Transcript What is Electricity?

What is Electricity?
Electricity is the flow of charge. It is a secondary
energy source, because it is produced from primary
sources like coal, oil, and natural gas. Primary
sources are burned to turn water into steam, which
then turns a generator to create electricity.
•Oil
•Nuclear
•Coal
•Natural gas
•Wind
•Solar
•Geothermal
•Water:
hydroelectric,
wave and tidal
•Biomass – waste
material
Energy sources
which naturally
replace
themselves or
which can be
reused. They
will not run out.
Energy sources which
cannot be remade as
they are being used –
they will eventually run
out.
Case study: DRAX POWER STATION
•Located near to Selby Coal fields,
as coal is bulky and expensive to
transport.
•The Humber estuary provides
deep water for ships to carry
imported coal
•River Ouse provides water supply
•Located in an area of relatively
high demand, near to conurbations
of Yorkshire and Kingston upon
Hull
•Most coal is imported, but Drax
uses British Coal transported by
freight line
•M62 provides excellent transport
links.
Facts about Drax:
• Largest single electricity generator in
the UK, second largest in Europe
•In 2005, Drax produced 20.8 million
tonnes of CO2, largest producer of CO2
in UK
•Produces enough electricity to supply 4
million people.
•Between 2007 – 2012, £100 million is
being spent on reblading turbines to
improve efficiency.
Sketch map of area
•Hot water from the power station is used
to heat glass houses where out of
season vegetables are grown.
Case study: Connah’s Quay
•Located in North Wales, just
across the English border
•Banks of Dee estuary which
provides water supply for cooling
•High demand for electricity from
Liverpool and Manchester
Connah’s Quay
•Markets of Liverpool and Chester
within 20km
•Gas transported by pipeline from
Irish Sea Gas Fields to an offshore
terminal
•Large flat site
The Dash for Gas
In 1999, gas supplied 38% of the
UK’s electricity demand. Estimates
say that 60% of electricity will be
generated form natural gas in 2010.
Sketch map of area
In the 1990s, the government
agreed to cut C)2 emissions by 10%
by 2000, in the Kyoto agreement.
They did this by replacing coal fired
power stations with gas, as gas has
a higher calorific value and is
cleaner.
Case study: Heysham Nuclear Power Plant
•North West England
•Cheap, underdeveloped land
•Large flat area of land in sparsely populated area
which is unsuitable for agriculture
•Coastal site provides water for cooling
Heysham
•Rail links for transportation of uranium
24% of British energy is supplied by
nuclear. The labour government
made a pledge not to build new
nuclear stations and to
decommission old ones. Political
and economic pressures have
forced the government to make a U
turn, and nuclear is back on the
energy agenda.
How Nuclear Works
Sketch map of area
1.
Radioactive minerals such as
uranium are mined
2.
Atoms are split (fission) or joined
together (fusion) in nuclear reactors
3.
Reaction created heat
4.
Heat boils water, produces steam
5.
Steam turns turbines producing
electricity
6.
Electricity goes into National Grid
for distribution
Case study: Dinorwic HEP
Massive increases in
pressure required a surge
pond to be built high in the
mountains
A corrie lake was dammed
for water source. The level
rises and falls 34 metres
daily. It provides 7 million
cubic metres of water.
Water is pumped back up
to fill Marchlyn Mawr at
times of low electricity
demand
The generating system is
housed in a cavern as
large as St Paul’s
Cathedral. It is capable of
producing 1320 MW of
electricity in 12 seconds.
High rainfall in Snowdonia
mountains creates a
reliable water supply
Dinorwic
Sketch map of area
There are 16km of tunnels drilled
underground providing a drop of
500m. They are lined with vibration
resistant reinforced shotcrete.
Case study: Dinorwic HEP
How does it work?
1. Reservoir provides water supply
2. Sluice gates control water flow
3. Water flows downhill in pipes
4. Force of water spins turbines, generating
electricity
5. National grid distributes electricity
6. Water pumped back using off peak
surplus electricity.
Case study: Lambrigg Wind Farm, Cumbria
• Located in Cumbria, North West England
•Located on top of ridge, 260m above sea level – very
exposed site
•Borders Eastern edge of Lake District National Park
Sketch
map of
area
•It is positioned outside the National Park otherwise planning
permission would have been refused
•East of M6 motorway – good access for building and
maintenance.
•The turbines work with winds between the speeds of 5 and
25 km per hour.
