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Marine Renewable Energy

Resource

Many studies suggest that the marine environment stores enough energy in the form of heat, currents, waves and tides to meet total world wide demand for power many times over. Two of the most significant forms around the UK are marine currents, caused by tidal effects, thermal and salinity differences; and waves, generated by the action of the winds blowing over the waters surface.

The Department of Trade and Industry (DTI) has commissioned a consortium led by ABP Marine Environmental Research Ltd (ABPmer) to produce the UK Marine Renewable Energy Atlas. The purpose of the Atlas is to spatially map wave, tidal and offshore wind resource potential within the limits of the UK Continental Shelf (UKCS).

Offshore Renewables Atlas

DTI plan to use the Atlas to assist decisions on future rounds of licensing for large-scale deployment of marine renewable technologies. This work is being undertaken as part of the DTI led Strategic Environmental Assessment (SEA) combined programme covering Oil & Gas and Marine Renewable agendas. For further information on the SEA programme please refer to www.offshore-sea.org.uk

Wave Power Potential

The worldwide wave power resource potential is huge. Future Energy Solutions highlight that the global power potential has been estimated to be around 8,000-80,000TWh/y (1-10TW), 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, attractive wave climates are also found within +30 degrees latitude where regular trade winds blow, the lower power levels being compensated by the smaller wave power variability. Figure 1 shows the annual mean wave height around the UK, highlighting the areas with the most potential for energy extraction.


Figure 1 Annual Mean Wave Height Crown ©2004

More detailed regional studies suggest that the accessible resource in waters around the UK (which takes into account constraints on available sites for a wide variety of reasons) could be as much as 700TWh/y, almost double electricity consumption. 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. Indeed, in 2001 the Science and Technology Committee reported that, based on estimates from the DTI's Energy Technology Support Unit (ETSU), in the UK alone, wave energy devices could practicably contribute more than 50 TWh/y.

Tidal Power Potential

The World Offshore Renewable Energy Report 2002-2007, released by the DTI, suggests that while a staggering 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, optimized only where tidal range is amplified by factors such as shelving of the sea bottom, funnelling in estuaries and reflections by large peninsulas (see Figure 2).


Figure 2 Average Annual Tidal Power Crown ©2004

In 2001, the former Energy Minister Brian Wilson listed 42 sites around the UK that would be suitable for tidal stream generation. This reflects the findings of the 2001 ETSU paper that also suggested that the ten most promising tidal stream sites could offer a potential of 36 TWh/y. However, Scottish Enterprise comment that it is estimated that at least 34% of the UK's electricity demand could be generated from tidal currents, which on a European level would be a contribution of nearly 5%. Tidal power has the distinct advantage of being highly predictable compared with some other forms of renewable energy. The regularity of the tides, along with the huge energy potential, therefore helps to make tidal energy development an attractive resource option.