Chapter 6 Multiple Choice Questions

1) The percentage of global electricity production due to hydropower in 2018 was…

1.2%.

5%.

12%.

16%.

21%.

2) The power per metre width in a typical ocean wave is about…

1 kW m^-¹.

10 kW m^-¹.

50 kW m^-¹.

200 kW m^-¹.

400 kW m^-¹.

3) Which one of the following statements is correct about a Fourneyron turbine?

It employs fixed guide vanes and fixed runner blades.

It employs fixed guide vanes and moving runner blades.

It employs moving guide vanes and fixed runner blades.

It employs moving guide vanes and moving runner blades.

4) The country with the largest hydropower capacity in 2019 was…

Brazil.

Canada.

China.

Norway.

USA.

5) The power output of a dam is given by…

η ρ g h Q

η ρ Q \sqrt{g h}

η ρ g h^{2} Q

η ρ g h^{2} Q^{2}

η ρ g h Q^{3}

6) The maximum power output of a Pelton wheel is given by…

ρ Q u

\frac{1}{2} ρ Q u^{3}

\frac{1}{2} ρ Q u^{\frac{1}{2}}

\frac{1}{2} ρ Q u^{2}

\sqrt{ρ Q u}

7) The maximum efficiency of a reaction turbine is given by…

u_{1}^{2} q_{1} cos β_{1} / g h

u_{1} q_{1} cos β_{1} / \sqrt{g h}

u_{1} q_{1} \cos^{2} β_{1} / g h

u_{1} q_{1} cos β_{1} / 2 g h

u_{1} q_{1} cos β_{1} / g h

8) Euler's equation provides a formula for the power output from a turbine. Does the fact that the derivation takes no account of the details of the flow inside the turbine (where the blades do work on the fluid) invalidate the formula?

Yes

No

9) Which of the following statements are true?
Please select all that apply.

Dams with high carbon emissions tend to occur in low-lying areas, while those with low carbon emissions are mainly in mountainous regions.

It has been estimated that 300,000 to 600,000 people worldwide have had to be relocated because of hydropower.

In 2019 pumped storage provided about 95% of global electricity storage.

Impulse turbines are suited for fast-moving mountain streams. Francis turbines are suitable for run-of-river sites and Kaplan turbines for large dams.

Hydropower was the largest source of renewable energy in 2019, providing about twice the electricity as solar plus wind power.

10) The typical capacity factor of a dam is of order…

1%.

10%.

25%.

40%.

90%.

11) The interval between high tides is about…

6 hours.

9.5 hours.

12 hours.

12.5 hours.

24 hours.

12) The velocity of a tidal wave of wavelength λ in a sea of depth h is given by…

\sqrt{g h}

\sqrt{g λ}

\sqrt{g λ / 2 π}

\sqrt{g / h}

13) The country with the largest tidal potential in Europe is…

France.

Germany.

Ireland.

Spain.

UK.

14) The velocity of a surface wave on deep water is given by…

g λ

\sqrt{g λ}

\sqrt{g λ / 2 π}

\sqrt{2 π g / λ}

g / 2 π λ

15) The total energy per unit width per unit length of a surface wave on deep water is given by…

$\frac{1}{2} ρ g λ^{2}$

\frac{1}{2} ρ g a^{2}

ρ g a

\frac{1}{4} ρ g a^{2}

\frac{1}{2} ρ g a λ

16) Which of the following statements are true?
Please select all that apply.

A Wells turbine spins in both directions.

The maximum efficiency of a Pelton wheel is obtained when the incident jet is not deflected.

Hydropower in the EU is quite well exploited, but the potential for growth elsewhere is considerable, particularly in Asia, Latin America, and Africa.

The energy of a wave in deep water increases with depth.

There would be no tides if the Moon did not exist.

17) Which of the following statements are true?
Please select all that apply.

The turbine in an oscillating water column is submerged in water.

Euler's turbine equation can be applied to a Pelton Wheel.

Wave energy convertors tend to operate near to the shore.

TAPCHAN has no moving parts (excluding the turbine).

The speed of a Pelton Wheel is controlled by a spear valve.

18) The maximum power output of a dam with a head of 100 m and a volume flow rate of 1 m³s^-1 is about…

1 kW.

10 kW.

100 kW.

1 MW.

10 MW.

19) Which of the following statements are true?
Please select all that apply.

Hydropower tends to be state-funded due to its high capital cost.

Hydropower has no carbon footprint.

The largest tidal range globally is in the River Severn, UK.

Water waves on deep water are dispersive.

Submerged wave energy convertors, with OWCs where appropriate, are emerging as the preferred technologies.

There is a larger global potential for tidal range plants than for tidal stream plants.

20) The accessible potential of hydropower by 2050 is about…

2000 TWh y^-1.

4000 TWh y^-1.

7000 TWh y^-1.

15000 TWh y^-1.

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