1. Warm Up: What is a tide? What causes the tides?
How often do tides occur?

2. Tidal Power

3. Essential Questions What is a tide? What causes the tides?
How often do tides occur?
What is tidal power?
How can oceanic currents be viewed as an energy source?

4. What Causes Tides?
Tides are periodic variations in the level of the water in oceans or in the bays/inlets that connect directly to them
But what causes tides???

5. What Causes Tides?
Tides are caused by the gravitational pull of the Moon and the Sun. Since the Moon is closer, its effect is more than double that of the Sun.
Tides repeat themselves once every 12 hours and 25 minutes - or twice a lunar day - which is the time it takes for Earth to rotate once relative to the Moon.

6. History of Tidal Power 200 A.D. 1966 900 A.D. 1157 1980 1984 2009 1883
Tidal mills may have been used by Romans to grind grains
La Rance Tidal Barrage commissioned in France
900 A.D.
1157
Naturally occurring basins were converted to tidal barrages and used to spin waterwheels which powered mills for grinding grains.
Farmers built ponds to trap seawater from rising tides in order to power tidal mills for grinding grain.
1980
1984
Jiangxia Tidal Barrage commissioned in China
Baltimore Polytechnic Institute was founded
 North America’s first and only tidal generating station was built in Annapolis Royal, Nova Scotia.
2009
North America's first and only commercial-scale in-stream tidal turbine deployed in Minas Passage: NSPI/OpenHydro 1 megawatt device.
1883

7. History of Tidal Power 200 A.D. 1966 900 A.D. 1157 1980 1984 2009
Tidal mills may have been used by Romans to grind grains
La Rance Tidal Barrage commissioned in France
900 A.D.
1157
Naturally occurring basins were converted to tidal barrages and used to spin waterwheels which powered mills for grinding grains. .
Farmers built ponds to trap seawater from rising tides in order to power tidal mills for grinding grain.
1980
1984
Jiangxia Tidal Barrage commissioned in China
 North America’s first and only tidal generating station was built in Annapolis Royal, Nova Scotia.
2009
North America's first and only commercial-scale in-stream tidal turbine deployed in Minas Passage: NSPI/OpenHydro 1 megawatt device.

8. History of Tidal Power 200 A.D. 1966 900 A.D. 1157 1980 1984 2009
Tidal mills may have been used by Romans to grind grains
La Rance Tidal Barrage commissioned in France
900 A.D.
1157
Naturally occurring basins were converted to tidal barrages and used to spin waterwheels which powered mills for grinding grains. .
Farmers built ponds to trap seawater from rising tides in order to power tidal mills for grinding grain.
1980
1984
Jiangxia Tidal Barrage commissioned in China
 North America’s first and only tidal generating station was built in Annapolis Royal, Nova Scotia.
2009
North America's first and only commercial-scale in-stream tidal turbine deployed in Minas Passage: NSPI/OpenHydro 1 megawatt device.

9. Tidal Barrages

10. What is a Tidal Barrages?
A barrage is a dam that impounds seawater from the rising tide in a tidal basin or estuary. The seawater is held in the basin until low tide, when it is released to power hydro turbines to generate electricity.

11. Other Forms of Tidal Power: Lagoons & In-Stream Turbines
A tidal lagoon is an enclosed dam that impounds seawater from the rising tide in a ring inside of a tidal basin or estuary. The seawater is held in the lagoon until low tide, when it is released to power hydro turbines to generate electricity.
An in-stream turbine is pretty much just like a wind turbine except it operates underwater, drawing energy from a tidal or marine current to produce electricity. These turbines turn much slower than wind turbines but can produce far more energy for their size.

12. How do Tidal Barrages Work?
1. The sluice gates are opened as the tide rises so that seawater can fill the tidal basin. Power is generated during the floodtide.
2. The sluice gates are closed as the tide ebbs in order to increase the difference in height between the water in the basin and the turbine. h
3. The sluice gates are opened again at low tide and the tidal basin empties, turning the turbine to generate a great deal of power.

13. How much power does a tidal barrage produce?
Example: Seawater (r= 1020 kg/m3) flows into a 10 square-kilometer tidal basin. If the tidal range in this area is 8.5m, what is the average power output [megawatts]?

14. What’s Coming Up? Tidal Barrages & In-stream Turbines
Impacts on Environment/Society