Management of Renewable Energies and Environmental Protection, Part II

The purpose of this project is to present an overview of renewable energy sources, major technological developments and case studies, accompanied by applicable examples of the use of sources. Renewable energy is the energy that comes from natural resources: The wind, sunlight, rain, sea waves, tides, geothermal heat, regenerated naturally, automatically. Greenhouse gas emissions pose a serious threat to climate change, with potentially disastrous effects on humanity

mediaimage
The use of Renewable Energy Sources (RES) together with improved Energy Efficiency (EE) can contribute to reducing energy consumption,Management of Renewable Energies and Environmental Protection, Part II Articles reducing greenhouse gas emissions and, as a consequence, preventing dangerous climate change. At least one-third of global energy must come from different renewable sources by 2050: The wind, solar, geothermal, hydroelectric, tidal, wave, biomass, etc. Oil and natural gas, classical sources of energy, have fluctuating developments on the international market. A second significant aspect is given by the increasingly limited nature of oil resources. It seems that this energy source will be exhausted in about 50 years from the consumption of oil reserves in exploitation or prospecting. “Green” energy is at the fingertips of both economic operators and individuals. In fact, an economic operator can use such a system for both own consumption and energy trading on the domestic energy market. The high cost of deploying these systems is generally depreciated in about 5-10 years, depending on the installed production capacity. The “sustainability” condition is met when projects based on renewable energy have a negative CO2 or at least neutral CO2 over the life cycle. Emissions of Greenhouse Gases (GHG) are one of the environmental criteria included in a sustainability analysis, but is not enough. The concept of sustainability must also include in the assessment various other aspects, such as environmental, cultural, health, but must also integrate economic aspects. Renewable energy generation in a sustainable way is a challenge that requires compliance with national and international regulations. Energy independence can be achieved: – Large scale (for communities); – small-scale (for individual houses, vacation homes or cabins without electrical connection).

Keywords: Environmental Protection, Renewable Energy, Sustainable Energy, The Wind, Sunlight, Rain, Sea Waves, Tides, Geothermal Heat, Regenerated Naturally.

Introduction
The purpose of this project is to present an overview of renewable energy sources, major technological developments and case studies, accompanied by applicable examples of the use of sources.

Renewable energy is the energy that comes from natural resources: The wind, sunlight, rain, sea waves, tides, geothermal heat, regenerated naturally, automatically.

Greenhouse gas emissions pose a serious threat to climate change, with potentially disastrous effects on humanity. The use of Renewable Energy Sources (RES) together with improved Energy Efficiency (EE) can contribute to reducing energy consumption, reducing greenhouse gas emissions and, as a consequence, preventing dangerous climate change.

At least one-third of global energy must come from different renewable sources by 2050: The wind, solar, geothermal, hydroelectric, tidal, wave, biomass, etc.

Oil and natural gas, classical sources of energy, have fluctuating developments on the international market. A second significant aspect is given by the increasingly limited nature of oil resources. It seems that this energy source will be exhausted in about 50 years from the consumption of oil reserves in exploitation or prospecting.

“Green” energy is at the fingertips of both economic operators and individuals.

In fact, an economic operator can use such a system for both own consumption and energy trading on the domestic energy market. The high cost of deploying these systems is generally depreciated in about 5-10 years, depending on the installed production capacity.

The “sustainability” condition is met when projects based on renewable energy have a negative CO2 or at least neutral CO2 over the life cycle.

Emissions of Greenhouse Gases (GHG) are one of the environmental criteria included in a sustainability analysis, but is not enough. The concept of sustainability must also include in the assessment various other aspects, such as environmental, cultural, health, but must also integrate economic aspects.

Renewable energy generation in a sustainable way is a challenge that requires compliance with national and international regulations.

Energy independence can be achieved:

Large scale (for communities)
Small-scale (for individual houses, vacation homes or cabins without electrical connection)
Today, the renewable energy has gained an avant-garde and a great development also thanks to governments and international organizations that have finally begun to understand its imperative necessity for humanity, to avoid crises and wars, to maintain a modern life (we can’t go back to caves).

Materials and Methods
The Micro-Hydropower Potential

Hydroelectric power comes from the action of moving water. It can be seen as a form of solar energy because the sun feeds the water circuit in nature. Within this circuit, the water from the atmosphere reaches the surface of the earth in the form of precipitation. Part of it evaporates, but much of it penetrates the soil or becomes flowing water to the surface. Rainwater and melted snow finally end up in ponds, lakes, reservoirs or oceans where evaporation takes place permanently.

Water resources due to inland rivers are estimated at about 42 billion cubic meters per year, but under unchecked storage, it can only account for about 19 million cubic meters per year due to fluctuations in river flows.

Low-power hydropower plants are a major contributor of renewable electricity at European and world level. Worldwide, it is estimated that there is an installed capacity of 47,000 MW, with a potential – technical and economic – close to 180,000 MW.

Low-Power Hydropower Plants (HMP) are powered by natural water flow, i.e., it does not involve large-scale water capture and therefore does not require the construction of large dams and reservoirs, although they help where they exist and can be used easily. There is no international definition of the HMP and the upper limit varies between 2.5 and 25 MW depending on the country, but the 10 MW value is generally accepted and promoted by European Association of Low Power Hydro Power Plants (ESHA).

Low power plants are one of the most reliable and cost-effective technologies for producing clean electricity.

