Wave Energy 

The Government is legally committed to meeting 15% of the UK's energy demand from renewable sources by 2020. As a result, exploiting renewable energy resources by harnessing wave energy is becoming increasingly important in the UK. Wave energy may have a crucial role to play in the UK energy mix, with many of these innovative technologies already being trialled in UK waters.

Attenuators are floating devices that are aligned perpendicular to the waves.  These devices capture energy from the relative motion of the two arms as the wave passes them.		Surface point absorbers are floating structures that can absorb energy from all directions. They convert the motion of the buoyant top relative to the base into electrical power.
Oscillating wave surge converters are near-surface collectors, mounted on an arm which pivots near the sea bed.  The water particles in the waves cause the arm to oscillate and generate power.		Oscillating water column technologies convert the rise and fall of waves into movements of air flowing past turbines to generate power.
Overtopping devices have a wall over which waves break into a storage reservoir which creates a head of water.  The water is released back to the sea through a turbine to generate power.		Submerged pressure differential devices capture energy from pressure change as the wave moves over the top of the device causing it to rise and fall.
Bulge wave technology consists of a rubber tube filled with water, moored to the seabed heading into the waves. The water enters through the stern and the passing wave causes pressure variations along the length of the tube, creating a ‘bulge’. As the bulge travels through the tube it grows, gathering energy which can be used to drive a standard low-head turbine located at the bow, where the water then returns to the sea.		Two forms of rotation are used to capture energy by the movement of the device heaving and swaying in the waves. This motion drives either an eccentric weight or a gyroscope causes precession. In both cases the movement is attached to an electric generator inside the device.

Images and descriptions courtesy of Aquatic Renewable Energy Technologies (Aqua-RET) www.aquaret.com 

There are a number of wave energy sites already leased within UK waters. The Crown Estate website lists information about each project, including test sites, and where each site is in the planning process. You can also click on the image below for a larger view of The Crown Estate map.

This map is courtesy of The Crown Estate.

Whilst the RYA acknowledges the Government's desire to promote renewable energy, it is keen to ensure that the navigational safety of recreational craft is safeguarded around the coast.

The RYA has developed a detailed position statement on offshore renewable wave energy developments, based on recreational craft data, which it provides to every developer during the consultation process. The RYA believes that the impact that wave energy devices have on recreational boating can be minimised provided developers fully consider the following key points:

• Collision risk. The RYA believes that the collision threat to recreational yachts can be minimised by specifying:
  • A minimum underwater clearance of 4 metres below chart datum for submerged wave energy converters, assuming flat water conditions. However, given the nature of these devices and the high wave energy environments that they will be located in, the RYA proposes that an underwater clearance of 8 metres below chart datum would give an appropriate safety margin for submerged devices.
  • Appropriate location, charting and marking of devices.
• Marking and Lighting. The RYA supports the guidance provided by the General Lighthouse Authorities and works with them to identify site specific issues that may occur.
• Navigational and communication equipment. Any proposed development should account for the effect on small craft navigation and communication equipment in detail.
• Location. Recreational routes, general sailing and racing areas must be accounted for when examining the impacts of offshore wave energy developments.
• Sailing and racing areas. A wave farm that encroached into a racing or sailing area would increase the risk of accidents occurring and could discourage visitors, therefore having the potential to have an adverse effect not only on the visitors but also on the local economy.

The RYA has also carried out an extensive mapping project to identify the main cruising routes, sailing and racing areas to better inform the management process. Initially this culminated in a detailed description of cruising routes, racing and sailing areas for the three strategic wind farm development areas in 2004 and is reported in the document 'Sharing the Wind'.

This project then evolved to cover the whole of the UK following considerable demand from the offshore renewable energy industry. In 2005, with funding from Trinity House, the RYA produced the first UK Coastal Atlas of Recreational Boating. This dataset has since been updated and is now regularly incorporated into developers’ consultations and navigational risk assessments.