On-shore wind

CTCN
Objective
Mitigation
Sectors
Renewable energy
Opportunities enabled
Reduce GHG emissions
CTCN Keyword Matches
Small-scale Combined Heat and Power
On-shore wind
Small-scale wind

The conversion of kinetic energy in wind into electrical power is known as wind energy. There are a number of ways in which this conversion can be done but the design dominating the market is known as the horizontal axis wind turbine (HAWT) with its archetypal three-bladed rotor. Wind energy is actually a form of solar energy; the temperature differences caused by the sun shining on the earth act, along with other factors, to cause large bodies of air, winds, to move across the face of the planet. As a result of these factors the highest wind speeds, and thus renewable resource, is found at larger latitudes, however there are also many localised regions with good wind speeds for electricity generation closer to the equator. Similar to for solar PV the price of wind is increasingly declining and in 2015 onshore wind became cost competitive with new fossil capacity even without accounting for externalities.

Responds to the following needs:

  • Diversification of energy sources
  • Cleaner energy sources
  • Reduced GHG emissions

Suitable for:

  • Areas with smooth surrounding topology and surface cover
  • Areas with access to grid infrastructure

Relevant CTCN Technical Assistance

Relevant Technology Needs Assessment 

For a list of more relevant TNA's, please see the TNA Database

Technologies

A wind turbine catches the wind due to the shape of its blades. The kinetic energy is transferred from the blades to a shaft and gearbox that drives a generator which is connected to the electricity network.

Type of turbine

  • Horizontal axis
  • Vertical axis

Size of turbine

Wind power technology comes in a wide range of sizes suitable for a broad range of applications.

  • Small wind turbines are turbines up to 10 kW in size. They are used to power individual homes, and are typically gridconnected, though in some cases are connected to a battery system or a hybrid system (for example, with solar photovoltaics). They are often used on small farms as well. Another use is for small, off-grid applications such as battery charging stations, water pumping, or telecom sites.
  • Intermediate-sized turbines are typically 10 kW-500 kW in size. They are used to power small villages, often in conjunction with hybrid systems relying on solar or diesel generators in remote areas. They can also be used to provide distributed power that is connected to the grid.
  • Large wind turbines range from 500 kW – 6 MW (currently, 5-6 MW prototypes are in development). These turbines typically are used in commercial, utility-scale wind farm applications for centralized power, but can also be used for distributed power in smaller quantities. Large wind turbines are also being used in offshore wind farms. Offshore sites tend to utilize the largest turbines, due to the costs associated with installation per turbine.

Components

  • Blades As wind turbines grow in size, so do their blades – from about 8 m long in 1980 to more than 40 m for many land-based commercial systems and more than 60 m for offshore applications today. New blade designs are more aerodynamic, use lighter materials, and reduce sensitivity to environmental factors. There is still much room for improvement, particularly in the area of dynamic load control and cost reduction
  • The Drivetrain (Gearbox, Generator, and Power Converter) Generating electricity from the wind places an unusual set of requirements on electrical systems. Wind systems can afford inefficiencies at high power, but they require maximum efficiency at low power – just the opposite of almost all other electrical applications in existence. The long-term reliability of the current generation of megawatt-scale drivetrains has not yet been fully verified with long-term, real-world operating experience. There is a broad consensus that wind turbine drivetrain technology will evolve significantly in the next several years to reduce weight and cost and improve reliability.
  • The Tower The tower configuration used almost exclusively in turbines today is a steel monopole on a concrete foundation that is custom designed for the local site conditions. Generally, a turbine will be placed on a 60-80 m tower, but 100 m towers are being used more frequently. Efforts to develop advanced tower configurations that are less costly and more easily transported and installed are ongoing.
  • Controls Today’s controllers integrate signals from dozens of sensors to control rotor speed, blade pitch angle, generator torque, and power conversion voltage and phase. In variable-speed models, the control system regulates the rotor speed to obtain peak efficiency in fluctuating winds by continuously updating the rotor speed and generator loading to maximize power and reduce drivetrain transient torque loads. Research into the use of advanced control methods to reduce turbulence-induced loads and increase energy capture is an active area of work.
  • Rotor The job of the rotor is to operate at the absolute highest efficiency possible between cut-in and rated wind speeds, to hold the power transmitted to the drivetrain at the rated power when wind speeds exceed it, and to stop the machine in extreme winds. Modern utility-scale wind turbines generally extract about 50% of the energy in the air stream below the rated wind speed, compared to the maximum energy that a device can theoretically extract of 59% (“The Betz Limit”).
  • Balance of Station The balance of the wind farm station consists of turbine foundations, the electrical collection system, power-conditioning equipment, supervisory control and data acquisition (SCADA) systems, access and service roads, maintenance buildings, service equipment, and engineering permits. Balance-of-station components contribute about 20% to the installed cost of a wind plant.

Co-benefits of this technology

  • Cost competitiveness: Wind energy is cost competitive with other fuel sources. In  favourable  circumstances  (i.e.,  good  resources and a secure regulatory framework), onshore wind is cost-competitive with new fossil capacity, even without accounting for externalities. For example, wind power was the most cost-effective option for new grid-based power in 2015 in many markets, including Canada, Mexico, New Zealand, South Africa, Turkey, and parts of Australia, China and the United States.
  • Job creation: Wind energy development creates long-term, high-paying jobs in fields such as wind turbine component manufacturing, construction and installation, maintenance and operations, legal and marketing services, transportation and logistical services, and more. 
  • Enhancing energy security: Wind energy is an indigenous, homegrown energy source that helps to diversify the national energy portfolio. Adding wind power to the nation’s energy mix diversifies the clean energy portfolio and helps reduce reliance on imported fossil fuels. Additionally, wind energy can help stabilize the cost of electricity and reduce vulnerability to price spikes and supply disruptions.
  • Community benefits: Wind energy can provide income for farmers and ranchers, as well as economic benefits to communities. Wind projects can provide revenue to the communities in which they are located via lease payments to landowners, state and local tax revenues, and employment. Even a utility-scale wind turbine has a small footprint, enabling farmers and ranchers who lease their land to developers to continue growing crops and grazing livestock.
  • Water savings: Wind turbines do not consume water. Most electric power plants require water to operate, but producing electricity from the wind does not require water.
  • Health benefits due to cleaner air and water: Electricity generated by wind turbines does not pollute the water we drink or the air we breathe, so wind energy means less smog, less acid rain, and fewer greenhouse gas emissions. Because it is a clean energy source, wind energy reduces health care and environmental costs associated with air pollution.

Some disadvantages of wind power that are important to consider: it relies for a large part on subsidies, a large number of turbines is required to make a contribution to the electricity network, and wind turbines are often criticised for spoiling the landscape (visual impact) and causing noise.

Market status 

The renewable nature of wind energy, the large available resource and the relatively advanced nature of the technology means that it has the potential to make a significant contribution to climate change mitigation. Representing the largest source of new renewable power capacity in Europe and the United States, and the second largest in China, wind power has a growing role in meeting electricity demand. In 2015 wind power capacity increased to 433 GW globally from 370 GW the previous year. The countries investing most in wind power that year was China, United States, Germany, Brazil and India. 

Corporations  and  other private entities continue turning to wind energy for reliable and low-cost  power,  while  many  large  investors  are drawn  by  its stable returns. Wind power is playing a major role in meeting electricity demand in an increasing number of countries, including Denmark (42% of demand in 2015), Germany (more than 60% in four states) and Uruguay (15.5%). Challenges  include  lack  of transmission  infrastructure  and  curtailment  of  wind  generation (particularly in China).

Case studies

References