2 Presentation to the Warrawee Probus Club 24 May 2013 Dr Ian Falconer School of Physics University of Sydney Some of the slides shown in this presentation were provided by ID: 741984
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Our energy
fu
ture: “renewable” or not?
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Presentation to the Warrawee
Probus
Club
24 May 2013Dr Ian
FalconerSchool of Physics, University of Sydney Some of the slides shown in this presentation were provided by: Dr Joe Khachan, University of Sydney Professor John O’Connor, University of Newcastle
Dr John How, ITER Organization Much material for this presentation was taken from: David JC MacKay Sustainable Energy — without the hot air (2009) UIT Cambridge Manfred Lenzen (2010) “ Current State of Development of Electricity-Generating Technologies: A Literature Review” Energies 15 462-591
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OUR ENERGY FUTURE:
“RENEWABLE” OR NOTSlide4
ENERGY
What is energy?Why energy is necessary to keep our 21st
Century civilization
running?Why it is important think about our sources of energy? And where will it come from in the future?
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ENERGY AND POWER
What is energy? What is power
How do we measure energy & power Energy in the 21st Century
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Energy is that which allows us to do work
(Physics definition)
Lift something up
Move from A to BI’m lifting this weight from the energy I get from the food I eat Over the past 200-odd years in particular humanity has used the energy stored in coal and oil to extend the work we do beyond that we are capable of using muscle energy alone
What is energy?
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- and do many more really exciting thingsSlide7
Energy is measured in
joules
(Physics definition)Power is the rate at which energy is supplied or
consumed – how fast we use energyPower is measured in joules per second – wattsA small electric radiator consumes electricity at the rate of 1,000 joule per second – 1,000 watts or 1 kilowatt – abbreviated 1 kWEnergy is also measured in kilowatt hours (kWh)
A 1 kW electric radiator, when operated for 1 hour,
consumes 1 kilowatt hour of electrical energy. Energy and power
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Liddell power station (Muswellbrook)
4 x 500 MW generators (steam turbine alternators)
Total installed capacity: 2 GW
1 megawatt (1 MW) = 1,000 kW = 1,000,000 watt
1 gigawatt (1 GW) = 1,000,000 kW = 1,000,000,000 watt
Australia’s installed electrical capacity (2008-2009): 51GW
G
enerating electricity: big numbersSlide9
Starting in the late18th Century humanity began using coal - and
in the 20
th
Century, oil – to extend what could be done by muscle power alone.
This required the development of many ingenious bits of machinery to replace muscle power - and do much more
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Mechanical gadgets
Food mixers, electric drills, vacuum cleaners, washing machines – all sorts of
labour-saving
devices
Transport
Electric trains, cars, aircraft, giant and fast cargo ships
Heating and cooling
Home heating, air conditioners, refrigerators and freezers
Communication
Radio, phones, TV, the internet
Energy in the 21
st
CenturySlide10
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VERY
Primary energy sources – the ultimate source of our energy:
Coal, oil, gas, wind, the sun, uranium,
thorium, and
– for fusion – deuterium, and lithium
Secondary energy sources – the energy we use directly:
Coal, oil, gas, hydrogen, electricityHow important is electricity?Slide11
THE ENERGY PROBLEM
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We are fast running out of oil, natural gas, (and uranium)
Burning of fossil fuels generates carbon dioxide (CO
2
)
For every tonne of oil or coal used for generating energy, around THREE tonnes of CO2 are generated Per capita energy consumption increases as nations become wealthier
Think about India and China For these reasons, we URGENTLY need an energy source to replace fossil fuels (and it must be “portable” - like petrol – so it can be used in cars and trucks)
12The world has real energy problemsSlide13
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Why do we need more and more energy:
standard of livingSlide14
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World
Why do we need more and more energy:
standard of livingSlide15
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World
AUSTRALIA
Why do we need more and more energy:
standard of livingSlide16
Oil ~50-100 years
Natural gas ~60-100 years
Coal Several hundred years
Nuclear fission energy (U235
burners) 50 to ~100 yearsNuclear fission energy (breeder reactors) Thousands of years Solar, wind, geothermal, tidal energy Renewable
Fusion energy Millennia
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How long will it last?Slide17
WHICH ENERGY SOURCE?