In particular, the key advantages of HMPs to wind-based, wave-based or solar power plants are:

High efficiency (70-90%), by far the best of all energy technologies
A high capacity factor (usually> 50%), compared to 10% for solar energy and 30% for wind power
High predictability, depending on yearly rainfall patterns
Low rate of variability; The energy produced varies only gradually from day to day (not from one minute to the next)
Good correlation with demand (eg output is maximum in winter)
It is a sustainable and solid technology; Systems can be designed to work for over 50 years
HMPs are also environmentally friendly. Most of the time, they work on the natural course of water. Therefore, this type of water-based installation does not have the same negative environmental effects as large hydropower plants.

Small hydropower plants can be located either in mountainous areas where rivers are fast or in low-lying areas with large rivers. The four most common types of micro-power plants are presented below.

For large and medium fall schemes, channel and duct combinations are used. If the terrain is injured, the construction of the canal is difficult and then only the forced duct that can sometimes be buried is used. In the barrage arrangements the turbines are placed in or in the immediate vicinity of the dam, so that there is almost no need for the channel or the pipeline.

Another option of placing the microturbines is to use the flows from the water treatment plants.

The objective of a hydroelectric system is to convert the potential energy of the volume of water flowing from a certain height into electricity at the bottom end of the system where the power plant is located. The water level difference, known as “fall”, is essential for the production of hydroelectricity; The simple rapid flow of water does not contain enough energy to produce significant electrical energy than on a very large scale such as coastal submarine currents. That is why two indicators are needed: Q water flow and H dropping. It is generally better to have a larger drop than a higher flow, because smaller equipment can be used.

Grossfall (H) is the maximum vertical distance between upstream and downstream water levels. The actual fall seen at the turbine will be somewhat lower than the gross fall, due to the loss of water in and out of the system. This low fall is called the Net Fall.

Flow rate (Q) is the volume of water passing into the unit of time, measured in m3/s. For small systems, the flow rate can also be expressed in liters/second, where 1000 l/s = 1 m3/sec. Depending on the fall, hydroelectric plants can be classified into three categories:

Large drop: Over 100 m
Average fall: 30-100 m
Reduced fall: 2-30 m
These categories are not strict, but are only a possible ranking system for locations.

Hydroelectric installations can also be defined as:

Installations on the water wire
Installations with a power plant located at the base of a dam
Integrated systems on a channel or in a water supply pipe
Generally, large-scale locations are less expensive to develop than small-fall ones, because for the same level of energy produced, the flow required by the turbine will be lower than hydro-technical constructions. For a river with a relatively high slope in a sector of its course, the level difference can be used by conducting part or all of the course and returning it to the river bed after passing through the turbine. The water can be brought directly from the source to the turbine via a pressure pipe.

Hydroelectric turbines convert water pressure into mechanical power to the shaft, which can be used to drive an electric generator or other equipment. Available electricity is directly proportional to the fall and flow rate.

The best turbines can have hydraulic efficiency in the order of 80-90% (higher than any other driving force), although it decreases with size.

The main component of a small hydropower plant is the hydraulic turbine. All of these turbines convert the falling water energy into kinetic rotation shaft energy, but confusion often arises as to which type of turbine should be used depending on the circumstances. The choice of the turbine depends on the location characteristics, especially the drop and flow, plus the desired generator speed and if the turbine has to operate under low flow conditions.

There are two main types of turbines, called “impulse” and “reactive”.

The impulse turbine converts the potential energy of the water into kinetic energy through a jet that comes out of a nozzle and is projected onto the rotor cups or blades.

The reaction turbine uses pressure and water speed to create energy. The rotor is completely immersed and the pressure and speed drop from intake to exhaust. By contrast, the rotor of a pulse turbine operates in air, driven by a jet (or jets) of water.

There are 3 main types of impetus turbines: Pelton, Turbo and Cross Flow (or Banki). The main 2 types of reaction turbines are helical (Kaplan) and Francis.

Most existing turbines can be grouped into three categories:

Kaplan and helical turbines
Turbine Francis
Pelton turbines and other impulse turbines
Kaplan and propeller turbines are axial flow turbines, generally used for small falls (typically less than 16 m). The Kaplan turbine has adjustable blades and may or may not have an adjustable stator head unit. If both the rotor blades and the steering gear are adjustable, we are dealing with a ‘double-tuned’ turbine. If the directing device is fixed, we are dealing with a ‘simple tuned’ turbine. In the conventional version, the Kaplan turbine has a spiral chamber (either steel or reinforced concrete); the flow enters radially inward and makes a straight angle before entering the rotor in the axial direction. If the rotor has fixed blades, the turbine is called a propeller turbine.

Propeller turbines may have mobile or fixed devices. Turbines with nipples are used only if flow and fall are practically constant.

Bulb and tubular turbines are derived from the Kaplan and helical variants, where the flow enters and exits with minor directional changes. In the Bulb turbine, the multiplier and the generator are located in a submerged capsule. The tubular turbines allow several arrangements, namely: Straight-angle transmission, Straflo turbines with S-ducts, belt drive generators, etc. Versions with straight-angle transmission are very attractive, but they are only manufactured to a power of 2 MW.

Francis turbines are radial-flow turbine engines with fixed rotor blades and mobile guides used for mid-fall. The rotor is made up of cups with complex profiles. A Francis turbine typically includes a spiral cast iron or steel chamber to distribute water throughout the perimeter of the rotor and a series of guide elements to adjust the flow of water into the rotor.

