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Tidal and Wave Energy. 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.
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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 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