Electrical
energy is the main energy type we use in our almost every aspect of our lives.
It is impossible to imagine a world without it. Although is a very basic need
in modern society most people take it for
granted but generating electricity power and distributing it with a good
efficiency to the places where it’s been used is a very complex and carefully
designed process. I recently read a report by climate council of Australia
(“Australia’s electricity sector: ageing inefficient and unprepared”) and as
the title implies it focuses on the matters related to Australia electricity
industry and propose the solutions for them .So I thought to share some key
points I read in that report and share with you. I personally believe that it’s
a responsibility of engineering community to educated general public about how
science and technology is important for a better future and for a sustainable
development. All the facts and data I go thorough in this article were
extracted from that report and all the credit should go to the writer and the
climate council of Australia.
Globally
the energy sector accounts for the largest proportion of greenhouse gas
emissions which is the main cause for climate change around the world as
scientists speculate. In order to avoid the effects of climate changes
countries have agreed to keep the temperature rise below 2 degrees and in order
to achieve this goal every country has to reduce their greenhouse gas emissions
it needs large scale changes to how countries produce their electricity and
other energy methods.
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Figure 1-Global
energy related CO2 emission
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The
above graph shows how the energy sector is responsible for the emission of CO2
one of the main component of greenhouse gases has increased over the time. As
the graph shows it is an exponential growth. Coal is the main reason for this
and as everybody knows coal is one of the main source for conventional
electricity production. Australia places as 9th country in the top ten
countries that emit greenhouse gases in electricity production. In 2011/2012
about 91% of Australia’s electricity was generated using fossil fuels.75% of
the portion was from coal and 25% from natural gas. Australia’s per capita CO2
emission is the world highest in 2011.So it is obvious that electricity
generation in Australia is not ecofriendly as people might think. Australia
produces 60% of emissions per MWh than USA. Even Australia is well behind China
when reducing the emission of GHG (greenhouse gases) .Over the decade to 2012,
China has reduced the GHG emission by electricity up to 16% but Australia was
able to reduce that by less than 4%.As a result electricity sector responsible
33% of GHG emissions in Austalia.
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Table 1-Global
Emitters of CO2
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The
reason behind this is the way electricity is generated in Australia. As
mentioned above coal and natural gas are the main sources used to generate
electricity .Coal and gas power plants operates in Australia are getting old.
Currently the average age of coal power plants in Australia is over 30 years
where it is less than 2 years in the global scale and by 2030 over 65% of coal
power plants will be over 40 years old. The age of the plant is an important
parameter when it comes to it’s efficiency since an old plant operates on
technology which is established over decades ago. The technology related with
electricity generation is developing rapidly since these plants operates on low
efficiency it becomes very expensive to produce electricity it’s and waste of
natural resource. Some might see this is not a problem since we have time but
building a megawatt scale power station will take at least a decade to plan,
finance and build and operate in the required manner. Various much efficient
technologies were introduced during the past decades in order to reduce the
Carbon emission from plants but the old power plants are unable to adopt to
these relatively new technologies since it’s not economically beneficial and
those plants are constructed on old technology hence they are locked down to
use that instead of moving to more efficient new technologies. One parameter to
measure the emissions from a plant is cycle efficiency. It is determined by the
steam temperature and the pressure conditions at the limits of a cycle. These
efficiency are divided in to 3 categories, Subcritical, Super critical and
ultra-critical. Most Australian coal power stations are subcritical hence they
have become one of the least inefficient power stations in world.
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Figure 2-Fuel usage
for electricity generation in Australia 2012-13
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Figure 3-Electricity
production in Australia
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As
people realise the negative effects of using fossil fuel based electricity
generation the world is slowly moving towards replacing fossil fuel with
renewable energy sources like solar, wind, hydro and fuel cell (H2)
technologies. Hydro power is the leading renewable source in the world at the
moment. AS it can be seen in above graphs it is the same trend in Australia. In
Australia hydro power has supplied 8186MW (16.1% of total capacity) .New South
Wales got the biggest portion of hydro power stations (55%). In global scale
hydro power has supplied around 15% of electrical energy needs.
