Gas versus Wind as an Energy Source - Jess


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A Year 12 student from Hawkesdale P12 College produced this slideshow as school assessed coursework for Unit 3 VCE Environmental Science.

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Gas versus Wind as an Energy Source - Jess

  1. 1. SAC 1B. Environmental Science A comparison of a fossil fuel and a non-fossil energy source Natural Gas VS. Wind Power Jess Figure 2. Turbines at the Macarthur Wind Farm. Figure 1. Mortlake Gas Plant.
  2. 2. Fossil fuel and a non-fossil energy sources Both fossil fuel and a non-fossil energy sources have pro’s and con’s. Fossil fuels, in this case natural gas, is energy dense and it’s production is non-stop, making it reliable. However it is a non-renewable source and supplies can only be replenished over very long periods of geological time. Natural gas is exhaustible, as we are using it at a much faster rate than it is being replaced. Alternatively is non-fossil energy sources, in this case wind power. Wind power is a renewable energy resource, meaning there is a never-ending supply, during production there is no releases of carbon dioxide emissions. However, wind power is unreliable as not every day is going to be windy. The Macarthur wind farm cost 1.4 billion dollars to build, and during the building process carbon dioxide was released into the atmosphere from transport and construction. Further comparisons of wind and natural gas will be shown and evaluated in this presentation.
  3. 3. Location & Accessibility The Mortlake Gas Plant is located in South-West Victoria, 12km west of Mortlake, approximately 110km north east of Portland as shown in figure 3. The Macarthur Wind Farm is also located in South-West Victoria, situated between Warrnambool and Hamilton, as shown in figure 4. The Mortlake gas plant is positioned close to high voltage power lines which run from the Latrobe Valley in Gippsland west to Portland. The plant is located 83km from the offshore gas refinery which extracts the natural gas from the Bass Strait basin (a map of this is shown further on). The wind farm is in a windy location which is ideal for the rotation of the blades of the 140 turbines, it is also located closely to the high voltage power lines. Figure 3. Location of the Mortlake Gas Plant Figure 4. Location of the Macarthur Wind Farm
  4. 4. Site map of the Macarthur Wind Farm Figure 5. Site map of the Macarthur Wind farm, wind turbines are represented by the blue circles.
  5. 5. Reliability The gas plant is very reliable as the generators which create the power can be initiated immediately when it is needed. Operating at full capacity, the power station generates 550 MW of power to the National Electricity Market (NEM). The wind farm however, is much less reliable in terms of power generation as a windy day is needed for the blades to turn the shaft to produce electricity. In order to determine the appropriateness of using wind power on a specific site, thorough analysis of the site is required. Figure 6. a typical large gas turbine.
  6. 6. Gas VS. Wind (Fossil fuels VS. Non-fossil fuels) What is it? Natural gas is a flammable gas, consisting mostly of methane and other hydrocarbons, occurring naturally underground and is used as fuel. Wind is a form of solar energy and is defined as: the perceptible natural movement of air, especially in the form of a current of air blowing from a particular direction. How is it formed? Natural gas is formed when the remains of decayed plant/animal matter is compressed under the earth’s crust for millions of years, hence the name “fossil fuel”. Wind is formed when sunlight falls unevenly on the Earth, heating the air unevenly. The warm air rises and cool air moves in to replace it. This circulation of air from cool areas to warm areas produces wind, as shown in figure 7. Figure 7. Circulation of hot and cold air.
  7. 7. Where might you find this energy source? Natural Gas reserves often occurs with oil reserves underground. Wind is found universally as it forms when sunlight falls unevenly on the Earth, heating the air unevenly. Gas VS. Wind (Fossil fuels VS. Non-fossil fuels), continued. Figure 8. Amounts of worldwide Natural Gas Reserves in trillion cubic metres (2008). How abundant and accessible is it? Figure 8 shows the locations of natural gas reserves around the world at the end of 2008. Australia alone has about 1% of the world’s reserves of natural gas. The world’s largest natural gas reserves are located in Russia, the second largest reserves are found in the Middle- East. Wind is plentiful, however the speed/strength of the wind varies according to location.