Pelton turbines are single or multiple jet turbines, each jet being designed with a needle nozzle to control the flow. They are used for medium and large falls. The nozzle axes are on the rotor plane.

The cross-flow turbine, sometimes called the Ossberger turbine, after a company that has been manufacturing it for over 50 years, or the Michell turbine is used for a wide range of falls, overlapping with Kaplan, Francis and Pelton turbine applications. This type is very suitable for a high-flow and low drop stream.

Turbo can operate under a fall ranging from 30-300 m. Like the Pelton turbine, it is a pulsating turbine, but the blades have a different shape and the water jets hit the plane of the rotor at an angle of 20°. The water enters the rotor through one side of it and goes out through the other. The high turbo turbine speed due to its smaller diameter than other models makes it more likely to directly engage the turbine and generator. A turbine of this type may be suitable for average falls where a Francis turbine could also be used. But, unlike Pelton, the water passing through the rotor produces an axial force that requires the installation of a transmission shaft on the shaft.

The type, geometry and dimensions of the turbine will be fundamentally conditioned by the following criteria:

The net fall
Turbine flow ranges
Rotation speed
Cavity problems
Cost
The efficiency of a turbine is defined as the ratio between the power delivered by the turbine (mechanical power transmitted to the axle) and the absorbed power (the hydraulic power equivalent to the flow measured under the net fall). To estimate overall efficiency, the efficiency of the turbine must be multiplied by the efficiency of the speed multiplier (if used) and the alternator.

For different types of turbines, efficiency drops rapidly below a certain percentage of nominal flow. A turbine is designed to operate close to the maximum efficiency point, typically 80% of the turbine’s maximum flow and when the flow deviates from this value, the hydraulic efficiency of the turbine decreases.

The flow rate range and thus the generated energy, varies if:

The system must provide power to a small network
The system was designed to connect to an extended distribution network
In the first case, it is necessary to select a flow that allows the production of energy almost all year round. In the second case, the nominal flow should be selected so that the net profit from the sale of electricity is maximum.

The control panel is the equipment that monitors the operation of the hydropower system. The main functions of the control panel are:

Turning the turbine on and off

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NACA and NASA, Part VII

Authors: Relly Victoria Virgil Petrescu and Florian Ion Tiberiu Petrescu

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Helios probes

Helios-A and Helios-B (also known as Helios 1 and Helios 2),NACA and NASA, Part VII Articles were a pair of probes launched into heliocentric orbit for the purpose of studying solar processes.

A joint venture of the Federal Republic of Germany (West Germany) and NASA, the probes were launched from the John F. Kennedy Space Center at Cape Canaveral, Florida, on Dec. 10, 1974, and Jan. 15, 1976, respectively.

The probes are notable for having set a maximum speed record among spacecraft at 252,792 km/h (157,078 mi/h or 43.63 mi/s or 70.22 km/s or 0.000234c).

Helios 2 flew three million kilometers closer to the Sun than Helios 1, achieving perihelion on 17 April 1976 at a record distance of 0.29 AU (or 43.432 million kilometers), slightly inside the orbit of Mercury.

Helios 2 was sent into orbit 13 months after the launch of Helios 1.

The Helios space probes completed their primary missions by the early 1980s, but they continued to send data up to 1985. The probes are no longer functional but still remain in their elliptical orbit around the Sun.

This spacecraft was one of a pair of deep space probes developed by the Federal Republic of Germany (FRG) in a cooperative program with NASA. Experiments were provided by scientists from both FRG and the U.S. NASA supplied the Titan/Centaur launch vehicle. The spacecraft was equipped with two booms and a 32-m electric dipole. The payload consisted of a fluxgate magnetometer; electric and magnetic wave experiments, which covered various bands in the frequency range 6 Hz to 3 MHz; charged-particle experiments, which covered various energy ranges starting with solar wind thermal energies and extending to 1 GeV; a zodiacal-light experiment; and a micrometeoroid experiment. The purpose of the mission was to make pioneering measurements of the interplanetary medium from the vicinity of the earth’s orbit to 0.3 AU. The spin axis was normal to the ecliptic, and the nominal spin rate was 1 rps.

The outer spacecraft surface was dielectric, effectively (because of the sheath potential) raising the low-energy threshold for the solar wind plasma experiment to as high as 100 eV. Also, sheath-related coupling caused by the spacecraft antennae produced interference with the wave experiments.

The spacecraft was capable of being operated at bit rates from 4096 to 8 bps, variable by factors of 2. While the spacecraft was moving to perihelion, it was generally operated from 64 to 256 bps; and near 0.3 AU, it was operated at the highest bit rate. Because of a deployment failure of one axis of the 32-m, tip-to-tip, dipole antenna, one axis was shorted, causing the antenna to function as a monopole. The major effect of this anomaly was to increase the effective instrument thresholds, and to introduce additional uncertainties in the effective antenna length. Instrument descriptions written by the experimenters were published (some in German, some in English) in Raumfahrtforschung, v. 19, n. 5, 1975.

Hubble Space Telescope

The Hubble Space Telescope (HST) is a space telescope that was carried into orbit by a space shuttle in 1990. Although not the first space telescope, Hubble is one of the largest and most versatile, and is well-known as both a vital research tool and a public relations boon for astronomy. The HST was built by the United States space agency NASA, with contributions from the European Space Agency, and is operated by the Space Telescope Science Institute. It is named after the astronomer Edwin Hubble. The HST is one of NASA’s Great Observatories, along with the Compton Gamma Ray Observatory, the Chandra X-ray Observatory, and the Spitzer Space Telescope.

