Wave Energy 101: Resource and Technology Primer

1
Wave Energy 101Resource and Technology Primer

• Pacific States MarineFisheries Commission
• 60th Annual Meeting
• San Diego, CA
• 17 September 2007
• George Hagerman
• Virginia Coastal Energy Research Consortium
  Virginia Tech Advanced Research Institute

2
Presentation Outline

• Resource characteristics
• Governed by local winds and offshore storms
• U.S. production potential
• 250-260 TWh per year (EPRI, 2004)
• Comparable to annual energy output of all
  existing conventional hydro-electric projects in
  US
• General types of conversion technology
• Highly diverse alternatives classified
  intoTerminators, Attenuators, and Point
  Absorbers
• Conversion technology status
• Has yet to converge on single best technical
  approach(if such exists)

3
Wind Over Water Generates Waves
Wave generating area may be bounded by coastlines
or by extent of wind system
The amount of energy transferred from the wind to
the waves depends on the mean wind speed, how
long it blows and the distance (fetch) over which
it blows.
4
Wave Energy Resource Distribution Governed by
Planetary Wind Patterns
Prevailing Westerlies
Inter-Tropical Convergence Zone (ITCZ)
NortheastTrade Winds
Wave conditions are governed by local winds, such
as the prevailing Westerlies or Northeast Trade
Winds, which produce short-period, choppy seas,
and by swell from distant storms, far offshore,
which produce long-period, more regular wave
trains.
5
Wave Energy Resource Distribution Governed by
Planetary Wind Patterns
Swell travels along great circle routes
Extra-tropical cyclone
Extra-tropical cyclone
Ocean swell can travel thousands of kilometers in
deep water with negligible loss of energy. Thus
wave energy produced anywhere in an ocean basin
ultimately arrives at its continental shelf
margins, virtually undiminished until it reaches
200 m depths.
6
Global Wave Energy Flux Distribution
7
U.S. Offshore Wave Energy Resources
Extracting 15 of total flux (315 TWh/yr) and
converting to electricity at 80 efficiency would
yield 252 TWh/yr
Southern AK 1,250 TWh/yr
New Englandand Mid-Atlantic 110 TWh/yr
WA, OR, CA 440 TWh/yr
Northern HI 300 TWh/yr
Total flux into all regions with mean wave power
density gt10 kW/m is 2,100 TWh/yr

8
Power Densities Less Variable Offshore, More
Variable Near Shore
Triangles are gt 50 m depth
Circles and line are 10 to 25 m water depth
9
Substantial Seasonal Variability
West Coast (Oregon)
East Coast (Massachusetts)
Hawaii
10
Wave Energy Devices Highly Diverse
Fixed Oscillating Water Column Terminator
(Oceanlinx )
Floating Attenuator (Pelamis)
FloatingPoint Absorber(AquaBuOY)
Floating OvertoppingTerminator (Wave Dragon)
11
OWC Terminator Onshore LIMPET
500 kWe demonstration project connected to
utility grid on Islay, Scotlandin November of
2000
www.wavegen.co.uk
LIMPET Land-Installed Marine Powered Energy
Transformer
12
OWC Terminator Oceanlinx Nearshore Device
Power Module
Capture Chamber
Parabolic Wall
Port Kembla 500 kWe Demonstration Project
Mooring Lines
www.oceanlinx.com
13
Overtopping Terminator Wave Dragon
www.wavedragon.net
14
Wave Dragon Prototype Trials
Prototype is 58 m wide (between tips of funneling
side walls) and 33 m long, with a reservoir
volume of 55 m3 and a displacement of 237 metric
tons. Total rated capacity is 17.5 kWe.
Funneling side walls are moored separately from
central floating reservoir.
15
Floating Attenuator Pelamis
www.oceanpd.com
TOP VIEW
relative YAW
Power module at front of each tube section
contains two hydraulic cylinders that are stroked
by relative pitch and yaw between adjacent
sections
SIDE VIEW
relative PITCH
16
Pelamis Engineering Development
1998 2003 1/20 and 1/33-scale models tested
to physically validate numerical simulations of
wave energy absorption efficiency and mooring
loads (survivability)
2001 ongoing 1/7-scale model tested in large
tank (regular waves) and Firth of Forth (random
waves) to develop control system
2002 ongoing Full-scale power module bench
rig tested to qualify mechanical and electrical
components and to assess MTBF (reliability) and
control system performance
17
Pelamis Sea Trials and Pilot Plant
Three 750 kW modules to be installed summer 2007
in 2.25 MW pilot plant off northern Portugal
3.5 m dia x 150 m long
Pelamis 750 kW prototype installed in August of
2004 in 50 m water depth, 2 km offshore the
European Marine Energy Centre, Orkney, UK
18
Point Absorber OPT PowerBuoy
OPT's PowerBuoy system extracts the natural
energy in ocean waves, and is based on the
integration of patented technologies in
hydrodynamics, electronics, energy conversion and
computer control systems. The PowerBuoy is a
smart system capable of responding to differing
wave conditions. The rising and falling of the
waves off shore causes the buoy to move freely up
and down. The resultant mechanical strokingis
converted via a sophisticated power take-off to
drive an electrical generator.The generated
power is transmittedashore via an underwater
power cable. OPT website June 2007
www.oceanpowertechnologies.com
19
Navy Funded Demonstration Projectat Kaneohe
Marine Base, Oahu, Hawaii
PB-40 deployed June 2004 and again in October 2005
20
Point Absorber Finavera AquaBuOY
http//finavera.com/en/wavetech
Inertia of seawater trapped above or below piston
in tube provides reaction point for hose to
stretch as buoy heaves up or down
Hose pump inner diameter contracts when
stretched, expands when relaxed
21
AquaBuOY 1 MW Project to be Installed off Makah
Bay, Washington
Four-buoy demonstration permitted by FERC and
NOAA in Olympic National Marine Sanctuary
AquaBuOY Version 2.0 deployed 2 mi off Newport,
OR first week of Sep 2007
22
Next-Generation Heaving Buoy Deviceswith Direct
Electromagnetic Power Take-Off
Uppsala University design with linear induction
generator in anchor base
Buoy
Mooringtether
End stop
Permanent magnet translator
Statorcoil
Spring
Translator tethered to anchor
Anchor
Stator coil fixed to heaving buoy
Translator heaves with buoy
Oregon State University design with linear
induction generator in heaving buoy
Stator coil fixed to anchor base
23
Technology Development Pyramid
Long-term (gt1 yr duration)prototypes in the
ocean(typically 100 kW to 2 MW)
a few
Short-term (days to months)tests in rivers, bays
or lakes(typically 10 kW to 100 kW)
a fewdozen
Rigorous laboratorytow- or wave-tank physical
model tests(1/50- to 1/5-scale)
hundreds
It typically takes 5 to 10 years for a technology
to progress from concept-only (not in pyramid) to
deployment of a long-term prototype
24
Thank You!
Any questions?
Email hagerman_at_vt.edu
25
Hybrid Offshore Wind-Wave Concept

