All the team.
HYDROPOWER ENERGY:
1. - INTRODUCTION and HISTORY:
1.1.-INTRODUCTION:
Hydropower is based on the use of the falling water
from a height. The potential energy becomes kinetic during the fall of the
water. This water passes through the turbine at high speed, causing a
rotational movement, which is finally converted into electrical energy, using
generators.
It is a natural resource that you can use in areas
with enough water that, once used, is returned down river.
It is a kind of green energy when the environmental
impact is minimal and it uses the power of water without hurt it. If it´s not,
it is considered only a form of renewable energy, and it is the most common of
them.
1.2. - HISTORY:
The old Romans and Greeks were already benefiting from
the power of water; they used water wheels to grind wheat. However, the
possibility of slaves and pack animals slowed general use until the twelfth
century.
Later, in the eighteenth century, the engineer John
Smeaton made the first cast iron hydraulic wheel.
During the Industrial Revolution, hydropower energy takes a lot of importance,
because it promoted the textile industries at the beginning of nineteenth
century.
Also in this century, hydropower made easier the growth of new industrial
cities. But the summer low flow, together with the winter ice, made necessary
the construction of large check dams, so the wheels were replaced..
In 1920 and hydroelectric plants generating an
important part of total electricity production. In the early nineties, the
first hydroelectric power producers were Canada and the United States, which
had more than 200 plants.
2. - TECHNICAL:
2.1.- Parts of the central:
-Reservoir:
It is the accumulation of water produced by an obstruction in the bed of
a river that closed partially or totally their banks.
- Dam:
It is a wall built of stone or concrete, which is put in the bed of the
river to divert water, producing an elevation of its level, for use or for
store it, regulating the flow of the river.
According to the function for which they are built, the dams are divided
into two groups:
-Diversion dams: built
to raise the water level.
-Reservoir Dams: built
to store water.
-Pass channel:
The pass channel is used to carry water from dam to the turbines of the
plant. Usually, to prevent
leaks on the ground, they are coated inside in masonry, mass concrete or
reinforced concrete.
-Pressure pipes:
They are used to carry the water from the pass channel to the turbines.
-Turbines:
They are rotary motors that convert the energy of a stream of water into
mechanical energy. Its
basic element is the wheel or rotor, with helices placed around its
circumference, so that flowing water produces a force that drives the wheel and
rotates.
They consist of two of these wheels, known rotor and stator. The first
is that, driven by the water, drag the axis on which the rotational movement is
get.
It is one of the most efficient engines that exist.
-Generator:
It is the device that can keep the electric potential difference between
two of its points (called centers).
Its function is to transform mechanical energy into electricity.
-Transformer:
It is an electrical device which can increase or decrease the voltage in
the circuit, but letting the power. It´s formed by two or more coils of
conductor material, insulated from one another.
-Power lines:
Its function is to transport electricity to the places where it is used.
- Hydraulic Gates:
It is the mechanical device to regulate the flow of water through pipes,
channels, etc.
2.2. - How it works?
The water is collected because of the dam, and it forms a reservoir.
When floodgates are opened, the water will pass through the pass channel
to the pressure pipes, where it gets speed. When it arrives here, the water
hits with the turbine blades, making them rotate.
When the turbine rotates the reel (funky wire) into the magnetic field
of a magnet produces electricity.
So, the mechanical energy (produced by the water) is transformed into
electricity.
After creating electricity, it travels through the power lines to the
places where it will be used.
And the water, once it has given up its energy, is returned to the river
downstream of the plant.
2.3. - TYPES OF HYDRAULIC CENTRALS:
Ø According to
architectural concept:
·
Central outdoors: they are at the foot of the dam, or a little away from this. Are connected
by a pressure pipe.
·
Central cavern: they are usually connected to the reservoir using tunnels, pipe
pressure, or a combination of both.
