Wave Energy

Wave Power Potential
An energy Scenario for the UK
NBS-M016 Contempory Issues in Climate Change and Energy
Wave Power: overview
• Sun makes wind and wind makes waves > Waves are third hand solar energy
• Waves generated by wind passing over the surface of the sea
– direct correlation between the power of the wind and the power of the wave
• Wave height determined by
– wind speed, duration the wind has been blowing, depth and topography of the
• Energy output (wave power) determined by
– wave height, wave speed, wavelength, and water density
• The energy provided most often used in
– electricity generation, water desalination, and water pumps
Wave Power: history
A bit of history…
– First concepts 200 years ago, but viable schemes only in the 1970’
– Increased interest for RE, and specifically for wage energy, after the energy
crisis in 1973, but insufficient money allocated to bring projects to maturity
– 80’ because of oil price fall, wave energy funding reduced significantly
– 90’ growing awareness of the potential of generating energy from waves
 Relatively new renewable technology in comparison to other RE
• 15-20 years behind technology wind
 Long process to develop this type of energy but economics of current
technologies are potentially attractive
Wave energy technology (1)
• Wave devices characterized by:
– Locations:
•Shoreline: tethered in intermediate depths
•Nearshore: fixed to the seabed in shallow water
•Offshore: more difficult to construct and maintain than shoreline but greatest
potential as waves in deep water have greater energy content
– Method used to capture the energy (fixed, tethered, floating devices):
1- Buoy moored to the seabed
2- Oscillating Water Column (OWC): can be fixed to the seabed
or installed on the shoreline; simple and robust
3- Floating device for offshore: use motion of waves; leading
technology currently
Wave energy technology (2)
Pelamis WEC: leading wave power technology
• 4 semi submerged cylindrical sections facing nose
on towards the incoming waves and which flex and
bend as waves pass > this motion is used to generate
• world’s first commercial wave farm to generate
electricity in Portugal opened in 2008:
 3 Pelamis machines with capacity of 2.25 MW (750
kW per snake); cost of 8.5 m € to deploy; project
suspended in 2009
• in Scotland: plan to install the world’s largest wage
farm : 3MW capacity; 4 Pelamis machines; costs 4 £m
Source: Pelamis Wave Power 2009
 Many devices and new technologies in emergence
 But they are not technically at the industrial production stage > just pilot
projects and prototypes
 Wave energy is currently in the early stage of commercialisation and it
is not yet a widely employed commercial technology
Worldwide potential of wave energy
• Wave energy offers a large potential resources to be exploited
• Total worldwide wave power estimated at 2TW (or 17 500TWh/year) - about
double current world electricity production - and between 1-10 TW in deep water
• Only 500 GW captured with current technology
Annual average wave power density (in kW per m):
any area with yearly averages of over 15kW per m has the potential to
generate wave energy at competitive prices
Best wave energy sites
around the world are
– USA,
– North & South America,
– Western Europe,
– Japan,
– South Africa,
– Australia
– and New Zealand
UK potential of wave energy
UK has a good wave climate
– Well situated: surrounded by water + good position for wind on West Atlantic
Coast (smaller waves on East Coast) (Lewis 42kW/m - Cromer 5kW/m)
–Waves arriving on the Atlantic Coast (1000 km) have an average power of
– Total annual average wave power in UK West Coast
•around 30 GW (260 TWh/year) at the shoreline
•about 80 GW (700TWh/year) in deep water
– Technical potential of offshore wave energy resource
• about 7-10 GW per year (61-87 TWh/year) depending on water depth
– Practical potential much smaller because of
• Operational and economic constraints
• Practical and technical constraints
 Potential of wave energy is huge
 The extent to which this will prove practical to harness will depend upon the
successful development of both near shore and deep water technologies
Wave energy: constraints and advantages
– Most turbines require a constant, powerful flow > waves are irregular in both
direction and power
– Storms damages and corrosive power of saltwater
– Devices still complicated at mechanic level and engineering difficulties
– Maintenance of devices expensive
– Problem of lose during conversion from mechanical energy to electricity
– Wave energy is environmentally friendly (low noise, low visual impact, no
impact for fish like tidal energy) > commercial and political attractiveness
– Wave power provides the highest kW intensity per m2
– Wave available 4000 hours per year (more than wind)
Wave power: assumptions
• Today contribution of wage energy is very small but it will become significant in the
long term: 15% in 2030 with a total wave energy devices production 50TWh
• Because of the huge potential, further investment in R&D (150 m£) will be done to
improve design, construction techniques, technological development, and
• This will help to decrease the cost of wave energy (today 0,08 € kWh) and to
improve the load factor
• Costs of producing wave power devices will be reduced by half with R&D and
economy of scale
• Power of Atlantic waves is about 40kW per meter exposed coastline; UK has
about 1000km of Atlantic coastline and around 60 M population
 1/60 m per person > incoming power 16 kWh per day per person
 If 300 km is used for wave power and wave devices are 50% efficient at turning wave
power into electricity
 we will have 2,7 kWh per day per person
Wave power: potential by 2030
% of energy usage supplied by wave energy
Total wave energy devices production (TWh)
Total wave energy devices production (MWh)
13 333 333
20 000 000
33 333 333
50 000 000
4 000 000
6 400 000
11 333 333
17 500 000
Total devices power (MW) 4000 h use
Power per device (MW)
1 000
1 600
2 833
4 375
Number of dev ices required
5 000
7 273
11 333
14 583
5 000
7 273
11 333
14 583
Load factor
Recoverable annual energy (MWh)
Km of coast estimated for wave power devices
Estimated Capex - 1m £ per dev ice
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