• Advantages
• Negligible visual impact beyond 20 km
  offshore
• Shared platform and power cable costs
• Greater wind and wave power densities with
  increasing distance from shore
• Greater continuity of output yesterdays
  winds are todays waves

In the Federal OCS over the horizon off
Virginia (40-80 m depth), mean annual wind power
is at least 800 watts/m2 of rotor swept area at
70 m hub height, and mean annual wave power is at
least 10 kW/m of wave crest width
26
Hybrid Offshore FloatingWind-Wave Energy
Conversion Module
3.6 MW wind turbine(104 m diameter rotor)
1.5 MW wave energy array(sixteen 15-m diameter
buoys)
150 m
27
Hybrid Offshore FloatingWind-Wave Energy
Conversion Module
8,500 sq.m rotor swept area intercepts 6.8
megawatts of incident wind power (annual average)
in Class 6 resource(800 watts/m2 wind
climate) Mean power output 1.4 MW
3.6 MW wind turbine(104 m diameter rotor)
1.5 MW wave energy array(sixteen 15-m diameter
buoys)
Heaving buoy array would intercept2.4
megawattsof incident wavepower (annual average)
in 10 kW/m wave climate Mean power output
0.6 MW
150 m
28
Hybrid Offshore FloatingWind-Wave Energy
Conversion Module
Based on Articulated Stable OffshorePlatform
originally developed byMcDermott and Offshore
Model Basin
8,500 sq.m rotor swept area intercepts 6.8
megawatts of incident wind power (annual average)
in Class 6 resource(800 watts/m2 wind
climate) Mean power output 1.4 MW
3.6 MW wind turbine(104 m diameter rotor)
1.5 MW wave energy array(sixteen 15-m diameter
buoys)
Heaving buoy array would intercept2.4
megawattsof incident wavepower (annual average)
in 10 kW/m wave climate Mean power output
0.6 MW
150 m
Lower hull provides a pitch-and-roll-stable
foundation for a pre-set wind turbine tower and a
submersible artificial seafloor
forpre-tethered and pre-interconnected heaving
buoy wave energy devices
29
Hybrid Offshore FloatingWind-Wave Energy
Conversion Module
Based on Articulated Stable OffshorePlatform
originally developed byMcDermott and Offshore
Model Basin
8,500 sq.m rotor swept area intercepts 6.8
megawatts of incident wind power (annual average)
in Class 6 resource(800 watts/m2 wind
climate) Mean power output 1.4 MW
3.6 MW wind turbine(104 m diameter rotor)
1.5 MW wave energy array(sixteen 15-m diameter
buoys)
Heaving buoy array would intercept2.4
megawattsof incident wavepower (annual average)
in 10 kW/m wave climate Mean power output
0.6 MW
150 m
Buoy-free lanefor service vesselis calmed by
breakwater effectof heaving buoys
Lower hull provides a pitch-and-roll-stable
foundation for a pre-set wind turbine tower and a
submersible artificial seafloor
forpre-tethered and pre-interconnected heaving
buoy wave energy devices