Pelamis is the result of over a decade of dedicated testing, modelling and development.
Since 1998, the Pelamis development programme has covered all aspects of the design from the fundamental concept refinement through to accelerated cycle testing of individual components for reliability.
During the first phase of Pelamis development prior to full-scale operations in 2004, extensive numerical modelling and analysis and a range of technology demonstration models at different scales were used to understand survival characteristics in extreme waves and verify the accuracy of our simulations. Numerical modelling and scale testing continues to be an important part of the research and development of Pelamis technology, and is discussed in more detail under 'Testing & Verification'.
The Pelamis Prototype
The Pelamis full scale prototype machine was tested at the European Marine Energy Centre between 2004 and 2007. It was launched in early 2004 and first installed at EMEC in August 2004 following a series of sea trials in the North Sea.
The Pelamis prototype was the world’s first commercial scale wave energy converter to generate electricity to a national grid from offshore waves.
In 2006 the prototype was upgraded to the same specification as the production machines used in the Aguçadoura project. Further sea trials were carried out on the upgraded machine before it was reinstalled at the EMEC site in March 2007. The machine then completed a further extensive phase of testing, meeting a large number of critical test objectives.
The prototype was 120m long and 3.5m in diameter and comprised four tube sections linked by three, shorter, power conversion modules. Testing of this machine proved the Pelamis concept, machine handling, grid connection, and that power generation and behaviour was matched with numerical models.
Aspects of the testing of the prototype were supported by the npower Juice Fund.
The Aguçadoura Wave Farm, 2008
Following on from the successful testing of the prototype machine, Pelamis Wave Power secured an order from Portuguese electricity utility Enersis to build the world’s first wave farm off the northwest coast of Portugal at Aguçadoura.
The three machine farm had an installed capacity of 2.25MW.
Pelamis carried out the main structural fabrication and project assembly of power conversion modules in Scotland before shipping the main units to Peniche, Portugal for final assembly and commissioning.
The three machines were installed and operated in 2008, generating sustained power to the grid with close agreement to the Pelamis simulations. However, the project ended earlier than planned, with the three machines returning to harbour, due the financial collapse of Enersis’s parent company, Babcock & Brown. Despite this disappointment, the project was an extremely important milestone for Pelamis Wave Power, proving the company’s ability to deliver, construct and control a farm of machines and to understand and solve the engineering challenges encountered along the way.
Two main technical issues were encountered. The first affected the foam buoyancy attached to the subsea quick connection system (not part of the machines), the replacement of which caused a delay to the first machine installation in July. The second involved the cylindrical bearings of the machine where online instrumentation detected a higher wear rate than was expected. This was discovered to be due to faulty lateral movement of the cylindrical bearing face which was subsequently resolved.
The experience of building and operating the three P1 machines transformed Pelamis into an organisation with a much more advanced understanding of all aspects of machine design, build, and operation. The experience gained feeds directly into the intensive two year development programme for our second generation, P2 Pelamis.
Some achievements from the Aguçadoura Wave Farm:
Built and operated the world’s first wave farm
Power matched very closely with simulations, giving confidence in design tools
Proved reliable and automated generation and transmission systems
Developed build procedures and processes – refined for application on subsequent builds with great success
Proved remote control & monitoring of the farm
Created a safe & cost effective maintenance base
Maintained high safety record in all operations
Installed all offshore mooring and electrical infrastructure without the need for large expensive vessels
Successfully demonstrated the off-site maintenance strategy
Demonstrated installation of 2 machines in less than 24 hours, with 5 hour towing time
Highly competent and experienced team was developed and maintained into the future
The supply chain for the Pelamis was further enhanced and developed
The Pelamis P2 machine is the second-generation Pelamis machine and includes a number of significant design improvements. The P2 design machine has been sold to utility customers E.ON and ScottishPower Renewables, and P2 machines are currently being tested for a number of commercial scale projects.
At 180m long, 4m diameter and approximately 1350 tonnes in weight (mostly sand ballast), the P2 Pelamis is wider, longer and heavier than the P1 design machine. This allows the Pelamis to capture more energy while substantially reducing the cost per MW.
Comprising of five tubes and therefore four joints, the P2 has an extra tube section and an extra power module.
Improved power take off system for the P2 allows higher efficiencies, enhanced control resolution and increased reliability.
The joint angle envelope has been increased allowing larger joint movement to significantly increase power absorption across sea states.
Rather than the separate sections of the P1, power modules are now integrated into the main tube sections. A universal joint allowing two-degrees of freedom replaces the single degree hinged joints. These changes reduce the number of costly end-cap fabrications in the machine.
The tube connection process has been simplified and de-risked for the P2, expanding structural and mechanical supply chain options.