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

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

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

Insert presentation title 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 CETO

Insert presentation title bioWAVE

Insert presentation title Pelamis

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

Insert presentation title 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 Australian company - BioPower bioSTREAM

Insert presentation title Ocean circulation

Insert presentation title Median energy flux of ocean currents

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