Geothermal Energy and Its Impact on Environment

The assignment provides an in-depth analysis of geothermal energy, highlighting its advantages over fossil fuels, such as lower emissions and stable temperatures. However, it also notes that geothermal energy requires high initial investment costs and can release methane and carbon dioxide, contributing to global warming. The document compares the cost of geothermal energy to other renewable sources like wind and solar power, showing that they are becoming increasingly competitive. Overall, the assignment provides a comprehensive evaluation of geothermal energy's impact on the environment and its potential as a sustainable source of electricity.

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Unit 44 Industrial Power, Electronics and Storage – Assignment 1
Introduction
The popularity of using fossil fuels to generate distributable electricity is rapidly
declining for two main reasons: the first being the decline in the availability as it
is being removed from the Earth faster than it can be formed, the second being
the impact that the toxic gases released from the refining/burning of the crude
minerals has on the atmosphere.
In order the combat the negative effects caused using fossil fuels research has
been led to convert energy into electricity from renewable sources such as
sunlight or wind power, with some being much more efficient than others. As
scientists continue their research into renewable energy technologies the
efficiencies of the product only increase and become cheaper and more
accessible.
Current Energy Sources
The most common sources of energy through history have been coal, natural
gas, oil and nuclear. The fact that these have been the longest running source
for our electricity means that the technology used in the creation is already very
well developed and efficient. They are also commonplace which makes them
easier to work on due to the sustained education in the population and the
production of parts required in the running equipment.
When the world became more aware of the issues surrounding fossil fuels,
alternatives were developed. Fossil fuels are made from the degradation of
fossils, rock and biological matter over millions of years to form coal or oils.
Research led to generating electricity from sources that were renewable and not
going to deplete over time, such as wind power or the light from the sun.
Demand
During the industrial revolution between in the 1800s data shows that demand
for electricity was maintained for a long period of time, relying mainly on
traditional biofuels. Near 1900 coal began its’ increase in popularity and by the
time of the second world war was the forerunner for providing electricity around
the world. From 1950 onwards, after world war 2 there has been a massive
increase in the demand for electricity around the Globe, as can be seen from the
data chat below.
In the last 30 years of the 19th century crude oil and natural gas were both
introduced as viable fuels for generating electricity, again with a major increase
in popularity from 1950. These however, are all non-renewable energy sources in
which supplies are rapidly depleting and also cause major issues with global
warming via the release of pollutants during their manufacture.
Renewable sources and cleaner energies have also been around pre-1900 but
only on a small scale in the form of hydropower and nuclear. The other main
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forms of renewable electricity did not start to take hold and have any impact on
supply until around 1990.
From 1800, the beginning of the available data, only 5,652TWh of electricity
were used over the year, comparable to 150 years later where it was over
27,000TWh, this is a 477% increase. The population increase over this period of
time went from 978 million to 2.5 billion, this is a 257% increase.
As seen below the massive increase in demand is from 1950 to current day, the
global demand of electricity recorded in 2018 was over 157,000TWh, which is a
581% increase. In this time the population has also increased majorly, up to 7.6
billion; a 304% increase. As can be seen from these figures, the increase in
demand for electricity is increasing at a much higher rate than the population,
indicating that today, people are using a lot more electricity per capita.
(Ritchie and Roser, 2020)
Environmental Impact
Nuclear plants require lots of expensive, important equipment with many safety
features as the heat generated in the plant comes from radioactive material.
However, should any of this fail, there could be huge repercussions such as in
the Chernobyl disaster in 1986. During this event radioactive material spread for
miles all over Europe and Asia, in the immediate vicinity of the explosion and the
surrounding town of Pripyat there were many deaths, the total number of deaths
has never been known but is thought to be in the tens of thousands. The
explosion in this instance has also left the entire surrounding area unliveable due
to the levels of radiation found, even over thirty years later.
