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GREEN ENERGY TO PROTECTING THE ENVIRONMENT/ ENERGIA VERDE PARA PROTEGER O MEIO AMBIENTE

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Resumo After 1950, began to appear nuclear fission plants. The fission energy was a necessary evil. In this mode it stretched the oil life, avoiding an energy crisis. Even so, the energy obtained from oil represents about 60% of all energy used. At this rate of use of oil, it will be consumed in about 60 years. Today, the production of energy obtained by nuclear fusion is not yet perfect prepared. But time passes quickly. We must rush to implement of the additional sources of energy already known, but and find new energy sources. Green energy in 2010-2015 managed a spectacular growth worldwide of about 5%. The most difficult obstacle met in worldwide was the inconstant green energy produced.
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GREEN ENERGY TO PROTECTING THE ENVIRONMENT
ENERGIA VERDE PARA PROTEGER O MEIO AMBIENTE
Relly Victoria V. Petrescu1, Aversa Raffaella2, Apicella Antonio2; Florian Ion T. Petrescu1
1ARoTMM-IFToMM,
Bucharest Polytechnic University, Bucharest, 060042 (CE) Romania
petrescuvictoria@yahoo.com; scipub02@gmail.com
2Advanced Material Lab, Department of Architecture and Industrial Design,
Second University of Naples, Naples 81031 (CE) Italy
raffaella.aversa@unina2.it; antonio.apicella@unina2.it
Abstract
After 1950, began to appear nuclear fission plants. The fission energy was a necessary evil. In this
mode it stretched the oil life, avoiding an energy crisis. Even so, the energy obtained from oil
represents about 60% of all energy used. At this rate of use of oil, it will be consumed in about 60
years. Today, the production of energy obtained by nuclear fusion is not yet perfect prepared. But
time passes quickly. We must rush to implement of the additional sources of energy already known,
but and find new energy sources. Green energy in 2010-2015 managed a spectacular growth
worldwide of about 5%. The most difficult obstacle met in worldwide was the inconstant green
energy produced.
Key-words: environmental protection, green energy, wind power, hydropower, pumped-storage.
Resumo
Depois de 1950, começaram a aparecer plantas de cisão nuclear. A energia de fissão era um mal
necessário. Neste modo ele esticou a vida do óleo, evitando uma crise de energia. Mesmo assim, a
energia obtida do petróleo representa cerca de 60% de toda a energia utilizada. A esta taxa de uso
de petróleo, ele será consumido em cerca de 60 anos. Hoje, a produção de energia obtida por fusão
nuclear ainda não está perfeita. Mas o tempo passa rapidamente. Devemos apressar para
implementar as fontes de energia adicionais já conhecidas, mas e encontrar novas fontes de
energia. A energia verde em 2010-2015 geriu um crescimento espectacular em todo o mundo de
cerca de 5%. O obstáculo mais difícil encontrado no mundo foi a energia verde inconstante
produzida.
Palavras-chave: a protecção do ambiente, energia verde, energia eólica, energia hidroeléctrica,
Armazenamento bombeado.
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1. Introduction
Energy development is the effort to provide sufficient primary energy sources and secondary
energy forms for supply, cost, impact on air pollution and water pollution, mitigation of climate
change with renewable energy.
Technologically advanced societies have become increasingly dependent on external energy
sources for transportation, the production of many manufactured goods, and the delivery of energy
services.
This energy allows people who can afford the cost to live under otherwise unfavorable
climatic conditions through the use of heating, ventilation, and/or air conditioning. Level of use of
external energy sources differs across societies, as do the climate, convenience, levels of traffic
congestion, pollution and availability of domestic energy sources.
All terrestrial energy sources except nuclear, geothermal and tidal are from current solar
insolation or from fossil remains of plant and animal life that relied directly and indirectly upon
sunlight, respectively.
Ultimately, solar energy itself is the result of the Sun's nuclear fusion.
Geothermal power from hot, hardened rock above the magma of the Earth's core is the result
of the decay of radioactive materials present beneath the Earth's crust, and nuclear fission relies on
man-made fission of heavy radioactive elements in the Earth's crust; in both cases these elements
were produced in supernova explosions before the formation of the solar system.
Renewable energy is energy which comes from natural resources such as sunlight, wind,
rain, tides, and geothermal heat, which are renewable (naturally replenished).
In 2008, about 19% of global final energy consumption came from renewable, with 13%
coming from traditional biomass, which is mainly used for heating, and 3.2% from hydroelectricity.
New renewable (small hydro, modern biomass, wind, solar, geothermal, and biofuel)
accounted for another 2.7% and are growing very rapidly.
The share of renewable in electricity generation is around 18%, with 15% of global
electricity coming from hydroelectricity and 3% from new renewable. Wind power is growing at
the rate of 30% annually, with a worldwide installed capacity of 158 (GW) in 2009, and is widely
used in Europe, Asia, and the United States.
At the end of 2009, cumulative global photovoltaic (PV) installations surpassed 21 GW and
PV power stations are popular in Germany and Spain.
Solar thermal power stations operate in the USA and Spain, and the largest of these is the
354 megawatt (MW) SEGS power plant in the Mojave Desert.
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The world's largest geothermal power installation is The Geysers in California, with a rated
capacity of 750 MW. Brazil has one of the largest renewable energy programs in the world,
involving production of ethanol fuel from sugar cane, and ethanol now provides 18% of the
country's automotive fuel.
