Grade 8 Alternative Energy

Alternative Energy:
The source of energy which can be used for an unlimited period of time are known as alternative energy. More precisely every forms of energy other than fossil fuels are alternative energy. some of the example of alternative energy are:
Solar
Hydro Power
Wind
tidal
Biomass

Solar Energy :
Solar energy refers to the energy that receives directly from sun as a form of light or radiation. It is the best alternative energy because the amount of energy one can generate from it is immense. One recent research suggested that the amount of solar energy stored for 10 weeks is equal to energy of whole fossil fuel.
There are two types of solar:
1. Passive Solar Energy (PSE)
2. Active Solar Energy (ASE)


1.Passive Solar Energy (PSE);

Passive solar design refers to the use of the sun’s energy for the heating and cooling of living spaces by exposure to the sun. When sunlight strikes a building, the building materials can reflect, transmit, or absorb the solar radiation. 


2. Active Solar Energy (ASE):
Active solar Energy refers to the use of sun energy to creating electricity with photovoltaic (PV) panels. The panels should sit on your roof or on a sunny wall where they can collect heat and generate electricity.

The major principle of solar energy is use solar panel cells that convert light energy into electricity.

Hydro power
Hydro power refers to generation of energy from water. It is another major alternative source of energy because water is used as unlimited source. according to the research, Nepal has the potential to generate more than 83000 MW of electricity.
There are two types of Hydro power:
1. Direct Hydro-power: It directly use water to turn the machinery. For e.g. water mill
2. Hydro Electric Power: It converts energy of water into electric energy. e.g. electricity

Principle or Mechanism of Hydro Electric Power Generation:
The flowing water of river is directed at a turbine so that turbine can rotate and produce mechanical energy. Turbine is connected to generator so that can convert mechanical energy into electric energy. In this way electricity is produced.

The amount of electricity generation mainly depends on:
1. Height of water falls
2. Quantity of water

Negative Aspects of Hydro Power:
1. Prevention of natural flow of water
2. Prevention of migration of fish
3. Upstream flooding
4. Declining fish population

Pico Hydro:
Pico hydro is used for for hydroelectric power generation of under 5 KW. It is a simple and cheap technology. It plays significance role in providing electricity for remote communities. 
There is a Pipe that divert water flow towards to turbine and electricity generated.
Characteristics:
1. It does not cost much.
2. It is easy to manage.
3. it doesn't need battery, inverter etc
4. It doesn't need special permission to build it.
5. The operation cost is nearly zero.