Ø According to its
flow regime:
·
Central flowing water: they use part of the flow of a river to generate electricity. They
operate continuously because they have not capacity to store water, as they
have not reservoir. In these plants, the turbines can be with vertical axis
when the river has a steep slope or horizontal when the slope of the river is
low.
·
Central dam: It is the most common type of hydroelectric power. Uses a dam to store
water and go graduating the water passing through the turbine. You can generate
energy all year if there are reserves enough.
·
Pump stations or reversible: A part of that transform the potential energy of water into electricity,
they can do the reverse, which means, increase the potential energy of water, for
what they consume electricity. In this
way they can be used like energy for store, (a kind of giant battery). They are
created to satisfy the energy demand in peak hours and storage energy in
off-peak hours.
Ø
According to the
height of water fall
·
Central High pressure: They correspond with head high, and they are the core of more than 200
meters of water fall.
·
Medium pressure
plants: They are plants with water fall from 20 meters 200 meters.
·
Central low pressure: They correspond with the head low, and they are water plants with
different levels of water, all of them less than 20 meters.
·
Very low pressure core: they are corresponding with new technologies plants.
3.-ADVANTAGES AND DISADVANTAGES.
3.1.-ADVANTAGES:
- It is a renewable energy and energy efficient.
- It is a tireless energy, because of the CO2
cycle.
- It's totally a clean energy, it doesn´t emit
gases, it doesn´t produce toxic emissions and doesn´t cause any kind of
acid rain.
- It stores water to easily provide recreation or
irrigation systems.
3.1.1.-Economic Benefits:
The great advantage of hydropower is the partial elimination of fuel
costs. Compared with other fuels such as gasoline or coal, the cost of using
water is almost immune. Also, it doesn´t need to import fuel from other
countries.
Hydraulic plants also tend to have longer economic lives than fuel power
plants. They are still operating after 50-99 years. Operating costs are low
because the plants are automated and have few people during normal operation.
3.2.- DISADVANTAGES:
- Capital costs per kilowatt are very high.
- The building has long.
- The availability of energy can change from season
to season and year to year.
- In addition, many areas of our planet have
serious water problems.
- Most of them are related to the environment.
4. - ENVIRONMENTAL IMPACT:
The consequences of hydroelectric installations can have on the environment
must be analyzed from two points:
a) BENEFITS:
-It reduces fossil fuel consumption, so it reduces the negative effects
of these on the environment (CO2 emissions, acid rain, toxic waste, etc).
b) ADVERSE EFFECTS:
Between the possible alterations of the physical environment that can
generate hydroelectric installations during the construction phase and the
operational phase include:
- The flooding of large areas.
- The loss of agricultural land, livestock, and /
or forest for erosion and flooding.
- Cuts roads.
- The adjustments of water currents, so, the
associated effects on the quality and quantity of water and aquatic fauna.
- Reduction of biodiversity.
- Disappearance of animal species because of the
degradation or the destruction of their habitat.
- Alterations local bioclimatic.
- The construction process, in itself, can cause
general changes, and even though the construction period can take only a
few years, the impact on a fragile environment can be longer. Even the dam
itself can be of concern, both for its visual impact like the possibility
of catastrophic failure.
5. - HYDRAULIC POWER COSTS:
They are paid 3-5 cents per kilowatt-hour.
6. - POWER COUNTRIES:
In 2008, four countries - Albania, Bhutan, Lesotho and Paraguay - they
generate all its electricity from hydropower, and 15 countries generated 90% of
its electricity from hydropower. Iceland, New Zealand and Norway produce the
most hydropower.
7. -HYDRAULIC ENERGY IN SPAIN:
Spain has a high hydraulic potential, developed over more than a
century. Spain is in
line with other countries regarding the production of electricity, with 18.5%
of this energy from hydropower.
The development of hydropower in Spain in
recent decades has been ever increasing.
In Spain, there are central hydraulic in most of the Autonomous
Communities. The River Aldeadávila Duero (Salamanca Province) has the greatest
installed capacity is in with 1140 MW.