Space telescopes were proposed as early as 1923. Hubble was funded in the 1970s, with a proposed launch in 1983, but the project was beset by technical delays, budget problems, and the Challenger disaster. When finally launched in 1990, scientists found that the main mirror had been ground incorrectly, severely compromising the telescope’s capabilities. However, after a servicing mission in 1993, the telescope was restored to its intended quality. Hubble’s orbit outside the distortion of Earth’s atmosphere allows it to take extremely sharp images with almost no background light. Hubble’s Ultra Deep Field image, for instance, is the most detailed visible-light image ever made of the universe’s most distant objects. Many Hubble observations have led to breakthroughs in astrophysics, such as accurately determining the rate of expansion of the universe.

Hubble is the only telescope designed to be serviced in space by astronauts. Four servicing missions were performed from 1993 to 2002, but the fifth was canceled on safety grounds following the Columbia disaster. However, after spirited public discussion, NASA administrator Mike Griffin approved one final servicing mission, completed in 2009. The telescope is now expected to function until at least 2014, when its scientific successor, the James Webb Space Telescope (JWST), is due to be launched.

The history of the Hubble Space Telescope can be traced back as far as 1946, when the astronomer Lyman Spitzer wrote the paper “Astronomical advantages of an extraterrestrial observatory”. In it, he discussed the two main advantages that a space-based observatory would have over ground-based telescopes. First, the angular resolution (smallest separation at which objects can be clearly distinguished) would be limited only by diffraction, rather than by the turbulence in the atmosphere, which causes stars to twinkle and is known to astronomers as seeing. At that time ground-based telescopes were limited to resolutions of 0.5–1.0 arcseconds, compared to a theoretical diffraction-limited resolution of about 0.05 arcsec for a telescope with a mirror 2.5 m in diameter. Second, a space-based telescope could observe infrared and ultraviolet light, which are strongly absorbed by the atmosphere.

Spitzer devoted much of his career to pushing for a space telescope to be developed. In 1962 a report by the United States National Academy of Sciences recommended the development of a space telescope as part of the space program, and in 1965 Spitzer was appointed as head of a committee given the task of defining the scientific objectives for a large space telescope.

Space-based astronomy had begun on a very small scale following World War II, as scientists made use of developments that had taken place in rocket technology. The first ultraviolet spectrum of the Sun was obtained in 1946, and NASA launched the Orbiting Solar Observatory to obtain UV, X-ray, and gamma-ray spectra in 1962. An orbiting solar telescope was launched in 1962 by the United Kingdom as part of the Ariel space program, and in 1966 National Aeronautics and Space Administration (NASA) launched the first Orbiting Astronomical Observatory (OAO) mission. OAO-1’s battery failed after three days, terminating the mission. It was followed by OAO-2, which carried out ultraviolet observations of stars and galaxies from its launch in 1968 until 1972, well beyond its original planned lifetime of one year.

The OSO and OAO missions demonstrated the important role space-based observations could play in astronomy, and 1968 saw the development by NASA of firm plans for a space-based reflecting telescope with a mirror 3 m in diameter, known provisionally as the Large Orbiting Telescope or Large Space Telescope (LST), with a launch slated for 1979. These plans emphasized the need for manned maintenance missions to the telescope to ensure such a costly program had a lengthy working life, and the concurrent development of plans for the reusable space shuttle indicated that the technology to allow this was soon to become available.

The continuing success of the OAO program encouraged increasingly strong consensus within the astronomical community that the LST should be a major goal. In 1970 NASA established two committees, one to plan the engineering side of the space telescope project, and the other to determine the scientific goals of the mission. Once these had been established, the next hurdle for NASA was to obtain funding for the instrument, which would be far more costly than any Earth-based telescope. The US Congress questioned many aspects of the proposed budget for the telescope and forced cuts in the budget for the planning stages, which at the time consisted of very detailed studies of potential instruments and hardware for the telescope. In 1974, public spending cuts instigated by Gerald Ford led to Congress cutting all funding for the telescope project.

In response to this, a nationwide lobbying effort was coordinated among astronomers. Many astronomers met congressmen and senators in person, and large scale letter-writing campaigns were organized. The National Academy of Sciences published a report emphasizing the need for a space telescope, and eventually the Senate agreed to half of the budget that had originally been approved by Congress.

The funding issues led to something of a reduction in the scale of the project, with the proposed mirror diameter reduced from 3 m to 2.4 m, both to cut costs and to allow a more compact and effective configuration for the telescope hardware. A proposed precursor 1.5 m space telescope to test the systems to be used on the main satellite was dropped, and budgetary concerns also prompted collaboration with the European Space Agency. ESA agreed to provide funding and supply one of the first generation instruments for the telescope, as well as the solar cells that would power it, and staff to work on the telescope in the United States, in return for European astronomers being guaranteed at least 15% of the observing time on the telescope. Congress eventually approved funding of US$36,000,000 for 1978, and the design of the LST began in earnest, aiming for a launch date of 1983. In 1983 the telescope was named after Edwin Hubble, who made one of the greatest scientific breakthroughs of the 20th century when he discovered that the universe is expanding.

