Wind Power Projects

Theory and Practice

Tore Wizelius

• Publisher: Routledge
• Year: 2015
• ISBN:
  9781317673217
• Edition: 1
• Topic: Technik & Maschinenbau
• Subtopic: Regenerative Energieressourcen

Wind power has developed rapidly in terms of the number of new wind power plants now installed in more than hundred countries around the world. This renewable energy source has become competitive, and to be able to combat climate change much more has to be installed in coming years. This also makes it necessary for policy makers, NGOs, research scientists, industry and the general public to have a basic understanding of wind power.

The majority of texts on wind power are written primarily for engineers or policy analysts. This book specifically targets those interested in, or planning to develop wind power projects. It can be understood by both specialists and non-specialists interested in wind power project development.

Having outlined the background of wind power and its development, explained wind resources and technology, the author explores the interactions between wind power and society and the role of wind power in the electric power system. Finally the main aspects of project development, including siting, economics and legislation, are explained.

This book will be an essential reference, or even a manual, for professionals developing new sites and for government officials and consultants involved in the planning or permission process. It can also be used as a textbook on wind power at schools and universities.

1 Development of wind power

Wind power has grown rapidly since the end of the 1970s. In these few decades wind power has developed from an alternative energy source to a new fast-growing industry, which manufactures wind turbines that produce power at competitive prices.

Wind turbines take kinetic energy in the wind and transform it into 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. Wind turbines do not require any fuel to be transported – a hazard to the environment – don’t create any air pollution and don’t leave any hazardous waste behind. Wind turbines produce clean energy.

The sun, the wind and running water are all renewable energy sources, in contrast to coal, oil and gas, which depend on fossil deposits from mines, oil- or gas-fields. In most countries, hydropower has already been fully developed. The technology to use direct solar radiation with solar collectors and photovoltaic (PV) panels has had a commercial breakthrough, but development is still about 10 years behind. The new renewable energy source that has the most successful development so far is wind power, but during 2014 more PV-cells are expected to be installed than wind power.

Modern wind turbines are efficient, reliable and produce power at reasonable cost. The wind power industry is growing very fast; the leading companies have, in the first years in this decade, increased their turnover by 30 to 40 per cent per year. Simultaneously the cost per kWh of electicity produced has been 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 current generation of wind turbines has a rated power of 3–6 MW, rotor diameters of 120 metres or even more, and towers up to 140 metres in height. New prototypes are even larger and mainly intended for the offshore market.

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 electronic power equipment makes it possible to use variable speeds and to optimize the capacity of the turbines.

In the same way as the wind turbines have grown in size, the installations have become larger and larger. In the early days of wind power development, the turbines were installed one at the time, often next to a farm. After a few years they were installed in groups of two to five turbines. Today, large wind power plants are built, on land and offshore, with the same capacity as conventional power plants. The largest wind power plants consist of hundreds of wind turbines and such large projects have now been developed in many parts of the world.

A challenge with the wind as an energy source is that the wind always varies. When the wind slows down or stops, power has to be produced by other power plants. This could lead to the conclusion that it will be necessary to have backup 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. Since wind power only constitutes one part in a large power system, this is, however, not necessary at all. A moderate proportion of wind power in a system does not need any backup capacity at all, since it already exists in the power system. In Scandinavia the power companies can simply save water in hydropower dams when the wind is blowing, and use this saved hydropower when the wind slows down.

In a power system, the power consumption varies continually, during the day as well as seasonally. 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 wind power penetration (that is the proportion 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 the power from wind turbines in situations with low loads (consumption) and high production, or by keeping a power reserve that can be used to balance power production with consumption at short notice. Few countries have however reached such penetration levels yet.

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

During the last few years, the market in China has expanded most and at the start of 2014 China had most installed capacity, followed by the USA where large wind power plants are installed on the plains of the Midwest and on the west coast. In Europe, Germany passed pioneering Denmark in 1994 with respect to installed wind power capacity, followed by Spain where a massive development of several thousand megawatts took place during the first decade of the twenty-first century (see Table 1.1 and Figure 1.4). There is still an immense potential for market growth in countries where development recently has taken off, like Australia, Brazil, Ireland, Canada and Poland, just to mention a few.

Table 1.1 Global wind power 2013/14 (MW)

Country	Installed 2014	Total 2014/15
China	23,351	114,763
USA	4,854	65,879
Germany	5,279	39,165
Spain	28	22,987
India	2,315	22,465
UK	1,736	12,440
Canada	1,871	9,694
France	1,042	9,285
Italy	108	8,663
Sweden	1,050	5,425
Denmark	67	4,845
Others	7,203	43,883
Total	51,477	369,553

Sources: GWEC, n.d.; EWEA, 2014

There are also ambitious plans to develop wind power plants offshore. Several offshore wind farms are already installed, in Denmark, Great Britain, the Netherlands and Sweden. Denmark has decided that wind power shall produce 50 per cent of the electric power in the country by 2030, and by the development of large offshore wind power plants this ambitious target is already within reach. Great Britain has also implemented an ambitious plan for offshore development.

In 2013 a further 35,467 MW of wind power was connected to the electric power grids around the world, and total installed capacity increased to 318 GW, an increase by 12 per cent from 2012. These 318 GW wind power produce around 650 TWh a year, which supplies some 160 million households with electricity. In Denmark wind power supplied 33 per cent of the total electric power consumption in 2013.

If this power had been generated by coal-fired power plants, some 220 million tons of coal would have been used, 220,000 railway wagons or 10,290,000 road transport lorries and some 500 million tons of carbon dioxide emitted.

Wind power has developed very quickly during the last 30 years. In the late 1970s and early 1980s wind turbines were small, manufactured in smithies and small workshops and installed next to farms. Thirty years later wind power plants on land and offshore are integrated parts of the dominant energy system, and are manufactured by industrial giants such as General Electric in the United States, Siemens in Germany and their counterparts in India and China. In 2013, around 4 per cent of all electric power in the world was produced by wind turbines (WWEA, 2013) a share that will grow for many years ahead.

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 5,000 kW (5 MW). 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 amou...