Wind Teachers Notes

Riches from the Wind A mini-wind turbine could soon become the latest fashion accessory, especially when homeowners realise that generating electricity can make their meters run backwards! Indeed, a community in Spain is making millions this way. This numeracy activity appeals to students’ entrepreneurial sides. They calculate how much they could make from wind power and decide whether wind turbines are a good investment.

Curriculum link The advantages and disadvantages of renewable energy. Energy transfer and cost calculations. 11 – 14(KS3) Energy and electricity QCA 9I • Renewable energy sources can be used to drive electrical generators. • Power ratings GCSE specifications AQA Core Science Unit P1a Energy and Electricity: 13.3 Why are electrical devices so useful? • Calculate the amount of energy transferred from the mains using: energy transferred = power × time (kilowatt-hour, kWh) (kilowatt, kW) (hour, h) • Calculate the cost of energy transferred from the mains using: total cost = number of kilowatt-hours x cost per kilowatt-hour Edexcel Core Science Unit P1a Topic 10: You’re in Charge •Use the equation to calculate the cost of electricity: cost = power × time × cost of 1kWh where power is measured in kilowatts and time is measured in hours Gateway Core Science Module P2 Living for the future: Item P2c Fuels for Power State that the unit of electrical energy supplied is the kilowatt hour. Calculate the number of kilowatt hours given the: • power in kilowatts; • time in hours. Calculate the cost of energy supplied. Twenty First Century Additional Science Module P5: Electrical circuits: P5.5 How much electrical energy do we use at home? •Use the following equation to calculate energy transfer in joules and kilowatt-hours: energy transferred = power x time (kilowatt hour, kWh) (kilowatt, kW) (hour, h) •use the equation: power = potential difference (voltage) × current (watt, W) (volt, V) (ampere, A) •calculate the cost of electrical energy given the power, the time and the cost per kilowatt hour.

Running the activity Page 1 makes students aware of the market for wind power and sets the task. Page 2 is an advert for wind turbines and includes a brief description of their benefits and how

they operate. Individuals or small groups will need copies of page 3 to structure their calculations. There are two versions of page 3 – one for KS3 students and the other for KS4. The answers to the KS3 version are:

Turbine’s maximum power in kilowatts (kW)

Average wind speed in m/s

Electricity generated per year, in kWh (Units)

‘Surplus’ electricity for sale each year, in Units

Income from sales each year at £0.05/Unit

1.5 6 1.5 6

12 12 7 7

10,500 42,000 6,000 12,500

6,500 38,000 2,000 8,500

£350 £1,900 £100 £450

In the KS4 version, students take the power output of two different turbines from a windspeed graph. They use these to calculate how many kWh of electricity each turbine can generate in a year. This involves multiplying their readings from the graph by 24 x 365 (number of hours in a year) and by 0.8 (assuming the wind turbine is generating electricity 80% of the time). The rounded answers to this version are: A Turbine’s maximum power in kilowatts (kW)

B Average wind speed in m/s

C Average power in kW from graph

D Electricity generated per year, in kWh (Units) (C x 24 x 365 x 0.8)

E ‘Surplus’ electricity for sale each year, in Units

F Income from sales each year at £0.05/Unit

1.5 6 1.5 6

12 12 7 7

1.5 6.0 0.8 1.8

10,512 42,048 5,606 12,614

6,512 38,048 1,606 8,614

£325 £1902 £80 £431

The calculations greatly simplify the economics of wind generation. A turbines power output can show drastic variations for the same average wind speed. The calculations also assume that wind will provide all the electricity a family needs, at all times. This is unlikely to be the case. They would need to pay for backup supplies when the wind can’t meet their demand for energy.

Web Links http://www.guardian.co.uk/uk_news/story/0,3604,1475034,00.html This story reports from a conference in which home wind turbines were presented as ‘homeowners’ latest fashion accessory’ and explains why owning mini-wind turbines can make meters turn backwards. http://www.dti.gov.uk/energy/sources/renewables/renewables-explained/wind-

energy/onshore-wind/what-can-i-do/page16108.html Advice on installing wind turbines.

http://www.bwea.com/noabl/index.html UK wind map – showing average wind speeds in specific locations. http://www.xcweather.co.uk/ UK wind map – showing current wind speeds across the country.

http://www.yes2wind.com/downloads.html A downloadable video that makes a case for renewable forms of energy.

http://www.gcse.com/energy/power.htm Bitesized notes on power, energy transfer and renewable energy sources. Science upd8 is a joint initiative from ASE and the Centre for Science Education, Sheffield Hallam University. We are grateful for core support from GlaxoSmithKline. Copyright rests jointly with the Association for Science Education (ASE) and the Centre for Science Education, Sheffield Hallam University (CSE). Teachers and others who have signed up may download and use UPD8 materials freely within their school, but other usage, or any other organization wishing to use the materials, should consult the joint ‘owners’ of the material (ASE and CSE) through [email protected]