Issue 46 – February 2013
As demand surges for clean power generation to meet the world's growing energy need, the renewable energy sector is set to expand rapidly. Wind energy is currently the most cost effective new renewable energy source. Many countries have goals for wind to supply more than 20% of their energy generation by 2030, with offshore turbines playing a significant role in some countries. With the growing demand for more efficient and reliable wind turbines, International Electrotechnical Commission (IEC) international Standards prepared by IEC technical committee (TC) 88: Wind turbines, are ever more central to the successful development of the industry.
Fast growth and major economic stakes
In 2009, the world relied on renewable sources for over 13% of its primary energy supply and renewables accounted for nearly 20% of global electricity generation, according to International Energy Agency statistics.
Wind power now supplies the greater part of the world's non-hydropower renewable electricity capacity. Global wind power capacity was 238 GW (gigawatts) at the end of 2011, up from just 18GW at the end of 2000, with a compound annual growth rate of over 25% over the past 5 years. According to Pike Research, a firm that provides in-depth analysis of global clean technology markets, that capacity is expected to reach 562.9 GW by 2017, representing a USD 153 billion global industry and cumulative investment in new wind power capacity of USD 820 billion.
The supply of wind turbines is a global business, with the six largest producers all based in different countries and the 10 top manufacturers accounting for nearly 80% of global production.
Demand for reliable products to feed the fast growth of this industry is satisfied primarily by the products' compliance with IEC 61400, Wind turbine generator systems, the series of 19 international Standards and Technical Specifications that have become the world's de facto Standards for the industry.
The IEC 61400 series of international Standards and associated referenced documents ensure the wind power industry has all the information needed to allow it to manufacture products that are internationally certified, accepted and marketable.
Environmental and other challenges
The increase in wind energy capacity has come from the installation of greater numbers of turbines and from the availability of larger, more efficient turbines.
IEC 61400-1 outlines design requirements for wind turbines. It isn't limited to the design of mechanical, electrical, and electronic parts, but also takes into account a thorough assessment of site-specific environmental and other conditions that determine the optimum and safe choice of sites on which to install wind turbines
The origin of wind turbines dates back to several centuries BC when windmills were used to pump water or mill cereals. It is estimated that some 100000 windmills were scattered throughout Europe during the 18th and 19th century before wind power was displaced by steam engines and other sources of mechanical power. In America, farmers and rural communities relied extensively on small electricity-generating wind turbines, which first appeared in the late nineteenth century.
For most uninformed observers, the term wind turbine evokes an image of a large three-blade propeller-like mechanism rotating on top of a tower. In fact wind turbines are complex installations that may come in different shapes and include structural (tower), mechanical (gearbox, drives, and so on), electrical (generator, motors, cables, and so on) and electronic (control and monitoring) systems.
The huge increase in electricity from wind power in recent years is the result of the greater number of turbines installed as well as of the launch of larger turbines. The average capacity of turbines is now greater than 2,5 MW; some now even achieve 7,5 MW with rotor diameters that can exceed 160 metres. The introduction of these very large turbines means that many technical challenges have to be overcome to ensure safe and proper operation of the devices.
Wind turbines can be set up on land and offshore. Their components share most design requirements but specific conditions for offshore installations are dictated by the marine environment.
IEC 61400-3 Design requirements for offshore wind turbines includes assessments of the external circumstances at an offshore site, such as wind conditions, waves, currents, water level, tides and storm surges, sea ice, earthquake conditions, and seabed movement. This international Standard also details recommendations for the assembly, installation, and erection of offshore turbines and for their commissioning, operation, and maintenance.
Other international Standards in the IEC 61400 series cover many additional aspects such as the measurement of mechanical loads and acoustic noise, structural testing of rotor blades, lightning protection, communications for monitoring and the control of wind power plants for maintenance, and conformity testing and certification.
Small is beautiful too
If the ten-fold increase in wind power cumulative capacity between 2001 and 2011 (from 23,9 to 238,4 GW) results mainly from the installation of large turbines, small wind power installations can also provide cost-effective electricity on a highly localised level, both in remote settings as well as in conjunction with power from the utility grid.
TC 88 has prepared IEC 61400-2 Design requirements for small wind turbines, to deal 'with safety philosophy, quality assurance, and engineering integrity' and to set out 'requirements for the safety of small wind turbines' including design, installation, maintenance, and operation under specified external conditions'.
Pike Research forecasts that the global market for small wind systems will have more than doubled in value between 2010 and 2015, from USD 255 million to USD 634 million.
During the same period small wind system installed capacity additions will nearly triple to 152 MW. 'The payback period for a small wind system can be 5 to 10 years in a region with adequate wind resources', says Pike Research senior analyst Peter Asmus, adding, 'these economics provide a strong value proposition for a variety of commercial, industrial, and residential applications.'
Summarised from IEC's e-tech, November 2012.
→ View the IEC 61400 series of Standards
- NZS 6808:2010 Acoustics – Wind farm noise
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