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Date May 2015 Marks available 5 Reference code 15M.2.HL.TZ1.6
Level Higher level Paper Paper 2 Time zone Time zone 1
Command term Deduce, Explain, and Suggest Question number 6 Adapted from N/A

Question

This question is about energy sources.

A small island is situated in the Arctic. The islanders require an electricity supply but have no fossil fuels on the island. It is suggested that wind generators should be used in combination with power stations using either oil or nuclear fuel.

Suggest the conditions that would make use of wind generators in combination with either oil or nuclear fuel suitable for the islanders.

[3]
a.

Conventional horizontal-axis wind generators have blades of length 4.7 m. The average wind speed on the island is 7.0 ms−1 and the average air density is 1.29 kg m−3.

(i) Deduce the total energy, in GJ, generated by the wind generators in one year.

(ii) Explain why less energy can actually be generated by the wind generators than the value you deduced in (b)(i).

[5]
b.

Markscheme

needs to be windy/high average wind speeds; space/land/room for wind turbines;

ability to import oil/nuclear fuel;

ability to dispose of nuclear waste;

comment relating to need for geological stability;

a.
(i) π4.72 or 69.4 m2;

power = 15300 to 15400 W; 470 to 490 GJ;

(ii) wind must retain kinetic energy to escape or not all KE of wind can be converted to KE of blades;
energy lost to thermal energy (due to friction) in generator/turbine/dynamo;
turbine will suffer downtime when no wind/too much wind;
Allow any two relevant factors.

b.

Examiners report

[N/A]
a.
[N/A]
b.

Syllabus sections

Core » Topic 8: Energy production » 8.1 – Energy sources
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