Oyster Wave

The Oyster from Aquamarine is another very interesting concept.

Technology:

• Wave damper
• Oyster® is a simple mechanical hinged flap connected to the seabed at around 10m depth.
• Each passing wave moves the flap, driving hydraulic pistons to deliver high pressure water via a pipeline to an onshore electrical turbine.
• Peak power output of around 2MW per Oyster®

Advantages:

• Simple and robust mechanical offshore component with innovative use of proven conventional onshore hydro-electric components
• Offshore component has minimal submerged moving parts
• There is no underwater generator, power electronics or gearbox. All complex power generation equipment is easily accessible onshore.
• Any excess energy is spilled over the top of Oyster®’s flap; its rotational capacity allowing it to literally duck under the waves.
• Its lightweight structure will reduce capital costs and gives an excellent power-to-weight ratio
• With multiple pumps feeding a single onshore generator, Oyster® offers good economies of scale.
• Uses water as its hydraulic fluid for minimum environmental impact
• Minimal environmental footprint and is effectively silent in operation

Disadvantages:

• Designed to be deployed in nearshore depths => Shore is a scarce resource
• Joints in contact with sea water
• Needs water pipes from the device to the onshore site.

Cost:

• Unknown

Other info:

• The first demonstration-scale Oyster® has been successfully deployed at sea at the European Marine Energy Centre (EMEC) in Orkney, Scotland November 2009

Links:

Official Website:

http://www.aquamarinepower.com/technologies/

Video:

http://www.youtube.com/watch?v=S4O0JcNfTKo&feature=channel

OPT: Ocen Power Technologies

Next the OPT Power Buoy concept.

Technology:

• Point Absorber
• The rising and falling of the waves off shore causes the buoy to move freely up and down.
• The resultant mechanical stroking is converted via a sophisticated power take-off to drive an electrical generator. Oil compression moving an hydraulic generator?
• The generated power is transmitted ashore via an underwater power cable.
• Rugged, simple steel construction.
• Utilizes conventional mooring systems.
• Simple installation using existing marine vessels and infrastructure.

Advantages:

• Floating device: easy to install, transport, maintain etc
• 
  

Disadvantages:

• Joints in contact with sea water
• Many moving parts
• Oil inside, not so environmentally friendly
• As a Point absorber it absorbs the energy of a reduced space, a small section of the wave. How much of the available energy is it able to capture?

Cost:

• Unknown

Other info:

• Expertimental plant at Santoña, Spain for Iberdrola

	OPT PowerBuoy®	Solar	Wind	Biomass	Natural Gas and Coal
Energy Density	High. Approx. 1000 x denser than wind	Low – Moderate	Low	Moderate	Very High
Predictability	High. Accurate forecasts days in advance	Moderate	Low except in some sites	Dispatchable, subject to fuel supply	Dispatchable
Load Factor	30% - 45%	10% - 20%	25% - 35%	50% - 90%	50% - 90%
Visual Impact	Minimal. PowerBuoys, in general, not visible from shore	Unobtrusive	Moderate	High	Very High
Potential Sites	Extensive	Limited for large capacity sites	Moderate	Extensive but permitting process can be lengthy	Extensive but permitting process can be lengthy
Cost Per Kilowatt Hour – Utility Power	15¢*	24 - 34¢	8 -16¢	14 - 20¢	4 - 7¢

Links:

Official Website:

http://www.oceanpowertechnologies.com/

Video:

http://www.oceanpowertechnologies.com/tech.htm

Pelamis

It's almost compulsory to begin with the probably most known solution: the Pelamis "worm"

Technology:

• Wave damper
• Semi-submerged, articulated structure composed of cylindrical sections linked by hinged joints.
• The wave-induced motion of these joints is resisted by hydraulic rams, which pump high-pressure fluid through hydraulic motors via smoothing accumulators. (100-350bar)
• The hydraulic motors drive electrical generators to produce electricity.
• Power from all the joints is fed down a single umbilical cable to a junction on the sea bed.
• Several devices can be connected together and linked to shore through a single seabed cable.
• Current production machines are 180m long and 3.5m in diameter with 4 power conversion modules per machine. 700Tm
• Each machine is rated at 3x2x125= 750kW.
• Depending on the wave resource, machines will on average produce 25-40% of the full rated output over the course of a year.=> 2,7GWh
• The machine is held in position by a mooring system, comprising of a combination of floats and weights which prevent the mooring cables becoming taut. It maintains enough restraint to keep the Pelamis positioned but allows the machine to swing head on to oncoming waves.
• The Pelamis is designed to be moored in waters approximately 50-70m in depth where the high energy levels found in deep swell waves can be accessed.

Advantages:

• Floating device: easy to install, transport, maintain etc.
• Able to withstand adverse maritime conditions due to its hydrodynamic profile

Disadvantages:

• How much of the available energy is it able to capture?
• Joints between sections in contact with sea water
• Many moving parts: hydraulic cylinders, electrical motors...

Cost:

• Unknown
• £4.8m of funding for the P2 version
• The Aguçadoura wave energy project in Portugal is supported by a specific feed-in tariff currently equivalent to approximately €0.23/kWh.

Other info:

• First prototype installed at EMEC in 2004
• Patents: US6476511, AU754950, ZA20012008, EP1115976B;
• Projects:

1. Aguçadoura: 2.25MW (3x750kW) in Portugal, commissioned
2. E.ON at EMEC: 750kW P2 prototype
3. Orcadian Wave Farm: 3MW (4 x 750kW) in project near Orkney, Scotland
4. Aegir: 20MW (26 x 750kW) in development near Shetland, Scotland

Links:

Official Website

http://www.pelamiswave.com/

Videos:

http://www.youtube.com/watch?v=JYzocwUfpNg

http://www.youtube.com/watch?v=F0mzrbfzUpM&NR=1

Introduction

Hi,


The idea behind this blog is to publish a summary of the Electrical Power generating devices that are being developed to seize the enormous power available in the sea, and specially in sea waves, as I believe this will be the next big renewable energy source developped.


The different devices that I know of will be shown with info taken from their webs and other webs and my personal opinion of their advantages and/or disadvantages. As this is highly subjetive, I would appreciate your comments, information etc to discuss and enrich our mutual points of view.


I hope this is usefull for somebody, if not, at the very least it will serve to clarify my ideas.