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Table 2-Hydro
power generation distribution worldwide
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Wind power is also another emerging renewable source
since it’s large reductions in costs associates with installation and equipment
.Australia got one of the best wind fields in the world and Australia was able
to generate over 6000 GWh in 2012/13 at an average capacity factor of
34%.(Capacity factor measures the ability to extract and store energy from wind
by a turbine over a period of time).South Australia is the leading state is
wind energy production. It is expected that there would be more 8900 MW of wind
energy will be available by 2020 but still Australia is well behind most
developed countries.
Solar power is another wildly used renewable energy
source. It’s becoming more popular than wind because of it’s domestic use.
While coal and other fossil fuels are expected to become expensive in future
it’s obvious that solar energy will be less expensive than coal in near future
because of the rising demand for solar PV. The advantage of solar is it can act
as a distributed power source in houses and commercial premises or it can be
scaled up to MW size and feed to the grid.
Over 1 157 000 Australian households had installed
3039 MW of solar PV by 2013. South Australia has the largest proportion of
power generated by Solar. Although there is a decline in installing new solar
PV in houses due to reductions in Feed in tariff rates it is expected that by
2020 the power generated by solar PV could be doubled. Although household solar
PV is a popular alternative to grid power, Australia has only few field scale
solar power stations. A 10 MW station at Greenough River in WA and 1MW project
at Uterne in Northern territory. Besides these existing projects there are
several new projects that are under construction. A 20 MW project at Royalla in
ACT. A 102 MW project at Nyngan in NSW. A 3 MW project at Brokenhill.
The popularity of PV has caused them to reduce it’s
price and more affordable to households. Furthermore many solar markets around
the world getting closer to achieving ‘Socket parity’ point, where it is more
economical to produce electricity using solar rather than buying it from the
grid. Nowadays it’s more economically beneficial if people use electricity
generated by solar for their needs rather than feeding into the grid. Because
in that way they will reduce the amount of electricity they consume from grid.
One of the major drawbacks of solar PV is it is unable to provide power when it
is needed most. In generally the maximum solar insolation is received during
noon time but the electrical peak arrives during evening times and most of the
time solar power is unable to supply the demand. Therefore households have to
use more grid generated power during this period. Therefore solution is to use
battery system to store excess energy produced during day time and consume it
during peak time. The price of the battery systems are relatively high but it’s
becoming cheaper because of it’s popularity and with new battery designs like Tesla
Power Wall it has become a worthy investment.
There is no doubt that sooner or later the whole
world has to change their way of producing energy therefore earlier is better.
It could be cheaper to use fossil fuels at present but in about 20 years it
won’t so nations should start planning and implementing renewable energy plants
from now. It is a fact that Australia’s existing fossil fuelled plants can’t
compete with renewable energy methods in long term because it’s obvious that
price of fossil fuel is becoming higher while the cost of renewable energy
solution becoming cheaper. According to the studies wind is the most suitable
energy source for Australia along with field scale solar PV.
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Table 3-Cost
reduction potential for onshore wind systems
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Table 4-Cost
reduction potential for PV modules and systems
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Although Solar, Wind, Hydro and other renewable
energy sources are very promising technologies one problem associating with
them is they are very sensitive to climate changes. It is very difficult to
predict what would be the climate conditions in a region by 10 or 20 years. If
the conditions changed dramatically in future the expected output will not be
achieved by those plants and the investments done will be wasted. Therefore
these aspects has to be taken into account when planning a large scale
renewable plants .On the other hand when more renewable sources have been used ,
governments and other corresponding authorities will be forced to take
environment protection more seriously. It will be helpful for a more
sustainable and greener development. In conclusion, the fate of future
generations in Australia and the rest of the world depends on how we address
the energy crisis and take necessary steps to switch to renewable energy.
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