Aquamarine Power is to shut down its wave energy device operating in Orkney, Scotland, in order to carry out a programme of improvements.

The company has released some production data from the Oyster 800 device and has also outlined a product improvement plan that will enhance the performance, reliability and availability of the wave energy machine.

The Oyster 800 has been operating since February at the European Marine Energy Centre. Aquamarine Power will work on five specific areas of the machine over the summer, it says.

"We have learned a tremendous amount about how Oyster operates in real sea conditions," said Aquamarine Power Chief Executive Officer Martin McAdam. "This year the Oyster 800 has been operational in significant wave heights of 5.3 me and peak waves of 9 m.

"The Oyster 800 structure has performed well in the most arduous storm conditions."

According to Aquamarine Power, the Oyster 800’s power production figures are starting to look "very promising" – including sustained generation of 1 MWh in a five-hour period.

However, some components have performed much less reliably than expected and the device’s power production and availability figures are lower than they might otherwise have been.

Components that have failed include control and instrumentation cable connectors, hydraulic hoses, non-return valves and accumulators.

"We are now implementing our Product Improvement Programme," said McAdam. "This is a planned shutdown which will allow us to install significant upgrades in five key areas."

These areas of work are: installation of enhanced cylinder and accumulator modules with upgraded hoses, non-return valves and instrumentation; installation of an enhanced control and instrumentation architecture with upgraded cable connectors; implementation of reliability-enhancing measures following general feedback and learning to date from technical subsea issues; analysis of all data generated on the machine to improve operating procedures and overall machine efficiency; and increasing the performance of the on-shore header tank, filtration plant and accumulator plant.

"We believe this is the best and most cost-effective way of using what we have learned so far to improve the Oyster 800’s performance and reliability," said McAdam. "Our goal is to have the Oyster 800 operating with increased reliability through the coming winter."