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

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. 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. 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. 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. 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. 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. 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. The Natural Greenhouse Effect

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. 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. 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. 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. 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. 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. 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. 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. 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. Bibliography (images)
Sunset Wind Turbines sourced from Shutterstock on 25/3/14:
http://earthtechling.com/2011/11/wind-power-storage-its-a-gas/
Natural Gas Power Plant on first slide sourced from GDF SUEZ on 25/3/14:
http://www.suezenergyna.com/gas-power-mexico/
Compressed Natural Gas Bus, Sydney sourced from Wikipedia on 21/3/14:
http://commons.wikimedia.org/wiki/File:Custom_Coaches_CB60_Evo_II_bodied_Mercedes-Benz_
O500LE_CNG_bus_%28Sydney_Buses%29_01.jpg
Mortlake Natural Gas Power Station sourced from Origin Energy on 21/3/14:
http://www.originenergy.com.au/corporateimages
Macarthur Wind Farm sourced from AGL on 21/3/14:
http://www.agl.com.au/about-agl/how-we-source-energy/renewable-energy/macarthur-wind-farm/locatio
n
Natural Gas Extraction Techniques sourced from roperld.com on 25/3/14:
http://www.roperld.com/science/minerals/shalegas.htm
Greenhouse Effect diagram sourced from Hong Kong Observatory on 25/3/14:
http://www.hko.gov.hk/climate_change/human_activities_e.htm
Golden Toad image sourced from Jaguar Ambassadors Gang on 25/3/14:
http://jaguarambassadorsgang.org/animals/

19. Bibliography (references)
[1] “Mortlake Power Station – Wikipedia, the free encyclopedia”. Accessed on 27/3/14:
http://en.wikipedia.org/wiki/Mortlake_Power_Station
[2] "AGL – The Project". AGL. Accessed on 27/3/14:
http://www.agl.com.au/about-agl/how-we-source-energy/renewable-energy/macarthur-wind-farm/the-project
[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:
http://www.agl.com.au/about-agl/how-we-source-energy/renewable-energy/macarthur-wind-farm/location
[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:
https://www.nationalwind.org/assets/publications/Birds_and_Bats_Fact_Sheet_.pdf
[8] “The Renewable Energy Target (RET) Scheme.” Accessed on 27/3/14:
http://www.environment.gov.au/topics/cleaner-environment/clean-air/renewable-energy-target-scheme
[9] “South Gippsland Shire Council – Sustainability Stratagy”. Accessed on 27/3/14:
http://www.southgippsland.vic.gov.au/Page/page.asp?Page_Id=832&h=0
[10] “South Gippsland Shire Council – Green Street Lighting Program.” Accessed on 27/3/14:
http://www.southgippsland.vic.gov.au/page/page.asp?page_Id=1214&h=0