Hydro EnergyHydroelectric, Waves and Tides

Mechanical Energy Due to gravity

Hydropower from dams Tides

Due to Waves Surface Currents Underwater Currents

Hydroelectric Power

Unlike steam powerplants, work instead of heat is directly available.

Animation

Equations

g.h (m/t) P.

hmgE

(W) watt as calculated isPower

(m) (head) fall ofheight h

)m/s (9.8constant nalgravitatio g

(kg/s) water of rate flow mass m/t

(kg) water of mass m

2

Power Production

Itaipu Hydroelectric power station with a capacity of 12,600 MWe is the largest power plant in the world.

Tidal Power

Newton’s Law of Gravitation

Tides

Gravity and centrifugal forces are in opposite directions

Spring and Neap Tides

Tidal Power Station

Tidal Power Stations The only operating

tidal power plant is in the Bay of Rance Estuary

Built in 1967 Power Production = 160

MW R=11.4 m; A=22 sq.km

Six other experimental tidal plants each generating less than 1 MW

Impact Advantages

Clean Renewable No waste Protecting coastlines against storm surge Water Recreation

Disadvantages Intermittent Disruption in local ecosystem (seabirds and

fish habitats

Energy From Waves

Wave Power Waves are characterized by their

wavelengths (length from crest to crest), amplitude (height from crest to trough), and period (time between two successive waves).

Average wavelength of waves is about 120 m. The maximum power a wave carries is about 100 kW/m in high seas, 60 kW/m around the Atlantic coasts of Europe and less than 20 kW/m off the southeast of the United States.

Surface and Deep Ocean Waves Surface waves are

neither longitudinal nor transverse.

surface waves undergo circular motions. The motion of particles tends to decrease as one proceeds further from the surface.

The Oscillating Water Column OSC works by forcing air

moving up and down in a closed column causing a turbine to turn.

As a wave enters the column, it increases the pressure within the column and forces air up the column past a turbine.

As the wave retreats, the air is drawn back past the turbine due to the reduced air pressure on the ocean side of turbine

Tapered Channel

Archimedes Wave Swing

Wave Ducks

Siting Near-shore vs. Off-shore

Efficiency Cost Noise Visual