Download power in a water wave

Survey
yes no Was this document useful for you?
   Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Document related concepts

Mitigation of global warming in Australia wikipedia, lookup

Energiewende in Germany wikipedia, lookup

Fossil fuel phase-out wikipedia, lookup

Transcript
Energy, Power, and Climate Change
8.8 Wave Power
WAVES
Common water waves are produced by the sun-driven
winds passing over the water's surface.
The height of the waves depends on the following three
factors:
The speed of the wind
The duration of the wind
The fetch
FYI: The
FETCH is thePower,
length of the
waterClimate
over which the
wind passes.
Energy,
and
Change
FYI: A NNE wind on Lake8.8
Michigan
produces
a much larger amplitude...
Wave
Power
than a west wind.
FETCH
FYI: The course of the Edmund Fitzgerald on Lake Superior.
Energy, Power, and Climate Change
8.8 Wave Power
POWER IN A WATER WAVE
A
L

The power of a water wave is complicated to calculate,
so we'll simplify it some.
Think of the crest as storage of potential energy, and
the falling water as conversion into kinetic energy.
FYI: The
AVERAGE HEIGHT
of theand
water Climate
is A / 2.
Energy,
Power,
Change
FYI: This much potential 8.8
energyWave
is converted
into kinetic energy each
Power
period T.
POWER IN A WATER WAVE
FYI: Power is energy per time:
U
FYI: Power is proportional to the SQUARE of the AMPLITUDE A.
U
Power is proportional to the WAVE SPEED V.
Power is porportional to the LENGTH of the WAVEFRONT L.
U
U
A
= mgh
= mgA/2
= VgA/2
= LAgA/2
A/2
L
U = LgA2/2

 = VT
K = LgA2/2
K =
VTLgA2/2
P =
gVLA2
2
Power Generated By A Wave
3.
FYI: The
mass densityPower,
of water is 1000
Energy,
andkg/m
Climate
Change
8.8 Wave Power
POWER IN A WATER WAVE
Waves having an amplitude of 2 m roll onto a beach at a
rate of one every 8 seconds. The wave crests are 75
meters apart.
(a) What is the wave velocity?
V = d/t = /T
= 75/8 = 9.75 m/s
(b) How much wave power is there, per unit length?
P =
gVLA2
2
2
2

gVA
(1000)(10)(9.75)2
P / L =
= 195 kW/m
=
2
2
(c) How much wave power is there along 25 km of beach?
P = (195 kW/m)L
P = (195 kW/m)(25000 m)
P = 4875 MW
Energy, Power, and Climate Change
8.8 Wave Power
POWER GENERATION FROM A WATER WAVE
THE OSCILLATING WATER COLUMN
Air Column - Compressed
and rarefied by rising and
falling wave.
Wind Turbine
Generator
Turbine generates
both ways
FYI: A pelamis
can generate
750 kW
of power.
Energy,
Power,
and
Climate
Change
8.8 Wave Power
POWER GENERATION FROM A WATER WAVE
THE PELAMIS
The pelamis is named after the sea snake for
obvious reasons.
Each of four sections is hinged to the previous
one.
Fluid inside moves back and forth.
The moving fluid drives a generator.