Ethanol fuel is also widely available in the USA, the world's largest producer in absolute
terms, although not as a percentage of its total motor fuel use.
While many renewable energy projects are large-scale, renewable technologies are also
suited to rural and remote areas, where energy is often crucial in human development.
Globally, an estimated 3 million households get power from small solar PV systems. Micro-
hydro systems configured into village-scale or county-scale mini-grids serve many areas.
More than 30 million rural households get lighting and cooking from biogas made in
household-scale digesters. Biomass cook stoves are used by 160 million households.
Climate change concerns, coupled with high oil prices, peak oil, and increasing government
support, are driving increasing renewable energy legislation, incentives and commercialization.
New government spending, regulation and policies helped the industry weather the 2009
economic crisis better than many other sectors.
Green energy in 2010-2015 managed a spectacular growth worldwide of about 5%.
2. Wind power
Airflows can be used to run wind turbines. Modern wind turbines range from around 600
kW to 5 MW of rated power, although turbines with rated output of 1.53 MW have become the
most common for commercial use; the power output of a turbine is a function of the cube of the
wind speed, so as wind speed increases, power output increases dramatically. Typical capacity
factors are 20-40%, with values at the upper end of the range in particularly favorable sites. Wind
energy is the cleanest and sufficient, the safest, cheapest and most sustainable. Where land space is
not enough, wind farms can be built and in the water. It must put the wind to work.
Wind energy or wind power is extracted from air flow using wind turbines or sails to
produce mechanical or electrical energy. Windmills are used for their mechanical power,
windpumps for water pumping, and sails to propel ships. A wind farm or wind park is a group of
wind turbines in the same location used to produce electricity. A large wind farm may consist of
several hundred individual wind turbines and cover an extended area of hundreds of square miles,
but the land between the turbines may be used for agricultural or other purposes. A wind farm can
also be located offshore. Many of the largest operational onshore wind farms are located in
Germany, China and the United States. In just five years, China leapfrogged the rest of the world in
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wind energy production, going from 2,599 MW of capacity in 2006 to 62,733 MW at the end of
2011. However, the rapid growth outpaced China's infrastructure and new construction slowed
significantly in 2012.
A windfarm or wind park is a group of wind turbines in the same location used to produce
electricity. A large wind farm may consist of several hundred individual wind turbines and cover an
extended area of hundreds of square miles, but the land between the turbines may be used for
agricultural or other purposes. A wind farm can also be located offshore.
Many of the largest operational onshore wind farms are located in Germany, China and the
United States. For example, the largest wind farm in the world, Gansu Wind Farm in China has a
capacity of over 6,000 MW of power in 2012 with a goal of 20,000 MW by 2020. The Alta Wind
Energy Center in California, United States is the largest onshore wind farm outside of China, with a
capacity of 1,020 MW. As of April 2013, the 630 MW London Array in the UK is the largest
offshore wind farm in the world, followed by the 504 MW Greater Gabbard wind farm in the UK.
There are many large wind farms under construction and these include Sinus Holding Wind
Farm (700 MW), Lincs Wind Farm (270 MW), Lower Snake River Wind Project (343 MW),
Macarthur Wind Farm (420 MW).
In just five years, China leapfrogged the rest of the world in wind energy production, going
from 2,599 MW of capacity in 2006 to 62,733 MW at the end of 2011. However, the rapid growth
outpaced China's infrastructure and new construction slowed significantly in 2012.
At the end of 2009, wind power in China accounted for 25.1 gigawatts (GW) of electricity
generating capacity, and China has identified wind power as a key growth component of the
country's economy. With its large land mass and long coastline, China has exceptional wind
resources. Researchers from Harvard and Tsinghua University have found that China could meet all
of their electricity demands from wind power by 2030.
By the end of 2008, at least 15 Chinese companies were commercially producing wind
turbines and several dozen more were producing components. Turbine sizes of 1.5 MW to 3 MW
became common. Leading wind power companies in China were Goldwind, Dongfang Electric, and
Sinovel along with most major foreign wind turbine manufacturers. China also increased production
of small-scale wind turbines to about 80,000 turbines (80 MW) in 2008. Through all these
developments, the Chinese wind industry appeared unaffected by the global financial crisis,
according to industry observers.
According to the Global Wind Energy Council, the development of wind energy in China, in
terms of scale and rhythm, is absolutely unparalleled in the world. The National People's Congress
permanent committee passed a law that requires the Chinese energy companies to purchase all the
electricity produced by the renewable energy sector (Fig. 1-2).
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Fig. 1 Wind farm in Xinjiang, China
Source: https://en.wikipedia.org/wiki/Wind_farm#/media/File:Wind_power_plants_in_Xinjiang,_China.jpg
Fig. 2 The Gansu Wind Farm in China is the largest wind farm in the world, with a target capacity of 20,000
MW by 2020.
Source: https://en.wikipedia.org/wiki/Wind_farm#/media/File:Gansu.Guazhou.windturbine_farm.sunset.jpg
U.S. wind power installed capacity in 2012 exceeded 51,630 MW and supplies 3% of the
nation's electricity.
New installations place the U.S. on a trajectory to generate 20% of the nation’s electricity by
2030 from wind energy. Growth in 2008 channeled some $17 billion into the economy, positioning
wind power as one of the leading sources of new power generation in the country, along with
natural gas. Wind projects completed in 2008 accounted for about 42% of the entire new power-
producing capacity added in the U.S. during the year.
