocks feed, is called the powerhouse.

Hydroelectric power plants are usually located in dams that impound rivers, thereby raising the level of the water behind the dam and creating as high a head as is feasible. The potential power that can be derived from a volume of water is directly proportional to the working head, so that a high-head installation requires a smaller volume of water than a low-head installation to produce an equal amount of power. In some dams, the powerhouse is constructed on one flank of the dam, part of the dam being used as a spillway over which excess water is discharged in times of flood. Where the river flows in a narrow steep gorge, the powerhouse may be located within the dam itself.