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.

Greenhouse gases

•Dioxide of coal Dioxide of coal (CO(CO22),),

• Methane (CHMethane (CH44))

• oxides of nitrogen oxides of nitrogen

(NOx)(NOx)

• τετραχλωράνθρακες (CFC)τετραχλωράνθρακες (CFC)

  Resource

SunSuninconsequential emissions of

pollutants, renewable sufficient

InstabilityExpensive technology(except for heating)

WindWind

inconsequential emissions of pollutants Renewable

sufficient

Occupies extensive region problems of maintenance

Bio-fuelBio-fuelMinimum emissions of pollutants

RenewableTransport of biomass

Use of water in the production of biomass likely repercussions in the ecosystems

WaterfallsWaterfalls

inconsequential emissions of pollutants

Free raw material

Low functional cost High cost of manufacture Repercussions in the

landscape Repercussions in the ecosystem

CoalCoalStability

SufficientHigh emissions of CO2, SO2

Non renewable sourceAccumulation of remains

OilOil

Developed technologyExceptionally flexible fuel

Limited availabilityCost of transport (particularly when it is transported

at big distances Non renewable sourceFlammable High emissions of CO2, NOx

GasGas

“relatively” friendly to the environment

Fuel of high energy value with easy handling

Limited availability Relative pollutionNon renewable source

Extensive network of distributionEmissions of CO2

Nuclear Nuclear PowerPower

Abundance of raw materialTransfer of raw material

Nuclear wasteDanger of nuclear arms spread

Radioactivity from operation and accidents

Renewable Renewable sourcessources

of energyof energy

Wind – Aiolos Greek MythologyGreek 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?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 pressur

e

Low pressur

e

North Hemisphe

re

Direction of Win

d

Wind EnergyWind EnergyHistorical retrospectionHistorical retrospectionFor 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!

Dutch Windmills 07.08.07 16:55Pictures 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.

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

Wind Wind generators generators

TechnologyTechnology

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 Anatomy of a wind generatorgeneratorThe rotor: consists of two or three blades

made of reinforced polyesterThe 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 Anatomy of a wind generatorgenerator

Φρένο

Άξονας χαμηλών στροφών

Κιβώτιο ταχυτήτων

Γεννήτρια ρεύματος

Ελεγκτής Λειτουργιών

Άξονας υψηλών στροφών

Σύστημα περιστροφής πτερύγων

Περιστρεφόμενο τμήμα

Κατεύθυνση ανέμου

Σύστημα περιστροφής κεφαλής

ΠτερύγιαΠύργος

Περίβλημα

Anatomy of a wind Anatomy of a wind generatorgenerator

Operation – A little bit of Operation – A little bit of PhysicsPhysics

Wind force

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

AerodynamicsNowadays, 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 generatorOperation 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. (Τhe 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 farmsWind farmsA 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 GreeceWind energy in GreeceGreece 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 Wind energy in EuropeEurope

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• Διεξαγωγή ασκήσεων για ενίσχυση

της μάθησης

1.0021.002

3.2413.241

428428 143143

1.0211.021

7878

3.1803.180

2.2252.225

38438423.90323.903 472472

3.4043.404

1414

3.7363.736

985985

16.75416.754

2.8622.862

433433

Development of Wind Development of Wind generators and the nominal generators and the nominal

outputoutput

Repercussions of wind Repercussions of wind farms installation 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

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 (CO2), methane (CH4), 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 CO2 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 effectThe greenhouse effect