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At the end of 2008, about 85,000 people were employed in the U.S. wind industry, and GE
Energy was the largest domestic wind turbine manufacturer. Wind projects boosted local tax bases
and revitalized the economy of rural communities by providing a steady income stream to farmers
with wind turbines on their land. Wind power in the U.S. provides enough electricity to power the
equivalent of nearly 9 million homes, avoiding the emissions of 57 million tons of carbon each year
and reducing expected carbon emissions from the electricity sector by 2.5%.
Texas, with 10,929 MW of capacity, has the most installed wind power capacity of any U.S.
state, followed by California with 4,570 MW and Iowa with 4,536 MW. The Alta Wind Energy
Center (1,020 MW) in California is the nation's largest wind farm in terms of capacity. Altamont
Pass Wind Farm is the largest wind farm in the U.S. in terms of the number of individual turbines
(Fig. 3-4).
Fig. 3 The Shepherds Flat Wind Farm is an 845 MW wind farm in the U.S. state of Oregon.
Source: https://en.wikipedia.org/wiki/Wind_farm#/media/File:Shepherds_Flat_Wind_Farm_2011.jpg
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Fig. 4 Brazos Wind Farm in the plains of West Texas.
Source: https://en.wikipedia.org/wiki/Wind_farm#/media/File:GreenMountainWindFarm_Fluvanna_2004.jpg
3. Wind power design
As a general rule, economic wind generators require windspeed of 16 km/h or greater. An
ideal location would have a near constant flow of non-turbulent wind throughout the year, with a
minimum likelihood of sudden powerful bursts of wind. An important factor of turbine siting is also
access to local demand or transmission capacity.
Usually sites are screened on the basis of a wind atlas, and validated with wind
measurements. Meteorological wind data alone is usually not sufficient for accurate siting of a large
wind power project. Collection of site specific data for wind speed and direction is crucial to
determining site potential in order to finance the project. Local winds are often monitored for a year
or more, and detailed wind maps constructed before wind generators are installed.
The wind blows faster at higher altitudes because of the reduced influence of drag. The
increase in velocity with altitude is most dramatic near the surface and is affected by topography,
surface roughness, and upwind obstacles such as trees or buildings. Typically, the increase of wind
speeds with increasing height follows a wind profile power law, which predicts that wind speed
rises proportionally to the seventh root of altitude. Doubling the altitude of a turbine, then, increases
the expected wind speeds by 10%, and the expected power by 34%.
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Individual turbines are interconnected with a medium voltage (usually 34.5 kV) power
collection system and communications network. At a substation, this medium-voltage electric
current is increased in voltage with a transformer for connection to the high voltage transmission
system. Construction of a land-based wind farm requires installation of the collector system and
substation, and possibly access roads to each turbine site (Fig. 5).
Fig. 5 First wind farm consisting of 7.5 megawatt (MW) Enercon E-126 turbines, Estinnes, Belgium, 20 July
2010, two months before completion.
Source:https://en.wikipedia.org/wiki/Wind_farm#/media/File:Windpark_Estinnes_20juli2010_kort_voor_voltooii
ng.jpg
4. Wind turbine
A wind turbine is a device that converts kinetic energy from the wind into electrical power.
The term appears to have migrated from parallel hydroelectric technology (rotary propeller). The
technical description for this type of machine is an aerofoil-powered generator.
The result of over a millennium of windmill development and modern engineering, today's
wind turbines are manufactured in a wide range of vertical and horizontal axis types. The smallest
turbines are used for applications such as battery charging for auxiliary power for boats or caravans
or to power traffic warning signs. Slightly larger turbines can be used for making contributions to a
domestic power supply while selling unused power back to the utility supplier via the electrical
grid. Arrays of large turbines, known as wind farms, are becoming an increasingly important source
of renewable energy and are used by many countries as part of a strategy to reduce their reliance on
fossil fuels (Fig. 6).
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Fig. 6 Offshore wind farm, using 5 MW turbines REpower 5M in the North Sea off the coast of Belgium.
Source:https://en.wikipedia.org/wiki/Wind_turbine#/media/File:Windmills_D14_%28Thornton_Bank%29
.jpg
Wind Turbine Types
Modern wind turbines fall into two basic groups; the horizontal-axis variety, like the
traditional farm windmills used for pumping water, and the vertical-axis design, like the eggbeater-
style Darrieus model, named after its French inventor. Most large modern wind turbines are
horizontal-axis turbines.
Turbine Components
Horizontal turbine components include:
- blade or rotor, which converts the energy in the wind to rotational shaft energy;
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- a drive train, usually including a gearbox and a generator;
- a tower that supports the rotor and drive train; and
- other equipment, including controls, electrical cables, ground support equipment, and
interconnection equipment.
Vertical-axis wind turbines (or VAWTs; Fig. 7) have the main rotor shaft arranged
vertically. One advantage of this arrangement is that the turbine does not need to be pointed into the
wind to be effective, which is an advantage on a site where the wind direction is highly variable. It
is also an advantage when the turbine is integrated into a building because it is inherently less
steerable. Also, the generator and gearbox can be placed near the ground, using a direct drive from
the rotor assembly to the ground-based gearbox, improving accessibility for maintenance.
Fig. 7 A vertical axis Twisted Savonius type turbine.
