Tidal

Question 1

What creates tides

Answer 1

The gravitational pull of the moon and the sun create a water bulge which changes with the as the moon and sun move.

Question 2

How long is the lunar cycle period

Answer 2

12h 25mins = 745 mins

Question 3

Explain how a tidal barrage system works

Answer 3

A basin is filled up when the tide is coming in. When the tide gets to high the sluice gates are shut. When the tide goes out the sluice gates are opened. The water flow runs through a turbine until the basin gets low. Cycle then repeats.

Question 4

disadvantages of tidal barrage

Answer 4

• Large cost
• ## Huge cost, takes a huge amount of infrastructure which can be damaging to nature society etc.

Question 5

How could tidal barrage performance be improved

Answer 5

Water could be pumped to increase the water level in the basin to maximise energy generation.

Question 6

Explain how tidal stream system works

Answer 6

The tidal flow around coastlines is utilised to extract energy via a range of turbine types

Question 7

Describe 2 examples of a tidal stream device

Answer 7

• The stingray - employs an oscillating motion due to the tidal stream which then powers hydraulic actuators to generate energy.
• SeaGen - Two large rotors are lowered into the sea that spin from the tidal stream. Installed in northern ireland.

Question 8

Disadvantages of tidal devices

Answer 8

• they are very expensive in comparison to wind or solar to implement for similar or less energy extraction.
• Corrosion and abrasion due to the sea water is an issue
• Maintenance issues
• Grid access
• Maritime and sea life impact

Question 9

What is a key advantage of tidal energy capture

Answer 9

Tides are reliable and predictable in comparison with wind and solar energy. helps demand and supply matching.

Question 10

What issues does energy generation have with tidal power.

Answer 10

Power output significantly decreases during neap tides in comparison with spring tides.

Question 11

How can we limit fluctuation of power during the lunar cycle

Answer 11

• size turbines to limit power extraction tho that during a neap tide (lowest).
• size turbines for average monthly output and introduce other energy sources for when power is low.
• Add in storage so excess power during spring tides can be kept for use at later times.

Question 12

Formula for the rise and fall of the sea if presumed sinusoidal

Answer 12

z1 = Z + a*sin(wt)

Question 13

Power formula for tidal barrage

Answer 13

P = pgCdasqrt(2g(z1-z2)^3)