Methods of Generating Electricity

the sun produces energy → plants take in the energy fromthe sun → plants change to coal over millions of years → coal is burnt in oxygen → water is heated to make steam → smeal turns the turbine → the turbine drives the generator → the generator produces electricity → electricity travels through wires to your home → electricity heats up the lamp and it shines

similarities

• use water as a cooling agent
• use steam to turn a turbine
• use a cooling tower
• use generators

differences

• fossil fuel power stations have chimenies
• fossil fuel power stations produce carbon monoxide
• nuclear power stations reach a higher tempreature
• nuclear power stations use uranium

wind is moving air, wind happens when warm air rises and more air blows in to replace it.

the faster something moves, the more energy is transferred to it. the heavier something is, the more energy must be transferred to make it move.

there is about 1kg of air under a 2-person desk

pros

• can charge phones without having to drive to the city
• solar power is reliable, efficient and renewable
• childeren can study after it gets dark
• electric lamps are safer
• the woman saves $35 a month on batteries and driving to charge her phone
• the womans neighbours pay her to charge their phones
• farmars can use manure to convert into electricity using biogas burners

cons

• solar cells cannot be bulk ordered
• people dont want to fund the project because it stops the big companies making money
• the fund money doesnt get to the very small settlements who need it most
• only 6 to 7 percent of the solar cells manufactured are not used for the national grid

our electricity is delivered from powerstations to homes by a network of pylons and cables called the national grid. the cables use very high voltages - up to half a million volts. this is because there is less energy loss at high voltages.

electrical power = current x voltage

if you distribute at high voltage, the current can be kept low. this is important because high current makes the cables hot and the energy is radiated away into the environment. this is calle line loss.

transformers are devices that change the voltage of an electric supply.

• step-up trasformers increase voltages
• step-down transformers decrease voltages

transformers only work with a.c. electricity (alternating current)