The profile of wind assets across Europe and the world is changing. The graph below shows the rapid change in age profile of Ireland’s wind portfolio and highlights the significance of this concern. In just 5 years you can see a drastic shift in the number of wind turbines which now fall into higher risk age groupings. You can also see the 20+ year age groups expanding. These periods are typically referred to as “End of life” and for good reason.
Let’s face it, wind turbines aren’t getting any younger and the value of maintenance contracts are continually being driven down by wind farm owners who no longer have the safety net of wind farm subsidies to prop up their revenues. This has an enormous impact on the quality of service provided by the maintenance contractors and at a time where inspection and maintenance quality must increase to meet the demand of the asset the opposite is often the case.
|Age Group||Age (WTG's in IRL 2020)||Age (WTG's in IRL 2025)||Age (WTG's in IRL 2030)|
|11-15 Years old||788||586 (74% increase)||660 (84% increase)|
|16-20 Years old||232||788 (340% increase)||586 (253% increase)|
|21-25 Years old||154||154 (100% increase)||788 (512% increase)|
|25+ Years old||31||185 (597% increase)||417 (1345% increase)|
Statistics here are based on the Irish wind turbine portfolio 10 years or older
Ageing assets will suffer in two primary areas;
10 years or more is a lot to ask of any machine in operation. And when huge mechanical loads and environmental weathering are continuous factors over this time major failures are commonplace. The life expectancy of a piece of working machinery is greatly affected by the quality of maintenance that component has received over its life. Even things that appear trivial such as oil cleanliness in gearboxes has been proven to reduce the life of components drastically. Wear & Tear on blades going unchecked also contributes to accelerated blade damages and ultimately failures. It should be noted however that it doesn’t always have to be long-term poor maintenance practices that cause issues. Some actions (or lack of action) may result in severe damages in a relatively short time frame such as 6-24 months. The tendency for wind farm owners to move to more “stripped down” maintenance service contracts to save costs has a knock on effect on maintenance service quality and therefore leads to increased failure rates.
A significant proportion of the assets in the wind sector are now either already in or are entering into the period which would be considered long-term operation. Years of continuous operation and high mechanical stresses are leading to the inevitable emergence of fatigue cracks in structural components. These can be observed in major structural components such as towers, blades, blade bearings, nacelle bed frames, main bearing housings and even hubs and other structurally significant areas.
The worst part is, these types of damages rarely occur in isolation and once one case is found it normally means multiple others will be detected in the surrounding turbines also. This is due to the fact that fatigue type damages are a product of the initial design + time in operation. Structural cracking and other damages occur primarily at high stress areas meaning they have the potential to rapidly deteriorate over a very short period of time if not monitored or repaired appropriately. Adding to this these types of damages are difficult and costly to repair which often results in them being patched and ignored rather than correctly rectified.
The only measures to protect against catastrophic failures are good engineering practices. This includes effective inspection regimes, measurement and good maintenance practice to the level expected from the general industry.
One of the common problems faced by the wind sector has been that compared with conventional power generation (such as coal or gas power plants) where you typically have a one or two high-value assets in one location you now have hundreds of generating units distributed across the country in remote mountainous areas. These turbines are also operating in the harshest of weather conditions which mean they demand more maintenance attention to protect them from the elements.
Monitoring and repair costs can quickly rise due to these facts and this has led to the industry adopting less than satisfactory approaches to mounting concerns for operational and structural integrity. The solution to this problem is not an easy one. The financial factors that have led to this are understandable however they do not offer an adequate defence for inaction where simple monitoring or repair solutions could have been applied to avoid the risk of failure.
We have experience of this first hand and know the best solutions the industry has evolved over time to approach the issue. Our experience in this area allows us to determine what the industry best practice is and whether or not these actions are being carried out effectively by those in control of the assets.
Keeping in mind the reality of the fact that operational costs must be kept to a minimum the best ways to minimise risk are;
It is very important that a routine inspection programme is carried out by knowledgeable engineering personnel. The extent and quality of the inspection should be matched to the type of asset, its design, age and known defects. Furthermore, it is important that inspections are carried out by impartial wind turbine inspectors at least once every 2-3 years or where other serious factors may dictate. This avoids biased parties (such as the wind farm Owner, Operator or Maintenance Contractor) from downplaying or side stepping issues they may not wish to highlight or have become familiar with over time.
Remote assets such as wind turbines largely rely on active monitoring (such as SCADA and CMS systems) and repeat field measurement programmes to monitor equipment condition and status of existing issues (such as foundation issues or cracks in structural components). When these systems are being appropriately monitored and field measurement programmes are being carried out correctly it is possible to use the information generated to prioritise maintenance and repair actions to the highest risk areas.
All good maintenance and repair actions are informed by the inspection and measurement programmes that precede them.
The findings of these programmes help to determine;
The cost and effectiveness of repairs is closely related to the quality of inspection and monitoring which precedes them. Catching issues early and taking action saves extensive costs further down the line (“A stitch in time saves nine” so to speak). Poor information gathered through the inspection regime will also typically result in insufficient repairs as they may not deal with the fundamental root cause of the issue.
Validating whether or not the monitoring systems, field inspection programmes or maintenance activities are being appropriately managed or whether important information generated from these is being acted upon is of vital importance. These activities are the only line of defence for assets operating in such remote environments and are the primary way in which integrity risk is managed on operating wind farms.
As with any profession or trade, deep technical knowledge is required to interpret this information. Having an ability to understand the data, make important connections and draw conclusions from these is what allows us to provide a valuable service to our clients.
Last Updated: 01 February 2022
Contact us today to see what we can do for you...