Once the Space Telescope project had been given the go-ahead, work on the program was divided among many institutions. Marshall Space Flight Center (MSFC) was given responsibility for the design, development, and construction of the telescope, while the Goddard Space Flight Center was given overall control of the scientific instruments and ground-control center for the mission. MSFC commissioned the optics company Perkin-Elmer to design and build the Optical Telescope Assembly (OTA) and Fine Guidance Sensors for the space telescope. Lockheed was commissioned to construct and integrate the spacecraft in which the telescope would be housed.

Optically, the HST is a Cassegrain reflector of Ritchey-Chrétien design, as are most large professional telescopes. This design, with two hyperbolic mirrors, is known for good imaging performance over a wide field of vie

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Management of Renewable Energies and Environmental Protection, Part I

The purpose of this project is to present an overview of renewable energy sources, major technological developments and case studies, accompanied by applicable examples of the use of sources. Renewable energy is the energy that comes from natural resources: The wind, sunlight, rain, sea waves, tides, geothermal heat, regenerated naturally, automatically. Greenhouse gas emissions pose a serious threat to climate change, with potentially disastrous effects on humanity.

mediaimage
The use of Renewable Energy Sources (RES) together with improved Energy Efficiency (EE) can contribute to reducing energy consumption,Management of Renewable Energies and Environmental Protection, Part I Articles reducing greenhouse gas emissions and, as a consequence, preventing dangerous climate change. At least one-third of global energy must come from different renewable sources by 2050: The wind, solar, geothermal, hydroelectric, tidal, wave, biomass, etc. Oil and natural gas, classical sources of energy, have fluctuating developments on the international market. A second significant aspect is given by the increasingly limited nature of oil resources. It seems that this energy source will be exhausted in about 50 years from the consumption of oil reserves in exploitation or prospecting. “Green” energy is at the fingertips of both economic operators and individuals. In fact, an economic operator can use such a system for both own consumption and energy trading on the domestic energy market. The high cost of deploying these systems is generally depreciated in about 5-10 years, depending on the installed production capacity. The “sustainability” condition is met when projects based on renewable energy have a negative CO2 or at least neutral CO2 over the life cycle. Emissions of Greenhouse Gases (GHG) are one of the environmental criteria included in a sustainability analysis, but is not enough. The concept of sustainability must also include in the assessment various other aspects, such as environmental, cultural, health, but must also integrate economic aspects. Renewable energy generation in a sustainable way is a challenge that requires compliance with national and international regulations. Energy independence can be achieved: – Large scale (for communities); – small-scale (for individual houses, vacation homes or cabins without electrical connection).

Keywords: Environmental Protection, Renewable Energy, Sustainable Energy, The Wind, Sunlight, Rain, Sea Waves, Tides, Geothermal Heat, Regenerated Naturally.

Introduction
The purpose of this project is to present an overview of renewable energy sources, major technological developments and case studies, accompanied by applicable examples of the use of sources.

Renewable energy is the energy that comes from natural resources: The wind, sunlight, rain, sea waves, tides, geothermal heat, regenerated naturally, automatically.

Greenhouse gas emissions pose a serious threat to climate change, with potentially disastrous effects on humanity. The use of Renewable Energy Sources (RES) together with improved Energy Efficiency (EE) can contribute to reducing energy consumption, reducing greenhouse gas emissions and, as a consequence, preventing dangerous climate change.

At least one-third of global energy must come from different renewable sources by 2050: The wind, solar, geothermal, hydroelectric, tidal, wave, biomass, etc.

Oil and natural gas, classical sources of energy, have fluctuating developments on the international market. A second significant aspect is given by the increasingly limited nature of oil resources. It seems that this energy source will be exhausted in about 50 years from the consumption of oil reserves in exploitation or prospecting.

“Green” energy is at the fingertips of both economic operators and individuals.

In fact, an economic operator can use such a system for both own consumption and energy trading on the domestic energy market. The high cost of deploying these systems is generally depreciated in about 5-10 years, depending on the installed production capacity.

The “sustainability” condition is met when projects based on renewable energy have a negative CO2 or at least neutral CO2 over the life cycle.

Emissions of Greenhouse Gases (GHG) are one of the environmental criteria included in a sustainability analysis, but is not enough. The concept of sustainability must also include in the assessment various other aspects, such as environmental, cultural, health, but must also integrate economic aspects.

Renewable energy generation in a sustainable way is a challenge that requires compliance with national and international regulations.

Energy independence can be achieved:

Large scale (for communities)
Small-scale (for individual houses, vacation homes or cabins without electrical connection)
Today, the renewable energy has gained an avant-garde and a great development also thanks to governments and international organizations that have finally begun to understand its imperative necessity for humanity, to avoid crises and wars, to maintain a modern life (we can’t go back to caves).

Materials and Methods
Solar Energy
Solar energy means the energy that is directly produced by the transfer of light energy radiated by the Sun into other forms of energy. This can be used to generate electricity or to heat the air and water. Although solar energy is renewable and easy to produce, the main problem is that the sun does not provide constant energy over a day, depending on the day-night alternation, weather conditions, season.

Solar Panels generate electricity approx. 9h/day (the calculation is minimal, the winter is 9 h), feeding the consumers and charging the batteries at the same time.

Solar installations are of two types: Thermal and photovoltaic.

Photovoltaics produce electricity directly, thermal ones help save 75% of other fuels (wood, gas) per year. A house that has both solar installations (with photovoltaic and vacuum thermal panels) can be considered “energy independence” (because the energy accumulated in the day is then sent to the grid and used as needed).

