Introduction Nowadays, we constantly hear terms like “renewable sources of energy”, “protection of the environment”, “the greenhouse effect” etc. In this presentation we will try to clarify these terms and to focus on the wind energy as its main subject. During the presentation, the personal contribution of each one of us to the protection of the environment with individual action will be stressed.

Nowadays, we constantly hear terms like “renewable sources of energy”, “protection of the environment”, “the greenhouse effect” etc.

In this presentation we will try to clarify these terms and to focus on the wind energy as its main subject.

During the presentation, the personal contribution of each one of us to the protection of the environment with individual action will be stressed.

Greenhouse gases Dioxide of coal (CO 2 ), Methane (CH 4 ) oxides of nitrogen (NOx) τετραχλωράνθρακες (CFC)

Greenhouse gases

Dioxide of coal (CO 2 ),

Methane (CH 4 )

oxides of nitrogen (NOx)

τετραχλωράνθρακες (CFC)

Resource Sun inconsequential emissions of pollutants, renewable sufficient Instability Expensive technology (except for heating) Wind inconsequential emissions of pollutants Renewable sufficient Occupies extensive region problems of maintenance Bio-fuel Minimum emissions of pollutants Renewable Transport of biomass Use of water in the production of biomass likely repercussions in the ecosystems Waterfalls inconsequential emissions of pollutants Free raw material Low functional cost High cost of manufacture Repercussions in the landscape Repercussions in the ecosystem Coal Stability Sufficient High emissions of CO 2 , SO 2 Non renewable source Accumulation of remains Oil Developed technology Exceptionally flexible fuel Limited availability Cost of transport (particularly when it is transported at big distances Non renewable source Flammable High emissions of CO 2 , NOx Gas “ relatively” friendly to the environment Fuel of high energy value with easy handling Limited availability Relative pollution Non renewable source Extensive network of distribution Emissions of CO 2 Nuclear Power Abundance of raw material Transfer of raw material Nuclear waste Danger of nuclear arms spread Radioactivity from operation and accidents

Renewable sources of energy

Wind – Aiolos Greek Mythology When Arny announced to her father that she is expecting to give birth to the sons of god Poseidon, he did not believe her and he married her to a man named Metapontus, king of Ikaria. When Boiotos and Aiolos were born they were raised by king Metapontus but their stepmother Autolyte had a quarrel with Boiotos and she sent them away. Boiotos accompanied by his mother Arny went to Thessalia where he occupied a region and named it Boiotia. His brother Aiolos went to an island complex at Tirinia sea which were named Aiolic islands after him. According to some, he founded a town called Lipari. Although, he is traditionally acknowledged to have lived on one of the Aiolic islands close to Sicely, a different version places him on Gramvousa, on the northwest coast of Crete Source : Wikipedia

What is wind? The wind is created because different parts of the surface of the earth are dissimilarly heated by the sun. The winds are directed from the points having high barometric (high pressure) to the points with low barometric (low pressure). During this movement they are diverted to the right on the Northern hemisphere because of the rotation of the Earth (forces Coriolis High pressure Low pressure North Hemisphere Direction of Wind

Wind Energy Historical retrospection For thousands of years, people have tried to make the wind their ally. They used it in order to propel windmills, to sail boats and to move objects and vehicles. That is to produce energy! Nowadays, wind energy is mainly used in the production of electricity by means of wind generators, while people are trying to use it again in sea transportation - [tankers]-in order to save fuel and to reduce the emissions of CO2 . Greek Windmill – Naxos Dutch Windmills 07.08.07 16:55 Pictures of windmills taken during our recent trip to Holland. They are dated from 1700. They were mainly used for draining regions and later in industry as well. They are believed to originate from distant Asia.

For thousands of years, people have tried to make the wind their ally. They used it in order to propel windmills, to sail boats and to move objects and vehicles. That is to produce energy!

Nowadays, wind energy is mainly used in the production of electricity by means of wind generators, while people are trying to use it again in sea transportation - [tankers]-in order to save fuel and to reduce the emissions of CO2 .

