Using the Sun's Energy
The sunis the ultimate source of loads of energy.
The Sun's light can be used in photocell and solar heating. You can capture the sun's energy using photocells.
1)Photocells (solar cells) generate electricity directly from sunlight.
2)They gernerate a DC (Direct Current)
3)Photcells are usually made from silicon - a semiconductore. When the sunlight falls on the cell:
i) the silicon atoms absorb the energy, knocking loose some of the electrons,
ii)these electrons then flow round the circouit - this is electricity
4)The current and power output of a photocell depend on:
i)its surface area ii)the intensity of the light iii)the distance from the light source
Advantages - Sturdy, Long lasting, Low maintenance, no power cables or fuel doesn't pollute where the solar panel is
Disadvantages - No sunlight = No power
Solar and Wind power
Passive Solar Heating is when energy from the sun is used to heat something directly.
- Glass lets in heat and light from the sun, which is absorbed by things in a room.
- The light from the sun has a shorter wavelength, so it can pass through glass in a room.
- Heated things in a room emit infrared radiation of a longer wave lengths, which can't escape - it is just reflected.
Wind power can also be used to power things like a kettle
- Wind power involves putting loads of wind turbines up in exposed places.
- Energy from the sun heats the atmosphere which causes convection currents which produce winds.
- Wind turbines convert the kenetic energy of moving air into electricity. The wind turns the blades, which turn a generator.
Advantages- Cheap to run, Tough, reliable and wind is free
Disadvantage- - visual pollution and noise pollution, wind may not be fast enough, hard to find a place and expensive to set up, especially out at sea.
Producing and Distributing Electricity
The national grid connects power stations to consumers.
The aim of a power station is to convert one kind of energy (e.g. fossil fuels or nuclear energy) into electricity.
1)The first stage is to use the fuel to produce heat which then generates steam - this is the job of the boiler.
2)the moving steam drives the blades of a turbine...
3)...and this rotating movement from the turbin is converted to electricity by the generator (using electromagnetic induction).
Usually most of the energy is lost in heat and noise