8.-HYDRAULIC ENERGY IN THE FUTURE:
Hydropower is one of the most profitable energy present, because
maintenance and exploitation are economical, and life is very long. They
usually last without maintenance for over 100 years. If we think about the
safety of these, we say that there are not pose problems for the environment
and people, and even more if we think of the dams to help control floods and
floods.
It is, along with solar and wind energies hope for future generations.
WAVE
POWER:
1.-INTRODUCTION AND
HISTORY:
1.1.-
INTRUCUCCIÓN:
Wave power is obtained using the tides. Like in
hydraulic energy, the water moves turbines, which are connected to a generator.
The generator transforms the mechanical energy into electricity.
It is a type of renewable energy,
because it uses water, that isn´t limited when you use it, and because it is
clean.
But, the relation between the
quantity of energy that can be obtained with the economic costs and the
environmental impact, have impeded the
use of this type of energy.
1.2.-HISTORY:
The use of tides, it goes back many centuries
ago, when the residents of the coastal rivers watched the current that make
rotate de teeth of their mills. These mills were built in the beds of some
rivers of France, and today, you still can see them.
In London, from 1581 to 1822, it worked on the
river Támesis, a big wheel moved by the tide, that lets pump water to the
center of the city.
The first patent for wave power energy was
made in France in 1799. But it wasn't until the summer of 1966, when the idea
was started in the estuary of Rance river, situated in the Canal de la Mancha,
in the northwest of France. The proyect consists of a wall that closes the
river, letting the dam to store water. The high and down of the tides caused
the water to pass through turbines, which generate electricity.
But the slow development of technology and the
huge costs were made some projects impossible, and they have emerged in the
last seven years.
2.-PARTE TÉCNICA:
2.1.- What does it
use?
Wave power uses the tides.
A tide is the periodic change of sea level. His rise and fall is
produced by the gravitational action of the sun and moon.
The variation between high and low tide can be between 2 and 15 meters,
and it happens in approximately 12 hours and 30 minutes.
The best place to install it is where the water can arrive, and it has
to be small to make an obstruction.
2.2.-How it Works:
The first step to create is building a dam to close the bay. When
the tide rises, the floodgates open, and the water enter to the reservoir. Then when it gets to its
highest level the reservoir gates are closed. Then when
the tides go below the level of the reservoir, gates are opened letting water
through the turbines. Then,
its exactly the same as a hydropower central. Turbines move the generator,
which transform the mechanical energy into electricity. This electricity is
transport by the power lines.
2.3.-Generation methods:
They can be classified into three:
-Generator tidal current:
The tidal current generators
making use of the kinetic energy of the water to movement of the turbines. This
method is gaining popularity because to lower costs because lower ecological
impact compared to the others.
-Tide dam:
Dams tidal
energy makes use of power that exists in the difference in height (or head
loss) between the high and low tides. Dams are essentially dams across the full
width of an estuary, and suffer high civil infrastructure costs, a worldwide
shortage of viable sites, and environmental issues.
-Tidal dynamics
Dynamic Tidal energy is a theoretical generation technology that
exploits the interaction between kinetic and potential energies in tidal
currents. It proposes that very long dams (for example: 30-50 km length) be
built from the coast out into the sea or ocean, without enclosing an area. Are
introduced by the dam tidal phase differences, which leads to a differential
water level important (at least 2.3 meters) in shallow coastal marine waters
with varying tidal currents parallel to the coast, such as those found in the
UK, China and Korea.
2.4.-TYPES OF WAVE
POWER PLANTS:
-Turbine-Central:
This type of plant is very similar to wind turbines. It consists of
placing under the water mills in areas with currents strong and fast. This type
of plant has a few years yet.
-Dam -Central:
They are built across an estuary or bay that must support a special
tidal range. The range should exceed 5 meters for the barrier to be useful. The
used of the dam is let the water flow into the basin at high tide. The dam has
gates that open the way to the water. The gates are closed when the tide
has stopped rising, keeping the water in
the basin or estuary. As the tide recedes beyond the barrier, the barrier gates
containing turbines are opened and the difference in water levels inside and
outside the barrier caused to flow through these gates, powering turbines and
generating. This can be generated in both directions through the barrier but
can affect the efficiency and economics of the project.
