Hydropower

· Hydropower is energy from water sources such as the ocean, rivers and waterfalls

· Because the source of hydropower is water, hydroelectric power plants must be located on a water source

· Energy can also be obtained from the wave motion on the sea (Wave Power)

· Energy can also be obtained from the tidal flow (Tide Power)

A hydroelectric dam

· Water is usually held behind a dam and forms an artificial lake, or reservoir.

· The water is released from the dam and the force of the water spins the blades of a giant turbine.

· The turbine is connected to the generator that makes electricity as it spins

· After passing through the turbine, the water flows back into the river on the other side of the dam.

Tidal power

· Sometimes called tidal energy is a form of hydropower that converts the energy of tides into electricity

· The tide is caused by the gravitational attraction of sun and moon on earth’s waters.

· Tidal power is not yet widely used,

· Tidal power has potential for future electricity generation.

· Tides are more predictable than wind energy and solar power

· In New Zealand, we have a bountiful source of energy that is natural and renewable

· has almost no environmental effects

· is totally predictable

· is 400 times more effective than wind

· Turbines that generate electricity are be submerged well below the ocean’s surface

· With tidal currents, there will never be gusty conditions when the turbine must be feathered to protect it

from damage Can be located in Greater Cook Strait and at harbour mouths.

How is hydroelectric power made/generated?

Drawing of an hydroelectric plant

Before water was used to generate electricity it has been used for many other things.

· People have harnessed the energy of moving water for centuries

· In Ancient Greece and China, waterwheels were installed in rapidly flowing rivers to turn millstones and other equipment.

· Waterwheels were also used to power saws and other equipment across North America when European colonists began rapidly expanding across North America.

· The Dutch used windmills to drain the water from the polders

What are the advantages and disadvantages of hydroelectric power for communities here in New Zealand? Please read up, research and then discuss.

a) Disadvantages

· Building large dams changes the natural environment dramatically

· The flow of a river is altered when a dam is build

· This poses problems for fish and aquatic plants on both sides of the dam.

· Dams can also have unintended consequences – not allowing annual floods to wash out rivers, bringing fertile soils to farmlands, allow rivers to silt up

· Often an obstacle for fish

· Dangers of dam breaking and causing death and flooding

· Depend on weather/climate changes

· The dams are expensive to build

b) Advantages

· This type of energy to generate electricity is not affected by prices of other fuels.

· The electricity costs are lower and more stable

· The pollution created by hydroelectric energy generation is very low

· It also does not produce radioactive waste or involve the environmental impact of fuel being transported to it.

· Only a few people are used to run a hydroelectricity plant

· Hydroelectric power stations can be set up in almost any size, depending upon the river or stream used to operate them

· Hydroelectric is a renewable form of energy, like wind and solar; it does not rely upon finite resources like natural gas or coal to generate power

· Hydroelectric stations can operate for many years after they are built.

· Small hydro electricity generation systems sometimes offer more economic advantages for home owners than solar power, and tend to last longer than solar panels do.

Readings

Worksheet