PHYS1211 part 1; energy intro, energy sources, nuclear energy

Transcription

1 PHYS1211 part 1; energy intro, energy sources, nuclear energy The syllabus is based on the textbook: Energy Its Use and the Environment, with some additional information provided in these slides Lecturer for the first half of the course: Prof. Michael Ashley, Room 137, Old Main Building, ph Dr. Oleh Klochan will be taking the last lecture in week 1, and all three lectures in week 2. These notes are available here: mcba/phys1211/ including a version with a white background to reduce the use of printer ink. A link to the Moodle website for the course is here NOTE: these notes will be changed (slightly) as the course goes on, so don t print them all out immediately!

2 Important points The laboratory handbook is available for collection from the First Year Lab, Level 1 Old Main Building. Read the course outline and Moodle site carefully, particularly with respect to the project and assessment. You will be giving a group presentation in the lab in one of weeks 5, 6, or 7. You will be handing in a group project report during the lab in week 7. Groups are normally three people in size.

3 Energy: introduction A brief introduction to the concept of energy Energy and society Energy in the news the big energy issues we are facing today: Climate change: is our energy usage wrecking our planet? Peak oil and oil prices: are we running out of one of the world s key energy resources? The food crisis: the struggle to provide the food energy for a growing world population. Energy and Australia: our place in the world, and how we are affected by coming changes.

4 Energy Energy is one of the most fundamental concepts in science This is true not only for physics, but also in... Chemistry: energy considerations determine which chemical reactions occur, and how fast they go. Biology: energy is fundamental for life; all living organisms have ways of extracting energy from their environment for their own use. Computation: there are fundamental limits to the minimum amount of energy required to process information.

5 Mechanical Energy Types of energy Kinetic (movement) and Potential (e.g., a compressed spring, or an object in a gravitational field) Energy. Thermal Energy Energy associated with heat. Chemical Energy Energy stored in the chemical structure of a substance. Electromagnetic Energy Energy in electric fields, or electromagnetic radiation (i.e., light). Nuclear Energy Energy contained in the atomic nucleus.

6 Law of Conservation of Energy Energy cannot be created or destroyed it can only be converted from one form to another, e.g., A pendulum converts between kinetic and potential energy as it swings An aircraft can convert between kinetic energy (proportional to the airspeed squared) and potential energy (proportional to altitude). I.e., you can dive to increase your speed. Note that there appear to be losses in the conversion; the energy isn t actually lost, but converted into other forms such as heat. Burning hydrocarbons (e.g., fossil fuels) produces thermal energy by extracting chemical energy. The resultant molecules (e.g., CO 2 and water) are more stable that the original hydrocarbons; you have to put energy in to reverse the process.

7 Relevance of energy to aviation An understanding of aircraft performance is aided by understanding energy conservation (e.g., flows between kinetic and potential energy). The aircraft engine is a device to convert chemical energy into kinetic energy. Energy efficiency, through clever engineering, reduces operating costs. With fossil fuel usage needing to be phased out, alternative fuels must be considered, e.g., biofuels, electricity, alternative aircraft designs, e.g., zeppelins.

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12 Annual global energy NOTE: energy is measured in Joules (more about this in the next lecture). Total annual energy requirement in food for the world population: J Total world energy production (coal, oil, nuclear, hydro etc.) J Total energy received from the Sun at the Earth s surface J This is about 6000 times our current energy needs.

13 Energy in society Energy is not just a concept used by scientists, e.g., Energy plays a major part in the national and global economy. Energy issues (such as climate change) are increasingly becoming central in politics. These issues affect our everyday lives e.g., high petrol prices, effects of climate change such as sea-level rise, drought, bushfires.

14 Energy and politics Climate change and energy supply have been major political issues recently, although less so than their seriousness deserves. Climate change and in particular the carbon tax, coal mining, and fracking, have been important political issues in Australia recently. Climate chance has been a significant factor in recent federal elections. Disagreements on climate change policy have been factors in leadership changes in both main political parties.

15 Energy and the economy Australia s exports energy to the value of $40 billion per year (mostly coal). Energy imports are about $20 billion per year (mostly oil). The Gillard-era carbon tax raised $4.2 billion per year. Six of the top 10 Fortune 500 largest companies are energy companies.

16 Energy issues in the news Climate change Caused by our use of fossil fuels for energy, producing greenhouse gases (particularly carbon dioxide, CO 2 ). The carbon tax introduced by the Australian Government. Recent energy-related disasters: Lac-Magantic crude-oil train explosion (Canada, 2013; 6 massive explosions killing 47 people). Power blackout (India, 2012; 670 million people, no power for 2 days). Fukushima nuclear plant (Japan, 2011; tsunami causes three core meltdowns; $300 billion in costs). BP Deepwater Horizon oil rig disaster (US, 2010; largest oil spill in US history; $80 billion in costs). Pikes River coal mine explosion (New Zealand, 2010; 29 deaths). Food crisis Food prices spiked in (global food crisis).

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18 The greenhouse effect The greenhouse effect warms the Earth by about 33 degrees celcius. Recent human-caused changes in greenhouse gas concentrations are changing the balance and causing increasing global temperatures. The Keeling Curve measures the CO 2 concentration in the atmosphere. Measurements were begun at Maula Loa Observatory (Hawaii) in Tasmania s Cape Grim is one of the best sites in the world to make the measurement. In February 2016, the Cape Grim average CO 2 levels exceeded 400 ppm (parts per million) for the first time, up from about 260 ppm pre-industrial. Without active, artificial, withdrawl of CO 2 from the atmosphere, CO 2 will not go below 400 ppm again for thousands of years. Without it the planet would be permanently frozen and uninhabitable.

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24 Melting arctic ice watch-arctic-oldest-sea-ice-disappear-over-last-25-years

25 Albedo effect Ice reflects sunlight and helps keep the Earth cool. Open ocean or land surfaces are much less reflective and absorb more solar energy. Melting ice means more future climate change. The CO2 has a direct effect on climate. But also a delayed effect due to melting ice.

26 Climate change: likely effects on Australia End to agriculture in the Murray-Darling Basin. Destruction of the Great Barrier Reef. Up to 9500 heatwave deaths per year. GDP collapse of 4.8%; a 7.8% fall in real wages. 5.5 million exposed to dengue virus. Political instability within neighbouring countries. (According to the Garnaut Report, 2008).

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28 Energy and Australia Australians use energy equivalent to about 6 tonnes of oil per person annually. Compare this with... America and Canada: about 8 toe/person/year. Europe and Japan: about 4 toe/person/year. China: about 1.3 toe/person/year. Australia is a major exporter of energy 4th worldwide after Russia, Saudi Arabia and Norway. World s largest exporter of coal.

29 Energy and Australia Australia has the fourth largest reserves of coal worldwide. Enough to last about 200 years at current production rates. But relatively lille oil and gas. Australia is a major producer and has large reserves of uranium.

30 Energy and Australia Unfortunately, coal the energy source we have in abundance is the dirtiest fuel in terms of its carbon pollution. Will we clean up our act by phasing out the use of coal? This could have significant impact on our economy. Can we work out how to use coal cleanly by means of carbon capture and storage? The technology is still in an early stage and unproven. Can we argue that Australia is a special case because of its coal dependence and too small to affect the global picture? This is what we argued in Kyoto however, it substantially weakens the case for a global agreement on emissions reduction. Should we be using our uranium reserves and adopting nuclear power on a significant scale?