Developing Wind Power Projects

Theory and Practice

Tore Wizelius

• Editorial: Routledge
• Año: 2015
• ISBN:
  9781317705376
• Edición: 1
• Categoría: Biological Sciences
• Categoría: Ecology

Wind power is developing rapidly, in terms of both the number of new installations and in interest from stakeholders including policy-makers, NGOs, research scientists, industry and the general public.

Unlike the majority of other texts on wind power, which are written primarily for engineers or policy analysts, this book specifically targets those interested in, or planning to develop, wind power projects.

Having outlined wind power basics and explained the underlying resource and technology, the author explores the interactions between wind power and society, and the main aspects of project development, including siting, economics and legislation. This book will be an essential reference for professionals developing new sites, government officials and consultants reviewing related applications, and both specialists and non-specialists studying wind power project development.

PART I

Introduction to Wind Power

Wind power is a renewable energy source that has developed rapidly since the end of the 1970s. This has been achieved by an energy policy that has created a market for renewable energy and by research and technical development. In these few decades wind power has developed from an alternative energy source to a new fast-growing industry which no longer needs subsidies and manufactures wind turbines that produce power at competitive costs. This introduction describes this development.

1

Wind Power Today and in the Future

Wind turbines catch kinetic energy in the wind and transform it into other forms of energy: mechanical work in water pumps and windmills or electric power in modern wind turbines. The wind is a renewable energy source; the wind is set in motion by the differences in temperature and air pressure created by the sun’s radiation on Earth. Wind turbines produce clean energy, don’t need any fuel transport that can be hazardous to the environment, don’t create air pollution and don’t leave any hazardous waste behind.

The sun, the wind and running water are all renewable energy sources, in contrast to coal, oil and gas, which depend on fossil fuels from mines or oil and gas fields. In many countries, for example Sweden, hydropower has already been fully developed. The technology to use direct solar radiation with solar collectors and photovoltaic (PV) panels is still waiting for a commercial breakthrough that is expected to come during the first decade of this millennium. Wind power is the new renewable energy source that has seen the most successful development so far.

Modern wind turbines are efficient, reliable and produce power at reasonable cost. Furthermore, the wind power industry is growing very fast, with the leading companies having increased their turnover by 30–40 per cent per year in the first years of this decade. Simultaneously the cost per produced kWh has become lower for each new generation of wind turbines that has been introduced on the market.

From the early 1980s the size of wind turbines has doubled approximately every four years. The largest commercial turbines today have hub heights of 110 metres, rotors with a diameter of 110 metres and a rated power of 3.6MW. The next generation, with a rated power of 5MW, have already been built as prototypes. If this development continues, wind turbines may have a rated power of 10MW by 2010.

The technology in the wind turbines has developed in several ways. The control systems have become cheaper and more advanced, new profiles for the rotor blades can extract more power from the wind, and new power electronic equipment makes it possible to use variable speed and to optimize the capacity of the turbines.

Just as wind turbines have grown in size, so installations have also become larger and larger. In the early days of wind power development, turbines were installed one at the time, often next to a farm. After a few years they were installed in groups of 2–5 turbines. Today large wind farms are built, on land and off shore, with the same capacity as a conventional power plant. The largest wind farms in Europe consist of up to one hundred turbines.

A problem with the wind as an energy source is that the wind always varies. When the wind slows or stops, power has to be produced by other power plants. This could lead to the conclusion that it will always be necessary to have a back-up capacity with other power plants with the same capacity as the wind power connected to the power system. If this were true, wind power would be very expensive. However, since wind power only constitutes one part in a large power system, this is not necessary at all. A moderate share of wind power in a system does not need any back-up capacity at all, since it already exists in the power system. In Sweden, for example, power companies can simply save water in the hydropower dams when the wind blows, and use this saved hydropower when the wind drops.

In a power system power consumption varies continually, during each day as well as during seasons. Every power system has a regulating capacity to adapt power production to actual power consumption. This can be used to adapt the system to the variations in the wind – and the output of wind turbines – as well. When the wind power penetration (that is the share of electric power produced by wind in a power system) increases to 10–20 per cent, it may be necessary to regulate the wind power as well, by reducing power from wind turbines in situations with low load (consumption) and high production, or by keeping a power reserve to be used to balance power production with consumption at short notice. Few countries, however, have yet reached such penetration levels.

Fast market growth

During the development from small single turbines connected to farms to large wind farms with the capacity of large-scale power plants, wind power has become more competitive: the power produced by wind turbines has grown cheaper. Today the cost of power produced by wind turbines (in places with good wind conditions) is competitive with the cost of power produced by oil, coal, gas or nuclear fuel in new power plants. Within this decade wind power could become the cheapest energy source available.

To lower the cost of wind power still further takes mass production of turbines. To attain this, the market has to grow. And indeed it is growing very fast. Germany, Denmark, Spain and the UK, as well as India and China and the US, are installing wind power plants on a large scale.

