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Our energy fu ture: “renewable” or not?. OUR ENERGY FUTURE: “RENEWABLE” OR NOT. 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:

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Presentation to the Warrawee Probus Club

24 May 2013

Dr IanFalconer

School 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 NewcastleDr 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 15462-591



  • What is energy?
  • What is power
  • How do we measure energy & power
  • Energy in the 21st Century

What is energy?

  • Energy is that which allows us to do work (Physics definition)
  • Lift something up
  • Move from A to B
  • I’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

- and do many more really exciting things


Energy and power

  • Energy is measured in joules (Physics definition)
  • Power is the rate at which energy is supplied or consumed – how fast we use energy
  • Power is measured in joules per second – watts
  • A small electric radiator consumes electricity at the rate of 1,000 joule per second – 1,000 watts or 1 kilowatt – abbreviated 1 kW
  • Energy is also measured in kilowatt hours (kWh)
  • A 1 kW electric radiator, when operated for 1 hour, consumes 1 kilowatt hour of electrical energy.

Generating electricity: big numbers

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


Energy in the 21st Century

  • Starting in the late18th Century humanity began using coal - and in the 20th 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

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 coolingHome heating, air conditioners, refrigerators and freezers

CommunicationRadio, phones, TV, the internet


How important is electricity?


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, electricity


The world has real energy problems

  • We are fast running out of oil, natural gas, (and uranium)
  • Burning of fossil fuels generates carbon dioxide (CO2) For every tonne of oil or coalused for generating energy, around THREE tonnes of CO2 are generated
  • Per capita energy consumption increases as nations become wealthierThink 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)


Why do we need more and more energy:

standard of living




How long will it last?

Oil ~50-100 years

Natural gas ~60-100 years

Coal Several hundred years

Nuclear fission energy (U235 burners) 50 to ~100 years

Nuclear fission energy (breeder reactors)

Thousands of years

Solar, wind, geothermal, tidal energy Renewable

Fusion energy Millennia



Wind farm near Yass



  • 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 average



  • 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 transistor


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 collectors


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 tube

Electricity from large-scale solar thermal plants

A way of using the sun to provide a steady supply of electricity

Concentrating solar collector systems

  • Advantages:
  • Provides “baseload” electricity supply – to some extent
  • Disadvantages:
  • Cost is still rather large
  • Unreliable baseload

Parallel raysof sunlight

Parabolic reflector

Glass envelope

Absorber tube with selective surface


A “typical” modern solar thermal plant

Collector tube coated with selective absorber



Tank of molten salt



Superheated steam to turbines



  • 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 life

The pros and cons of nuclear power?

  • Advantages:
  • NOT a (direct) source of greenhouse gases
  • Little non-nuclear waste and pollution
  • Volume of nuclear waste small
  • Relatively low-cost
  • Disadvantages:
  • 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 years
  • Proliferation of nuclear weapons is a concern

Does nuclear have a future?


  • Waste 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 level
  • Fission products – the waste from the energy-generation process – are highly radioactive, but decay away to become harmless in around 1,000 years
  • Modern reactor designs are inherently less accident-prone
  • Thorium – 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.


Fusion energy powers the Sun


What is fusion?

  • The release of the energy stored in the nuclei of “heavy hydrogen” atoms - deuterium and tritium

Hydrogen: nucleus consists of 1 proton Deuterium: nucleus consists of 1 proton and 1 neutron Tritium: nucleus consists of 1 proton and 2 neutrons

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


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

Toroidal field produces

greater confinement



ITER – “the way”

International 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)



ITER – the next generation tokamakDesign completed – construction has just commenced





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



And, for further reading, I recommend:David JC MacKay Sustainable Energy — without the hot air

Available online as a FREE .pdf file from