1. Tidal Energy Brandi Alfaro Sheyla Gonzalez

2. Howit Works • Tides are created by the flowing of water due to the gravitational interaction between the moon, sun, and rotating planet. • tidal energy is an energy source direct result of tide shifting from low to high. • There consistently has to be a 16 feet (5 m) difference • There are 20 sites that are suitable for a tidal power station • Not one can be found in the US  • Tidal power is harnessed in a couple of ways: • kinetic energy that powers turbines as the water moves between surge and ebb tide • potential energy in which barrages are used to the difference between high and low tide.

3. How does it produces energy? • Tidal power is harnessed in a couple of ways: • kinetic energy that powers turbines as the water moves between flow and ebb tide • potential energy in which barrages are used to exploit the difference between high and low tide. Tidal Turbines • Tidal turbines look like wind turbines. They are underwater in rows • Any number of turbines can be built and installed at any time underwater. • The tide moves a huge amount of water twice each day, and harnessing it could provide a great deal of energy • It does not cost too much to operate tidal power plants but its expensive to build it http://www.darvill.clara.net/altenerg/tidal.htm

4. Tidal Barrage • Huge dam built across a river estuary. • the water flows through tunnels. The ebb and flow of the tides is used to turn a turbine, or can be used to push air through a pipe, which then turns a turbine. • Process • water flows in the basin/estuary • Turbines spin as the water flows to the basin/estuary • gates open and the water flows back to the seas • tide recedes out through the barrage • while water travels from basin to sea, the turbines are spun again

5. Highest tides of the global ocean Country Site Tide range (m) • Canada Bay of Fundy 16.2 • England Severn Estuary 14.5 • France Port of Ganville 14.7 • France La Rance 13.5 • Argentina Puerto Rio Gallegos 13.3 • Russia Bay of Mezen (White Sea) 10.0 The largest tidal power station in the world (and the only one in Europe) is in the Ranceestuary in northern France

6. Tidal Energy Pros Cons It could only be in places with water level changes. Only works for 10 hours a day, when tides are flowing in or out. It can harm the marine ecosystem. • tidal turbines do not affect navigation or shipping • Does not generate greenhouse gases. • It function without any fuel requirement. • Source of electricity with low maintenance cost . • Completely predictable and constant (unlike sun and wind energy)

7. Why should we use it? • The initial cost of creating a barrage is high. • This problem could be solved by: • government funding and/or large organizations • In terms of long term costs, once the construction is complete, there are: • very small maintenance and running costs • turbines only need to be replaced every 30 years • life of the barrage is indefinite • it will receive free fuel from the tide its entire life

8. Mini Quiz • What causes tides to form? • What are 2 methods of converting tidal energy to electricity? • What is one reason why tidal energy should be used? • What is the BIG IDEA? Hint: think about basics.