Oscillating Water Column Group H John Wissing
Oct 15, 2014
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?