Source:https://en.wikipedia.org/wiki/Wind_turbine#/media/File:Twisted_Savonius_wind_turbine_in_ope
ration@60rpm.gif
The key disadvantages include the relatively low rotational speed with the consequential
higher torque and hence higher cost of the drive train, the inherently lower power coefficient, the
360 degree rotation of the aerofoil within the wind flow during each cycle and hence the highly
dynamic loading on the blade, the pulsating torque generated by some rotor designs on the drive
train, and the difficulty of modelling the wind flow accurately and hence the challenges of analysing
and designing the rotor prior to fabricating a prototype.
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When a turbine is mounted on a rooftop the building generally redirects wind over the roof
and this can double the wind speed at the turbine. If the height of a rooftop mounted turbine tower is
approximately 50% of the building height it is near the optimum for maximum wind energy and
minimum wind turbulence. Wind speeds within the built environment are generally much lower
than at exposed rural sites, noise may be a concern and an existing structure may not adequately
resist the additional stress.
5. Hydropower and pumped-storage
Hydropower or water power (from the Greek: ύδρω, "water" ) is power derived from the
energy of falling water or fast running water, which may be harnessed for useful purposes. Since
ancient times, hydropower from many kinds of watermills has been used as a renewable energy
source for irrigation and the operation of various mechanical devices, such as gristmills, sawmills,
textile mills, trip hammers, dock cranes, domestic lifts, and ore mills. A trompe, which produces
compressed air from falling water, is sometimes used to power other machinery at a distance.
In the late 19th century, hydropower became a source for generating electricity. Cragside in
Northumberland was the first house powered by hydroelectricity in 1878 and the first commercial
hydroelectric power plant was built at Niagara Falls in 1879. In 1881, street lamps in the city of
Niagara Falls were powered by hydropower.
Since the early 20th century, the term has been used almost exclusively in conjunction with
the modern development of hydroelectric power. International institutions such as the World Bank
view hydropower as a means for economic development without adding substantial amounts of
carbon to the atmosphere, but in some cases dams cause significant social or environmental issues.
In India, water wheels and watermills were built; in Imperial Rome, water powered mills
produced flour from grain, and were also used for sawing timber and stone; in China, watermills
were widely used since the Han dynasty In China and the rest of the Far East, hydraulically
operated "pot wheel" pumps raised water into crop or irrigation canals (Fig. 8).
The power of a wave of water released from a tank was used for extraction of metal ores in a
method known as hushing. The method was first used at the Dolaucothi Gold Mines in Wales from
75 AD onwards, but had been developed in Spain at such mines as Las Médulas. Hushing was also
widely used in Britain in the Medieval and later periods to extract lead and tin ores. It later evolved
into hydraulic mining when used during the California Gold Rush (Fig. 9).
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Fig. 8 The Three Gorges Dam in China; the hydroelectric dam is the world's largest power station by installed
capacity
Source: https://en.wikipedia.org/wiki/Hydropower#/media/File:The_Dam_%282890371280%29.jpg
Fig. 9 Saint Anthony Falls, United States
Source: https://en.wikipedia.org/wiki/Hydropower#/media/File:SaintAnthonyFalls.jpg
In the Middle Ages, Islamic mechanical engineer Al-Jazari invented designs for 100
hydraulic devices in his book, The Book of Knowledge of Ingenious Mechanical Devices, including
water wheel designs that rival designs of even the 21st century. He took a particular interest in
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pumping water to other regions, and because of this he created several "scooping" designs that were
designed to employ buckets, cranks, and cogs to lift water up from rivers.
In 1753, French engineer Bernard Forest de Bélidor published Architecture Hydraulique
which described vertical- and horizontal-axis hydraulic machines. By the late 19th century, the
electric generator was developed and could now be coupled with hydraulics. The growing demand
for the Industrial Revolution would drive development as well.
At the beginning of the Industrial Revolution in Britain, water was the main source of power
for new inventions such as Richard Arkwright's water frame. Although the use of water power gave
way to steam power in many of the larger mills and factories, it was still used during the 18th and
19th centuries for many smaller operations, such as driving the bellows in small blast furnaces and
gristmills, such as those built at Saint Anthony Falls, which uses the 50-foot (15 m) drop in the
Mississippi River.
In the 1830s, at the early peak in U.S. canal-building, hydropower provided the energy to
transport barge traffic up and down steep hills using inclined plane railroads. As railroads overtook
canals for transportation, canal systems were modified and developed into hydropower systems; the
history of Lowell, Massachusetts is a classic example of commercial development and
industrialization, built upon the availability of water power.
Technological advances had moved the open water wheel into an enclosed turbine or water
motor. In 1848 James B. Francis, while working as head engineer of Lowell's Locks and Canals
company, improved on these designs to create a turbine with 90% efficiency. He applied scientific
principles and testing methods to the problem of turbine design. His mathematical and graphical
calculation methods allowed confident design of high efficiency turbines to exactly match a site's
specific flow conditions. The Francis reaction turbine is still in wide use today. In the 1870s,
deriving from uses in the California mining industry, Lester Allan Pelton developed the high
efficiency Pelton wheel impulse turbine, which utilized hydropower from the high head streams
characteristic of the mountainous California interior.
The Chief Joseph Dam is a concrete gravity dam on the Columbia River, 2.4 km (1.5 mi)
upriver from Bridgeport, Washington. The dam is 877 km (545 mi) upriver from the mouth of the
Columbia at Astoria, Oregon. It is operated by the USACE Chief Joseph Dam Project Office, and
the electricity is marketed by the Bonneville Power Administration (Fig. 10). Among sources of
renewable energy, hydroelectric plants have the advantages of being long-lived (many existing
plants have operated for more than 100 years). Also, hydroelectric plants are clean and have few
emissions (Fig. 11).