The use of solar radiation for the production of electricity can be done by several methods:

The use of photovoltaic modules – by capturing the energy of the photons coming from the sun and storing it in free electrons, thereby generating an electric current, solar photovoltaic panels generating electricity
The use of solar towers
Using Parabolic Concentrators – This type of concentrator consists of a gutter-shaped parabolic mirror that concentrates solar radiation on a pipe. A working fluid is circulating in the duct which is generally an oil that takes up the heat to give it water to produce the steam that drives the turbine of an electric generator. The concentrator requires adjusting the posture position of the sun in the apparent daytime displacement
Using the Dish-Stirling system
Solar installations work even when the sky is dark. They are also resistant to hail (in the case of the best panels).

Solar-thermal systems are mainly made with flat-bottomed solar collectors or vacuum tubes, especially for smaller solar radiation in Europe. In the energy potential assessments, applications concerning water heating or enclosures/swimming pools (domestic hot water, heating, etc.) were considered.

Locations for solar-thermal applications (thermal energy).

In this case, any available space can be used if:

Allows the location of solar thermal collectors
Preferential orientation to the South and inclination according to location latitude
This is the case for roofs of houses/blocks, adjacent buildings (covered parking lots, etc.) or land on which solar-thermal collectors can be located (Aversa et al., 2017 a-d; 2016 a-d; Petrescu et al., 2016 a-b; Mirsayar et al, 2017; Blue Planet; World Tree, From Wikipedia; Giovanni et al., 2012).

For the solar photovoltaic potential, both photovoltaic power grid applications and autonomous (non-grid) applications for isolated consumers were considered.

Solar energy can be used very easily – with a photovoltaic system. This type of system transforms the sunlight into electricity throughout the year, with the point that only high-quality photovoltaic systems that produce electricity over a long time are profitable. The system also allows other energy sources to be coupled with solar energy such as wind energy produced by a turbine. Obviously, besides the converter, it is also necessary to have a battery that is strong enough to retain as much energy as possible during the night, or when the consumption amount is very low and to release it when necessary. A system for producing, distributing and maintaining renewable energies for a house, cottage, motel, hospital, even located in isolated places, where the power grid does not reach, is presented in the figure 3. If the wind does not blow in a long period and the sky is not sunny, it is necessary to have an electric generator inserted into the system.

Wind Potential
The winds are due to the fact that the Earth’s equatorial regions receive more solar radiation than the polar regions, thus creating a large number of convection currents in the atmosphere. According to meteorological assessments, about 1% of the solar input is converted to wind energy, while 1% of the daily wind energy contribution is roughly equivalent to the world’s daily energy consumption. This means that global wind resources are in large, widespread quantities. More detailed assessments are needed to quantify resources in certain areas.

Wind energy production began very early centuries ago, with sailboats, windmills and grain mowers. It was only at the beginning of this century that high-speed wind turbines were developed to generate electricity. The term wind turbine is widely used today for a rotating blade machine that converts the kinetic energy of the wind into useful energy. Currently there are two categories of base wind turbines: Wind turbine Wind Turbines (HAWT) and Vertical Wind Turbines (VAWT), depending on the axis orientation of the rotor.

Wind power applications involve electricity generation, with wind turbines operating in parallel to network or utility systems, in remote locations, in parallel with fossil-fueled engines (hybrid systems). The gain resulting from the wind energy exploitation consists both in the low consumption of fossil fuels as well as the reduction of the overall costs of generating electricity. Electric utilities have the flexibility to accept a contribution of about 20% of wind power systems. Combined Eolian-diesel systems can offer fuel savings of over 50%.

Wind power generation is a fairly new industry (20 years ago in Europe, wind turbines had not yet reached commercial maturity). In some countries, wind energy is already competing with fossil fuel and nuclear energy, even without considering the benefits of wind energy for the environment.

When estimating the cost of electricity produced in conventional power plants, their influence on the environment (acid rain, effects of climate change, etc.) is usually not taken into account. Wind energy production continues to improve by reducing costs and increasing efficiency.

The cost of wind energy is between 5-8 cents per kWh and is expected to fall to 4 cents per kWh in the near future. Maintenance of wind energy projects is simple and inexpensive. Amounts of money paid to farmers for land renting provide additional income to rural communities. Local companies that carry out the construction of wind farms provide short-term local jobs while long-term jobs are created for maintenance work. Wind energy is a rapidly growing industry in the world.

An indispensable requirement for the use of wind to produce energy is a constant flow of strong wind. The maximum power Wind Turbines (WTS) are designed to generate is called “rated power” and the wind speed at which nominal power is reached is “wind speed at rated power”. This is chosen to suit the wind speed in the field and is generally about 1.5 times the average wind speed in the ground. One way to classify wind speed is the Beaufort scale that provides a description of the wind characteristics. It was originally designed for sailors and described the state of the sea, but was later modified to include wind effects in the field.

The power produced by the wind turbine increases from zero, below the starting wind speed (usually around 4 m/s, but again, depending on the location) to the maximum at wind speed at rated power. Above the wind speed at rated power, the wind turbine continues to produce the same rated power, but at lower output until it stops, when the wind speed becomes dangerously high, ie over 25 to 30 m/s (vigorous storm). This is the shut off speed of the wind turbine. Exact specifications for identifying the energy produced by a wind turbine depend on the wind speed distribution during the year in the field.

