OWC Presentation

Oscillating Water ColumnGroup HJohn Wissing

Why wave energy?• The World Energy Council has estimated that the

potential amount of wave energy available is 2 Terawatts (approximately 2/3 of the worlds consumption of energy)

• Other countries such as Denmark, Wales, Portugal, Spain, Scotland, Ireland, Australia, Nova Scotia, South Africa and China already have wave energy conversion projects ether in place or in the planning process.

• Wave energy is clean, renewable and abundant.

Potential Locations

Wave and Tidal Distribution (https://ceprofs.civil.tamu.edu/mhkim

/2008-301-ocean%20energy.ppt)

Continued

Approximate global distribution of wave power levels (kW/m of wave

front) T. W. Thorpe, ETSU, November 1999

History of OWC•The first patent to utilize energy from

ocean waves dates back to 1799 and was filed in Paris by Messrs Girard and his son.

•Modern scientific pursuit of wave energy was pioneered by Yoshio Masuda's experiments in the 1940s.

History Continued• The OWC was originally

named The Masuda Device

• Early OWC designed by Yoshio Masuda

• http://daedalus.gr/OWCsimulation2.html

PICO• 400 kW OWC• Construction began 1996• Completed in summer

1998

OSPREY (Ocean Swell Powered Renewable EnergY)

• Constructed in 1995• Wavegen re-designed the

OSPREY (OSPREY 2000) with composite steel and concrete unit after the OSPREY was damaged by a large wave

Sakata, Japan• Operational in 1989• Only three of the five air

chambers used• Front wall of the OWC

inclined to 45 degrees to reduce horizontal force and stabilizing the caisson

Limpet (Land installed Marine Pneumatic Energy Transformer) 500

• 500kW OWC• Constructed began on

1998• Completed and

commissioned at the end of 2000

• Inclined column offers an easier path for water to flow in and out

• Reduces turbulence and energy loss

LIMPET Civil Construction

The Islay Device• Most successful OWC

• Onshore installation

• The OWC has an opening at the rear, through expelled air is ducted into a biplane Wells Turbine

Powering our lives• Rated at 500 kW @ 40% capacity

• 500 kW * 8760 Hr/Yr = 4,380,000 kWh

• 4,380,000 kWh * .40 = 1,752,000 kWh

• 1,752,000 kWh * (Annual household consumption/4377 kWh)

• = 400 Households

Oscillating Water Column•Uses the up and down motion from waves

to generate energy•Acts just like a wind turbine•The Wells Turbine utilizes bidirectional

air flow

Wells Turbine Blades• The solution to the biggest problem –

bidirectional air flow• Higher drag coefficient and slower rotational

speed than traditional asymmetric airfoils• Efficiency between 60% to 70%

Wells Turbine Blades

Oscillating Water ColumnPros Cons• Currently a leading

approach to wave energy• Most OWC’s are onshore

and all cables are dry• Design and Maintenance

are simple and effective• Plenty of potential

locations

• Installation can be difficult and dangerous due to large waves

• Operation is noisy• Waves generally lose large

amounts of power by the time they reach the shore

Compared with other existing devisesOWC Other• Little too no underwater

network• Only one moving part• Easy maintenance

• Pelamis, Overtopping device, Point Absorbers, The Duck, Powerbuoy, and Gulf streams turbine

• All but the Gulf Stream turbine

• All

Type of energy conversion

Structure/device Assumed Efficiency %

Wave to pneumatic Oscillating water column 42

Pneumatic to mechanical

Wells turbine65

Mechanical to electrical

Generator91

Overall efficiency   24.8

Economic Model(Assumed yearly averaged efficiencies)

OWC (42-52), Turbine (65-67.5), Generator (91-94)

OWC Improvements• Column design – allow the water to rise and fall with the least amount of turbulence = lower energy loss• Less delay in the bypass valve – better air flow control so the turbine does not stall

Turbine Improvements• Develop a range of standard turbines with known characteristics• Use CFD (Computational Fluid Dynamics) tools – Uses numerical methods and algorithms to solve and analyze problems that involve fluid flows. CDF software can model waves, viscous effects, air pressure movement and turbine rotation. • Variable pitch blades (Denniss-Auld Turbine) – uses a system a lot like DART (early warning for tsunami), it has a pressure sensor on the sea floor and uses this to adjust blade angle and turbine speed (Efficiency Peak over 80%)

Denniss-Auld Turbine

Cost Break down

Grand total = 3.5 millionStructure = 2.3 million

Grand total = 11 millionStructure = 6.3

Cost Improvement•Civil construction cost is about 60% - 70%

of the total project▫Concrete is the main material▫Develop a structure that is suitable in a

wide range of locations for mass production

Videos

• OWC - Pico Power Plant

• Ocean Energy - Wave Power Station

Impacts of ocean wave energy on environment•Loss of seabed from structural foundation•Affects fish reproduction around device•Oil leakage•Noise emissions•Animals being swept into chamber

Sources•http://www.carbontrust.co.uk/SiteCollecti

onDocuments/Various/Emerging%20technologies/Technology%20Directory/Marine/Other%20topics/OWC%20report.pdf

•http://homepages.cae.wisc.edu/~vining/JVining_WaveEnergyConversion.pdf

•http://thefutureofthings.com/pod/6415/efficient-wave-power-in-sight.html

Questions?