ORKNEY RENEWABLE ENERGY FORUM

Wind

The use of wind as a renewable energy resource involves harnessing the power contained in moving air. Wind represents a vast source of energy that has already been harnessed for hundreds of years. The UK has the largest potential wind energy resource in Europe and wind power is currently one of the most developed and cost-effective renewable energy technologies. Wind turbines can be situated either onshore or offshore. Offshore wind is just beginning to be developed, but has enormous potential.

European Marine Energy Centre (EMEC)

Orkney is home to the European Marine Energy Centre (EMEC) and this has placed us at the forefront of the development of marine-based renewables – technologies that generate electricity for homes and businesses by harnessing the power of waves and tidal streams. As the first centre of its kind to be created anywhere in the world, EMEC offers developers the opportunity to test full scale grid connected prototype devices in unrivalled wave and tidal conditions.

Wave

Ocean waves are created by the interaction of wind with the surface of the sea. The size of the waves is determined by the wind (speed, period and fetch), bathymetry of the seafloor (which can focus or disperse the energy of the waves) and currents. Waves have the potential to provide a completely sustainable source of energy which can be captured and converted into electricity by wave energy converter (WEC) machines. These WEC’S have been developed to extract energy from shoreline out to the deeper waters offshore.

Future Energy Solutions highlight that the global wave power potential has been estimated to be around 1000-10,000GW, which is the same order of magnitude as world electrical energy consumption. The best wave climates, with annual average power levels between 20-70 kW/m of wave front or higher, are found in the temperate zones (30-60 degrees latitude) where strong storms occur. However, the extent to which this will prove practical to harness will depend upon the successful development of both near shore and deep water technologies.

Tide

Tidal energy exploits the natural ebb and flow of coastal tidal waters caused principally by the interaction of the gravitational fields of the earth, moon and sun. The fast sea currents are often magnified by topographical features, such as headlands, inlets and straits, or by the shape of the seabed when water is forced through narrow channels.

The tidal stream devices which utilise these currents are broadly similar to submerged wind turbines and are used to exploit the kinetic energy in tidal currents. Due to the higher density of water, this means that the blades can be smaller and turn more slowly, but they still deliver a significant amount of power. To increase the flow and power output from the turbine, concentrators (or shrouds) may be used around the blades to streamline and concentrate the flow towards the rotors.

The World Offshore Renewable Energy Report 2002-2007, released by the DTI, suggests that while 3000GW of tidal energy is estimated to be available, less than 3% is located in areas suitable for power generation. Tidal current energy is therefore very site specific, optimised only where tidal range is amplified by factors such as shelving of the sea bottom, funnelling in estuaries and reflections by large peninsulas. However, tidal power has the distinct advantage of being highly predictable compared with some other forms of renewable energy which makes tidal energy development an attractive resource option.

Orkney Marine Renewables