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Fig. 10 Chief Joseph Dam near Bridgeport, Washington, U.S., is a major run-of-the-river station without a
sizeable reservoir
Source: https://en.wikipedia.org/wiki/Hydropower#/media/File:Chief_Joseph_Dam.jpg
Fig. 11 Hydroelectric plants
Source: Grand Coulee Dam.jpg
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Most hydroelectric power comes from the potential energy of dammed water driving a water
turbine and generator. The power extracted from the water depends on the volume and on the
difference in height between the source and the water's outflow. This height difference is called the
head. A large pipe (the "penstock") delivers water from the reservoir to the turbine (Fig. 12-13).
Fig. 12 A conventional dammed-hydro facility (hydroelectric dam) is the most common type of
hydroelectric power generation
Source: https://en.wikipedia.org/wiki/Hydropower#/media/File:Hydroelectric_dam.svg
Fig. 13 Turbine row at Los Nihuiles Power Station in Mendoza, Argentina
Source: https://en.wikipedia.org/wiki/Hydroelectricity#/media/File:Sala_de_turbinas.jpg
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Run-of-the-river hydroelectric stations are those with small or no reservoir capacity, so that
only the water coming from upstream is available for generation at that moment, and any
oversupply must pass unused. A constant supply of water from a lake or existing reservoir upstream
is a significant advantage in choosing sites for run-of-the-river. In the United States, run of the river
hydropower could potentially provide 60,000 megawatts (80,000,000 hp) (about 13.7% of total use
in 2011 if continuously available).
Pumped-storage
This method produces electricity to supply high peak demands by moving water between
reservoirs at different elevations. At times of low electrical demand, the excess generation capacity
is used to pump water into the higher reservoir.
When the demand becomes greater, water is released back into the lower reservoir through a
turbine.
Pumped-storage schemes currently provide the most commercially important means of
large-scale grid energy storage and improve the daily capacity factor of the generation system (Fig.
14).
Fig. 14 Diagram of the TVA pumped storage facility at Raccoon Mountain Pumped-Storage Plant
Source: https://en.wikipedia.org/wiki/Pumped-storage_hydroelectricity#/media/File:Pumpstor_racoon_mtn.jpg
Pumped storage is the largest-capacity form of grid energy storage available, and, as of
March 2012, the Electric Power Research Institute (EPRI) reports that PSH accounts for more than
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99% of bulk storage capacity worldwide, representing around 127,000 MW. Typically, the round-
trip energy efficiency of PSH varies in practice between 70% and 80%, with some claiming up to
87%. The main disadvantage of PHS is the specialist nature of the site required, needing both
geographical height and water availability. Suitable sites are therefore likely to be in hilly or
mountainous regions, and potentially in areas of outstanding natural beauty, and therefore there are
also social and ecological issues to overcome (Fig. 15).
Fig. 15 Pumped-storage hydroelectricity the upper reservoir (Llyn Stwlan) and dam of the Ffestiniog
Pumped Storage Scheme in north Wales. The lower power station has four water turbines which generate 360 MW of
electricity within 60 seconds of the need arising
Source: https://en.wikipedia.org/wiki/Hydropower#/media/File:Stwlan.dam.jpg
At times of low electrical demand, excess generation capacity is used to pump water into the
higher reservoir. When there is higher demand, water is released back into the lower reservoir
through a turbine, generating electricity. Reversible turbine/generator assemblies act as pump and
turbine (usually a Francis turbine design). Nearly all facilities use the height difference between two
natural bodies of water or artificial reservoirs. Pure pumped-storage plants just shift the water
between reservoirs, while the "pump-back" approach is a combination of pumped storage and
conventional hydroelectric plants that use natural stream-flow. Plants that do not use pumped-
storage are referred to as conventional hydroelectric plants; conventional hydroelectric plants that
have significant storage capacity may be able to play a similar role in the electrical grid as pumped
storage, by deferring output until needed.
Taking into account evaporation losses from the exposed water surface and conversion
losses, energy recovery of 80% or more can be regained. The technique is currently the most cost-
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effective means of storing large amounts of electrical energy on an operating basis, but capital costs
and the presence of appropriate geography are critical decision factors.
The relatively low energy density of pumped storage systems requires either a very large
body of water or a large variation in height. For example, 1000 kilograms of water (1 cubic meter)
at the top of a 100 meter tower has a potential energy of about 0.272 kW•h (capable of raising the
temperature of the same amount of water by only 0.23 Celsius = 0.42 Fahrenheit). The only way to
store a significant amount of energy is by having a large body of water located on a hill relatively
near, but as high as possible above, a second body of water. In some places this occurs naturally, in
others one or both bodies of water have been man-made. Projects in which both reservoirs are
artificial and in which no natural waterways are involved are commonly referred to as "closed
loop".
This system may be economical because it flattens out load variations on the power grid,
permitting thermal power stations such as coal-fired plants and nuclear power plants that provide
base-load electricity to continue operating at peak efficiency (Base load power plants), while
reducing the need for "peaking" power plants that use the same fuels as many baseload thermal
plants, gas and oil, but have been designed for flexibility rather than maximal thermal efficiency.
However, capital costs for purpose-built hydrostorage are relatively high.