  8. 8. Extraction How is it extracted? Natural gas is most commonly extracted by drilling vertically from the Earth’s surface. As shown in figure 9. From a single vertical drill, the well is limited to the gas reserves it encounters. Raw gas is extracted from underwater underground, using the remotely operated Thylacine platform and brought to the shore via offshore and onshore pipelines to the gas processing plant located north of Port Campbell. This is then piped to Mortlake’s Power plant via an 83km underground pipeline. Wind is not extracted as it is present in the atmosphere. Wind is harnessed to spin blades of the turbine. Figure 10. Spinning turbines in Minnesota, USA Figure 9. The extraction of natural gas.
  9. 9. Extraction (continued) What energy conversions are involved? Chemical energy from natural gas from natural gas can be transformed into heat energy (process of burning the fuel). The heat energy can be converted into kinetic energy by gas turbines or into electrical energy by generators. Wind power How efficient are these conversions? Natural gas has an overall energy efficiency of approximately 30% for electricity production and 90% for heating. The use of wind to produce electricity under current methods is approximately 40% efficient in terms of energy. How much land is used? 120 hectares is used and Origin is the sole user of the land. 10,000 hectares is used for the wind farm. Unlike the gas plant, the wind farm is a dual use site (see figure 11) where farmers are paid by AGL for the turbines on their land and they can raise sheep and cattle on the very same land. Dual use is an economic advantage, as later discussed. Figure 11. The Macarthur Wind farm is a dual use site, both the turbines and cattle can be seen in this photograph.
  10. 10. Transport Can it be transported and how? Raw gas is extracted from underwater underground, using the remotely operated Thylacine platform (figure 12) and brought to the shore via offshore and onshore pipelines to the gas processing plant located north of Port Campbell. This is then piped to Mortlake’s Power plant via an 83km underground pipeline. Figure 13 shows a map of gas pipelines in the region, including the pipeline running from the Otway Gas plant to Mortlake. Wind does not need to be transported as it is an onsite resource. However parts for the turbines such as the blades, towers and the turbines themselves had to be transported by vehicles to the site. How efficient is this transport? The transportation system for natural gas consists of a complex network of pipelines, designed to quickly and efficiently transport natural gas from its origin, to areas of high natural gas demand. Wind is extremely efficient as no transportation is required. Figure 12. The remotely operated Thylacine platform Figure 13. Gas pipelines in the SW Victorian region
  11. 11. Use How is this fuel/energy source used? Natural gas is used in homes for heating and cooking, and by industry for heating and manufacturing. The Mortlake power station uses natural gas to operate the 2 turbines. Air and gas are mixed together and combusted within the turbine, this force causes the rotor of the turbine to turn. The turbine is coupled to a generator, and as the turbine turns the generator rotates and creates electricity. Electricity from the generator is then passed through a transformer and uploaded to the grid. Wind energy is primarily used for electricity generation, both onsite and for transport to the grid. Wind energy is also used to pump bore water particularly in rural areas. Wind turbines come in 2 basic forms, those with horizontal axis and those with vertical axis. Wind turbines are made up of a propeller that spins when the wind is caught by the blades. These spinning blades drive a shaft which is connected to a to a mechanical device such as an electric generator. A simplified diagram of a wind turbine is shown in figure 14. What percentage of Australian energy does it provide? Natural gas constitutes about 20% of Australia’s energy use. In October 2011, wind power generated 6432 gigawatt hours (GWh) of electricity accounting for 2.4% of Australia's total electricity demand and 21.9% of total renewable energy supply. Figure 14. Diagram of a wind turbine motor.
  12. 12. Economic Impacts What financial advantages an disadvantages are there for each energy source? The Mortlake Gas Plant is a financial advantage for Origin, as the more plants they possess the more electricity they can generate which creates profit for the company. On a local economic scale- the plant provided construction jobs which would have for the duration, boosted expenditure in Mortlake. Shops and local businesses would have benefitted economically while the plant was being constructed. The Macarthur Wind Farm also created many jobs in the construction process, which would have also given local businesses opportunities to sell to workers passing through. Both sites provided positive economic impacts during construction, through creating paying jobs. After completion, the gas plant only employs 8 workers, while the wind farm employs 20 workers. Furthermore, the wind farm is a dual use site, which means that sheep and cattle can roam in the paddocks where turbines are present. Farmers with turbines on their land are payed five-thousand dollars for each turbine annually. Farmers have two sources of income, payments from AGL and their own livestock. Negative economic impacts on both sides, includes the conditions of the roads during and after construction. Both the wind farm and gas plant required many parts to be delivered to their specific sites. With many heavy vehicles carrying heavy loads, damage to roads was inevitable. Damaged roads are repaired by local councils which cost money, that could have been spent elsewhere if the construction of the wind farm and gas plant never happened.
