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Gas versus Wind as an Energy Source - Stewart


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A Year 12 student enrolled in VCE Environmental Science Online produced this slideshow as school-assessed coursework for Unit 3.

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Gas versus Wind as an Energy Source - Stewart

  1. 1. Gas or Wind? Electricity can be generated by harnessing the energy in gas or wind. Both methods of generation have advantages and disadvantages, with the main difference being that wind is a renewable energy source. This means that it can be harnessed forever, whereas there is only a finite supply of natural gas. The biggest advantage of natural gas is that it can be used on demand; it is a reliable source of power.
  2. 2. The Uses of Natural Gas Natural gas is mainly used for electricity generation in gas power plants and as a fuel in transport. It can also be used for industrial processes and domestic purposes. This is achieved by the release of the chemical potential energy stored in the bonds of the CH4 molecules to heat energy and either used directly or converted again into electrical energy. Compressed Natural Gas Bus in SydneyMortlake Natural Gas Power Station
  3. 3. The Uses of Wind Energy The energy contained in the motion of wind is mainly used for electricity generation through large wind farms. This is done by tall wind turbines, which convert the kinetic energy of the wind to electrical energy. This can then be used in any application requiring electric power. Macarthur Wind Farm
  4. 4. Extraction Natural gas is extracted by drilling wells into the ground to natural reservoirs. This process consumes energy and money while in operation. To harness the energy of wind, a wind turbine must first be constructed. This is the main expense, although the turbines must be repaired and maintained to ensure longevity. A natural gas power station is cheaper initially but has relatively high operational costs. For example,the Mortlake Power Station only cost $640 million[1] whereas the Macarthur Wind Farm costed approx. $1 billion[2] to construct.
  5. 5. Transportation After extraction, natural gas is then pumped through high pressure pipelines to a gas plant. The pipes can be hundreds of kilometres long and are a significant investment in energy and money. This is similar to the conduction of the electricity produced by wind turbines, which require a large amount of high-voltage power lines to effectively distribute the power produced by multiple wind farms so as to increase the reliability of the power source. The efficiency of the gas pipes is greater than the power lines as some of the electrical energy is lost as heat.
  6. 6. Efficiency of Use The efficiency of natural gas for heating is about 90%. For electricity production, the efficiency is approximately 30%, although this can be increased when the heat produced by the plant is used in other industrial processes through cogeneration. This is less efficient than wind turbines, which are about 40%[3] efficient. If the natural gas plant did couple energy production with industrial processes, then it would be more efficient. However, it is important to remember that there are other advantages and disadvantages between the two electricity sources other than just their efficiency.
  7. 7. Modification of Land Use The land must be totally modified in order to be used as a gas plant, but this is in part mitigated by the smaller footprint. A wind farm requires a large area for all of the turbines and is requires a windy area. This is often near the sea and wind farms are known for ruining the aesthetics of beach panoramas. The large footprint can often be offset by combining land use with agriculture. In some cases, there is little modification of land use as turbines are often installed on pre-existing farms. A gas plant requires heavy infrastructure off-site, such as high-pressure pipes to transport the gas and drilling equipment to extract the gas. So although the actual power station is small, it can have detrimental effects that extend across continents. For example, the Macarthur Wind Farm extends across 5500 hectares of agricultural land[4] but the Mortlake Power Station only uses 20 hectares[5] for a comparable output of energy.
  8. 8. The Natural Greenhouse Effect
  9. 9. The Enhanced Greenhouse Effect The enhanced greenhouse effect is a warming of the Earth caused by the extra greenhouse gases in our atmosphere, which are present due to anthropogenic activity such as burning fossil fuels and removing carbon sinks such as forests. The enhanced greenhouse effect will cause climate change.
  10. 10. Impacts of Climate Change The projected impacts of climate change affect the ecology of the entire Earth. The average global temperature is expected to increase, which will lead to the extinction of many species of animals and plants, as well as threatening entire ecosystems such as reefs, deserts and rainforests. The Great Barrier Reef is already experiencing coral bleaching and the Golden Toad which previously inhabited a cloud forest near Costa Rica has been declared extinct. In addition to affecting animals, climate change is projected to increase the amount of severity of extreme weather events such as cyclones, thunderstorms and droughts. This places strain on the human population as it threatens water security and food production, as well as decreasing general health due to a shortage of quality food and an increased number of infections. The Golden Toad