Air currents can be used to train wind turbines. Modern wind turbines produce a power of between 600 KW and 5 MW, the most used being the 1.5-3 MW output power, being more simple and constructive and more suitable for commercial use. The output power of a typical wind turbine is dependent on the wind speed at the third power so that wind speed increases, the power generated by the turbine increases with the wind speed cube, the increase being spectacular. The world’s technical potential for wind power can provide five times more energy than it is consumed now.

In the strategy for capitalizing on renewable energy sources, the declared wind potential is 14,000 MW (installed power), which can provide an amount of energy of about 23,000 GWh/year. These values represent an estimate of the theoretical potential and must be reproduced in correlation with the possibilities of technical and economic exploitation. Starting from the theoretical wind potential, what interests the energy development forecasts is the potential for practical use in wind applications, which is much smaller than the theoretical potential, depending on the possibilities of land use and the conditions on the energy market. That is why the economically profitable wind potential can be appreciated only in the medium term, based on the technological and economic data known today and considered as valid in the medium term.

Under ideal conditions, the theoretical maximum of cp is 16/27 = 0.593 (known as the Betz limit) or, in other words, a wind turbine can theoretically extract 59.3% of the airflow energy. Under real conditions, the power factor does not reach more than 50%, as it includes all wind turbine wind turbine losses. In most of today’s technical publications, the cp value covers all losses and represents the product cp * h. The power output and the extraction potential differ depending on the power coefficient and the turbine efficiency.

If cp reaches the theoretical maximum, the wind speed immediately behind the rotor – v2 is only 1/3 of the speed in front of the rotor v1. Therefore wind turbines located in a wind farm produce less energy as a result of the reduction in wind speed caused by the wind turbines in front of them. Increasing the distance between wind turbines can reduce energy loss as wind flow will accelerate again. A correctly designed wind farm may therefore have less than 10% losses due to mutual interference effects.

Average annual power will vary from land to land. In high wind speeds, more energy will be obtained. This highlights the importance of strong winds and hence the implications of the wind climate on economic issues related to wind energy production.

Blasts are responsible for mixing air and their action can be considered in a similar way to molecular diffusion. As the vortex passes through the measuring point, the wind speed takes the value of that whirlpool for a period of time proportional to the magnitude of the whirlpool; this is a “gust”. In most cases, load variation is not significant. However, if the vortex scale is of the same magnitude as the scale of a component of the turbine, then the variation in load may affect the overall component. A gust of 3 sec corresponds to a whirl of about 20 m (e.g., similar to the length of a rotor blade), while a 15 sec burst corresponds to a 50 m swirl.

To calculate the maximum possible load for a turbine or its components over the lifetime of the turbine, the highest burst value is used for a relevant period of time. This is formulated as the maximum wind speed and gust speed over a 50-year period. Of course, wind speed can be exceeded during this period, the sizing reserve will allow for some overtaking. Calculation of stresses is particularly important for flexible structures, such as turbines, which are more susceptible to wind-induced damage than rigid structures such as buildings.

A wind turbine can be placed almost anywhere in a sufficiently open terrain. Nevertheless, a wind farm is a commercial project and therefore it is necessary to try to optimize its profitability. This is important not only for the profitability during the lifetime of the exploitation but also for the mobilization of capital in the initial phase of project development. For economical planning of investments in wind energy, it is necessary to know as safely as possible the prevailing wind conditions in the area of interest.

Due to lack of time and financial reasons, long-term measurement periods are often avoided. As a substitute, mathematical methods can be used to predict wind speeds at each location. Wind conditions and energy production resulting from the calculation can serve as the basis for economic calculations. In addition, simulation of wind conditions can be used to correlate wind measurements at a particular location with wind conditions in neighboring locations in order to determine the wind regime for a whole area.

Since wind speed can vary significantly over short distances, for example several hundred m, wind turbine location assessment procedures generally take into account all regional parameters that are likely to influence wind conditions.

Such parameters are:

Obstacles in the immediate vicinity
Topography of the environment in the measure region, which is characterized by vegetation, land use and buildings (description of the roughness of the soil)
Horoscopes, such as hills, may cause airflow acceleration or deceleration effects
For the calculation of the annual average power density in the field, a more accurate estimate of the average annual wind speed is required. Then, information on the wind speed distribution over time is needed. To obtain these trusted data, data sets that cover several years are needed, but usually these data are estimated using appropriate models from shorter-date data sets. After that, it is possible to determine the potential energy produced in relation to the performance of the wind turbine.

The most widespread procedure for long-term prediction of wind speed and energy efficiency in a land is the WAsP Wind Atlas.

The model quantifies the wind potential at different heights of the rotor shaft above ground for different locations, taking into account the distribution of wind speed (in time and space) at meteorological stations (measurement points).

The reference station could be up to 50 km away from the site. The projected energy output for this location can be calculated in relation to the power curve associated with the wind turbine (wind power). A key element of the WASP model is that it uses polar coordinates for the origin of the location of interest.

The WAsP incorporates both physical atmospheric models and statistical descriptions of the wind climate.

The physical models used include:

The similarity in the surface layer – considering the logarithmic law
The Geostrophic Wind Law
Stability corrections-to allow for variation from neutral stability
Change of roughness-to allow changes in land use throughout the area
Shelter model-modeling the effect of an obstacle on wind flow
Orographic model-modeling the effect of accelerating the wind speed in the field
The wind regime is described statistically by a Weibull distribution derived from the reference data. The Weibull distribution is designed to best fit the high wind speeds.