Along with energy management, pumped storage systems help control electrical network
frequency and provide reserve generation. Thermal plants are much less able to respond to sudden
changes in electrical demand, potentially causing frequency and voltage instability. Pumped storage
plants, like other hydroelectric plants, can respond to load changes within seconds.
The upper reservoir (Llyn Stwlan) and dam of the Ffestiniog Pumped Storage Scheme in
north Wales. The lower power station has four water turbines which generate 360 MW of electricity
within 60 seconds of the need arising.
The first use of pumped storage was in the 1890s in Italy and Switzerland. In the 1930s
reversible hydroelectric turbines became available. These turbines could operate as both turbine-
generators and in reverse as electric motor driven pumps. The latest in large-scale engineering
technology are variable speed machines for greater efficiency. These machines generate in
synchronization with the network frequency, but operate asynchronously (independent of the
network frequency) as motor-pumps.
The first use of pumped-storage in the United States was in 1930 by the Connecticut Electric
and Power Company, using a large reservoir located near New Milford, Connecticut, pumping
water from the Housatonic River to the storage reservoir 230 feet above.
The important use for pumped storage is to level the fluctuating output of intermittent
energy sources. The pumped storage provides a load at times of high electricity output and low
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D.O.I.: 10.7198/S2237-072220170001011
electricity demand, enabling additional system peak capacity. In certain jurisdictions, electricity
prices may be close to zero or occasionally negative (Ontario in early September, 2006), on
occasions that there is more electrical generation than load available to absorb it; although at
present this is rarely due to wind alone, increased wind generation may increase the likelihood of
such occurrences. It is particularly likely that pumped storage will become especially important as a
balance for very large scale photovoltaic generation.
6. Using hydropower and pumped-storage together the wind power
Every day, the planet produces carbonic acid gas that's free to the earth’s atmosphere and
which is able to still be there in 100 years time. This augmented content of carbonic acid gas and
increases the heat of our planet. One answer to heating is to exchange and retrofit current
technologies with alternatives that have comparable or higher performance, however don't emit
carbonic acid gas.
By 2050, minimum of one third of the global energy has to be came from stars (solar), wind,
and different renewable resources. Who says that? Even “British Oil” and “Royal Dutch Shell” two
of the world's largest oil corporations. Global climate changes, increment of planet population, and
fuel depletion, mean that renewables ought to play an even bigger role within the future than they
are doing it now (Pineda, 2016).
All new energies need to have no desagreable consequences such as for example the fossil
fuels or nuclear energy. Real planetary alternative energy sources need to be renewable and are
thought to be "free" energy sources. These need to have decreased carbon emissions, compared to
conventional energy sources. It may be included: Biomass Energy, Wind Energy, Solar Energy,
Geothermal Energy, Hydroelectric Energy, Tidal Energy, Wave Energy, (Petrescu and Petrescu,
2011, 2012; Petrescu et al., 2016 a-b).
Nuclear fission energy was virtually a necessary evil. With all its risks, he managed to stop
the increasing of energy crisis of humanity until the advanced technology has allowed us the
transition to alternative energy.
Nuclear fusion energy will be the most powerful energy source for mankind when it will be
implemented (Petrescu and Petrescu, 2014). Although great advances have been made in this
direction, the nuclear fusion power plants did not yet built. Because it is not known when they will
be operative in large quantity, should be required to equip us in advance with green energy farms.
Most that are easy to be built and used now are the wind farms and the solar ones (Ramenah
and Tanougast, 2016).
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Their great technical problem is to have times when they produce less, or do not produce
anything.
Hydropower was used since ancient times for many kinds of watermills or has been used as
a renewable energy source to irrigation and to operate various mechanical devices (Sabău, 2015),
(Sabău and Iovan, 2015).
A known method for produces energy (electric energy) for supply high energy demands is to
moving and storing water between reservoirs at different elevations. This method is named pumped-
storage.
At the times with low energy demand, the excess generation capacities are used to pump
water into a reservoir upper positioned.
In the moments when the demand becomes greater, water is released back into a lower
positioned reservoir by a turbine (see the Fig. 14; Petrescu et al., 2016a).
It can build such a hydropower plant in that area with the great advantage to be constantly
supplied with water pumped even further by the surplus electricity generated by wind (that
otherwise would be lost in vain).
For a better understanding of the ideas, we will present below, very briefly, special technical
characteristics of a windmill (Dubău, 2015).
Electric power generated by wind is proportional to the cube of the wind speed.
A windmill is set to function optimally for a small or medium wind speed. If the speed of
wind in the area increases 10 times for example, one single windmill will produce wind power such
as a normal production given from the 1000 windmills (El-Naggar and Erlich, 2016).
Obviously, this surplus energy cannot be picked up by any electric network and is lost.
There is thus a large amount of energy produced but not used. If this energy could be used to act the
pumps which lift water to a storage energy system, it would solve two problems simultaneously.
Once, it would use the extra energy produced, which is lost otherwise. Second would store energy,
that is then used in periods of high consumption, or when the wind stops beating.
In other words, when wind energy is very high (when strong wind) energy production on
coal and hydro are limited and even stopped temporarily. But the inverse problem (when not too
windy and the demand is high from population and industry) is more difficult to solve.
Usually in such situations are utilized at maximum capacity all hydro and coal plants.
A more viable solution would be to introduce into a national power grid yet two nuclear
fission reactors.
