technologies, focusing on the most promising devices, is needed to bring them to the point where they are acquired by major industrials and commercialised. The Crown Estate estimates that c£100m of public funding over 5 years is necessary to ensure that the first array projects are taken forward.
Wave energy technologies fall broadly into three categories:
- Machines which channel waves into constricted chambers. As the waves flow in and out of the chamber, they force air in and out of the chamber. These airflows are in turn channelled through a specialised turbine, which is used to drive a generator. This type of machine is principally designed for use on or near the shore, or for incorporation into breakwaters. This kind of machine is particularly advantageous when incorporated into coastal protection.
- Fixed or semi-fixed machines which utilise the pressure differential in the water that occurs at a submerged point as the wave passes over that point. The pressure differential is used by a variety of means to cause a fluid to flow in a circuit, which is then used to drive a turbine and generator.
- Machines which utilise their buoyancy to cause movement in a part of the device as it responds to the waves. The movement is used either directly or indirectly to drive a generator.
Tidal stream
It is possible to extract power from the tidal flow that occurs between headlands and islands or in and out of estuaries. This application is the focus of much research and development, with new products for this purpose now being commercialised. These “in-flow” tidal turbines can be arranged individually or in arrays, allowing a range of power outputs to be produced.
Tidal stream technologies have recently attracted support from original equipment manufacturers (OEMs) but to enable several projects to be constructed and start operating, additional capital grants for first array projects and commercial funding (equity
and debt) from Government agencies must be made available. The Crown Estate estimates that £50m in capital grants is required for the next 5 years.
Tidal range
In areas where there is a high tidal range, a barrage with turbines may be built across an estuary or a bay. As the tide falls and rises, it creates a height differential between the inner and outer walls of the barrage. Water can then flow through the turbines and drive generators. Some tidal barrages, particularly estuarine barrages, are designed to operate purely on the falling tide, but others operate on both the rising and falling tide. A recent variation on this theme has seen proposals for tidal lagoons in areas of high tidal range, which operate on a similar principle with turbines built into the lagoon walls.
MANIFESTO ASKS
• Better grid regulation - Facilitate access to grid connection, since the UK’s marine energy resource is concentrated in remote locations
• Support public/private ventures - Greater collaboration from Government with the private sector over funding to achieve commercialisation and standardisation
• Industry certainty - Policy certainty over future revenue support to encourage investment
• Joined up Government - Cross Government departmental support to achieve the industrial and environmental potential for the UK
• Encourage Green Investment Bank to develop bespoke project financing offer for sector - Building on experience of Scottish Enterprise and the Crown Estate
• Support towards commercialisation - Establish appropriate capital grant scheme for next 5 years
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