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Wind
Wind farm near YassSlide19
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Advantages
:
Wind is cheap
Disadvantages:
Wind is not a steady source of electricity: wind speed is highly variable
Suitable (low cost) sites are limited
Cairngorm mean wind speed in metres per second, during six months of 2006. Red line: daily average Turquoise line: half-hourly averageSlide20
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Installed wind generating capacity in Australia: 2.6 GW (2012)Slide21
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Solar
photovoltaicsSlide22
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Advantages:
Produces electricity directly
Ideal for remote locations
Disadvantages:
Output depends on instantaneous amount of sunlight falling on surface
Output depends on time of day (very much) cloud cover, and season of year Cost is still rather large – but falling rapidly
A photovoltaic cell is similar in construction to a transistorSlide23
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Solar ThermalSlide24
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Solar hot water
“A no-brainer” David McKay, author,
Sustainable
Energy — without the hot air
Water in pipes underneath flat black plates is heated by sunlight absorbed by the black plates.The plates are coated with a selective surface – a coating that strongly absorbs the visible sunlight, but only weakly emits infra-red (heat) radiation.Maximum energy is absorbed, but not much radiated by the hot plates.
Flat plate solar collectorsSlide25
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Evacuated tube solar collectors
A double-walled glass “tube” is evacuated – heat can only be transferred though a vacuum as radiation
The inner surface of the glass is coated with a selective absorbing material
Heat absorbed by this surface is transferred to water inside the tubeSlide26
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Glass envelope
Parallel rays
of sunlight
Parabolic reflector
Absorber tube
with selective surface
Electricity from large-scale solar thermal plants
A way of using the sun to provide a steady supply of electricity
Advantages:
Provides “
baseload
”
electricity supply
– to some extent
Disadvantages:
Cost is still rather large
Unreliable
baseload
Concentrating solar collector systemsSlide27
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A “typical” modern solar thermal plant
Sunlight
Reflector
Collector tube coated with selective absorber
Heat
exchanger
Heat
exchanger
Tank of molten salt
Superheated steam
to turbinesSlide28
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Geothermal
Water pumped deep underground in to hot rock is converted to steam, which rises up another drill hole to drive an electrical generator
Advantages:
Clean, low environmental impact
Disadvantages:
Rock cools, so that the plant has a limited lifeSlide30
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N
uclearSlide31
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Advantages:
NOT a (direct) source of greenhouse gases
Little non-nuclear waste and pollution
Volume of nuclear waste smallRelatively low-costDisadvantages:Nuclear reactors are regarded as “unsafe” as nuclear accidents, although infrequent, have serious and widespread consequences
Radioactive waste remains a hazard for many years
* Plutonium and other “transuranics” for hundreds and thousands of years * Fission products have decayed to a “harmless level in around 1,000 yearsProliferation of nuclear weapons is a concernThe pros and cons of nuclear power?Slide32
32Waste disposal is a political problem, not a technical problem
Plutonium can be separated from other waste and be “burnt” in a reactor to produce even more nuclear energy
Most waste is low levelFission products – the waste from the energy-generation process – are highly radioactive, but decay away to become harmless in around 1,000 yearsModern reactor designs are inherently less accident-proneThorium – another “fissile” element – can also be used to fuel a reactor. Thorium cannot be used in nuclear weapons, and thorium reactors are inherently safer than uranium reactors.
Does nuclear have a future?YESSlide33
Fusion energy powers the Sun
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FusionSlide34
Chemically these
isotopes
are the same, but the deuterium and
tritium store considerable energy in their nuclei – this is the energy that holds the nuclei together
The release of the energy stored in the nuclei of “heavy
hydrogen” atoms - deuterium and tritiumWhat is fusion?
Hydrogen: nucleus consists of
1 proton
Deuterium: nucleus consists of
1 proton
and
1 neutron
Tritium: nucleus consists of
1 proton
and
2 neutrons
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The Most Promising Fusion Reaction
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How do we harness fusion energy?
Bang a deuterium nucleus and a tritium nucleus
HARD together so they “fuse”
To make lots atoms move really fast a mixture of
deuterium and tritium gases must be heated
to a very high temperature if the nuclei are to “fuse”
– about 100 million degrees! Under these conditions all the atoms are ionized and form a PLASMA These high temperatures can only be achieved if the gases are contained in a “bottle” constructed from a really strong magnetic field And a high density of colliding nuclei is required if we are to get more fusion energy from the reactor
than we put into it
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Toroidal field produces
greater confinement
A TOKAMAK
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ITER – “the way”
I
nternational
Thermonuclear Experimental Reactor
An international project to produce a prototype fusion reactor
ITER partners
European Union
Japan China Russian Federation USA South Korea India (and possibly Brazil – and Kazakhstan)
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ITER
Person
ITER – the next generation tokamak
Design completed – construction has just commenced
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SUMMARY
HOW MUCH WILL WE PAY?
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What will clean energy cost?Slide42
External costs:
“estimated” impact costs to the environment, public and worker health.
Prospects for fusion electricity
, I. Cook et al. Fus. Eng. & Des. 63-34, pp25-33, 2002
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THAT’S ALL, FOLK
And, for further reading, I recommend:
David JC MacKay
Sustainable Energy — without the hot air
Available online as a FREE .
pdf
file from www.withouthotair.com.
www.withouthotair.com