* not completed

. What is the source of the energy in the wind?

The difference in solar heating between the Earth's equator and the poles correct incorrect

The kinetic energy of rotation of the Earth correct incorrect

The gravitational pull of the Sun and Moon on the Earth's atmosphere correct incorrect

* not completed

. The power in the wind depends on the wind velocity. It is proportional to:

the wind velocity correct incorrect

the square of the wind velocity correct incorrect

the cube of the wind velocity correct incorrect

* not completed

. What is unusual about a Darrieus wind turbine?

It has curved blades correct incorrect

It can be folded up and moved correct incorrect

It has only got one blade correct incorrect

* not completed

. In 1928 Albert Betz showed that there was an upper limit to the fraction of the power in the wind that could be extracted. What was it?

37.8% correct incorrect

59.3% correct incorrect

72.1% correct incorrect

* not completed

. Figure 8.28 on page 376 shows the wind speed-power curve of a sample wind turbine. At what wind speed does it reach a half of its maximum rated power?

9.5 metres per second correct incorrect

7.5 metres per second correct incorrect

5.5 metres per second correct incorrect

* not completed

. Figure 8.31 on page 380 shows the different wind resources across Europe. Scotland is shown as having a (very windy) 'wind class' of 5. Where else in Europe has the same wind class?

The northern French coast correct incorrect

The southern French coast correct incorrect

Portugal correct incorrect

* not completed

. Much of modern wind turbine development took place in Denmark in the 1970s. Which US state provided them with an early export market for turbines in the early 1980s?

California correct incorrect

Hawaii correct incorrect

Texas correct incorrect

* not completed

. UK onshore wind turbines have a capacity factor of about 25%. What are the likely capacity factors for future European offshore wind farms?

33% correct incorrect

About 37% correct incorrect

Over 42% correct incorrect

* not completed

. How much sea area does the UK's London Array offshore wind farm cover?

100 square kilometres correct incorrect

50 square kilometres correct incorrect

25 square kilometres correct incorrect

* not completed

. The UK peak electricity demand in 2010 was nearly 60 gigawatts. The UK 'Round Three' licences aim for the development of how many gigawatts of offshore wind power?

15 GW correct incorrect

22 GW correct incorrect

33 GW correct incorrect