Tidal and Wave Energy

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					Tidal and Wave Energy

By: Patrick Blomberg Adam Womack

How it Works – Tidal Barrages
• • • • Tidal Barrages Dam an estuary As water flows out or in, a turbine is spun Electricity is generated by the turbine

How it Works – Tidal Barrages

How it Works – Tidal Barrages

from http://www.esru.strath.ac.uk/EandE/Web_sites/01-02/RE_info/tidal1.htm)

How it Works - Wave Energy
• Many experimental technologies • Example: Pelamis Project

from http://www.worldenergy.org/wec-geis/publications/reports/ser/wave/wave.asp

How it Works - Wave Energy
• Offshore Turbines • Have gearboxes, anchored by a monopile

from http://www.marineturbines.com/technical.htm

How it Works - Wave Energy
• Swanturbines • No gearboxes, anchored by concrete

from http://www.swanturbines.co.uk

How it Works - Wave Energy

from http://www.worldenergy.org/wec-geis/publications/reports/ser/wave/wave.asp

Environmental – Tidal Barrages
• Under Construction –
– Essentially the barrage is a dam – Stagnating water – Increase in pollutants – Given time, returns to normal

Environmental – Tidal Barrages
• After Construction
– Tidal height changed
• Decrease in mud flats area during low tide • Unpredictable effect on bird migration (30-50%) • Outside high tide increase; excess flow

– Turbidity decreases
• Increase in phytoplankton • Unpredictable changes to food chain

– Sediment gradient altered
• Severn Estuary Solution

Environmental – Wave Energy
• Blade Speed 10-20 rpm
– Boat propeller up to 10x faster

• Monopile/Concrete
– Easily Avoided

• Other Designs
– Stationary, surface

• Vortex
– Unsure, expected to be avoided

Image from: http://www.marineturbines.com/home.htm

Economic – Tidal Barrages
• Historical Example – Rance Estuary
– Cost about 530 Million Euros in today’s costs, not including inflation in mid 60’s – 240 MW output – Estimated energy cost (Not including startup)
• 18 cents Euro / kW • Nuklear estimated similarly at 25/kW

Economic – Tidal Barrages
• Severn Estuary
– Estimated $12-16 million construction
• About 3 Nuclear plants

– 8640 MW Output
• About 8 Nucler plants

– Running costs about 1.5x Nuclear – Estimated lifespan – 120 years
• Nuclear is about 60

• Alternate Design - Lifts

Economic – Wave Energy
• MCT – About $16 million US
– Plotted Velocities – 300 kW design – 1 MW design

• Other Estimates
– ‘Cheaper than tidal’ – ‘About the same as wind’

Conclusions
• Wave Energy
– More area for utilization – Promising research – Potential for higher than 10% of world need

• Tidal Barrages
– Widely varying environmental impact – Expensive, but long lasting – Very placement specific

Questions?