But another important solution would be the introduction of hydro energy storage systems,
as it has already been described previously.
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7. Conclusions
After 1950, began to appear nuclear fission plants. The fission energy was a necessary evil.
In this mode it stretched the oil life, avoiding an energy crisis. Even so, the energy obtained from oil
represents about 60% of all energy used. At this rate of use of oil, it will be consumed in about 60
years.
Today, the production of energy obtained by nuclear fusion is not yet perfect prepared. But
time passes quickly. One must rush to implement of the additional sources of energy already
known, but and find new energy sources. Green energy in 2010-2015 managed a spectacular growth
worldwide of about 5%.
The most difficult obstacle met in worldwide was the inconstant green energy produced
(especially the wind power).
A more viable solution would be to introduce into a national power grid yet two nuclear
fission reactors.
But another important solution would be the introduction of hydro energy storage systems,
as it has already been described previously.
References
Dubău C., (2015) Vertical Axis Wind Turbine Power Rating, Analele Universităţii Oradea,
Fascicula Protecţia Mediului, 24:313-316; Retrieved from:
http://protmed.uoradea.ro/facultate/publicatii/protectia_mediului/2015A/silv/05.%20Dubau%20Cali
n.pdf
El-Naggar A., Erlich I., (2016) Analysis of fault current contribution of Doubly-Fed Induction
Generator Wind Turbines during unbalanced grid faults, Renewable Energy, 91:137-146; Retrieved
from:
http://www.sciencedirect.com/science/article/pii/S0960148116300453
Muthumeenal A., Pethaiah S.S., Nagendran A., (2016) Investigation of SPES as PEM for hydrogen
production through electrochemical reforming of aqueous methanol, Renewable Energy, 91:75-82;
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Petrescu, R.V.; Aversa, R.; Apicella, A.; Berto, F.; Li, S.; Petrescu, FIT.; 2016a Ecosphere
Protection through Green Energy, American Journal of Applied Sciences, 13(10):1027-1032.
Petrescu, FIT.; Apicella, A.; Petrescu, RV.; Kozaitis, SP.; Bucinell, RB.; Aversa, R.; Abu-Lebdeh,
TM.; 2016b Environmental Protection through Nuclear Energy, American Journal of Applied
Sciences, 13(9):941-946.
Petrescu F.I., Petrescu R.V., (2011) Perspective energetice globale (Romanian Edition) December
26, 2011, 80 pages, Publisher: CreateSpace Independent Publishing Platform, ISBN-10:
146813082X, ISBN-13: 978-1468130829; Retrieved from:
http://www.amazon.com/Perspective-energetice-globale-Romanian-Petrescu/dp/146813082X
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Petrescu F.I., Petrescu R.V., (2012) Green Energy, Paperback November 5, 2012, Books On
Demand, 118 pages, ISBN-13: 978-3848223633; Retrieved from:
http://www.amazon.com/Green-Energy-Florian-Tiberiu-
Petrescu/dp/3848223635/ref=la_B006T2UHJM_1_25?s=books&ie=UTF8&qid=1432305411&sr=1
-25
Petrescu, F.I., Petrescu, R.V., (2014) Nuclear Green Energy, IJAP, 10(1):3-14; Retrieved from:
http://www.iasj.net/iasj?func=fulltext&aId=88317
Pineda S., Bock A., (2016) Renewable-based generation expansion under a green certificate market,
Renewable Energy, 91:53-63; Retrieved from:
http://www.sciencedirect.com/science/article/pii/S0960148115305656
Ramenah H., Tanougast C., (2016) Reliably model of microwind power energy output under real
conditions in France suburban area, Renewable Energy, 91:1-10; Retrieved from:
http://www.sciencedirect.com/science/article/pii/S0960148115304377
Sabău N.C., (2015) Energy Production in Hydropowers and Electric Thermal Power Plants from the
Perspective of European Community Legislation, Analele Universităţii Oradea, Fascicula Protecţia
Mediului, 24:235-248; Retrieved from:
http://protmed.uoradea.ro/facultate/publicatii/protectia_mediului/2015A/im/15.%20Sabau%20Nicu
%20Cornel.pdf
Sabău N.C., Iovan I.C., (2015) Some Aspects of Determination Galbena Valley Hydropower
Characteristics, Using Method for Determining the Flow from the Possible Locations of Small
Hydropower (MHC), Analele Universităţii Oradea, Fascicula Protecţia Mediului, 25:267-278;
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%20Cornel%202.pdf
Recebido: 30/07/2016
Aprovado: 19/02/2017
... Gansu wind farm[1]. ...
... PHS station[1]. ...
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Water Energy is one of the most important renewable energy source, is used mainly to produce electricity in small hydropower (MHC). In MHC construction in Romania have been reported numerous negative environmental impact problems, especially in protected areas, the destruction of the flora and endangered aquatic species protected. Given the increasing trend MHC on small water streams in remote areas without hydrometric measurements, determining the flow characteristic problems of their locations sections. Of these easements flow of particular importance in order to avoid problems related to the protection of aquatic species during operation. The objective of this study is to evaluate the hydraulic characteristics values (theoretical hydropower potential, theoretical energy, potential linear, linear energy, the amount of theoretical potential, technical potential arranged and installed flow, on Galbena Valley from Apuseni Mountains, in the event of lack of flow measurements. The most accurate estimates of installed flow measurements are obtained when the hydrometric ratchets, the average differences are -1.05% of from the reference flow (23***). Given the impact on the environment MHC is recommended to estimate flow, method with hydrometric ratchets measurements, which provides the nearest determination the easement flow. Key words: mycrohydropower (MHC), theoretical hydropower potential, theoretical energy, technical potential conversion, easement flow, installed flow.
