SAC 1B. Environmental Science
A comparison of a fossil fuel and a non-fossil energy source
Natural Gas VS. Wind Power
Figure 2. Turbines at the
Macarthur Wind Farm.
Figure 1. Mortlake Gas Plant.
Fossil fuel and a non-fossil energy
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
Further comparisons of wind and natural gas will be shown and
evaluated in this presentation.
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
Site map of the Macarthur Wind Farm
Figure 5. Site map of the Macarthur Wind
farm, wind turbines are represented by the
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.
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
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
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.
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
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.
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
Figure 10. Spinning turbines in
Figure 9. The extraction of natural gas.
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
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
Figure 13. Gas pipelines in the SW Victorian region
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.
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
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.
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.
What environmental advantages or disadvantages are there for each energy
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.
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
dioxide, methane, nitrous
oxide, ozone and some artificial
chemicals such as
(CFCs), which are man made.
Figure 15. a simplified diagram illustrating the natural
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
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
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
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)
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
• Preparation of a National Greenhouse Gas Inventory (NGGI) of emissions
• 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
• Continued research into energy-efficiency programs.
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
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
• 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.
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