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The use of the main fossil fuels generates many pollutants, the main of these
pollutants being carbon dioxide. Carbon dioxide is a greenhouse gas that forms a
layer in the atmosphere which traps heat inside the environment, much like a
greenhouse does, reflecting the heat back down to the earths surface. An
increase in the average temperature of the Earth’s atmosphere can have
catastrophic effects on the polar ice caps at the North and South Poles. As these
formations of ice gradually melt over time the water formed will cause a raise in
the sea levels, in turn this could potentially reduce the amount of available land
mass as shorelines around countries recede.
In the case of renewable energies, the impact on the environment is based
around the space required to generate the electricity. Off-shore wind farms often
receive complaints of being an eye-sore and of ruining the landscape, they also
pose issues on-shore with the amount of land space they take up. A further
issue, which goes across most renewable energies, is the impact on wildlife and
their habitats. It is known that wind turbines frequently harm bird life, where
solar farms require large areas of flat land which must be cleared and void of all
shrubbery to be effective and receive the most sunlight. The breaking down of
organic matter such as trees and other plants in water storage facilities used in
hydro-electric power can cause great releases of greenhouse gases such as
methane and carbon dioxide when the water shifts to generate electricity.
Renewable Energy Sources
Hydropower
Accounting for 4200TWh in 2018 – 2.60%
As described previously, hydroelectric power (hydropower) has been around
since before 1900 and as such is the most developed of renewable energy
technologies. The main expense coming from hydropower is in the initial
planning and construction. The electricity is generated by directly moving a
turbine using the effects of gravity on moving water. The water is stored behind
large dams built across valleys; these prevent the water from flowing through
the rivers natural course and will build up to great volumes. This is not always
done on a river; it can also be carried out in man-made reservoirs.
Hydropower is typically used when demand and cost for electricity is high. When
peaks approach the stored water in the reservoir can be released, thus turning
the turbine as the pressure from the high volumes of water starts it spinning as it
passes through the pipework. Where this form of electricity is used in a reservoir
application the water can be pumped back up to the top storage. This will be
done during the night-time when there are cheaper tariffs in place, in effect
making it somewhat less efficient as it will use up just as much energy to pump
the water back up.
The outlaying costs for the initial construction of a dam can be over one billion
pounds which means there must be significant investment to start with. There
are also ethical issues with the building of reservoirs as there may be
communities that live in the catchment of the storage of the water who will be
forcibly moved out in some cases. A further issue is the breaking down of
biological matter; as the level of the reservoir fluctuates this will release the
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greenhouse gases that are stored in the bed of the water that are created when
biological matter degrade, the release of these gases will contribute to global
warming.
There are further benefits from using hydropower in the form of recreational
activities. Large volumes of water as such can be used for fishing, swimming and
water sports which will bring in further revenue. The downsides to this are that in
the event of releasing the water the wildlife may become injured if they flow
through with the high velocity water and past the turbine. On the output side of
the dam this would also have negative effects of flooding the old waterways; any
wildlife in the area at the time could be washed away or killed, they could also
have their homes destroyed.
U.S. Energy Information Administration (EIA), 2020)
Wind
1270TWh in 2018 – 0.83%
Wind farms are becoming increasingly popular over the UK. When comparing the
prices of the crop yield and generating it is without a doubt much more beneficial
to have the electricity generating equipment on your land. It would also take up
a minority of the space and so a large percentage of the land would remain
arable. Another popular location for installing a wind farm is on the coast or
offshore. Due to the long open distances available from the sea, wind farms
mounted here are much more likely to encounter wind than in built up areas as
there are almost no obstructions which may remove the wind power.
The blades on a wind turbine turn a shaft which is contained in the head, called
the nacelle. This shaft is directly connected to a generator; as the blades turn the
generator an alternating current is naturally made. This kinetic energy is thus
converted to electrical energy which can then be inverted to a desired frequency
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or voltage as required by the local grid. The nacelle has the capability of
rotating, allowing the blades to be at an acute angle to the wind to keep them
turning at the most efficient pace.
