’s Wind Energy industry’s concerns and initiatives relative to Cold Climate Author: Matthew Wadham-Gagnon, project manager at TechnoCentre éolien

Produced in association with: Optimization, Maintenance and Repair Summit Toronto, Canada December 8-9, 2014

© FC Business Intelligence Quebec’s Wind Energy industry’s concerns and initiatives relative to Cold Climate

On the 11th of June 2014, as part of the 8th Quebec Wind Energy Annual Conference, a workshop was held to discuss cold climate issues related to our industry. This workshop was animated by members of the International Energy Association’s (IEA) Task 19 work group on wind energy in cold climate. For the purpose of this text, we will use IEA Task 19’s definition of cold climate which encompasses low temperature climate and/or icing climate.

People representing most of Quebec’s wind energy supply chain were in the room, from original equipment manufacturers (OEMs), developers and operators to consulting firms and independent service providers. Within the first few minutes of brainstorming one thing became abundantly clear, this diverse group of wind energy professionals, representing nearly 2400 MW of installed capacity in this province, all take cold climate issues very seriously.

The Quebec wind industry has good reason for being concerned with the challenges surrounding cold climate, considering that by the end of 2012, Canada had 37% of the 11.5 GW of wind energy capacity installed globally in moderate to severe icing climate which is more than in all of Europe (33%) or all of the United States (29%) at the time (BTM World Market Update, 2012). Furthermore, it is forecasted that 57% of the globally added capacity by 2017 in severe to moderate icing climate will be in Canada. And knowing that Quebec has the second highest wind energy capacity in Canada, after where icing is less of an issue, icing climate is undoubtedly something that La Belle Province needs to be taking seriously.

During the workshop, the group raised concerns related to ice assessment, ice protection systems, health and safety (ice throw) and turbine icing loads and dynamics. Here are selected highlights of the topics discussed during the workshop and during the conference along with examples of efforts being made to address these issues.

Produced in association with: Wind Turbine Optimization, Maintenance and Repair Summit Toronto, Canada December 8-9, 2014

www.windenergyupdate.com Quebec’s Wind Energy industry’s concerns and initiatives relative to Cold Climate

Ice assessment

The presence of a sufficient amount of ice on a wind turbine blade (e.g. in Figure 1) will affect its aerodynamics which will lead to lower energy yield. According to Lacroix (2012), an average of 7.5% of annual wind energy production was lost in the province of Quebec in 2011 due to icing climate. Some wind farms, or specific turbines within a wind farm, can be stand still due to ice for days, weeks and even months, leading to significant loss in revenue, which can have a disastrous impact on project profitability especially if the severity of icing was underestimated during the site assessment phase.

Figure 1: Image of ice accretion on the leading edge of a turbine blade at the TCE test site in Rivière-au-Renard

There is a significant variability in year-to-year severity of icing, and without proper correlations between long term climatology, instrumental icing and production losses, the additional cost in instrumentation for ice assessment during a standard wind assessment measurement campaign barely makes sense.

In light of the current call for tender in Quebec of 450 MW, many people in the industry agree that the upcoming contracts with Hydro Quebec will be won or lost based on ice assessment. Overestimate and you might lose the bid, underestimate, and you could lose your profit margin, or worse. The industry is therefore keen to have reliable icing maps and validated correlations between meteorological icing, instrumental icing and production losses. It is also in everyone’s best interest for these icing maps to be publicly available so that wind energy consultants and developers all have access to the same knowledge and can consequently submit competitive proposals in future calls for tender.

Finland’s national research institute, VTT, in collaboration with the TechnoCentre .éolien Produced in association with: (TCE), established a preliminary ice map of Quebec, which was unveiled at the 8th Wind Turbine Optimization, Quebec Wind Energy Annual Conference (Figure XX). This map is based on 30 years’ Maintenance and Repair worth of weather observations from the Gaspé airport calibrated to 3 winters’ worth of Summit correlations between meteorological icing and production losses at the TCE test site in Toronto, Canada Rivière-au-Renard then extrapolated to the surrounding topography. December 8-9, 2014

www.windenergyupdate.com Quebec’s Wind Energy industry’s concerns and initiatives relative to Cold Climate

Figure 2: Preliminary ice map of Quebec produced by VTT in collaboration with TCE

The ice map shown here is already very useful in highlighting areas where icing can be a significant problem, but in order to improve the reliability of such a map, more long term climatology data as well as more wind farm data are required.

The relationship between production losses due to icing and elevation has been known for some time, but has been very clearly demonstrated recently by Klintström et al. (2014), shown in Figure 2, as part of a case study under the IEA Task 19 initiative.