Depending on the complexity of the examined regions, different procedures are used to determine the wind conditions. In addition to the WAsP model mentioned above, there are other procedures such as mesoscales models.

Such measurements, usually performed over a period of one year, may be related to neighboring areas or may be extrapolated to the height of the rotor axis of certain types of turbines using the flow simulation described above.

Evaluating wind resources at a location ideally asks for data series for as long as possible at the location of the turbines. In addition, it is useful to understand the turbulence in the field and the rotor axis for the design of wind turbines. To do this, a quick time sample and spatial distribution of measurement points is required. In practice, time and expenses often exclude such a thorough investigation. Imitations are provided in the section on meteorology and wind structure.

Wind velocity measurements are the most critical measurements for wind resource valuation, performance determination and energy production. In economic terms, uncertainties are transformed directly into financial risk. There is no other branch in which the uncertainty of the measurements is as important as in wind energy. Due to the lack of experience, a lot of wind speed measurements have inaccurately high uncertainties, as best practices in the anemometer selection standards, anemometer calibration, anemometer fitting and measurement field selection have not been applied.

Investigations have shown that certain anemometers are highly susceptible to vertical air flow, which, under real conditions, even appear in open ground due to turbulence. In complex terrain these effects are of great importance and lead to over or underestimation of real wind conditions. Only a few types of anemometers can avoid these effects.

A representative positioning of the measuring point within the wind farm shall be chosen. For large power plants in complex terrain, 2 or 3 representative positions should be chosen for the installation of the pillar. At least one of the measurements must be made at the height of the rotor shaft of the future turbine to be installed, since extrapolation from a smaller height to the height of the rotor shaft gives rise to additional uncertainties. If one of the measuring posts is positioned close to the wind farm area, it can be used as the reference wind speed measuring pole during the boiler operation and for determining the wind energy performance by sectors.

Measurement of wind speed and direction are obviously necessary, but also other parameters, particularly air pressure and temperature. The equipment used for these measurements must be robust and safe, since it will generally be left unattended for long periods of time.

Average wind speed is usually collected using cup anemometers because they are safe and cheaper. These anemometers often have better response characteristics than those used at weather observation centers. Wind direction is measured with a girue. Giruetes are usually wound potentiometers. Giruge will be affected by the shade of the pillar and is often oriented so that the pillar is in the least likely wind direction. If data about the vertical flow of air is required, three-dimensional data is useful. These are obtained if lesser robust propeller anemometers are used, or sonic anemometers, which are more expensive.

These anemometers indicate information about both speed and wind direction. The data should be taken at a high frequency, possibly 20 Hz.

It is important that data transmission and storage is secure. For this purpose, the logger must be carefully isolated from atmospheric conditions, especially rain. Many experiments have suffered significant data loss due to various problems, including water infiltration or loss of electricity. The most promising locations for wind farms are usually in hostile environments, but a host of trusted data loggers are available on the market.

It is possible to collect data remotely and download data via a telephone line. The advantage is that data can be monitored on a regular basis and any other problems that occur with the tools can be resolved quickly. For the development of a wind energy project it is essential to carefully plan the data collection step.

Daily weather information is usually available free of charge from weather services. However, for statistical data and consultancy services fees are charged.

In South Europe, the wind regime is dominated by seasonal winds. Winter cold weather is associated with the northern and northest winds. These variations can be seen in station records for wind speed and temperature.

Certain studies suggest that a minimum of 8 months of data is required for the adequate estimation of wind resources. Other researchers have suggested that winter wind is the most important because it coincides with peak demand for electricity. The data can then be sorted into ranges or “boxes” for wind speed or wind direction, either as a whole. The number of measurements in each box is then counted and the sorted data is plotted as a percentage of the total number of readings to indicate the frequency distribution.

From these data it is possible to calculate the average wind speed and wind speed most likely. It is possible to obtain the distribution of the wind power density (proportional to the cubic wind speed). Data may also be presented as the probability of a higher wind velocity than another given value, usually zero, u> 0. These data can be represented by two parameters from the Weibull distribution, the k and C parameters resulting from the use of certain techniques such as the moment method, the least squares method and many others. The two parameters of the Weibull distribution match for many wind data with acceptable accuracy.

The data collected are representative, for example, that the year is not particularly windy or calm. To be sure, data is needed for about 10 years. Obviously this is not practical for a location. However, it is possible to compare the wind data from the location with those of a nearby weather station and apply a MCP-type methodology to increase the data set actually measured at 10 years.

There are a number of available MCP methods, such as:

Calculate the Weibull parameters from the location of interest and the reference location and correlate them over the measurement period and then apply the correction for the rest of the reference data
Calculation of the correction factor (coefficient) for the wind speed between the location of interest and the reference point, during the measurements and on each step of the wind direction
Correlate measured data with reference data by determining a continuous function between the two for all data over the measurement period and applying it for the rest of the reference data
Once the wind distribution probability density is established, the power curve of a turbine can be correlated with wind data to determine the turbine power density density. The data can of course apply to different types and configurations of turbines for optimizing results.

The annual energy output of a wind turbine is the most important economic factor. Uncertainties in determining the annual speed and power curve contribute to the overall uncertainty of predicted annual energy production and lead to a high financial risk.

Annual energy production can be estimated by the following two methods:

Wind velocity histogram and power curve
Theoretical wind distribution and power curve

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