  11. 11. Greenhouse Gas Emissions A wind farm produces no greenhouse gas, except in construction, maintenance and repair. This is in stark comparison to a gas plant, which not only produces greenhouse gases in construction, maintenance and repair but also during operation. The amount of CO2 produced by a gas power plant corresponds with the amount of power produced because natural gas is a fossil fuel and contains carbon. Because of this, a natural gas plant has a much greater contribution to the enhanced greenhouse effect than wind farms. For example, the Macarthur Wind Farm saves approximately 1.5 million tonnes of greenhouse gases per year.[6]
  12. 12. Environmental Impacts The main environmental impact of a natural gas plant is carbon dioxide emissions, whereas wind farms produce no emissions while in operation. The biggest environmental impact of wind farms is land use which can be reduced by sharing the land with agriculture. There is little concern about impacts upon bird species.[7] A wind farm is a much more environmentally friendly source of power than natural gas.
  13. 13. International Policies The Kyoto Protocol was the first major step towards globally reducing greenhouse gas emissions, setting legally-binding reduction targets. It was organised by a Framework Convention on Climate Change (FCCC). This is the main international treaty on climate change. The Intergovernmental Panel on Climate Change (IPCC) is the main body responsible for analysing and reporting on climate change, supporting the FCCC with scientific evidence.
  14. 14. National Policies Australia has implemented a fixed-price emissions trading scheme, incorrectly labelled the “carbon tax” and also a Mandatory Renewable Energy Target to increase the amount of renewable electricity generation to 20% by 2020[8]. The Macarthur Wind Farm is part of this initiative. In addition, the Government has also committed to a Clean Energy Future plan. All of these schemes aim to reduce our greenhouse gas emissions and/or reliance on fossil fuels..
  15. 15. State Policies The Victorian Greenhouse Strategy aims to: ● Increase renewable energy source ● Research carbon capture and removal opportunities ● Increase end-use efficiency The Future Coast program aims to enlighten stakeholders about the risks of Climate Change and enable them to take effective action to adapt. In addition, the state Government has issues legislation that requires businesses to improve their energy efficiency.
  16. 16. Local Council Policies The Cities for Climate Protection is an international program that aims to help local councils reduce their greenhouse gas emissions. The South Gippsland Shire Council has a Sustainability Strategy that focuses on becoming an advocate, leader and taking direct action to reduce our ecological footprint.[9] For example, they have implemented a Green Street Lighting Program which aims to reduce greenhouse gas emissions from street lamps.[10]
  17. 17. Final Notes Natural gas is an initially cheaper source of energy but a wind farm is more environmentally friendly in that it has less greenhouse gas emissions, as exemplified by Macarthur Wind Farm and Mortlake Power Station. There has been concern about climate change and legally binding policies have appeared in an attempt to limit the damage of global warming, although there is still a lot of room for improvement.
  18. 18. Bibliography (images) Sunset Wind Turbines sourced from Shutterstock on 25/3/14: Natural Gas Power Plant on first slide sourced from GDF SUEZ on 25/3/14: Compressed Natural Gas Bus, Sydney sourced from Wikipedia on 21/3/14: O500LE_CNG_bus_%28Sydney_Buses%29_01.jpg Mortlake Natural Gas Power Station sourced from Origin Energy on 21/3/14: Macarthur Wind Farm sourced from AGL on 21/3/14: n Natural Gas Extraction Techniques sourced from on 25/3/14: Greenhouse Effect diagram sourced from Hong Kong Observatory on 25/3/14: Golden Toad image sourced from Jaguar Ambassadors Gang on 25/3/14:
  19. 19. Bibliography (references) [1] “Mortlake Power Station – Wikipedia, the free encyclopedia”. Accessed on 27/3/14: [2] "AGL – The Project". AGL. Accessed on 27/3/14: [3] Duke, G. and Thornton, Lang and Donaldson “Issues of Sustainability” (2001) published by V.A.E.E., Carlton, Victoria. [4] “AGL – Location”. AGL. Accessed on 27/3/14: [5] “Mortlake Power Station – Wikipedia, the free encyclopedia” op. cit. [6] “AGL – The Project” op. cit. [7] “Wind turbine interactions with birds, bats, and their habitats: A summary of research results and priority questions.” National Wind Coordinating Committee (NWCC). 2010. Accessed on 27/3/14: [8] “The Renewable Energy Target (RET) Scheme.” Accessed on 27/3/14: [9] “South Gippsland Shire Council – Sustainability Stratagy”. Accessed on 27/3/14: [10] “South Gippsland Shire Council – Green Street Lighting Program.” Accessed on 27/3/14: