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The UK Marine Resource

The UK Marine Resource. Professor Ian Bryden University of Edinburgh. Resource Assessment. Meaningful resource assessment needs to be considered in three distinct phases: Theoretical resource: A top level statement of the energy contained in the entire marine resource.

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The UK Marine Resource

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  1. The UK Marine Resource Professor Ian Bryden University of Edinburgh

  2. Resource Assessment • Meaningful resource assessment needs to be considered in three distinct phases: • Theoretical resource: A top level statement of the energy contained in the entire marine resource. • Technical resource: The proportion of the theoretical resource that can be exploited using existing technology options. • Practical resource: The proportion of the technical resource that can be exploited after consideration of external constraints (eg grid accessibility, competing use (shipping lanes, etc.), environmental sensitivity)

  3. Mean Annual UK Wave Resource • Note high offshore resource in Scotland and South West England

  4. Annual Resource Variability • Resource is highly seasonal • But broadly correlated with UK energy demand • Can be “predicted” using meteorological data

  5. Wave Forecasting

  6. Resource Assessment • …. Is meaningless unless it takes into account the limitations of technology! • In the case of wave power, this requires appreciation of directionality, mooring etc. • Significant wave height and period is not enough, directionality is also required, as is the temporal/spectral behaviour

  7. Sea State Specification • Sea characteristics can be expressed as a 2 dimensional “histogram” expressing number of hours in the year on a domain of mean wave period (Tz) and significant height.

  8. Directional wave power densities in Scottish watersfrom UK Met Office hindcast data 1st April 2000 – 31st March 2004 61N 4W 5W 60N Best site: 53kW/m 59N 58N 57N 56N 9W 55N 8W 1W 7W 3W 6W 2W

  9. Determination of Energy Capability In principle, the annual energy production can be determined by cell by cell multiplication Notice that this is a very simple linear approach to the analysis!

  10. Alteration of on-offshore sediment movement Habitat disturbance with coastal installations Alteration of energy distribution Interaction with other users of the sea (fishing, leisure, transport) What About Environmental Concerns?

  11. OK, so how much? • I don’t know! • It is now possible to robustly estimate the capacity of a site to deliver energy but this has not really been done over the whole country! • There have been multiple estimates published: • Estimates of economically exploitable resource vary from 50 TWh/yr (16 GW installed) to 2000 TWh/yr (650 GW installed) • The differences tend to reflect different technological and economic assumptions – remember: theoretical; technical and practical • 50TWhr/yr is used in the Carbon Trust Report “Future Marine Energy (Results of the Marine Energy Challenge: Cost competitiveness and growth of wave and tidal stream energy)”

  12. Tidal Currents • Tidal devices respond to the kinetic flux in a tidal current! • The resource itself, however, is a complex mixture of kinetic flux, potential flux and frictional dissipation, all of which must be considered in a resource assessment

  13. Tidal Current Resource Assessment • Three dimensional modelling techniques are required to predict the response of energy extraction upon the resource and to set limits on acceptable extraction and upon machine related constraints

  14. What is an “Acceptable, Theoretical Resource”? • Tidal flows are highly turbulent. I suggest that acceptable extraction does not alter the flow speed, outside of the immediate wake of the device(s), beyond the local ambient turbulent fluctuation, provided that the wakes themselves do not impinge in a damaging manner REMEMBER THE WAKES THEMSELVES ARE TEMPORALLY VARIABLE

  15. Case Study: Strangford Narrows A study by Whittaker and co in 2003, suggested that array ”2” could have an acceptable rated capacity of 33MW. This would be well below the energy potential of the Narrows

  16. Case Study: Pentland Firth The case study assumed the use of “SeaGen” devices as presently located in Strangford narrows This implies severe device related constraints on water depth

  17. Characteristics of the Proposed Array

  18. Theoretical Resource of the Pentland Firth • Estimates vary, primarily because of limited survey information. • If the turbulence related “limit” is used to define acceptable exploitation, the theoretical limit is equivalent, at least, to an installed capacity of between 6GW and 12GW

  19. UK Acceptable Theoretical Tidal Current Resource • There is as yet no definitive figure and there is not yet a case for a fully developed numerically supported estimate • BUT, the Pentland Firth would appear to offer between 25% and 50% of the UK tidal current resource, • This suggests a potential theoretical installed capacity of between 20GW (60TW hrs/annum) and 40GW (120 TWhrs/annum) with capacity factors between 35% and 50%

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