•The turbines generate enough electricity to meet the average
annual needs of around 4,000 homes.
•The electricity produced by these turbines flows through
underground cables to a substation located on the site.
•The wind turbines have a lifespan of 20-25 years leaving no
trace of their existence and no legacy of pollution to pass on
to future generations.
Advantages;
•Capable of being developed commercially in UK
•Safe, clean, does not contribute to global warming or
acid rain
•Has only a small effect on local ecosystems
•Winds strongest in winter when electricity demand peaks
•After initial construction, electricity is relatively cheap
•Can provide a source of income for farmers and may
attract industry in isolated areas
Disadvantages;
•Expensive to build and maintain
•Wind doe s not blow all the time – unreliable
•Spoils scenic countryside areas
•Noisy and can interfere with radio and TV signals
•Inefficient – 7000 turbines needed to produce the power that 1 nuclear power station can produce
Fuel
Advantages
Disadvantages
Coal
• Reserves are likely to last for over
250 years.
•Improved efficiency has increased the
output per worker, allowed coal mining
with fewer accidents and made
conversion to electricity more
economic
•Coal can be used not only for making
electricity but also for heating and
making gas.
•Most easily accessible deposits have been used
up and production costs have risen
•Increasing competition form other types of
energy; coal has gone from producing 40% of UK
energy in 1970 to less than 30% in 2000.
•Combustion of coal releases CO2 contributing to
global warming, and SO2 contributing to acid rain
•Coal mining can be dangerous and exposed
mining often harms the environment.
Gas
•High calorific value
•More efficient to burn, easier to transport and distribute by pipeline
and tanker than coal.
•Cleaner, cheaper and less harmful to the environment than coal.
•Safer than nuclear.
•Increasingly the most popular of all non renewable sources; during
1990s most new power stations were gas and many coal were
converted to gas.
•Releases CO2
and SO2
contributing to
global warming
and acid rain
•Will eventually run
out
Nuclear
•Very small amounts of raw
material needed – 50 tonnes
of uranium per year compared
to 540 tonnes of coal per hour
•Safeguard make accident
risk minimal
•Reserved of uranium will last
much longer than cal and gas
•Waste is limited and is stored
underground
•Nuclear power contributes
less to greenhouse effect and
acid rain
•Not clear how safe nuclear power is:
several serious leaks at Sellafield
•One serious accident may kill many and
ruin land for hundreds of years
•Irish Sea increasingly contaminated
•Potential health risks: High incidences of
leukaemia around Sellafield and DounRay
are linked to proximity to nuclear stations
•Nuclear waste can remain radioactive for
150 years
•Cost of decommissioning power stations in
very high; the first was in 1989 at Berkely.
Hydro-Electric
Power (HEP)
•Renewable and often
produced in highland areas
where population is sparse
•Relatively cheap and
produces only limited pollution
•Dams built to store water for
HEP production can reduce
risks of water shortages and
floods.
•Dams are very expensive to build
•Large areas of farmland and wildlife habitat
may be flooded forcing people and animals
to move
•Unattractive pylons cause visual pollution
•Possibility of dam collapsing
•Silt which was previously spread out over
farm land will be deposited in the lake.
•When an area is flooded, the decaying
vegetation can release methane and CO2,
greenhouse gases.
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Coal:
Sulphur scrubbers installed to remove sulphur from emissions at a cost of £1
million
Freight lines to minimise environmental impacts of transportation
Temperature of water returning to river is monitored and controlled
Strict controls on open cast mining
Gas
New gas stations have improved thermal efficiency – produce 50% less CO2
than coal fired station
People friendly – education centres on site
Cooling water is only abstracted and returned from River Dee at specific times,
around full tide, to cause as little environmental damage as possible.
Use of hybrid cooling towers to reduce pollution of local areas and reduce
impact of “microclimates” they create
Nuclear
Build plants in sparsely populated areas away from large cities
Transport uranium in huge steel flasks with high safety requirements
Constant safety checks, especially on water returning to sea
HEP
Dam built in remote area to reduce human impact
Main power plant, service tunnels and pipe work all located underground to
minimise visual impact on National Park.
Surge pond created to minimise risk of plant failure or flooding.
Wind
Turbines positioned below ridge summit so blades cannot be seen from Cumbria
Away from villages and farms so noise pollution does not disturb
Support of locals encouraged; turbines named after local school children who
won a competition at their primary school.