Pelamis P-750 Wave Energy Converter

Pelamis Ocean Power

“The Company was founded in 1998 by Dr Richard Yemm, Dr Dave Pizer and Dr Chris Retzler with the aim of developing the Pelamis Wave Energy Converter” (“History – PelamisWave”, n.d.). Despite the company’s founding date the technology for the Pelamis project was started in the early 1980s and has continued development for more than two decades. The Pelamis design works by using “[four] cylindrical sections linked by hinged joints” (“Pelamis Wave Energy Converter”, n.d.). Due to the shape and motion of the Pelamis the technology has been alternatively named by some “Sea Snakes”. Pelamis Wave Power company and the wave energy conversion technology produced by it have been awarded multiple times over the years, to mention a few in 2003 Pelamis wave energy converter won the award for “Best Renewable Technology, Scottish Green Energy Awards” (“Awards – PelamisWave”, n.d.) and in 2007 “Ocean Energy Pioneer Technology Award” (“Awards – PelamisWave”, n.d.).
The main goal of “PWP [Pelamis Wave Power] works with project developers, energy companies and utilities seeking to harness wave energy in order to meet the global need for clean, sustainable, renewable power generation” (“Business Strategy – PelamisWave”, n.d.). At present the Pelamis system is at the stage of development where it is now capable of being used in practical use. Plans have already gone through in the South West of England and Scotland.

Pelamis P-750 Wave Energy Converter Research

The Pelamis P-750 wave energy converter is the production version of the Pelamis project. Pelamis has now reached the stage of development where it is able to be used as a practical source of renewable power generation. One of the current concepts for Pelamis is in the form of wave farms. One wave farm will consist of 40 Pelamis units covering an area of approximately 1km. “ 30MW offshore ‘wavefarm’ would consist of 40 machines occupying a square kilometre providing sufficient power for over 20,000 homes” (“Pelamis Wave Brochure”, n.d.).

Pelamis Wave Farm
Image source: http://www.pelamiswave.com/media/op-illus1.jpg

In the Pelamis Brochure it is stated that the “Overall power rating 750kW,
Annual output 2.7GWh, Nominal wave power 55kW/m” (“Pelamis Wave Brochure”, n.d.). At the time I conducted my research this information was not present on the PWP company website. The original purpose of the research was to determine how much power a single Pelamis wave converter could produce using the information available on the website at the time.
The primary source of information from the site that made it possible to determine how much power could be generated was the diagram of the Pelamis power matrix which showed how much power could theoretically be generated at a certain wave height and over a certain period of time. I collected historical weather information from a national buoy centre website where information such as significant wave height (metres) and average wave period (seconds) were stored. The data gave both pieces of essential data for each hour of everyday in the year. The historical data was taken from the years 2003 to 2006. I considered this a suitable sample of information since the purpose of the research was to determine how much power a Pelamis unit can generate. Parts of the data were omitted where necessary, such as the anomalous results which had a value of 99 for a sustained period of time or random invervals. These results are most probably due to faults or maintenance, since it is not possible for a wave to have lasted for 99 seconds or be 99 metres high, unless there was some unreported tsunami.

Pelamis Power Matrix
Image source: http://www.pelamiswave.com/media/power-matrix.jpg

The significant wave height and average wave period were averaged for each month of every year. The average is used because it takes all the values into consideration and generates the middle value. Using the average wave height and significant wave period for each month was manually compared to the Pelamis power matrix, this gave the amount kilowatts that would be produced per average wave for that month. To understand how much would power would be produced per month as a whole. The power rating for each month went through the following mathematical calculation.

Power Generation Calculation

The average wave period was about six seconds so multiplying it by ten gives the amount of power generated for one minute then multiplied by sixty to give the power generated in one hour. When the hourly value is multiplied by the total hours in each month it gives the total amount of power that could be generated in that month.

Results of Research

From the results generated by the research it can be seen that the Pelamis P-750 is capable of generating power in the area of gigawatts. The average amount of power generated per month is 15GW. According to the Pelamis brochure a single Pelamis unit is capable of producing a yearly output of 2.7GWh worth of power. This information contradicts what I researched, given the information that was available during the time of research made the calculations in theory correct. The most probable reason for these exaggerated results is due to certain conditions not mentioned by PWP that lead to the miscalculation of the information I used.

Results

Graph of Results

Technological Alternatives and Consequences

A number of alternative technologies were considered for assessing before Pelamis was chosen. One of these was the OWEL Grampus Wave Energy Converter. This wave converter works by moving into the path of a water current by moving on its pivot mooring, as the water flows into the wide end of the Grampus. The water is forced out by the constant flow of water going into the Grampus. The pressurised water flows through turbines before leaving the Grampus. It also uses wind pressure to generate power by forcing trapped air into a pressure chamber before the pressurised air is forced through separate turbine to produce power.
The Grampus system while being a possible alternative it was passed over the Pelamis due to a number of reasons. The first being the fact that unlike Pelamis the technology is still in the development stage and has yet to be prove worth the cost. A single Grampus costs around £2 million to build and install. One of the recent plans for a small wave farm consisting of four Pelamis wave converters will cost £10 million to make which is about £2.5 million to build and install each one.
The second issue with the Grampus is an inconvenience, if the Grampus were to break down its size and the fact that it is designed to be mainly submerged makes accessing broken areas difficult. If a breakdown were to occur it would stop all power production in a single unit of the structure. The Grampus would need to be shut down for maintenance which is a costly process. In the event a Pelamis breaks down it can easily be towed back to a dry dock for maintenance or repaired onsite depending on the damage since the design of Pelamis allows access to the structure from all sides easily.

Grampus

OWEL Grampus
Source: http://owel.co.uk/lib/grampus1.jpg

Political and Financial Effects

Planning has already been approved for a wave farm in Cornwall as one of many plans to introduce renewable energy to the region. The deal made for Pelamis is a £28 million plan. The benefit of this that this project could Clark (2007, para. 8) “could create 1,800 jobs and £560 million in the UK economy over 25 years. Almost 1,000 of these jobs and £332 million would be generated in South West England.” Such projects benefit Cornwall politically because it gives the appearance and reputation for being eco-friendly. This is good for tourism because eco-friendly is associated with a positive image of a place having a healthy environment
The fact that this project will also generate jobs is beneficial to the economy financially. The production of more jobs helps and economy grow because it provides the people with work that allow them to contribute to the economy.

Sustainable Development

Pelamis is a sustainable technology due to a number of considerations. The hydraulic fuel used by the hydraulic joint to generate the power is biodegradable so in the event that a Pelamis unit is badly damaged there will be no adverse effects to the environment. This feature of Pelamis meets the environmental needs of sustainable development because it does not harm the environment, it meets the economic needs because there will be no need to contain the fluid that has already leaked out. The social needs of the people are met because the environment and sea life are not harmed by the Pelamis.
The crucial issue of boats and other sea vessels is possibly colliding with a Pelamis unit. Certain matters are assessed to determine if an area is suitable for Pelamis units, these matters are assessed and surveyed. The matters looked at are environmental, shipping routes, collision assessment based on the area. These are partly what help determine an areas suitability for a wave farm. This takes all areas of sustainable development into account.
On a national scale it shows that steps are being made to make use of technology that draws power from all renewable sources. The more citizens are made aware of what is happening the more people may start to realise the small things do make a difference. Renewable energy might not contribute much to the overall power that is produced on a national scale. However, thousands of homes running on renewable power is better than none in reflection.

References

History - PelamisWave. (n.d.). Retrieved January 11, 2008, from
http://www.pelamiswave.com/content.php?id=158

The Pelamis Wave Energy Converter. (n.d.). Retrieved January 11, 2008, from
http://www.pelamiswave.com/content.php?id=16

Awards - PelamisWave. (n.d.). Retrieved January 11, 2007, from
http://www.pelamiswave.com/content.php?id=140

Business Strategy - PelamisWave. (n.d.). Retrieved January 12, 2008, from
http://www.pelamiswave.com/content.php?id=136

Pelamis Wave Power Brochure. (n.d.). Retrieved January 12, 2008, from
http://www.pelamiswave.com/media/pelamisbrochure.pdf

Clark, J. (2007). Government go-ahead for Wave Hub project. Retrieved January 12, 2008, from http://www.southwestrda.org.uk/news/release.asp?ReleaseID=2136

Offshore Wave Energy limited. (n.d.). Retrieved January 12, 2008, from http://owel.co.uk/