1. Science A Physics – P1 Science A Physics – P1 Topic 1: Electricity Generation - 3 Topic 1: Electricity Generation - 3

2. 1. a. With reference to the Nuclear Power factsheet (12), how many kg of nuclear fuel are needed to produce 1200MW of electricity. 1200MW = 1200 x 1000 kW = 1,200,000 kW

3. b. How many kg of coal would be needed to produce the same output. Each kg of uranium is equivalent to 15,000kg of coal. To produce the same output obtained from 26.67 kg of uranium we need

4. 2. A typical 6kW roof mounted domestic wind turbine produces an average power output of 10,000 kWh/year. a. What is the maximum number of kWh/year the turbine could produce? We need to work out the number of hours in a year and multiply by the power of turbine.

5. b. Use the equation to calculate the efficiency of the turbine.

6. c. Explain why your answer to part (b) is so low. Wind does not blow at the same speed constantly all the time. When there is no wind no power is generated. If the wind is too strong the turbine has to shut down to prevent damage. The turbine cannot therefore generate anything like it’s maximum capacity.

7. 3.a. Many new homes are now having solar thermal panels fitted on their roof. Using data from Fact Sheet 2, calculate the estimated time to recover the cost of installing the panels. Savings are between £50 and £85 per year. Payback time is therefore between 56.5 and 96 years

8. b. Suggest why the solar thermal panels are generally only fitted to new properties. Solar thermal panels are expensive to purchase. Existing roof structure may not be strong enough to support the panels incurring extra cost. Existing heating pipework will need to be modified. The savings are too small to recover the installation costs.

9. 4. An alternative to solar thermal panels are solar voltaic panels. a. How much does it cost to install a 2.7kW solar voltaic panel? £12000.00

10. b. How much can it save in electricity cost per year ? £1100.00

11. c. How long would it take to recover the installation cost of the solar voltaic panels.

12. 5. What is the total amount of power available from Dinorwig before the water in the upper reservoir runs out? Total capacity at Dinorwig = 1320MW/second Max run time with water reserves = 5hr

13. 6. Refer to the data from the fossil fuel fact sheet. a. If 1 pound is equivalent to 1.7 dollars, show that the cost per kW of generating output is approximately £760.

14. b. Hence show that the cost of building a 2000MW coal fired power station is approximately £1.5 billion. 2000MW = 2000 x 1000 kW = 2,000,000kW Cost = 2,000,000 x 764.70 Cost = £1,529,400,000

15. c. Show that the cost of the coal used to produce 2000MW of power for one week is approximately £1.25 million. 250 tonnes per hour 24 hours/day £30.00 per tonne 7 day/week Cost = 7 x 250 x 24 x 30 = £1,260,000

16. d. 1 Watt = 1 Joule of energy per second. Therefore a 2000MW station produces 2000MJ of energy per second. Domestic electricity is sold in units of kWh where 1kWh = 3.6MJ. i. How many kWh’s does the power station produce per second?

17. ii. How many kWh’s does the power station produce per week? 7 days per week 24 hours per day 60 minutes per hour 60 seconds per minute 556kWh’s produced per second kWh’s/week = 556 x 60 x 60 x 24 x 7 kWh’s/week = 336,268,800 kWh

18. iii. If each kWh is sold for 15p, how much money will be made each week? 336,268,800 kWh produced in each week 15p (£0.15) per kWh Money made = 336,268,800 x 0.15 Money made = £50,440,320

19. iv.The weekly wage bill and admin running costs for the power station excluding fuel are £28,500,000. What is the weekly profit for the power station? Profit = 50,440,320 – 28,500,000 – 1,260,000 Profit = £20,680,320

20. v. How many weeks will it take to cover the cost of building the power station? Cost of building power station = £1,529,400,000 Weekly profit = £20,680,320

21. e. i. How many litres of oil would be needed to produce the same number of kWh’s as the coal? 1 litre of oil = 10kWh Coal output = 556kWh

22. ii.How much would this cost. Number of litres = 55.6 litres / s Cost per litre = 56p Cost of oil = 55.6 x 56 = 3113.6 = £31.14

23. f. A 2000MW power station produces 2GJ of energy per second. The fuel source is Brown coal. Using the information on Fact Sheet 11 determine the following. i. grams of CO 2 produced per second 101,000 x 2 = 202,000g = 202 kg ii. grams of NO X produced per second 183 x 2 = 336g

24. g. A similar gas plant produces the same amount of electricity. How does it’s emissions compare to that of the coal fired station in part (f). i. grams of CO 2 produced per second 56,100 x 2 = 112,200g = 112.2 kg ii. grams of NO X produced per second 93.3 x 2 = 186.6g