# Lesson Worksheet: Tidal Power Physics

In this worksheet, we will practice describing the advantages and disadvantages of generating electricity from tidal barrages.

Q1:

Water is allowed to pass through a tidal barrage until the tide is at its highest. The barrage is then closed, and the tide beyond the barrage lowers, while the water behind it stays at the same height. The water behind the barrage is then allowed to flow back through the turbines into the sea.

If the mass of the extra water held back by the barrage is kg, and it has an average height of 1.5 m above the water in the sea beyond the barrage, what is the gravitational potential energy of the water held back by the barrage? Use a value of 9.8 m/s2 for the acceleration due to gravity.

Q2:

A proposed tidal barrage power station has an expected maximum power output of 950 MW. If the tidal barrage has 38 turbines, what is the maximum power output of each turbine?

Q3:

Which of the following statements correctly describe the disadvantages of building a tidal barrage?

1. Tidal barrages can alter the habitat of wetland wildlife.
2. Tidal barrages have very high maintenance costs.
3. There are only a few locations where tidal barrages can be built. Only some river estuaries are suitable for tidal barrages.
4. Once built, tidal barrages release large quantities of methane into the atmosphere.
5. Once built, tidal barrages release large quantities of carbon dioxide into the atmosphere.
6. Tidal barrages can only generate electricity at certain times of the day. Tidal barrages can only generate electricity following the peak of a high or low tide; they can not adjust to changes in demand.
• Aa, b, d
• Ba, e, f
• Ca, b, c
• Dd, e, f
• Ea, c, f

Q4:

Which of the following statements correctly describe the advantages of building a tidal barrage?

1. Once the barrage has been built, no pollutants such as carbon dioxide or methane are released into the environment by electricity production.
2. Tidal barrages are very cheap to build.
3. There are no fuel costs.
4. The maintenance costs for tidal barrages are very high.
5. Tides are highly predictable; thus a tidal barrage is a reliable source of energy.
6. Tidal barrages can alter the habitat of wetland wildlife.
• Ab, e, f
• Bb, d, e
• Ca, c, e
• Dd, e, f
• Ea, b, c

Q5:

What type of electric current do the turbines in a tidal barrage produce?

• APulsating current
• BRectified alternating current
• CDirect current
• DAlternating current

Q6:

The four diagrams in the image show a cross section of a tidal barrage. When water from one side of the barrage passes through the turbines to the other side, the turbines generate electricity. In which two of the diagrams shown will water flow from one side of the barrage to the other?  • A(b) and (c)
• B(b) and (d)
• C(a) and (c)
• D(a) and (b)
• E(c) and (d)

Q7:

The Severn Barrage is a proposed tidal barrage that would be built across the River Severn between England and Wales. The Severn Barrage would have an installed capacity of 8,640 MW. In 2016, electricity consumption in the UK was 304 TWh. If the Severn Barrage had been built in 2016, what percentage of the electricity consumption in the UK would the barrage have supplied? Assume that the power station would be running at its installed capacity throughout the year. Use a value of 365 for the number of days in a year. Give your answer to the nearest percent.

• A
• B
• C
• D
• E

Q8:

The Incheon Tidal Power Station is a proposed tidal barrage power station in Incheon Bay, just outside the capital city of South Korea. The barrage would have 44 turbines each with a power rating of 30 MW. What would the installed capacity of the Incheon Tidal Power Station be if it is built?

Q9:

A tidal barrage converts the energy of water into energy.

• Ainternal, electrical
• Bgravitational potential, electrical
• Cgravitational potential, kinetic
• Dinternal, kinetic
• Ekinetic, gravitational potential

Q10:

2,000 kg of sea water passes through a tidal barrage. The height of the center of mass of the sea water drops by 0.750 m. By how much does the gravitational potential energy of the water decrease? Use a value of 9.80 m/s2 for the acceleration due to gravity.