Chapter 1. Feel the need to
Renewable Energy

 

 1.1 Global warning of Energy and Environment

 

 Energy, environment and associated global
warming concerns are the focus of raging debates as the global climate system
impacts the political climate. The impending energy crisis and the soaring oil
prices have their roots in the fast depleting non-renewable source of energy:
petroleum. Petroleum takes the spotlight as the world’s primary energy resource
as the petroleum industry produces indispensable gasoline and other fuel
derivatives.

 

 
Worse, the increased usage of gas online has resulted in the release of
poisonous chemicals into the earth’s atmosphere, not sparing the water bodies
which get heavily polluted by petroleum based industries.

 
So, the search is on for safe, renewable sources of sustainable energy
that won’t pose any hazards in the long run. Efforts are also on to find
effective means for creating green energy, meaning energy that is
environmentally less damaging. For example, wind energy, solar energy, hydro
energy can be tapped and channelled from different natural sources either to
generate power(through solar cells, wind turbines, etc) for myriad
applications. These sources are in exhaustible, unlike petroleum and its
derivatives, which are getting used up faster with each passing day.

 

Chapter 2. About Renewable Energy

 

 2.1 Renewable energy

 

 

? Solar Energy
Solar energy is the sun’s rays
(solar radiation) that reach the Earth. This energy can be converted into
other forms of energy, such as heat and electricity.

 

 

 

? Wind Energy
Wind turns the blades of a
turbine, which in turn spin a shaft that is connected to a generator. This
produces kinetic energy, which the generator uses to produce electricity

 

 

? Water Energy
Hydropower is power, usually
electricity, that is generated by the use of water. For example, Niagara
Falls is used to generate electricity using large turbines under the water
which are turned by the energy of the falling water.

 

 

 

? Geothermal
The term geothermal simply relates to the internal heat of the
earth. Through this people are able to obtain the geothermal energy and
transform it into electricity. Geothermal electricity does not require fuel,
just pumps and therefore environment friendly.

 

 

 

? Biomass
Biomass is organic material made
from plants and animals. Biomass contains stored energy from the sun. Some
examples of biomass fuels are wood, crops, manure, and some garbage.

 

 

 

? Tidal Energy
Tidal energy refers to a form of
power that converts the efficiency of tides into useful forms of dynamism. It
is generated by the surge of oceanic rise and fall of tides. This type of
energy is renewable and that is one of the biggest advantage it has.

 

 

 

? Wave Energy
Wave energy refers to the act of
harnessing and using energy that is produced by surface waves from the ocean.
This type of energy can be used for water desalination, the generation of
electricity and pumping water into reservoirs.

 

 

Chapter 3. About tidal energy

 

 3.1 What is tidal energy

 

 
Tidal energy is a form of hydropower that converts the energy of the
tides into electricity or other useful forms of power. The tide is created by
the gravitational effect of the sun and the moon on the earth. Tidal energy is
therefore a predictable form of renewable energy, which can be harnessed in two
forms.

? Tidal Range

 

 
Tidal Range is the vertical difference between the high tide and the
succeeding low tide. Tides are the rise and fall of sea levels caused by the
combined effects of the gravitational forces exerted by the moon and the sun
and the rotation of the Earth. The tidal range is not constant, but changes
depending on the relative positions of the Earth, sun and moon. Barrages and lagoons
use this potential energy component of the tide to generate energy.

 

? Tidal Stream

 

 
Tidal Stream is the flow of water as the tide ebbs and floods, and
manifests itself as tidal current. Tidal stream devices seek to extract energy
from this kinetic movement of water, much as wind turbines extract energy from
the movement of air.

 

 
The sea currents created by movement of the tides are often magnified
where water is forced to flow through narrow channels or around headlands.
There are a number of locations around the coastline of the UK where the tidal
stream resource is high, and it is in these areas where early technology
developments are taking place to explore the prospect of realising the energy.

 
Recent developments indicate that the total availability of tidal power
may be much higher than previously assumed. Given that tidal power is more
predictable than wind and solar power and that economic and environmental costs
can be brought down to competitive levels, the untapped tidal stream resources
of the UK coast have made it a natural home for innovative research.

 

 
Over the last decade, research companies have striven to identify the
most efficient designs that can be installed and maintained cost effectively.
Tidal Energy Ltd (TEL) have developed a commercial scale tidal energy device
called DeltaStream, and are poised to tap into the enormous potential for
renewable power generation from the tidal currents around the UK and beyond.

 
The UK Government aims to meet a 15% renewable energy target by 2020 and
in Wales, where TEL are carrying out their first installations, the Welsh
Government is aiming to capture at least 10% of the potential tidal stream and
wave energy off the Welsh coastline by 2025. The UK’s long term goal is to
reduce CO2 emissions by at least 80% by 2050 compared to 1990 levels.

 

 
The inherent predictability of tidal power makes it highly attractive
for grid management. Tidal stream energy presents a significant economic
opportunity through synergies with the offshore wind industry and its
suitability for clusters of large-scale projects, allowing a business model
favoured by utility companies.

