Tidal Barrage Advantages Renewable No air pollution No fuel costs Produces lots of

power

Disadvantages Huge initial cost Environmental

concerns

Lesson Objectives Know how to calculate costs using

meter readings Consider the payback time of

renewable sources in the home

Electric Meters The numbers on

an electric meter tells you how many units you have used

Electricity BillPresent meter reading (kWh)

Previous meter reading (kWh)

Units used (kWh)

Price per unit (p)

Amount (£)

5396 4946 450 10 45

Home Renewable Energy Systems If you install your own renewable

energy system at home you can save money

These are usually expensive to build – the amount of time taken to pay for the initial cost in savings is called payback time

Photovoltaic Cells These convert

sunlight into electricity

They can save you 50% on your electricity bill

They cost between £8000-£18000 but the UK government will give you 50% towards the cost

Photovoltaic cells – worked example You fit a solar cell at a cost of £4000.

You save £150 a year on your bills. How many years will it take you to payback the cost of the cell?

Payback time = 4000 ÷ 150 Payback time = 27 years

Wind generators A wind turbine will

cost around £2500-£5000 to install

An average generator will generate 1500kWh a year

Estimate how many years it would take to payback a £2500 turbine

Is it worth buying solar panels or wind turbines?