  13. 13. Social Impacts What social advantages or disadvantages are there for each energy source? The Macarthur Wind provided generous grants to clubs within the community, including the Hawkesdale Macarthur Football Netball Club. The wind farm also currently employs 20 workers, which is more than the Mortlake power plants 8 workers. More employment, contributes economically and also socially, as the more people there are working in the community the more interaction there is amongst these workers and clubs and businesses in the community, such as with local businesses and FNC’s. Less interactions between the workers at the Mortlake Gas plant occurs due to the fact that there are less workers. In advance to the construction, during construction and on completion locals in the Hawkesdale/Macarthur area have been divided on the Wind Farm. Some people were angry with the building of the wind farm near their properties, as many people would rather live without a wind farm then having one a few kilometres from them. Furthermore some farmers believe that the turbines devalue land as buyers are not want to buy a property with 140 turbines as a backdrop. Protests also took place at the opening of the of the wind farm. Protests took place due to health impacts of wind farms. This is a negative social impact as it divided the community. In contrast to the wind farm, the gas plant’s construction did not divide the community nor does the operation of the plant. This is a positive social impact as there is no opposition in the local community to the plant.
  14. 14. Environmental Impacts What environmental advantages or disadvantages are there for each energy source? Although natural gas is considered a “clean” energy resource compared to oil and coal, both construction and the running of the plant creates pollution which contributes to the enhanced greenhouse effect and global warming. On the other hand, while the wind farm is running, no emissions are released into the atmosphere as wind is a form of kinetic energy, and this kinetic energy drives the shaft in the turbine which is connected to the generator. Transport and construction releases CO2 into the atmosphere, as fuel is used to run vehicles and heavy machinery. Construction for both sites required the clearing of land- which strips away vegetation and any species living amongst it. During the construction of the wind farm, CO2 emissions were released into the atmosphere. However once the wind farm was completed, the turbines generation of power “pays back” emissions created during construction, whereas the gas plant continues to release emissions while it is running. The wind farm took six months to become carbon neutral. The gas plant cleared a 120 hectares, and the wind farm cleared smaller areas of land to construct the turbines, however 140 cleared zones and management sites adds up to a substantial proportion of land being cleared. In addition, the towering turbines may obstruct native birds and bats flight paths.
  15. 15. The Greenhouse Effect The greenhouse effect is a natural process that warms the Earth’s surface. When the Sun’s energy reaches the Earth’s atmosphere, some of it is reflected back to space and the rest is absorbed and re-radiated. Greenhouse gases include water vapour, carbon dioxide, methane, nitrous oxide, ozone and some artificial chemicals such as chlorofluorocarbons (CFCs), which are man made. Figure 15. a simplified diagram illustrating the natural greenhouse effect.
  16. 16. The Enhanced Greenhouse Effect The Enhanced Greenhouse Effect is defined as: The increase in the natural greenhouse effect resulting from increases in atmospheric concentrations of GHGs due to emissions from human activities. The operation of the Mortlake gas plant directly contributes to the enhanced greenhouse effect as emissions are released into the atmosphere which contributes to the trapping of heat in our atmosphere. Figure 16 shows the process of the natural greenhouse effect and how human influences, such as the burning of natural gas and other fossil fuels, impacts on this natural process. Figure 16. The Enhanced Greenhouse Effect
  17. 17. Contribution to Greenhouse Effect Natural gas is made up of a mixture of hydrocarbons mostly methane, and small amounts of ethane, propane and butane. The combustion of methane releases energy, and forms carbon dioxide and water. The combustion of natural gas is a relatively clean process compared to the combustion of other fossil fuels which produces pollutants such as sulfur dioxide, nitrous oxide and carbon dioxide. The Mortlake gas plant contributes to the enhanced greenhouse effect as pollutants are released from the burning of natural gas, these pollutants are trapping excess heat. This excess heat being trapped is leading to global warming, as the heat is trapped in the atmosphere. Wind power however does not produce any pollutants, during operation. Greenhouse gases were released from construction of both sites. In the USA natural gas combustion accounts for about 16% of total US greenhouse gas emissions. Figure 17 on the next slide shows the intensity of emissions by several energy sources, including both natural gas and wind. Emissions produced by the combustion of natural gas are lower than coal and oil, but wind is a better alternative to this.
