WIND ENERGY

What is wind energy, how is it converted into electricity and what are its advantages?

#environmental sustainability #renewable energy #engineering

Wind energy, which transforms the power of an inexhaustible resource such as wind into electricity, is a sustainable and valuable investment for the future. Utilising wind requires the construction of wind farms, either on land or at high sea, with dozens of wind turbines. These giants have become part of the landscape in recent years, but do we know how they work?

How is wind generated? Solar radiation does not affect the earth's surface equally: some areas are warmer than others, and in these areas the air, which weighs less, tends to rise, creating low pressure areas, while in colder areas the air descends and weighs more, creating high pressure areas. The difference in pressure causes the air to move and creates wind, an element so powerful that it can be used to generate energy.

WHAT IS WIND ENERGY

Wind energy is energy obtained from the force of the wind. How? Through a wind turbine that transforms the kinetic energy of air currents into electrical energy. The energy is mainly extracted with the rotor, which transforms the kinetic energy into mechanical energy, and with the generator, which transforms this mechanical energy into electrical energy. We are talking about a renewable, efficient, mature and secure energy that is key to the energy transition and the decarbonisation of the economy.

HOW DOES WIND POWER WORK. CHARACTERISTICS

As we have already mentioned, in order to utilise the kinetic energy of the wind and convert it into electrical energy, it is necessary to use a wind turbine. The optimal use of these giants, (they are usually between 80 and 120 metres high) depends on the strength of the wind. For this reason, wind farms, which pool a large number of wind turbines and make it possible to obtain this energy in large quantities, must be set up in places where windy conditions are predominant.

The wind turbines have to be oriented in the direction of the wind, which is done by means of a vane on the nacelle. From there, the force of the air currents will set the three main parts of the wind turbine in motion:

  • The rotor: composed of three blades and the bushing that joins them together, its function is to capture the force of the wind and convert it into mechanical rotational energy.
  • The multiplier: connected to the engine by means of a shaft, its function is to increase the rotational speed from 30 revolutions per minute (rpm) to 1500 rpm.
  • The generator: this element is responsible for converting the mechanical energy of rotation into electrical energy.

Each of the wind turbines that make up a wind farm are linked together by underground cables that carry the electricity to a transformer substation. From there it is transported to homes, factories or schools, among other recipients, through the distribution networks of the various electricity companies.

THE IMPORTANCE OF THE ROTOR
The air that passes over the sweeping surface of the blades makes them turn. The resistance of the blades makes it lose speed. This is the energy that the generator 'harvests'. The more blade time, the greater the capacity to collect energy.
COMPONENTS OF A WIND TURBINE

WIND POWER: clean, efficient and safe

BASIC INFORMATION 2019

Onshore and offshore wind farms in Europe

iberdrola

205 GW

OF WIND CAPACITY INSTALLED IN EUROPE

GW

190

180

170

160

140

120

100

80

60

40

20

0

94.8

iberdrola

3.8

91

2011

106

iberdrola

5.0

101

2012

117.6

iberdrola

6.6

111

2013

129.1

iberdrola

8.1

121

2014

142

iberdrola

11

131

2015

154

iberdrola

13

141

2016

178

iberdrola

16

162

2017

189

iberdrola

18

171

2018

205

iberdrola

22

183

2019

Onshore wind power

Offshore wind power

Source: Wind Europe, Wind energy in Europe in 2019,

Onshore and offshore wind farms around the world

iberdrola

651GW

OF WIND CAPACITY INSTALLED AROUND THE WORLD

GW

600

500

400

300

200

100

0

238

iberdrola

+41

2011

283

iberdrola

+45

2012

319

iberdrola

+36

2013

370

iberdrola

+52

2014

433

iberdrola

+64

2015

487

iberdrola

+55

2016

540

iberdrola

+53

2017

591

iberdrola

+51

2018

651

iberdrola

+61

2019

Wind capacity installed last year

New wind capacity installed this year

Source: REN21, Renewables 2020 Global Status Report.

 SEE INFOGRAPHIC: Wind energy: clean, efficient and safe [PDF]

TYPES OF WIND ENERGY

There are currently two types of wind energy depending on where the wind turbines are erected:

Onshore wind energy

Onshore wind energy is responsible for producing electricity by harnessing the wind from wind farms located on land. To do this, we install wind turbines capable of transforming kinetic energy from the wind into electricity suitable for use and send it to the distribution network.

Offshore wind energy

Offshore wind energy is the energy obtained by harnessing the force of the wind that is produced on the high seas, where it reaches a higher and more constant speed than on land due to the absence of barriers. In order to make the most of this resource, mega-structures are installed that are seated on the seabed and equipped with the latest technical innovations.

MAIN ADVANTAGES OF WIND ENERGY

Wind energy offers numerous benefits, both for the companies that invest in it and for society by helping to minimise the impact of climate change:

 Clean

As it does not require any combustion process, it is an energy with low greenhouse gas (GEI) emissions, the main culprits of global warming.

 Inexhaustible

Wind is an unlimited resource, and so is its use as long as there are sufficient air currents.

 Cheap

Both the cost per kW produced and its maintenance is quite low. In areas where the wind blows harder, the benefit is even greater.

 Low impact

Wind farms are built after a rigorous analysis and planning process. In addition, depopulated areas are sought to avoid negative effects on inhabitants.

 It generates green jobs

According to the International Renewable Energy Agency (IRENA), wind energy already employs more than 1.2 million people today and the number of green jobs will not stop growing.

HOW A WIND FARM IS BUILT

The process involved in building a wind farm is very complex since there are many characteristics that must be analysed to know where and when it should be built. Of these, the most important characteristics that must be analysed are the spatial, temporal and vertical variation of wind through time. These parameters are studied with wind vanes and anemometers and the future production of the wind farm is estimated to guarantee its potential efficiency. Cutting edge supercomputing techniques optimise the design of the wind farm complex to maximise the generation of energy.

Innovation is also allowing us to make great progress in offshore wind energy. An example is the Romeo project, a European initiative led by Iberdrola to reduce the operating and maintenance costs of wind farms.