P3- Sustainable energy

Seite 1

ELECTRICAL ENERGY

energy is transferred in forms of light, sound, heat or movement.

energy is measured in joules.

power is the rate at which engird transfers its measure in watts or kilowatts.

A Kilowatt-hour (kWh) is how much power has been used in 1hr.

ENERGY(joules or kWh) = POWER(watts or kilowatts) X TIME(secs or hours).

COST(£)= NUMBER OF kWh X COST PER kWh.

Not all energy is used usefully some is wasted.

an appliance with a higher power will have a large current because it transfers a lot of energy(which comes from the current) in a short amount of time.

appliances convert energy to take new forms, some useful some not.

POWER(watts)= VOLTAGE(volts) X CURRENT(amps).

EFFICIENCY = USEFUL ENERGY / TOTAL ENERGY X 100%

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SANKEY DIAGRAMS

energy is always used (conserved), but not always converted

SD are energy transformation diagrams

the thicker an arrow the more energy it represents

the arrows can be proportional to the number of joules

energy wasted in both generation and distribution.

Power stations generate electricity but not very efficiently.

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SAVING ENERGY

As the population increases the demand for more energy is needed.

The fossil fuels we use are bad for the environment and will run out.

Reducing heat transfer stops energy being wasted.ie insulation, curtains,double glazing... you can also buy energy efficient appliances.

This can also save money- cost efficient.

Work places and the government also can reduce energy use by limiting excessive printing, cycling to work, offering grants for better insulation, improving public transport, alternative energy sources.

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ENERGY SOURCES AND POWER STATIONS

Electricity is generated by using primary energy sources to heat water in power stations - THERMAL POWER STATIONS.

energy is released by burning fuel to generate steam

the steam turns a turbine

a generator converts the movement of the turbine (kinetic energy) into electricity.

Non-Renewable energy sources : fossil fuels (coal, oil, gas) , nuclear fuels (uranium, plutonium)

FF release CO2 into the atmosphere, which contributes to global warming and climate change

coal and oil release sulphur dioxide = acid rain which harms sit and trees.

coal mining messes up the landscape

oil spillages cause serious environmental problems

produce a lot of energy, cheap

Renewable energy sources: wind, waves, tides, hydroelectric, biofuels, solar, geothermal.

Electricity is a secondary energy source as its produced by other things.Its convenient because it can be transmitted over the National Grid and can be used a number of ways.

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NUCLEAR ENERGY

In a Nuclear power station energy is produced in nuclear fission, where atoms in nuclear fuel (uranium) are split in two, releasing a lot of energy, this produces the heat which makes steam to turn the turbine and generator .

ADVANTAGE

produces a lot of energy

doesn't produce CO2

is relatively cheap

DISADVANTAGE

produces radioactive waste - very dangerous , difficult to dispose of as emits ionising radiation, stays radioactive for longtime

-exposure to ionising cells damages cells -high doses of it kill cells causing radiation sickness -lower doses damage cells which causes cancer.

radioactive waste puts people at risk of : -irradiation, being exposed without contact. -contamination, contacting radioactive waste.

it needs extra precautions

its supported by some people

overall cost is high

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RENEWABLE ENERGY SOURCES

WIND

wind turbines have generators inside so electricity is being generated directly

there no pollution

spoil the view , need a lot of land

very noisy

unreliable source

initial cost is quite high

no permanent damage to the landscape

SOLAR CELLS

solar cells generate electric directly from sunlight

initially expensive

often used in remote places

no pollution

very reliable in sunny countries (daytime)

energy is freenot practical to connect to the national grid

WAVE POWER

need lots of small wave powered turbines around coast

waves provide an up and down motion = can drive a turbine and generator

no pollution

hazard to boats

spoil the view

fairly reliable

initil costs are high but no fuel cost

not large scale material

TIDAL BARRAGES

are big dams built across river estuaries, with turbines in them

as tide comes in fills uptestuary, drives the turbines

source of energy is moon and sun

no pollution

prevents boat access

spoils the view

alters habitat

tides are pretty reliable, although height is a variable restricting the amount of energy produced

initial costs are high

no fuel cost

significant amount of energy

Seite 7

BIOFUELS, GEOTHERMAL AND HYDROELECTRICITY

Biofuels

renewable energy resource

used in thermal power stations (burnt)

used in some cars

solids gases or liquids

quickened natural source

carbon neutral

loss of habitat

Geothermal Energy

only possible where hot rocks are close to the surface

used in thermal power stations, water pumped down returns as steam to drive turbine

renewable energy

free

cost of drilling

very few places geographically possible

Hydroelectricity

requires flooding a valley by building a dam, rainwater caught allowed through turbines (drives them), drives generators

no pollution

big impact on environment:rotting vegetation(releases methane and CO2), loss of habitat

fairly reliable

initial cost are high

no fuel costs

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COMPARISON OF ENERGY RESOURCES

The world needs a reliable, affordable, large and environmentally friendly energy source

but no single source can provide all these needs:

Renewable resources struggle to produce enough output energy

^they're also free and won't run out but often rely on a variable.

Our Uranium and half of our coal (in the uk) is imported,= were not independent .Its also costly and creates CO2

fossil fuels are predicted to run out within 50 years

cost considerations:

-running costs, renewables usually have a low RC because theres no fuel

-setup costs, renewables often need bigger power stations for the same output

-nuclear power, hydroelectric dams and geothermal power stations also need a lot of engineering which is costly.

environmental considerations:

-if fuels used there will be waste pollution, CO2 and you'll be using up resources

-if rely on weather is often in a untouched place where its exposed

Seite 9

GENERATOR AND THE NATIONAL GRID

Generators

-Electromagnetic induction, creating a voltage and maybe a current in a conductor by moving a magnet in or near a coil of wire .

-When the magnet moves it changes the magnetic field inside the coil, the change creates a voltage and a current flow (if in a complete circuit).

-Generators use electromagnetic induction to turn kinetic energy (from turbines) to main electricity.

-For a bigger voltage and current, you can turn the magnet faster

-To move the magnet faster more energy to turn the turbine is needed, which uses up the primary source

-The bigger the current and voltage the more fuel is used

National Grid

-Its a network of pylons and cables that cover the whole of Britain.

-Transfers energy from power stations to homes and industry

-Enables power to be generated anywhere, and then be supplied anywhere else on the grid.

-To transmit a huge amount of power , either a high voltage or current is needed.

-High current loses a lot of energy through heat in the cables

-A really high voltage keeps the current very low (reducing energy loss) which is cheaper and more efficient

-Voltage is reduced before it reaches homes at 230V (mains supply voltage)