Produced in association with: Wind Turbine Optimization, Maintenance and Repair Summit Figure 3: Figure from Klintsrtöm et al. 2014 showing correlation between production losses due to icing and turbine Toronto, Canada elevation above sea level at the Stör-Rotliden wind farm operated by Vattenfall in Sweden. December 8-9, 2014

www.windenergyupdate.com Quebec’s Wind Energy industry’s concerns and initiatives relative to Cold Climate

Wind turbines are often placed on the tops of the highest hills purely based on . If more accurate long term icing forecasts were available, it is likely that not all hill tops would lead to the highest energy yield. Or maybe it would, provided the turbines are equipped with an appropriate ice protection system…

Ice protection systems

Another topic discussed during the workshop was the need for ice protection systems (IPS). Whether production losses due to ice have been estimated correctly or not during the assessment phase, if there is ice, there is a potential business case for an IPS.

The general idea behind an IPS is to recover all or part of the energy potentially lost due to icing by preventing ice from building up on the blades or by shedding the ice from the blades (see example in Figure 4 and Figure 5).

IPSs closest to technological maturity include hot-air and electro-thermal de-icing systems. Anti-ice coatings, while very appealing due to their potential low cost and low maintenance, still need to prove effective and durable in the field. Retro-fit options are much more limited for wind turbines already in operation that don’t have an IPS built in. Some independent service providers are proposing de-icing solutions using helicopters, rope access or even robots.

The general consensus is that these systems still lack a proven track record and would benefit from standardised performance validation. Many developers would like performance warranties similar to other performance warranties that come with a standard turbine.

Produced in association with: Wind Turbine Optimization, Maintenance and Repair Summit Toronto, Canada December 8-9, 2014 Figure 4: Ice shedding from a blade during a de-icing trial using a prototype electro-thermal retrofit system at the TCE test site in Rivière-au-Renard

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Figure 5: Above: heated (blue) and unheated (red) anemometers during an icing event. Below: Calculated (blue) and actual (red) power during the same icing-event with a de-icing trial using a prototype electro-thermal retrofit system.

Health and Safety (ice throw and ice shed)

It is nearly impossible to discuss wind energy in cold climate without addressing the risks of ice throw or ice shed from a turbine. The force of impact of a 1 kg block of ice being projected from the tip of a 40m blade rotating at 15 revolutions per minute can land at a significant distance from the turbine and be severely harmful to a person, but also to vehicles or infrastructure such as power transmission lines, transformers or even tower access stairs. Even a fragment of ice detaching from a blade on a turbine that is not in operation and free falling from 120m can do just as much harm. Ice projected from a blade in motion is often referred to as ice throw, whereas as ice falling off a turbine that is not in operation will generally be referred to as ice shed.

There are different methods of determining what is considered a safe distance from a turbine; some will use empiric formulas such as:

d = 1.5*(D+H) for ice throw (WECO, 2000) or

for ice shed (Seifert, 2003)

where “D” is the rotor diameter and “H” the hub height, “v” is wind speed, and “d” is the safe distance from a turbine.

Others have developed simulation models in order to predict the probability of impact of ice fragments based on turbine characteristics (e.g. hub height, rotor diameter, tip speed), wind statistics (e.g. direction and speed) and assumptions regarding ice (hours of icing per year, size and weight of ice fragments, etc). TCE has collaborated with RES providing them with ice throw data in order to validate (see Figure 6) and improve a Produced in association with: theoretical model they have developed. Wind Turbine Optimization, Maintenance and Repair During the planning phase of a project, the proximity of public roads, snow-mobile Summit trails, or ski slopes for example, may affect the location of turbines for safety reasons. Toronto, Canada December 8-9, 2014 Many wind farms have signs warning of the danger of ice and recommending a safe distance to be kept from turbines. Some operators will adopt a more proactive

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approach and distribute flyers explaining the risks and providing recommendations to the locals.

The risk of ice shed can prevent service technicians from accessing turbines that require maintenance thereby preventing these turbines to resume production until it is free of ice. Some operators have developed procedures to access turbines using vehicles equipped with ice shields to ensure staff can access these turbines safely.

Figure 6: The ice throw model developed by RES and validated with ice throw data from the TCE can be used during the planning and layout phase by considering risk to public safety and infrastructure (Hutton, 2014).

Turbine ice loads and dynamics

There is concern in the industry that ice build-up on blades may cause aerodynamic and mass imbalances leading to increased fatigue loads or even extreme loads.

Simulations conducted by VTT on , and TCE ice and load measurement data suggest ice build-up can increase side-to-side fatigue loads in the tower, but there is no evidence yet that these loads will reduce the design life of the turbines. However, when it comes to the effect of icing on the behaviour of turbine components and sub-components, there is still very limited data available and still a lot of work to do on understanding fatigue and extreme loads caused by ice. Produced in association with: Wind Turbine Optimization, Senvion and TCE have been collaborating for a few years now on ice characterisation Maintenance and Repair and have contributed in part to the currently available knowledge base on ice induced Summit loads on wind turbines by conducting load and ice measurements and analysis on TCE’s Toronto, Canada wind turbines in Rivière-au-Renard. December 8-9, 2014

www.windenergyupdate.com Quebec’s Wind Energy industry’s concerns and initiatives relative to Cold Climate

Senvion is optimising their “ice operation mode” in order to improve production yield during icing events by modifying pitch and tip speed ratio settings in the turbine controller (Figure 7).