There are three main types of tidal barrier:
·
Lightbulb:
The water flows around the turbine
·
-De
rim: the generator is mounted at a right angle with respect to the turbine, making
it easier to access.
·
-Tubular-turbines:
They have blades that are connected to a long shaft and which are
oriented at an angle so that the generator is located
3.- ADVANTAGES AND DISADVANTAGES
Advantages of Wave Power
·
Capable of high
efficiency (60-80%) in ideal conditions.
·
Renewable energy
source obtained by wind via the Sun’s heating of our atmosphere.
·
Minimal
environmental impact when properly placed.
·
Low operation
and maintenance costs after construction.
·
Low upfront construction costs.
·
No emissions during operation.
Disadvantages
of Wave Power
·
Improperly
placed wave power plants can damage the marine ecosystem.
·
Efficiency drops
significantly in rough weather due to safety mechanisms.
·
Limited
locations where waves are strong enough to produce electricity without damaging
equipment.
·
Power only
produced near oceans making transmission to inland customers difficult.
·
Winds (and thus
waves) can be unpredictable and far from reliable. Can’t produce
electricity at all times.
4.-
COSTS:
It has been estimated
that improving technology and economies of scale will allow wave generators to
produce electricity at a cost comparable to wind-driven turbines, which produce
energy at about 4.5 cents kWh.
For now, the best wave
generator technology in place in the United Kingdom is producing energy at an
average projected/assessed cost of 7.5 cents kWh.
In comparison,
electricity generated by large scale coal burning power plants costs about 2.6
cents per kilowatt-hour. Combined-cycle natural gas turbine technology, the
primary source of new electric power capacity is about 3 cents per kilowatt
hour or higher. It is not unusual to average costs of 5 cents per kilowatt-hour
and up for municipal utilities districts.
5. -ENVIRONMENTAL IMPACT
Unlike
dams, wave power structures that are equally long-lived promise comparatively
benign environmental effects. Wave power is renewable, green, pollution-free,
and environmentally invisible, if not beneficial, particularly offshore. Its
net potential (resource minus "costs") is equal to or better than
wind, solar, small hydro or biomass power.
6. - POWER COUNTRIES
United Kingdom
Globally, the UK remains at the forefront of the development of wave energy technology.
Globally, the UK remains at the forefront of the development of wave energy technology.
Portugal
Portugal plays a leading role in the wave energy sector and saw the world's first commercial wave power project installed during 2008. The Wave Energy Centre (WavEC), founded in 2003, continues to promote and support the implementation of wave energy technology and the commercialisation of devices.
Portugal plays a leading role in the wave energy sector and saw the world's first commercial wave power project installed during 2008. The Wave Energy Centre (WavEC), founded in 2003, continues to promote and support the implementation of wave energy technology and the commercialisation of devices.
Ireland
Sustainable Energy Ireland (SEI, Ireland's national energy agency) and the Marine Institute prepared the National Strategy for Ocean Energy in 2006.
Sustainable Energy Ireland (SEI, Ireland's national energy agency) and the Marine Institute prepared the National Strategy for Ocean Energy in 2006.
Denmark
The emphasis in the Danish wave sector is currently on developing the technology by private enterprise, rather than on a governmental policy for utilising wave energy.
The emphasis in the Danish wave sector is currently on developing the technology by private enterprise, rather than on a governmental policy for utilising wave energy.
Australia
The Australian Federal Government and the State Governments are currently supporting the development of wave energy by issuing licences and by being party to MOU's. There has been considerable testing and development of the various wave schemes in recent years.
The Australian Federal Government and the State Governments are currently supporting the development of wave energy by issuing licences and by being party to MOU's. There has been considerable testing and development of the various wave schemes in recent years.
