Renewable energy (3) Wave power and tidal barrage power
Doc Brown's Physics Revision
Suitable for GCSE/IGCSE Physics/Science courses or
wave power for generating electricity
tidal power electricity generation
advantages and disadvantages of these
The technology of wave power
power: One method of using wave movement is to use its kinetic energy of
up and down oscillation to compress air in a funnel and tunnel the air
through a turbine connected to a generator on the sea shore. It has not so
far (as I know?) proved very successful.
kinetic energy store of the waves ==
mechanically ==> kinetic energy of the turbine and generator rotor ==>
electrical energy as the rotor of the generator rotates in a magnetic field
Note that most of the energy in the
waves originally comes from the kinetic energy store of the wind -
stronger winds make bigger waves.
Advantages of wave power
The initial cost is high, but bar storm
damage, the running costs are low.
Free source of energy.
There is no pollution.
A successful scheme might be useful for
an island with a small population.
Disadvantages of wave power
There are several problems eg variable
wave height giving variable power output.
Storm damage is a regular risk.
Spoiling the view.
Hazard to boats.
The seabed may be disturbed affecting the
You need lots of small wave-powered
turbines on the coast to generate a significant power output.
Unreliable due to the variability of wind
speed which affects the wave height and power.
power - hydroelectricity
The technology of tidal power
Tides are caused by the gravitational
pull of the moon and sun, and the flow of tides involving huge quantities of
water, and a rise and fall in height of water of several metres.
The Earth spins through the maximum
height of water created by the combined gravitational pull of the Sun
and moon (but don't forget the Earth and moon pull on the sun too!).
A tidal barrage scheme consists of
building a long relatively low dam across a river estuary.
Generators are built into the dam
Note that the turbine blades can
be designed to operate in both directions so you can extract energy
as the tide comes in and when the tide flows out.
A tidal barrage scheme is the most
common way of utilising the power of the tides.
The incoming tide, collected behind a
barrier, acts as gravitational potential energy store in a suitable location e.g. a river
You can use the incoming tide to
generate power too.
At the turn of high tide we now
have a great store of gravitational potential energy (GPE).
back down is controlled and acts as a kinetic energy store which is then
electricity via a generators in the wall of the barrage.
tide drives the turbines as does the controlled released of the huge amount
of stored water (GPE) stored behind the barrage at high tide.
It is an advantage to store huge quantities of water that can be
released at electricity peak demand times.
energy store (water held behind the barrage)
mechanically ==> kinetic energy
store (turbine and generator rotor)
mechanically ==> electrical energy
(generator output via rotation of the rotor in a magnetic field)
Advantages of tidal barrage power
The energy from seawater is free and
there is no pollution and maintenance costs are relatively low.
Its a reliable source of energy - the
tides rise and fall twice every day due to the combined gravitational
attraction of the Sun and Moon.
Tides are reliable and times/heights can be accurately
predicted, but there periods of time when the water levels are similar on
both sides, therefore little effective water flow and electricity
A tidal barrage power station can
generate large amounts of electrical energy, unlike many other renewable
Disadvantages of tidal power
Hydroelectric tidal barrage schemes are very costly
to build needing a large capital investment and take a long time to build,
but there are no fuel costs.
There are problems with the water course
become silted up with sand.
Environmental costs: Wildlife habitats are affected disrupting
local ecosystems on the estuary bed/seabed and other species from wading birds to fish stocks.
Some might find, as with wind farms,
barrage schemes unsightly.
The height of the tides is variable and
you need a good difference in height to have a large GPE store of water.
Disruption of leisure/commercial craft
on the river and estuary.
Limited locations where you can build a
hydroelectric tidal barrage scheme.
Energy resources, and
transfers, work done and
electrical power supply revision notes index
Types of energy store - a comparison with examples explained,
mechanical work done and power calculations
Conservation of energy,
energy transfers, efficiency - calculations and
Sankey diagrams gcse physics
Energy resources & uses, general survey & trends, comparing sources of renewables, non-renewables
Renewable energy (1) Wind power and
solar power, advantages and disadvantages gcse physics revision
Renewable energy (2) Hydroelectric power and
advantages and disadvantages physics notes
Renewable energy (3) Wave power and tidal barrage power,
advantages and disadvantages gcse
Comparison of methods of generating electricity, 'National Grid' power supply,
mention of small scale supplies
effect, global warming, climate change,
carbon footprint from fossil fuel burning gcse physics
The Usefulness of Electricity gcse
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IGCSE physics revision
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