The blades of the turbine are affected by the density of air, due to this fact,
installing them in colder areas, such as out at sea, will allow them to run more
efficiently as there will be less losses on the drag of the blades cutting through
the air. This also creates another issue in that there aren’t many people who
actually live in the areas of the low-density air, such as out at sea or in the
middle of the fields. This means that the transmission costs of the electricity are
much higher as the demand for that required electricity could be miles away.
A larger span of blades will be more effective as they will absorb more wind
power, causing them to turn easier ad generate more electricity, smaller blades
and a smaller generator will limit the total wattage output. These smaller
turbines could be used to power establishments with a lower demand for
electricity such as a single house or farm but would not necessarily generate
enough to export to the grid. The areas of less dense air are typically much
colder in temperature, because of this, the freezing of critical components must
be prevented by the continual turning of the turbine. In this instance, and when
there is no wind, the turbines would then be using electricity instead of
generating it, rendering them less efficient. A wind turbine will only be around
30-50% efficient, with there higher end of the scale only being at times of peak
wind flow.
There are many benefits to using wind power as a renewable energy source and
the popularity of using it is increasing by around 25% every year. Measuring the
actual land space used up by the wind turbines shows that they are the most
efficient as the rest of the land between each turbine can still be used for profit,
such as crop or animal farming. As the technology improves and popularity
drives upwards, this means the cost of creating and installing a wind turbine is
also dropping, making them more available on a personal level.
Solar
584TWh in 2018 – 0.38%
The Sun generates 3.846×1026 W of energy every second, most of this energy
will dissipate out across the nearby universe but naturally, some will be sent
directly into the path of Earth. The estimated catchment area for the suns energy
is 93,000,000 miles which puts Earth well within the reach of its effect, it is
estimated that the amount of energy received on earth from the Sun in just one
hour could power all electricity over the world for a whole year, it just needs
harnessing.
Solar panels are made up of photovoltaic (PV) cells that can convert the energy
emitted from the sun into electricity. The most common material used in solar
panels is silicon which is a good conductor; this layer of silicon will sit between
two layers of PV cells and will have differing electronic properties, this is what
creates the electric field and is known as the photovoltaic effect. The photons
emitted by the Sun will be received by the PV cells which causes it to lose its
electrons, this passing of charge is what generates the electricity in the panel.
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The electricity formed by the solar panels is received as a DC voltage which must
then be inverted into an alternating current to allow for it to be used
domestically or put out into the National Grid.
The general structure of a solar panel is very slim lined which allows for them to
be placed almost anywhere; from small arrays that are installed on the roof of a
home, to large solar farms that take up acres of space in a field. There are no
moving parts so there is virtually no wear and tear on the components in the
array, the only real maintenance required is to keep them clean which allows for
them to maintain efficiency. Due to the lack of moving parts a solar panel will
generally come with a long warranty also, usually around 20-25 years meaning
even in the unlikely event of a fault, costs would be covered by the
manufacturer. As with most other renewable technologies, solar is rapidly
developing with the latest research being carried out on nanotechnologies which
will make panels smaller, more flexible and up to three times more efficient.
The initial outlaying costs for installing a solar power system is quite large, the
panels must be bought, along with he inverters, cabling and potentially some
form of framework too if not going on a building’s roof, though this is expected to
decrease as the technology develops. Although during daytime hours solar
panels are very efficient, the amount of sunlight received will change depending
on where in the world the solar panels are placed. For example, a solar array in
Africa will receive a much more intense sunlight as it is closer to the Sun than
those installed in Greenland, there will also be longer durations of exposure as
during months October to February a country such as Greenland may only
receive up to six hours of weak sunlight. Solar panels cannot generate electricity
during night-time hours; however, this can be compensated by installing
batteries to be charged during daylight hours that will discharge when light
levels are low. Furthermore, these will come at a great cost and will also require
more maintenance.
Efficiency of Solar panels depends on what kind is purchased; monocrystalline
solar panels can achieve efficiencies ranging from 22-27% but are more robust.
