Gas VS Geothermal

GeothermalV

Natural Gas

What is Geothermal energy?Geothermal energy is heat energy that comes from deep within the earth. The water is conveyed through a loop down in to the earth and then up again. The heat from the water is then transferred to another loop and turned into steam which then acts to run a turbine.

On a global scale the resource is so extensive that it can be considered a renewable energy source. Geothermal energy occurs in places where the earth’s temperature and pressure is high, with one planned to be based in Koroit in the coming years. Geothermal energy has been used in the past in Portland to heat the public pool.

What is Natural gas?Natural gas is actually a mixture of hydrocarbon gases. It consists mainly of methane (CH4), but also contains small amounts of ethane (C2H6), propane (C3H8) and butane (C4H10). Natural gas can be formed by two mechanisms: biogenic (a substance produced by life) and thermogenic (producing heat). The combustion of these gases release energy, and carbon dioxide and water are formed.

Natural gas is a non-renewable source which contributes about 20% of the world’s energy use. In Australia it can be found mainly in the basins of the Northwest Shelf, off the coast of Western Australia and in Bass Strait, just off Victoria. There is currently a local natural gas plant based just outside of Mortlake.

Natural Gas

Geothermal

ExtractionBoth geothermal energy and natural gas is extracted with the involvement of the ground. For geothermal energy water is pumped down through an injection well, from there it passes through joints in the hot rocks. It then rises to the surface through a recovery well and may be converted to steam or run through an exchange heater. The steam should then be directed through the turbines which spin to make electricity. The water which has potential energy is conveyed through the wells in the form of kinetic energy. As it passes through the turbine it now takes the form of mechanical energy. Natural gas is extracted through wells drilled directly into the porous layer of deposits which is generally about 3kms under the surface. It can however be gathered from depths much greater, up to 8kms. Natural gas can come from land deposits, such as in Russia, Algeria and Holland, or deposits located under the sea bottom, such as the North Sea. The potential energy in the ground is then transferred into kinetic energy after it passes up through the drilled wells.

TransportationBoth geothermal energy and natural gas can be transported for their use. Geothermal energy is transported via pipes, as in the water required to heat your home. The transportation of geothermal energy involves multiple, geographically dispersed wells for preheating the fluid, multiple separate conduits for conducting the fluid, a central thermal plant and multiple concentrating solar collectors to heat the fluid.Natural gas can be exported overseas in the form of liquefied natural gas (LNG). Australia has been a major exporter of liquefied natural gas (LNG) ever since it first exported to Japan in 1989. In 2002 Australia exported over 7.6 megatonnes of LNG to Japan and other over seas markets. Natural gas becomes a liquid at -161°C and is then better for shipping because it occupies 1/600th the space of natural gas. Natural gas can also be transported across country through a complex set of pipelines which are designed to transport the gas quickly and efficiently.

Geothermal Natural gas

UsesBoth geothermal energy and natural gas is commonly used in the home and industry for both heating and cooking. The main uses of geothermal energy is heating and air conditioning with 60% of all geothermal energy being used for this purpose. The main use of natural gas is manufacturing with 36% of all natural gas being used for this. Electricity generation is a close second with 32.5%.

Economic benefitsBoth geothermal energy and natural gas are cost effective energy alternatives.Geothermal energy is on par with the price of hydrocarbons. Hydrocarbons are organic compounds which consist entirely of hydrogen and carbon.Natural gas on the other hand is so cost effective because it is currently an abundant source. It is however a non-renewable source and consequently as the source begins to run out the price will rise.

Social impactsBoth geothermal energy and natural gas open the door to new employment opportunities for both skilled workers and those workers with professional degrees. Both energy options require many employees during the construction phase such as builders and other labourers. Both geothermal energy and natural gas require architects to design their plants and workers in the agricultural and environmental areas to take into account the environment around and under the plant. Engineers (electrical and mechanical) will be needed and so will electrical and heating experts. Natural gas uses gas pipelines and so they will also require both workers to construct and install the pipes as well as fencers to remove and reinstall fences. Both geothermal energy and natural gas plants will require workers to operate their plants also.

Environmental ImpactsBoth geothermal energy and natural gas are viewed as relatively clean energy options. Geothermal plants do not create high levels of emissions because they do not burn fossil fuels and as a result they produce less than 1% of the carbon dioxide emissions of a fossil fuel plant. Geothermal energy produces 97% less acid rain than the worst polluting fossil fuel. After the steam and water from a geothermal reservoir are used they are injected back into the earth. However natural gas is commonly viewed as the cleanest fossil fuel available. In comparison with emissions from coal, natural gas produces only half as much carbon dioxide and less than a third of the amount of nitrogen oxides. However pollutants and heat build up in the water used in natural gas boilers and is often discharged into lakes and rivers. Natural gas extraction and exploration can also drastically change and destroy natural habitats.

