Greater Efficiency and Reliability of Wind Turbines – The Requirements are Changing


old, so we will see a lot of them being repowered in the next 10 years. This is currently occurring on a small scale in Denmark and Germany’. Meanwhile, a US wind turbine builder also commented that: ‘In Europe, land is restricted and many plants are ageing, therefore they will have to be replaced.’


Respondents generally agreed that operators were increasing the scale of wind power locations and would demand higher levels of operational efficiency. A European consulting firm responded: ‘Large energy suppliers will become the main operators of wind farms. This also means that requirements in terms of quality and efficiency will become more demanding.’ A European wind turbine builder commented: ‘The more plants they operate, the more they are forced to address efficiency.’


For the more efficient operation of wind turbines it is also necessary to make accurate predictions of wind power output. As wind energy’s share of total power generation rises, accurate weather forecasts as well as wind power predictions will be required to enable system operators to schedule the input of wind energy and the operation of other generation resources. As shown in Figure 1 the wind share today is 3% in Europe. In some specific countries (e.g. Denmark) this share reached a double digit. The 450 scenario assumes that countries take co-ordinated action to control greenhouse gas emission.


Implication I – Reliability


These new trends are likely to change the main requirements of wind farm operators. Operators will need to validate the wind turbines they purchase. If the new requirements are becoming more important, their buying behaviour will change. Therefore, the turbine builders will be forced to react to these new trends otherwise they will lose market share.


There was general agreement among survey respondents that reliability is becoming more important as a purchasing criterion. A European consultancy responded: ‘Operators want more output and there is a trend towards larger wind turbine systems. However, the larger the system (and consequently the output), the bigger the loss when breakdown or failure occurs. In other words, reliability and uptime are extremely important.’ A US turbine builder said: ‘Technical availability is more important, even if the price (of the turbine) is higher. Our contracts guarantee technical availability and actual performance. If these are not fulfilled, we provide rectification and/or compensation.’ A European turbine builder stated: ‘It (reliability) has become more important. Plants have been improved, availability has been raised. With this, operators’ expectations also have risen.’


Reliability is seen by survey respondents as especially important for offshore installations, since these locations can be difficult and expensive to access in the event of a failure. A European wind farm operator commented: ‘We primarily operate offshore farms, where reliability is extremely important. Offshore parks are not as accessible as onshore parks, making downtime and replacement much more crucial factors than costs for the actual spare parts.’ A competing company agreed: ‘Offshore systems need to be more resistant (corrosion-proof) and have reliable back-ups; the aim being a failure-free system with 100% uptime/power delivery. Again, this is because service and maintenance are logistically more difficult for offshore systems.’ Another critical consideration is the increase in financial requirements


MODERN ENERGY REVIEW – VOLUME 2 ISSUE 2 Figure 1: Wind Energy Share of Total Power Generation (%) 0.9% World 3.1% EU 0.8% US 0.3% China 2007 Source: International Energy Agency.


and risk. As the capital that must be outlaid by wind farm operators increases, it exposes them to greater losses in the event of a failure. Consequently, it is no surprise that operators confirmed that reliability will remain a primary concern.


Implication II – Condition Monitoring


Larger wind installations and more efficient turbines have prompted increased requirements for realtime monitoring of operations. If realtime monitoring is provided for sites with difficult access, operators can better plan expensive on-site operation. This could also eliminate the need to send someone on-site. This suggests the growth of tools such as condition-monitoring systems.


Condition-monitoring systems, which usually monitor the gearbox, bearings and generator, are likely to become more widely adopted in the future for a number of reasons. The growing size of wind turbines exposes operators to greater loss of revenue in the event of failure, as well as the increased cost of repair. Therefore operators are more


Respondents generally agreed that operators were increasing the scale of wind power locations and would demand higher levels of operational efficiency.


willing to invest in monitoring systems so that potential problems can be detected early, preventative maintenance carried out and downtime minimised. A US wind farm operator commented: ‘The other important factor is the size of the turbine. If I have a US$2million machine and the gearbox costs US$500,000, then I definitely want to use condition monitoring.’ Large utility operators, such as energy suppliers, are more willing to invest in condition-monitoring systems because they have used these for other forms of power generation and understand the value they provide.


For offshore installations with their poor accessibility and high maintenance cost, the use of condition monitoring is becoming increasingly important. The growth of offshore wind farms will therefore lead to a growth in condition monitoring. This is also the


59 2.5% 9% 2030 Reference scenario 2030 450 scenario 6.2% 10.4% 14.6% 20.1% 4.5% 9.3%


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