Book
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Energia de fisiune nucleară a reprezentat un rău necesar. Ea a reuşit să lungească viaţa petrolului şi să prevină o criză energetică globală foarte gravă. Chiar şi aşa, energia obţinută din hidrocarburi (petrol, cărbune, gaze, biomasă) reprezintă aproximativ 66% din totalul de energie produsă şi utilizată astăzi la nivel mondial. Dacă menţinem acest nivel de producţie şi consum petrolul se va epuiza în circa 40 ani. Pe de altă parte, astăzi, producţia de energie nucleară (superioară), bazată pe fuziune nucleară, nu este încă perfect pusă la punct (deşi studiile se află într-un stadiu foarte avansat). Însă timpul trece repede. Trebuie să ne grăbim să implementăm şi să dezvoltăm noile energii regenerabile deja cunoscute, dar şi noi posibile energii regenerabile. În aceste condiţii, prezenta lucrare vine să propună noi posibile surse de energii regenerabile. PARTEA I 1. 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Micro-hidro sistemele configurate pentru localităţile mici de provincie deservesc deja foarte multe arii din toată lumea, şi se extind în continuare (doar că acest potenţial energetic este limitat). Peste 30 milioane de locuinţe rurale primesc deja energie (lumină, apă caldă şi căldură pentru gătit) de la sistemul cu biogaz. Sistemele cu biomasă sunt şi mai extinse pe întreaga suprafaţă a planetei, deservind astăzi circa 160 milioane gospodării. 2. TIPURILE PRINCIPALE DE ENERGII REGENERABILE CUNOSCUTE o 2.1. Energia eoliană o 2.2. Hidroenergia o 2.3. Energia solară o 2.4. Biomasa o 2.5. Biocombustibilii o 2.6. Energia geotermală o 2.7. Energia mareelor o 2.8. Hidrogen obţinut prin fotosinteză artificială o 2.9. Energia de tip „Lumină neagră” 2.1. Energia eoliană (a vânturilor) Curenţii de aer pot fi utilizaţi pentru a antrena turbine eoliene.
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Quota obligations represent a policy instrument to reduce carbon emissions and incentivize renewable-based electricity generation. This support scheme places an obligation on generating companies to comply with a quota of renewable-based production. Eligible renewable units receive one certificate for each MWh, while fossil-based generating companies must buy certificates to comply with the requirement. This paper proposes a family of generation expansion models that include both an electricity and a certificate market to investigate to which degree a given quota obligation and non-compliance penalty incentivize the capacity expansion of renewable-based generation. Two market players are considered, namely, a renewable-based generating company with null operating cost and a weather-dependent capacity factor; and a fossil-based generating company with a fixed capacity and known fuel cost function. First, a complementarity model that determines the optimal capacity of the renewable-based producer considering a perfectly competitive market is proposed. Next, market players are assumed to compete in quantities à la Cournot to maximize their profits, being the generation expansion model formulated as a mathematical problem with equilibrium constraints. The relevance of properly setting the non-compliance penalty for each level of competition to comply with a given quota obligation is quantified and discussed using an stylized example.
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Micro-wind turbine are now specially designed for rural or urban environment and one of the main advantages of such turbine is that it can be propelled by a wind speed as low as 3 m/s. However, due to terrain roughness in urban environments wind flow is reduced compared to open spaces reducing power output and increasing payback time on capital investment. Well mounting turbines in urban areas may provide the perfect opportunity for onsite generation from wind power. In this paper, we investigate the performance of a micro-wind turbine in a complex urban area and show that due to long time period and very subtile onsite measurements the ideal position for the wind turbine can be determined. Well measured data, wind speed, power output at this particular location are approximated by the Weibull function. The considered model is tested and validated at an urban landscape location in Metz City, France, where an anemometry is positioned at adjacent to the turbine and the instrumentation is positioned specific to its surrounding location and, record wind turbine data thanks to real time wireless communications. Technical data including wind speed and output power were analyzed and reported allowing to provide an reliable estimation of the wind energy potential in an urban location.
  • F I Petrescu
  • R V Petrescu
Petrescu F.I., Petrescu R.V., (2012) Green Energy, Paperback – November 5, 2012, Books On Demand, 118 pages, ISBN-13: 978-3848223633; Retrieved from: http://www.amazon.com/Green-Energy-Florian-Tiberiu
Perspective energetice globale (Romanian Edition)1468130829; Retrieved from: http://www.amazon.com/Perspective-energetice-globale-Romanian
  • F I Petrescu
  • R V Petrescu
Petrescu F.I., Petrescu R.V., (2011) Perspective energetice globale (Romanian Edition) – December 26, 2011, 80 pages, Publisher: CreateSpace Independent Publishing Platform, ISBN-10: 146813082X, ISBN-13: 978-1468130829; Retrieved from: http://www.amazon.com/Perspective-energetice-globale-Romanian-Petrescu/dp/146813082X
  • F I Petrescu
  • R V Petrescu
Petrescu, F.I., Petrescu, R.V., (2014) Nuclear Green Energy, IJAP, 10(1):3-14; Retrieved from: http://www.iasj.net/iasj?func=fulltext&aId=88317