Marine renewable energy

Question 1

What are the main categories of marine or ocean renewable energies?

Answer 1

• Wave Energy
• Tidal Energy (Tidal Range vs Tidal Stream)
• Offshore Wind Energy
• Ocean Thermal Energy

Question 2

Why are marine renewables successful?

Answer 2

Reduction of their Levelised Cost of Energy

Question 3

Which renewable energy source has high technological maturity and market potential with low innovation risk?

Answer 3

Tidal Energy

Question 4

Which renewable energy technology has low technological maturity and market potential, requiring significant innovation effort?

Answer 4

Ocean Thermal Energy Conversion (OTEC)

Question 5

What types of energy can be extracted from waves?

Answer 5

• Kinetic
• Potential
• Mechanical
• Electrical
• Thermal

Question 6

What is the primary source of ocean wave energy?

Answer 6

Ocean waves are a concentrated form of solar energy

Question 7

Which two factors determine the characteristics of ocean waves?

Answer 7

The fetch and the duration of wind action

Question 8

What is “fetch” in the context of wave energy?

Answer 8

Fetch is the distance over water that the wind blows in a single direction

Question 9

What is typical value of wave power for deep water?

Answer 9

6 – 70kW/m

Question 10

What is the minimum wave energy flux required for economical wave energy extraction?

Answer 10

20-25 kW/m is required for it to be economically viable

Question 11

Whats is the gross potential of wave energy?

Answer 11

18500 TWh/year

Question 12

What is the technical potential of wave energy?

Answer 12

2000 TWh/year

Question 13

What is a wave energy converter?

Answer 13

A device that absorbs part of the ambient incident wave energy

Question 14

How does a WEC transform mech energy to electricity?

Answer 14

A mechanical system commonly called Power Take-Off

Question 15

How is wave energy absorption described in terms of wave interaction?

Answer 15

It’s a wave interference process where waves generated by the motion of the WEC cancel out incident waves

Question 16

What design consideration is crucial in civil engineering to prevent structural failures like the Tacoma Narrows bridge collapse?

Answer 16

Avoiding a match between the natural frequency of the structure and the frequency of external loads

Question 17

How is wave energy absorption maximized in wave energy converters (WECs)?

Answer 17

When the WEC operates at resonance with the waves

Question 18

Has technological convergence been observed in wave energy converters?

Answer 18

No

Question 19

What are the three common criteria for classifying wave energy converter (WEC) technologies?

Answer 19

• The working principle
• The dimension/configuration
• The location (offshore, nearshore, shoreline)

Question 20

What are the three main categories of WECs based on their working principle?

Answer 20

• Oscillating water columns
• Oscillating bodies
• Overtopping devices

Question 21

What is an example of a floating oscillating water column?

Answer 21

Buoy

Question 22

What are the two categories in oscillating bodies?

Answer 22

• Heaving wave energy converters
• Pitching wave energy converters

Question 23

Examples of pitching wave energy converters (submerged)?

Answer 23

Wave Roller

Question 24

What are the two categories in oscillating Water Column?

Answer 24

• Fixed - Isolated/Breakwater
• Floating