1. Tidal Barrage  Advantages  Renewable  No air pollution  No fuel costs  Produces lots of power  Disadvantages  Huge initial cost  Environmental concerns

2. Lesson Objectives  Know how to calculate costs using meter readings  Consider the payback time of renewable sources in the home

3. Electric Meters  The numbers on an electric meter tells you how many units you have used

4. Electricity Bill Present meter reading (kWh) Previous meter reading (kWh) Units used (kWh) Price per unit (p) Amount (£) 539649464501045

5. 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

6. 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

7. 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

8. 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

9. Is it worth buying solar panels or wind turbines?