During the last few years the German market has grown fastest. Germany passed pioneering Denmark in 1994 with respect to installed wind power capacity and currently has the most wind power installed in the world. German manufacturers are now competing with the Danish industry. Both Germans and Danes have found new large export markets in India and China. Spain has installed several thousand MW in the last few years, and in the US large wind farms are installed on the large plains in the Midwest and on the west coast. In Denmark and Germany development on land has now reached a level where it is harder to find new sites for wind turbines and consequently growth in their domestic markets has declined. Thus in 2004 Spain took the lead in terms of most installed capacity in a year. In short, most of the growth so far has been concentrated in a few countries and there is still an immense potential for market growth in countries where development has hardly taken off – Australia, Brazil, Ireland, Canada, Poland, Norway, to mention a few.

BOX 1.1 WIND POWER STATISTICS

To indicate how much wind power there is in a country, the total installed capacity is used as a measure. Every wind turbine has a rated power (maximum power) that can vary from a few hundred watts to 5000kW (5MW). The number of turbines does not give any information on how much wind power they can produce. How much a wind turbine can produce depends not only on its rated power, but also on the wind conditions. To get an indication of how much a certain amount of installed (rated) power will produce per year, this simple rule of thumb can be used: 1MW wind power produces 2GWh/a on land and 3GWh/a offshore.

1TWh (terawatt hour) = 1000GWh (gigawatt hours)

1GWh = 1000MWh (megawatt hours)

1MWh = 1000kWh (kilowatt hours)

1kWh = 1000Wh (watt hours)

International information on wind turbine installations is available at www.windpowermonthly.com (the Windicator), www.ewea.org and www.ieawind.org.

Table 1.1 Global wind power capacity in 2005 (MW)

Country	Installed in 2005	Total 2005
Germany	1798	18,247
Spain	1764	10,027
US	2424	9124
India	1430	4430
Denmark	4	3128
Italy	452	1717
UK	465	1353
China	496	1260
Netherlands	141	1219
Japan	144	1040
Other	2192	7436
Total	11,310	58,981

In 2005, 11,310MW of new wind power was connected to the world’s power grids. Total installed power increased to almost 60GW, an increase of 24 per cent from 2004.

Source: World Wind Energy Association (2006)

There are also ambitious plans to develop wind power plants offshore. Several offshore wind farms are already installed in Denmark, the UK, the Netherlands and Sweden. Denmark has decided that wind power shall produce 50 per cent of the electric power in the country by 2030, a significant increase from the 20 per cent today, and the development of large offshore wind farms necessary to realize this ambitious target has already started. The UK has also started an ambitious plan for offshore development.

2

Historical Background

The ancient Greeks had no windmills, and while they used sails on their ships to harness the power of the wind, their knowledge of wind power generally was weak. The Greeks, the Romans and the Vikings used square sails, and steered using oars instead of rudders, which made it hard to keep a straight course when the wind came from the side and avoid drifting away in the direction of the wind. Therefore their ships had large crews – they needed many strong oarsmen and galley slaves to reach a destination within a reasonable time. When winds increased to storm force, the sails were taken down, a simple method of power control. In other words they had respect for the unpredictable and unreliable wind that could turn even the best of ships into disabled wrecks.

Exactly how long man has known how to utilize wind for work is unknown, but some kinds of windmills were probably used in China and Japan some 3000 years ago. The first historically well-documented windmill dates from AD947, in Persia, close to the border with Afghanistan. There, as in many other places on Earth, the wind varies according to a regular pattern. Some times of the year the wind always blows from the sea inland, through a pass. Those who built the windmill didn’t have to worry about the wind direction.

This windmill had a vertical axis, on which mats were mounted. This is the same principle as for a small watermill. To make it rotate, half of the rotor has to be protected from the wind. This was easily done, since the wind always came from the same direction. A wall surrounded the mill, with one opening facing the wind, so that the wind only hit the mats on one side of the axis. Power control was simple. If the winds blew too hard, a door was closed. At the back there was no wall at all, to utilize the power of wind the air must be able to get away behind the turbine (see Figure 2.1).

By the end of the 12th century the first windmills in Europe had been built on the Mediterranean coast and in northern France. These demonstrate a radical change of technology: while the Persian windmills had a vertical axis, these had a horizontal one.

Figure 2.1 Persian windmill

The Persian vertical axis windmill is sited inside a building where a wall screens off the part of the rotor that turns into the wind.

Source: Bo Göran Johansson

To be able to build a horizontal axis windmill, another fundamental technological item has to be used – the cogwheel. The power has to be transformed from the horizontal to the vertical axis for the millstones to be turned around. The cogwheel had, however, already been invented and was used in watermills. To transfer this technology to windmills was a simple matter.

With a horizontal axis and a vertical rotor, a new technical problem has to be solved – how to direct the rotor towards the wind. The windmills used in the Medite...

Índice

• Cover
• Half Title
• Title Page
• Copyright Page
• Table of Contents
• List of boxes, figures and tables
• Preface
• Part I – Introduction to Wind Power
• Part II – Wind Energy
• Part III – Technology
• Part IV – Wind Power and Society
• Part V – Wind Power Project Development
• Acronyms and abbreviations
• Glossary
• Bibliography
• Index