Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Ocean & Wind Energy > Wave Energy > Flashcards

Wave Energy Flashcards

(42 cards)

Start Studying
1
Q

How are waves formed?

A

From winds, wind storms.

Wind creates small ripples, ripples turn into wind waves, and leaving the storm area as swells.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What parameters are wave height and period dependent on?

A

Wind speeds, fetch length, duration of storm.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What parameters are used to describe a wave?

A 
height: H
Wavelength: lambda
Period: T
phase velocity: c
zero crossing period: To
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What kind of statistical parameters are used in wave description?

A

mean wave height: Hs = average of largest 1/3
mean wave period: Tm = average of all wave periods
peak wave period: Tp = period of waves representing the highest energy in the wave spectrum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What kind of distribution are used for waves?

A

Rayleigh distribution

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

How are deep water waves classified?

A

depth > 1/2lamda

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the phase velocity of deep water waves?

A

see slide 153 for formula

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How is the transitional regional waves classified?

A

1/2 lamda > depth > 1/20 lamda

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the phase velocity in the transitional region?

A

see slide 153 for formula

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How are shallow water waves classified?

A

depth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what is the phase velocity of shallow water waves?

A

see slide 153 for formula

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

mention three things that happens to waves when they run ashore.

A
  • wavelenght decreases
  • wave height decreases
  • waves are getting steeper
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What path does the water molecules follow?

A

deep water - orbital

gets more and more elliptical as the depth decreases.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the critical wave steepness before a wave breaks?

A

H/L = 1/7

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What happens to the energy of a breaking wave?

A

Dissipated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What types of sea waves do we have?

A 
capillary waves
wind waves
swells
tsunami
storm floods
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the energy flux density of waves?

Study These Flashcards
A

see slide 156

18
Q

Where is the largest wave energy potential on the earth?

Study These Flashcards
A

northern and southern west wind belts. Formed from the westerlies.

19
Q

When did the first wave energy utilization patent dated?

20
Q

List soe epros and cons for wave energy utilization in comparison with other renewable resources.

Study These Flashcards
A

+ high energy concentration
+ offshore, no land mass required
+ ecologically and aesthetically unproblematic
+/- potential comparable to biomass, wind and hydro power
- extremely hostile environments for engineering structures
- offshore, difficult to maintain
- high number of load cycles
- storm loads can be as high as 50-100 times the avg. load.

21
Q

Santa cruz’s West Cliff Drive Wave Motor

22
Q

What does WEC stand for?

Study These Flashcards
A

Wave Energy Converter

23
Q

What are the three main categories of wave energy converters?

Study These Flashcards
A
  1. Floating Body Converters
  2. Oscillating Water Column Converters (OWC)
  3. Overtopping Converters
24
Q

What’s the principle of a floating body converter?

Study These Flashcards
A

A floating body is moved up and down by the waves. The work resulting from the movements is exploited via high pressure hydraulics or electric linear generators.

25
Explain the principle Power Takeoff system (PTO) of a floating body converter.
see slide 166-167.
26
What kind of different PTO systems do we have?
Oil Hydraulic PTO, Water Hydraulic PTO, Pneumatic PTO, Mechanic PTO
27
List efficiency, and some pros and cons for each of the PTO systems for Floating Body Converters.
see slides 168 - 171.
28
Linear Electric generator PTO system, pros and cons, efficiency.
+ 85% - waterproofing - costly power electronics
29
How does the Floating Body Converter from CETO, Australia work?
Floating bodies creates high pressure salt water which is taken ashore to drive a pelton turbine.
30
List a few wave energy project that has emerged over the recent years.
PELAMIS Salter's Duck (succesful lab test) Aqua BuOY (pelton) Fred Olsen FO3 Wave Star Archimedes Wave Swing Searev, high pressure oil hydraulics, inner pendulum Circular Wave Energy Converter, CWEC - floater mounted on crank, circular motion The Oyster, util. circ. motion of water molecules, oil hydr. The Anaconda, high pressure waves, water turbine
31
What is the working principle of a Oscillating Water Column (OWC)?
- Waves are exciting oscillations of an enclosed water col. - Air displaced is driving an air turbine - On shore or floating offshore device
32
What is the main advantage of an OWC?
slow movement of big water surface results in high air velocity. Small turbine with high energy density.
33
Problems with the OWC?
reciprocating air stream --> continuos rotary motion of the generator. One turbine reversing twice during every wave period. most of the energy is lost in acceleration and deceleration of the turbine.
34
Explain the power takeoff on an OWC.
Wells turbine. symmetrical blade, thick leading edge. Turbine moves in same direction irrespectively of the flow direction.
35
Projects using OWS?
Mighty Whale, Japan Pico Plant, Onshore, damaged by storm flood LIMPET: WaveGen and Voith Siemens
36
Explain the principle of Overtopping Converters
Waves run up a slope and overtop into a reservoir situated above the mean sea water level. Potential energy in the reservoir exploited usin low head hydrturbines. Shape and slope is optimized for maximum energy capture --> capturing the biggest volume possible.
37
What are some adv. with the overtopping system?
+ no moving parts except for the turbine offcorse + proven to be a durable technology for power takeoff + steady
38
Some restrictionswit overtopping system?
Only onshore | Only feasible with small tidal range.
39
Examples of overtopping Converters?
Tapchan, Norway -> planned installation on Java | WaveSSG, Norway
40
Explain the WaveSSG system
Overtopping in three stages with separate turbines for each stage --> utilizing the whole wave spectrum ++++ can be combined with wave breakers in harbours
41
WaveSSG project:
``` Kvitsøy, Norway --> Kvitsøy project 2005 Wave climate survey from Aalborg Uni Power Simulation from TUM Turbine layout, TUM Project stopped 2007 - still looking for a new site! ```
42
Explain the Wave Dragon functional principle + project history.
see slides 199 - 229 (lots of pictures)!

Ocean & Wind Energy (3 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions