Scottish wave power company Aquamarine Power has today announced “exceptional results” following lengthy sea trials of its Oyster 800 wave machine following extensive sea-trials in the North Sea off Orkney.
The Edinburgh-based firm – which is part owned by the massive Scandinavian ABB conglomerate – spent months testing the device at the European Marine Energy Centre (EMEC) in Orkney.
It said operational data verified that the Oyster turbine generated power as predicted in wave tank and numerical tests. The tests, conducted last year, included operating during major storms with waves up to 25-ft high.
John Malcolm, Chief Executive, Aquamarine Power, said: “These exceptional results have been gathered in more than 750 distinct sea states encompassing 94% of Oyster’s power matrix and verify, for the first time, that predictions of the energy Oyster can generate in any given sea state are accurate – and in the case of large sea states is actually greater than our original calculations.
“Very few, if any, other wave energy technologies have been able to verify as much data across as wide a range of sea states, including operations through major storms. In simple terms, Oyster does exactly what it says on the tin.
“As a business this gives us confidence in Oyster near shore technology, and confirms that future iterations of Oyster technology can be developed at laboratory and test tank scale – secure in the knowledge that subsequent full-scale machines will perform as predicted.”
Dr Paddy O’Kane, Chief Technical Officer, Aquamarine, added: “Over the last year we have gathered real-time operational data representing 94% of the energy capturing seas of Oyster’s power matrix at EMEC. The data includes periods where Oyster 800 was working in waves over 8m high. These are among the largest waves that can occur at our machine’s location.
“We are now well advanced in analysing this data. The results show a very high correlation between Aquamarine Power’s predictions of how we thought Oyster 800 would perform and the machine’s actual performance. This, we believe, is a significant endorsement of the Oyster concept (‘a bottom-mounted, surface-piercing near shore oscillating wave surge converter’, to give it its full technical description)
“The availability of genuine concept validation data is sparse in the industry at present. However, we are one of the very few companies that has made the bold leap to full scale ocean trials of our device and have gathered data from some of the most energetic seas possible at our water depth.”
During ocean trials of Oyster 800, Aquamarine Power has gathered a wealth of high quality prototype data across a wide range of wave and tidal conditions, or sea states. This data covers 86% of the annual average sea states that are expected to occur at the EMEC site, representing 94% of the energy capturing seas of Oyster’s power matrix.
The trials employed a targeted operational strategy which focused on operating the device in a standardised way, in a range of specifically targeted sea states to maximise knowledge capture and learning. This strategy led to pressurising the Power Take-Off (PTO) system (referred to as ‘damped operation’) and capturing power in some of the most energetic sea conditions containing waves over eight metres in height.
O’Kane added: “In fact, in the larger more energetic sea states the prototype has consistently performed better than our initial predictions. We found that tank test results and numerical model predictions of performance were generally within a tolerance band of ±10%.
“These initial findings show that the research techniques developed by Aquamarine Power to model the Oyster device are robust and have a high degree of accuracy. In addition to this, for the wider industry it also shows that small scale wave tank tests and numerical modelling techniques are indeed valid tools to aid the development of wave energy converter technologies.”
Aquamarine Power is currently writing up the findings from the Oyster 800 analysis in a series of technical conference and journal papers for dissemination and knowledge sharing across the entire industry to help advance the development of the sector as a whole.
The first of these papers – “The Value of Full Scale Prototype Data: Testing Oyster 800 at EMEC, Orkney” – is due for publication at the 11th Wave and Tidal Energy Conference (EWTEC) being held in Nantes, France, in September.