  18. 18. Figure 17. A bar graph of amounts of emission produced for certain energy resources. Note that Natural gas is higher (500 tonnes CO2 e2/GWh) than wind (26 tonnes CO2 e2/GWh)
  19. 19. International Agreements The Kyoto Protocol is an international treaty that sets binding obligations on industrialized countries to reduce emissions of greenhouse gases. Targets for the first commitment period The targets for the first commitment period of the Kyoto Protocol cover emissions of the six main greenhouse gases, namely: • Carbon dioxide (CO2); • Methane (CH4); • Nitrous oxide (N2O); • Hydrofluorocarbons (HFCs); • Perfluorocarbons (PFCs); and • Sulphur hexafluoride (SF6)
  20. 20. National Strategies Australia began addressing the enhanced greenhouse effect & its consequences in a formal way through the National Greenhouse Response Strategy, which was sanctioned in 1992. Key elements of the strategy were to limit greenhouse gas emissions, conserve and enhance greenhouse gas sinks, improve knowledge and understanding of the greenhouse effect and prepare for the potential impact of climate change. To achieve this, priority areas were identified, including: • Preparation of a National Greenhouse Gas Inventory (NGGI) of emissions and sinks. • Development of mechanisms that involve the community in strategy involvement and implementation. • Establishment of a National Greenhouse Advisory panel. • Development of a variety of strategies which encourage effective use of energy. • Continued research into energy-efficiency programs.
  21. 21. State Policies for Victoria In 2002, the Victorian Greenhouse Strategy was released and outlined a number of ways to reduce emissions in Victoria, these include: • Increasing end-use energy efficiency. • Increasing the use of renewable energy sources for the supply of electricity and transport fuels. • Exploring opportunities for carbon capture and storage. • Investigating further opportunities for large-scale clean energy projects and new vehicle technologies, including hybrid buses and energy efficient street lighting.
  22. 22. Local Strategies Many Australian local government councils have made a commitment to reduce their generation of greenhouse gas emissions. These councils are participating in the Cities for Climate Protection (CCP) program. CCP is a program that assists local governments achieve sustainable reductions in greenhouse gas emissions. Local strategies also include the strategies locals themselves use in order to lower greenhouse gas emissions, and their electricity bills. Some of these strategies include: • Converting old incandescent light globes to fluorescent light globes- incandescent light globes lose energy as heat and are less efficient than the fluorescent light globes. • Turning off lights and appliances when leaving a room. • Using cold water in washing machines, rather than hot. Also drying clothes outside rather than in a dryer.
  23. 23. Evaluation After visiting both a fossil fuel resource (Mortlake Gas Plant) and a Non-fossil fuel resource (Macarthur Wind farm) it can be determined that both energy resources exhibit both positive and negative impacts on the environment, economy and the surrounding communities. As both resources have detrimental and beneficial traits, it is difficult to label one as a better energy resource than the other. For example, the Mortlake Gas plant was relatively cheap to build compared to the Macarthur Wind Farm. Although cheap initially, the gas plants operation releases CO2 emissions into the atmosphere which is contributing to the enhanced greenhouse effect which is causing the gradual warming of our planet. Alternatively is the Macarthur Wind Farm, which costed a staggering 1.4 billion dollars to build, construction and the transport of supplies released a considerable amount of CO2 into the atmosphere. However after a six months, the turbines “payed back” emissions and became carbon neutral. To formally label one energy source as better than the other, individual opinions need to be taken into account. If a person wants a sustainable future for their children and grandchildren, they would say that wind power is the way to go. If a person is looking for a cheap short term energy supply, they are going to favour natural gas and other fossil fuels. In the short term, natural gas is a suitable resource as it is cleaner compared to the combustion of oil and coal, making it environmentally better. Socially, it is better also as there is not as much reluctance to gas plants as there is to wind farms, and economically as gas plants are cheaper to build. In the long term however, wind power is better- it produces no carbon emissions once production starts, although costly to construct the pro’s far outweigh the cons. Figure 17. The Macarthur Wind Farm
  24. 24. References/Bibliography farm-opening/