 

 3.2 History of tidal energy

 

 
People have harnessed the tides and used its energy for many centuries.
Tide mills which are the precursors to today’s tidal power plants have great
similarity to water wheels. The difference is that water must first be
collected from the incoming tide before it can be released to rotate the water
wheel.

 

 

 The oldest, excavated tide mill is dated to
the year 619. It was discovered at Northern Ireland’s Nendrum Monastery on
Mahee Island in Strangford Lough. The power generated by this mill was
probably used for grinding grain.

 

 

 Tide mills became more common during the
Middle Ages. A tide mill would have a storage pond which filled up as the
tide came in. As the tide went out, the pond emptied and the moving water
rotated a water wheel.

 

 

 By the 18th century, 76 tide mills were
being used in London alone. At one time there were about 750 tide mills in
operation around the shores of the Atlantic Ocean. This included about 300 on
North American shores, about 200 in the British Isles, and about 100 in
France.

 

 

 The Rance estuary in France was home to some
of the historical tide mills. Now the Rance river has the world’s first tidal
power generating station. It opened in 1966. As an improvement to early tide
mills, it generates power during high tide and low tide.

 

 

 3.3 How to work tidal energy?

 

 
Tidal energy is used for tide’s difference. If there is one thing we can
safely predict and be sure of on this planet, it is the coming and going of the
tide. This gives this form of renewable energy a distinct advantage over other
sources that are not as predictable and reliable, such as wind or solar.

 
The diagram shows how the gravitational attraction of the moon and sun
affect the tides on Earth. The magnitude of this attraction depends on the mass
of the object and its distance away. The moon has the greater effect on earth
despite having less mass than the sun because it is so much closer. The
gravitational force of the moon causes the oceans to bulge along an axis
pointing directly at the moon. The rotation of the earth causes the rise and
fall of the tides. When the sun and moon are in line their gravitational
attraction on the earth combine and cause a “spring”tide. When they are as
positioned in the first diagram above, 90°from each other, their gravitational
attraction each pulls water in different directions, causing a “neap”tide.

 

 
The rotational period of the moon is around 4 weeks, while one rotation
of the earth takes 24 hours; this results in a tidal cycle of around 12.5
hours. This tidal behaviour is easily predictable and this means that if
harnessed, tidal energy could generate power for defined periods of time.

 

 
How to generate method for harnessing tidal energy is a barrage, or
tidal barrier, which is very much like a dam. When the water level is higher on
one side of the barrage than the other, water is allowed to flow through the turbines
to generate electricity.

 
During high tide the gates are closed and water is stored “upstream”of
the tidal barrage. As the tide falls, the water level on the downstream side of
the dam drops. When it’s low enough, the valves are opened for water to flow
from the higher, upstream side—through turbines—to the lower, downstream side.
The movement of the water rotates the turbines to generate electricity.

 
Due to the design of the barrage, the reverse can also happen. When the
tide reaches its low point and the water level behind the dam is at the low
tide level, the valves are again closed and the tide rises again. Water rises
on the “downstream”side and when the valves are opened, flows “upstream”where
the water level is at low tide.

 

 
Thus, barrages can effectively generate power four main times during the
day—during the two fall and the two rising tides.

 

Chapter 4. Current Status of Tidal
Power Plant

 

 4.1 Tidal Power Plant in Korea

 

? Shiwha Tidal Power Station

 

 
From now on I will explain about the world’s biggest Tidal Power Plant.
the machines that we use and that help us are operated by electricity or
petroleum. Machines and technology gradually developed in order to make people’s
lives convenient, and more energy was consumed accordingly. Energy is
absolutely necessary to humans. It is said that there are only petroleum to
sustain 45 years of use, 113 years’of natural gas, and 63 years’of coal, on the
entire globe. With this said the expansion of new renewable energy such as
tidal power generator is very necessary and urgent assignment in order to solve
the energy problem that humans encountered.

 
Currently, South Korea is giving full effort in researching and
developing new renewable energy across over ten fields such as fuel cell, solar
energy, wind force, geothermal heat, and ocean. In last November, world’s best
tidal power plant was constructed in South Korea.

 

 
World’s largest tidal power plant Shihwaho is in similar size to Rance
tidal power plant in France, but its capacity and efficiency are exceptionally
advanced compared to smaller tidal power plant in China or Annapolis tidal
power plant in Canada. The generation capacity of Shihwaho tidal power plant is
254MW, generating more capacity than 240MW of Rance tidal power plant, which is
known to be the largest in the world. The annual generation capacity is no less
than 552 million kWh, which is the amount that can supply 500,000 households in
a city.

 

 
It gives the effect of substituting imported oil that reaches $88
million by reducing 862,000 barrels of petroleum that is used for the
generation of electricity annually, and it is expected to have the reduction effect
of CO2 of 315,000t. Also, it is approved as CDM by UNFCCC, allowing the sales
of emission to the advanced countries that has the reduction responsibility of
greenhouse gasses. Thus it is predicted that it will contribute to national
creation of VA.

 

 
If the condition of tidal generation is 4~5m, Shihwaho reaches 9m, which
is the best condition. It is the experts’common opinion that it is hard to find
a place with the best conditions as Shihwa sea that has huge difference in flux
and reflux of tides with severe curve of coastline. Just as much, South Korea
is a country equipped with geographical condition that can generate clean ocean
energy source, having the best condition to build a tidal power plant.

 

? Garorim Bay Tidal Power Station

 

 
Garorim Bay Tidal Power Station is a planned tidal power plant in
Garorim Bay, on the west coast of South Korea. The project is developed by
Korea Western Power Company Limited and was in the process of receiving
government approval as of November 2008. Garorim Bay is located between Seosan
City and Taean County of Chungnam Province, South Korea, at the western
seashore of South Korea. The electric power generation capacity of the plant
will be 520 megawatt (26 MW * 20 sets). This is more than twice the capacity of
the Rance Power Plant in France, which is the biggest tidal power plant in the
world as of 2007.

 

 
In 1981, the Assessment Report on the Construction of Tidal Power Plant
in Garorim Bay was issued. Environmental research conducted by Korean Ocean
Research and Development Institute and supported by UNESCO was partly used in
this assessment. The report assessed that the project was economically
efficient. But in 1986, as oil prices went down and construction costs rose,
the project was assessed as economically inefficient. The economic efficiency
was assessed again from 2004 to 2005, and the basic design was completed as of
March 2007.

 

 
Garorim Bay is regarded as one of the important tidal flats in South
Korea. The Korean government included this bay in the National Wetland
Inventory. The Yellow Sea Large Marine Ecosystem (YSLME) Project, managed by
the United Nations Development Programme and the Global Environment Facility,
also surveyed the ecology of this bay. According to a survey on fishery
resources in 1981, supported by the Korean Ocean Research and Development
Institute, this bay is an important spawning ground for many species of fish.
The study predicted that the plant’s construction would cause critical damage
to the bay’s ecology.

 

 
Garorim Bay Tidal Power Plant Project is now being included in the South
Korean government’s renewable energy strategy. The Korean government classifies
tidal power as renewable, and the Garorim Bay Project is included in the
renewable energy plan which the government announced in September 2008.

 

5. Discussion

 

 
we have chance to rethink of renewable energy by this report. In
addition, we checked fact tidal energy’s history, theory and instance of Korea
by trying more deeply investigating about tidal energy. Firstly, tidal energy
is applied in tide mill which used to some areas for grind grain a long time
ago. after the Middle Ages,  generally
tidal are used and become popular method perfectly in 18th century. Over time,
A tidal plant is built primally at Rance in France in the year of 1966. In
early days, developed tide mill make electricity while initiating of the tide.
Tidal-generator is developed by this principle. Recently, it is installed area
that growed continental shelf. So tidal-generator operate turbine in the center
of dam by difference in tide. Sihwa-ho tidal generator use the principle. So,
Sihwa-ho become generally known through broadcast media. Sihwa-ho tidal power
plant produce the energy of 552 million kWh annually, and it is capable of
supplying electricity to 500,000 households. and we save $88 million because we
use producted electricity in plant instead of 862,000 barrel of petroleum. And
we save 315,000ton of CO2.

 

-Why we choose the tidal energy?

 

 
Today, we depend on fossil energy that consist of coal, petroleum,
natural gas and etc. Commonly, fossil energy are used to operate machines(car,
airplane, power plant, and etc). But we are confronted with a difficulty which
is lack of fossil energy increasingly. So, many countries take an interest in
renewable energy. we choose to tidal energy in many renewable energy.  we want to know tidal energy of renewable
energy because tidal is the most efficient in the renewable energy of all.
Produced  tidal energy  is clean and non polluting. And there is no
carbon dioxide or any other by-products released. It produces no greenhouse
gases or other waste. We think that the best renewable energy is tidal energy.
But tidal energy have many disadvantages. so we discussed topic.

 

-We thought about how to produce
additional energy of tidal power

 

 
We find out about one of problems that is irregular in energy production
efficiency because difference in tidal isn’t move in a cycle at all the times.
So, We think about additional method that is combination of using the principle
of turbines at wave force generation and tidal generation.

 

 
I tried to draw a picture of combination.

A lot of see water are gathered
near blocked part(A) while tidal generator work. At that time,  wave occur from surface. Those wave are
transformed into energy.

Shown in the picture, B turbine
generate electricity energy. A generator make some energy according to using
wave force. Generating energy is made for rising-lowering movement by the wave
force, using a piston after changing the air flow. its turbin is operated by
air flow. But this our idea has a shortcoming. technical side is able to
combine to have been existing technique.

  Consequently, this way
would like to generate the wave energy and tidal energy at same time. and also
when storm or blowing are come to accompanying a strong wind and rain, wave
energy is generating energy. However, although we installed the combination
plant, we would be not convinced of energy efficiency. And it needs terrain
which have rough wave and severe difference in tidal.

If all of these issues improved,
efficient enough, I think that this way makes enough efficiency

 
Even a small idea,  we want to
express our thoughts with this report. Although this new method is the wrong
way,  I wanted to try different ways to
approach.