Wind generators Technology There are a lot of different types of wind generators which can be classified in two basic categories : 1. Those with horizontal shaft whose rotor is α type of helix and always parallels the direction of the wind and the ground. 2. Those with vertical shaft , which remains constantly stable and is vertical to the surface of the ground. The output of a wind generator depends on its size and the speed of the wind. Its size is relevant to the needs that it is called to serve and it varies from hundreds up to millions of Watt

Anatomy of a wind generator The rotor : consists of two or three blades made of reinforced polyester The transmission: consists of the main shaft, its mounts and the gear box . The generator: it is connected to the exit of an amplifier via a flexible or hydraulic contact and turns the mechanic energy into electric energy. The orientation/positioning system: it continuously drives the rotor to the direction of the wind. The tower : it supports the above electromechanical installation. The electronic table and the control panel : they are placed on the base of the tower . The control panel , monitors, coordinates and checks all the functions of the wind generator, ensuring its unhindered operation.

Anatomy of a wind generator Φρένο Άξονας χαμηλών στροφών Κιβώτιο ταχυτήτων Γεννήτρια ρεύματος Ελεγκτής Λειτουργιών Άξονας υψηλών στροφών Σύστημα περιστροφής πτερύγων Περιστρεφόμενο τμήμα Κατεύθυνση ανέμου Σύστημα περιστροφής κεφαλής Πτερύγια Πύργος Περίβλημα

Anatomy of a wind generator

Operation – A little bit of Physics Wind force Intersection of the wind generator’s rotor Component which causes the movement of the rotor Component which tends to reverse the wind generator Wind force

Aerodynamics Nowadays, in order to move the blades of the wind generators we apply aerodynamics in manufacturing (but also in rotating through a suitable mechanism) the blades in such way that the lift is more than ten times bigger than the drag.

Operation of a generator According to Physics, when a frame of a conductor is rotating in a magnetic field there appears to be electric voltage at its ends. ( Τ he magnetic field moves the free electrons of the conductor towards a specific direction in each rotation of the frame. The electric voltage depends on the number of coils that the frame has the intensity of the magnetic field and the speed of rotation

Wind farms A number of wind generators together comprise a wind farm. These wind farms are economically preferable compared to individual wind generators because they require only one connection installation to the national power grid . They are placed in regions with powerful winds after a thorough examination. Nowadays, for reasons that are related to the aesthetics of the landscape the wind farms are installed offshore .

Wind energy in Greece Greece due to its geophysical characteristics has a high wind potential with especially powerful winds on the islands of Aegean. The region of Ipeiros constitutes the only exception. The first wind farm in Europe was manufactured and operated in Greece, on the island of Kythnos in 1982. This jump start however, did not continue in the next 27 years. Nowadays the energy provided by the wind farms is about 1.850GWh and it represents the 6% of the total electric energy produced in our country. Today there appears to be a high interest in investing in wind farms.

Wind energy in Europe Εξηγήστε τις λεπτομέρειες Δώστε ένα παράδειγμα Διεξαγωγή ασκήσεων για ενίσχυση της μάθησης 1.002 3.241 428 143 1.021 78 3.180 2.225 384 23.903 472 3.404 14 3.736 985 16.754 2.862 433

Εξηγήστε τις λεπτομέρειες

Δώστε ένα παράδειγμα

Διεξαγωγή ασκήσεων για ενίσχυση της μάθησης

Development of Wind generators and the nominal output

Repercussions of wind farms installation Alteration of the natural environment Noise pollution Aesthetic nuisance or aesthetic differentiation Reflection on the salvage of the installations after the subsidies have ceased Economic repercussions on other sectors like tourism

Alteration of the natural environment

Noise pollution

Aesthetic nuisance or aesthetic differentiation

Reflection on the salvage of the installations after the subsidies have ceased

Economic repercussions on other sectors like tourism

The Earth, while it is heated by the Sun, emits infrared radiation. The greenhouse effect is caused by the absorption of this radiation from the atmosphere, resulting to the increase of the atmospheric temperature (Global Warming). Normally, a part of this radiation would be emitted to outer space. Now, however, it is absorbed by various gases which are produced by human activities. Such gases are the carbon dioxide (CO 2 ), methane (CH 4 ), the various oxides of nitrogen ([NO]x), and CFCs. The continuous destruction of the forests, which turn carbon dioxide into oxygen, results to the increase of CO 2 in the atmosphere. The oxides of nitrogen are mainly produced by the engines of various vehicles. CFCs are used as propellants in various sprays and aerosols, as coolants in refrigerators, and in fire extinguishers. They are devastating for the ozone layer. The results of the global warming due to the greenhouse effect are difficult to forecast. The most probable case scenario is that the ice in the two Poles will melt and the level of the sea will rise. Regions like the Netherlands and Venice will face the danger to disappear under the sea like a new Atlantis. The greenhouse effect