During 2012, there were 905 natural catastrophes worldwide, 93 percent of which were weather-related disasters, costing US$170 billion. Unpredictable global climate conditions are thought to be on the increase and have recently been evidenced by major events, such as typhoon Haiyan in the Philippines, flooding in the UK and the big freeze in North America. The direct cost of this weather volatility is also rising significantly with insurers paying out US$701 billion globally for damages from extreme weather events every year for the last three years alone.
New research suggests that long-term ten-year cycles in the ocean are affecting the position of the jet stream and this is contributing to the unusual weather patterns such as those recently seen in the UK. The severe storms at the end of 2013 and into 2014 are testament to the dramatic change and increased frequency that the changing climate can bring.
Such extreme weather events are headline news, particularly in relation to the impact on infrastructure, travel delays, etc. But what about the damage caused to renewable energy equipment?
In October last year, a wind turbine in Devon, UK collapsed due to strong winds that swept across the region. More notably was the destruction of a £2 million wind turbine in North Ayrshire, Scotland, which caught fire in 2011 due to a severe storm in the area.
Whilst the reliability of renewable energy installations to withstand such events is dependent on its initial design and with consideration to its location – there are additional measures that can be taken to reduce such severe weather exposures.
Wind is the number one weather risk for most equipment and as such all renewable energy equipment should be prepared for the highest winds and storms.
- Regular checks should be carried out on the foundations, tower, and blades of wind turbines along with any other structures and equipment on site. Monitor the tower for the effects of turbulence from other wind turbines or structures nearby and ensure that the automatic shut-down mechanism for high wind speeds and braking systems are working.
- Dual axis photovoltaic plants have a higher exposure from wind damage than ground mounted installations due to their elevation and the overall size of the panels. There is a ‘fail-safe’ control in the event of high winds and this should be checked to ensure it is operational.
- The condition of trees in the vicinity of any buildings or transmission lines should be inspected. Any suspect branches and trees should be removed to prevent any potential damage.
Heavy rain is the most likely cause of floods, however thawing after heavy snowfall can also cause major flooding.
- Flooding could result in water ingress into transformer and inverter housings together with site buildings. Site drainage should be inspected regularly along with any debris screens to ensure they are clear especially at locations where culverts and drains are specifically provided. Any site drainage pumps should be checked and tested to ensure they are in working order together with the condition of seals in underground cable ducts to prevent water ingress into critical areas due to flooding.
- Hydro facilities are particularly susceptible to flood damage as although the turbine is designed to be submerged, the associated transformer and electrical equipment is not. As these are often housed nearby it is imperative that the powerhouse is located at an elevated location above the high water line.
- In anticipation of severe rain storms and adverse weather conditions, it is important to ensure that any susceptible equipment is moved to a location where it will not be affected by water and that temporary flood barriers are installed and activated.
Hail stones over two inches in size can cause serious damage to renewable energy facilities and particular PV panels. Typically hail storms of this magnitude are found in locations such as the central states of the USA (Nebraska, Kansas, Oklahoma and parts of New Mexico). Last year various regions around the UK and in Australia also experienced hail stones the size of tennis balls. In areas with an increased risk of hail events, measures can be taken to reduce the damage potential.
- Use PV panels that have been certified to IEC1215/61646, ASTME1038, UL 1703 or FM4476/4478 standards to ensure that the panels are strengthened to withstand routine hail events.
- Check the orientation of the PV panels. Angled orientation of fixed mounted
panels (generally 30º facing southward) can help to deflect falling hailstones and reduce the force imposed onto the panel. Panels that are direct-mounted on low slope roofs, or are mounted horizontally (0º tilt, facing directly upward) pose a higher risk of potential damage from direct strike of large hailstones.
Structures such as wind turbines and steel framed buildings are more at risk from being damaged by lightning. Measures to protect wind turbines against lightning strike are described in the international standard IEC 61400-24.
- A lightning protection system Class III is normally required for turbines up to 60m and Class II if the turbine is more than 60m. The protection system comprises of air-termination systems, down-conductor/s and an earth termination system to protect against mechanical destruction and fire. Lightning strikes to wind turbines usually affect the rotor blades and bearings. To mitigate the damage affects, lightning receptors should be integrated to defined strike points along the rotor and body.
- For steel frame factories units housing (for example) biomass units, waste-to-energy plants etc., lighting rods or air terminals are the more familiar type of lightning protection. These must be installed to the relevant local standard. Lightning rods are good at conducting electrical surges away from the actual structure of a building but they will not necessarily protect against power surges.
- Surge protection should be fitted to help against excessive power outages, which can be caused by lightning strikes and can potentially damage computerized control units installed on biomass plants, anaerobic digesters and other waste-to-energy plants. Such measures together with appropriate lightning protection can help to prevent damage which might otherwise occur during a lightning storm.
Once a renewable energy plant has been installed it will be difficult to make any modifications without incurring significant costs. It is therefore vital that it is designed to be appropriate to the environmental and weather conditions and that the equipment is installed is in accordance with both design and manufacturers recommendations.
Each renewable energy installation brings different risk challenges and access to knowledge on risk management provided by specialist insurers and their engineers can be invaluable in helping to mitigate against weather related risk exposures.
Lead image: Wind turbine lightning via Shutterstock