Mortlake Natural Gas PlantMortlake is the home of a new Origin Energy gas plant. This plant is a 550 MW gas-fired open cycle power station. This project involves an 83km underground natural gas transmission pipeline. The project was approved by the origin board on the 4th of July 2008. It is expected to be fully completed in the first half of 2011.

Koroit Geothermal ProjectThe planned Koroit Geothermal project has been instigated by the Hot Rocks Limited corporation. The temperatures measured by Hot Rocks Limited in oil and gas wells in the Koroit area are in excess of 130°C at a depth of 2,800m and geothermal resource temperatures of up to 160°C at 3500m depth are estimated from the results of temperature modelling studies.

Contribution to the greenhouse effectGeothermal energy makes very little contribution to the greenhouse effect. The production of geothermal energy produces few greenhouse gas emissions or any other form of pollutant. If it was to be used on a more widespread basis there is a good chance that it could go a long way to combating climate change.Natural gas on the other hand does make a contribution to the greenhouse effect. It’s biggest contribution is it’s principle component, methane. Methane has the ability to trap heat almost 21 times more effectively than carbon dioxide. This means that the more natural gas is used, the more methane is in the air and the more methane is in the air, the more the planet’s temperature will rise, hence the greenhouse effect. After it is burnt the methane is converted to CO2.

International AgreementsKyoto ProtocolThe Kyoto protocol is an international agreement which is linked to the United Nations Framework Convention on Climate Change (UNFCCC). It sets targets for 37 industrialized countries to meet for reducing greenhouse gas emissions. These are generally a 5% decrease in the period of 2008-2012 in comparison with the 1990 levels. Australia has signed as a member of the Kyoto protocol.

Bali RoadmapThe Bali Roadmap was adopted at the UNFCCC in Bali which included 10,000 participants and representatives from 180 countries. It consists of a number of forward-looking decisions that represent the various tracks that are essential to reaching a secure climate future.

Copenhagen ProtocolThe Copenhagen Protocol was adopted at the UNFCCC in Copenhagen in 2009 to prevent global warming and climate change. There were roughly 8,000 people in attendance, with about 170 countries represented.

BangkokAt the Bangkok UNFCCC an extension to Kyoto protocol was discussed, as they believed the 5% decrease by each of the 37 countries was working well to combat climate change.

National Climate Change StrategiesThe Australian Government has recently introduced a new Carbon Pollution Reduction Scheme (CPRS). This legalisation was passed in 2011 by the Julia Gillard Government after being twice rejected in August and December of 2009. The new national strategy is a cap-and-trade emissions trading scheme developed by the government to reduce greenhouse gas emissions. This means that there is now a tax on the carbon emissions. This has a profound impact on large-scale businesses and large-scale organisations who, through their business operations create a large amount of carbon emissions. This forces them to explore other energy alternatives which are renewable such as solar energy and geothermal energy. Both of these options are renewable and produce very little carbon emissions.

Victorian Climate Change StrategiesThe Victorian Government recognises that if Climate Change projections are correct then seal levels will rise over the next century so they have implemented a Future Coasts Program. This is a $13.5 million investment which will be used to produce information about the impacts of sea level rise along the Victorian Coast, with a focus on coastal erosion and flooding. It is hoped that this information will be used by coastal land managers and decision makers to be used when planning and managing the coastal areas. This program will help to ensure that structures are not being inappropriately built on the coast which will become threatened in the future due to the results of climate change.

Moyne Shire Climate Change StrategiesThe Moyne Shire is a member of the Cities for Climate Protection Australia Program. The Council began this program at it’s December 2002 meeting. Through this program the council selects five key milestones which they will work towards achieving.

1. Conduct an inventory and forecast for community and corporate (Council) greenhouse gas emissions.2. Establish emission reduction goals.3. Develop and adopt a Local Action Plan.4. Implement the Local Action Plan.5. Monitor and report on achievements.

The Moyne Shire achieved all of it’s milestones when it achieved it’s 5th and final milestone in late April of 2006. The Council is now working hard to ensure that it continues to meet these values and milestones in the future.

ReferencesTextbookDuke, Geoff (2001) Issues of Sustainability, Victorian Association for Environmental Education Inc, Carlton, Vic.

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