Figure 7: Expected increase in yield from Senvion’s optimised ice operation mode during severe icing events (Camion, 2014).

It is also worth noting that the next edition of the IEC61400-1 standard on turbine design loads is expected to include a chapter on cold climate requirements.

Operation and Maintenance in the winter

Production yield is greater in the winter due to higher average wind speeds and higher air density, therefore losses due to downtime will be more expensive. Furthermore, access time and costs are likely to be greater. Planned annual maintenance will generally be scheduled in the summer months for these reasons. While winter access can be minimised, there is inevitably going to be maintenance activities during the winter months. To access turbines in the winter, many operators must make the difficult decision between opting for a snow removal strategy or using winterised vehicles (Figure 7) such as snow mobiles or snow cats. The decision often depends on the number of kilometers of access roads, expected annual snow fall and other factors that Produced in association with: are site dependent. Wind Turbine Optimization, Maintenance and Repair Boucher (2013) estimated based on a case study that certain O&M activities can be 30% Summit more expensive in the winter when considering increased power yield, increased access Toronto, Canada costs and increased technician time. Signal trending or condition health monitoring December 8-9, 2014 can help predict failures thereby reducing the costs of maintenance, particularly if the maintenance activities must happen during the winter.

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Figure 8: Tracked vehicles are used in certain wind farms to access turbines for maintenance in the winter (source: Prinoth)

Conclusions

Wind farms currently operating in cold climate must deal with the realities of production losses due to icing, health and safety risks due to ice throw (and ice shed), potential structural failures due to ice loads, and increased O&M costs in the winter.

These challenges have forced OEMs to adapt and innovate, they have brought operators together to share lessons learned, and they have inspired ISPs to develop new services and technologies. The ultimate result is a stronger industry capable of competitively harnessing the immense potential of wind in cold climate. And there are still significant gains to be made in this relatively young industry.

Produced in association with: Wind Turbine Optimization, Maintenance and Repair Summit Toronto, Canada December 8-9, 2014

www.windenergyupdate.com Quebec’s Wind Energy industry’s concerns and initiatives relative to Cold Climate

About the TechnoCentre éolien

Founded in 2000, the TechnoCentre éolien is a research and technology transfer centre that helps companies develop new products for the industry, integrate the power supply chain in Québec and adapt their technology to withstand the northern climate. The TechnoCentre éolien has four principal areas of endeavour: technical assistance for businesses, applied research, economic development and communication/events. The TechnoCentre éolien is represented on a variety of international committees including the IEA Task 19 working group on wind energy in cold climate. It is responsible for carrying out the mission of the college centre for technology transfer (CCTT) in wind energy in Québec and houses Gaspésie-Îles-de-la- Madeleine ACCORD Wind Power Cluster management.

Produced in association with: Wind Turbine Optimization, Maintenance and Repair Summit Toronto, Canada December 8-9, 2014

www.windenergyupdate.com Quebec’s Wind Energy industry’s concerns and initiatives relative to Cold Climate

1st Annual Wind Turbine Optimization, Maintenance and Repair Summit, Canada 8th-9th December, 2014 // Westin Prince Toronto

The Wind Energy Operations and Maintenance Series is now recognized as the Americas most reputable and rewarding commercial business forum. Since 2009 over 2000 delegates, 400 companies, 90 exhibitors and sponsors, from 28 different countries have come together to develop winning O&M strategies, conduct important business and to cement their company’s name in the growing industry.

The Wind Turbine OMR Summit 2014 will unite investors and owners of wind power projects with the biggest operators, service providers and suppliers making this a must-attend event at a tipping point for the industry.

Topics at a glace:

NAVIGATING COLD WEATHER CHALLENGES: Ensure I found the event well organized and the maximized power production for turbines operating during individual presentations very informative periods of extreme cold and snow using highly valued equipment and strategies to ensure maximized profits TransAlta BLADE PROTECTION & REPAIR: Explore the latest advances on how to mitigate production losses resulting from icing, lightening and leading edge erosion so that turbines are operating to their full potential For turbine owners and especially operators, the conference was the best OPTIMIZATION: THE KEY TO POWER PRODUCTION balanced and most informative sharing INCREASES: Evaluate the different optimization strategies and technologies that will provide a real event I have participated in. increase in power levels Kruger Energy WORKFORCE MANAGEMENT: Find, recruit and retain a competent team to perform only the best service for Experts in Optimization, Maintenance and Repairs your organization confirmed to speak in Toronto include:

BUILD A STRONGER SUPPLY CHAIN: Devise a new supply chain plan to source parts at a reduced price without compromising on quality or longevity

GEARBOX, GENERATOR AND CONDITION MONITORING: Recognize ways to see premature wear, cracks and issues in your drivetrain and methods for fast repair so that the turbine stays operational for as long as possible

For more information on the event and to stay in tune with updates, visit the website: www.windenergyupdate.com/omr