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Ocean Power - Waves and tides

Ocean Power - Waves and tides. Dr David Griffin Research Scientist (Oceanography). Wave power – the basics. When the wave height is 5m the energy flux is about 150kW/m. Tasmania’s average usage is 1200MW 1200MW ÷ 150kW/m = 8km

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Ocean Power - Waves and tides

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  1. Ocean Power -Waves and tides Dr David Griffin Research Scientist (Oceanography)

  2. Wave power – the basics • When the wave height is 5m the energy flux is about 150kW/m. • Tasmania’s average usage is 1200MW • 1200MW ÷ 150kW/m = 8km • waves west of Tasmania are 5m only 10% of the time (and that’s in winter) Insert presentation title

  3. Wave heights west of Tasmania • most of the time, the wave height is between 2m and 4m: Insert presentation title

  4. Wave energy flux west of Tasmania • mostly 30-100kW/m, depending on season • 1200MW ÷ 40kW/m = 30km Insert presentation title

  5. Capture fraction, efficiency • Wave devices do not capture all the incident energy • (You wouldn’t want them to) • Not all the energy they capture can be converted into electricity • let’s assume just 10% of the incident wave energy flux is turned into electricity • 1200MW ÷ 4kW/m = 300km • = the length of the west coast Insert presentation title

  6. CETO Insert presentation title

  7. bioWAVE Insert presentation title

  8. Pelamis Insert presentation title

  9. Wave power - conclusion • If we really wanted to, we could power Tasmania using 10% of the wave energy incident on the west coast. • that would be ~1000 devices, ie 3 per km on average – a massive project Insert presentation title

  10. Tidal currents – 2m/s in Banks Strait Insert presentation title

  11. SeaGen – 16m dia x 2, 1.2MW at 2.4m/s • Power (W/m²) = ½ ρν³ • 2.4m/s → 6.9kW/m² • 400m² → 2.8MW • 40% efficiency → 1.2MW • Banks Strait peaks at 2.6m/s • → ~200kW average • 6km line of 30 SeaGens → 6MW • insignificant for Tasmania • significant for Flinders Island Insert presentation title

  12. Australian company - BioPower • bioSTREAM Insert presentation title

  13. Ocean circulation Insert presentation title

  14. Median energy flux of ocean currents Insert presentation title

  15. Currents near Tasmania are weaker than up north • If anywhere, off Brisbane is where it might be worth exploiting the East Australian Current. Median speed = 0.9m/s • 0.35kW/m² → 60m dia for 1MW Insert presentation title

  16. Conclusions • For Tasmania, the only significant marine source of renewable energy is the waves off the west coast • Environmental impact and multiple-use conflicts are probably not show-stoppers • engineering and economics are more serious concerns • but west Tasmania is as promising a location as anywhere in the world Insert presentation title

  17. Thankyou • Mark Hemer (CSIRO) – high resolution wave climatology • John Andrewartha (CSIRO) – tidal currents • Stuart Gibson - photo of Ross Clarke-Jones surfing Pedra Branca Insert presentation title

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