Cheaper, less durable alternatives found in thin film solar panels can achieve
much lower efficiencies of 15-20%
Geothermal
Less than 600TWh – less than 0.4%
There are two main types of geothermal energy production; that is through
power plants and heat pumps. Power plants are large scale systems where holes
are drilled down one or two miles into the Earths surface. The Earths core
generates over 10,000 degrees Celsius of heat, this is transferred through the
different layers and drops considerably, but 1-2 miles below the surface is still
warm enough to turn water into steam. The springs of hot water or steam are
pumped up to the earths surface where the speed of the flow is fast enough to
turn a turbine which is attached to the generator for the electricity. The water is
pumped to the surface under a high pressure, as the water reaches the surface
the pressure is dropped drastically which allows the water to turn to steam. Once
the steam has served its’ purpose it will then be condensed in a cooling tower
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and returned underground through an injection well. It is more common in areas
that have an abundance of geysers, natural springs or volcanoes locally as the
temperature of the earth is warmer much closer to the surface.
The smaller scale projects can be used for domestic buildings such as blocks of
flats, warehouses or individual homes. A geothermal heat pump can go as little
as just two metres underground where the temperature is held at a steady 50
degrees. The geothermal heat pumps can work in both directions, as heaters
bringing the earths warm temperatures up to the surface during winter; in
summer they can act as a cooler by removing the heat from the home and
replacing with cooler flowing air that would be underground at the time. It works
in a continual process where the warmer water dissipates its stored heat into the
cooler areas of the household. Once the water is then cool it will return down
underground to be re-heated naturally. A process like this has been used for
thousands of years, sometimes in the form of ice huts. Estates would contain a
small brick building which would go down underground where it would be used to
store ice and keep food cool during the summer months.
The savings generated by using geothermal energy are much greater than many
other renewables and it is also one of the cleanest energies as no fossil fuels are
required at all to keep it running. It is one of the most reliable sources of
renewable energy, it does not depend on the weather at all such as solar or wind
may do and due to the constant temperature from the Earths core, the
temperature or energy generated from the plant will also be constant. The
smaller scale systems that are used to heat homes also use up to half the
amount of electricity as conventional methods and take up a lot less space.
The stirring of settled fluids underground will cause the release of gases built up
from debris degrading. The gasses include methane and carbon dioxide which
are both known to contribute to global warming, although the amount is
significantly less when comparing to the use of fossil fuels. Although the running
costs of a geothermal plant may seem very appetising, the initial start up costs
are very high as there is a lot of construction work required. Some works can
take 2-10 years to pay, and the cost benefit over a gas heating system installed
in a home is minimal.
Costs
Global
average
2018
IRENA
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Global
comparis
on to
non-
renewabl
es
Both tables above are representative of global energy costings in
the year 2018. The top table, provided by data solely gathered by
IRENA, is measured USD($)/KWh, in just one year it is clear that the
cost of producing electricity using renewable sources is rapidly
declining, with most showing a decrease of 10-15%. The data in the
second table is representative of the cost of renewable energies
during their creation in comparison with the costs of fossil fuels.
Lazard is the only body that holds data on the fossil fuels, but both
of those come in at an average of coal at 109 and gas at 56, where
renewables such as wind is costing 41 and solar PV costing 37,
both much lower.
Evaluation
Greenhouse gases are having a severe effect on the environment and the
majority of these gases and other pollutants in the atmosphere are released
when burning fossil fuels to generate electricity. It is proven that using
renewable energies does not always have a positive impact on the environment
but they are also increasingly cleaner to use. The other facts raised about using
fossil fuels is the length of time in which it takes to create them. There may be
plenty available at the minute, but statistics show that the underground stores of
these materials are depleting at a much quicker rate than which they are being
replenished. It is likely that fossil fuels will never be completely abandoned as a
legitimate source for electricity as they will forever hold their potential. Whilst
taking into account the rate at which the stores of fossil fuels are declining and
the rapid rate of improvement in the renewable energies technologies it is clear
that in the future they will become the more reliable source for supplying
electricity.
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