How to minimise risk in renewable power generation
The power generation industry in the UK has changed significantly over the past thirty years, since deregulation was introduced in 1990. The effect of privatisation has resulted in increased competition and greater commercial pressures on companies. However, the introduction of renewable energy sources into this competitive market place will create a variety of different challenges and risks for power generation companies.
These risks can range from issues connected to the installation of roof-mounted solar panel systems, to wind turbines running over-speed in high-wind conditions. Additionally, the parallel growth of battery storage facilities within power generation facilities also represents a significant fire risk for unwary operators.
Power generation companies need to ensure that the risks that renewables pose are understood and the exposure they face is reduced to ensure that resilience is built into the very culture of the organisation, making the organisation more successful in the long-term.
Whilst generation from renewable energy sources are in some ways less risky than traditional power generation, the use of new technologies can create exposure to risks which were not present for traditional operators. Greater exposure to extreme weather events is a clear example of a risk that is less of a concern for traditional power generation operators.
Firstly, large scale installations of solar panel systems create a significant exposure due to their innate design. Installations are at risk from hail and wind storms as acres of panels are by their nature exposed to the elements. Hail storms can cause physical damage to the panels upon impact, whilst high winds can remove inadequately secured panels. There have been a number of fires in large scale roof-mounted installations fuelled largely by plastic mounting and support systems. In addition, some roof constructions which would not by themselves propagate a fire could do so when overlaid with photovoltaic systems. Roof-mounted solar panel fires can be difficult for firefighters to stop if the panels cannot be isolated to prevent electrical shock and due to poor access. Ground level systems may be in remote areas with limited fire service response.
Surprisingly perhaps for wind farms the most common cause of losses is wind storm. Turbines are designed to cease operation and feather their blades when their maximum operating wind speed is exceeded but mechanical failures can prevent this with the turbine then over-speeding to destruction (which can be a spectacular event). The second highest cause of loss is fire. Nacelles and other components are often of combustible plastic construction and combustible lubrication and control fluids are used. Electrical or mechanical failure can start a fire which is impossible to fight manually given that nacelles could be up to 170m in the air.
A further risk that wind turbines and their support equipment face in colder areas is ice accretion. Studies have shown that sections of ice of up to 14 kg can be dropped from turbines while smaller pieces can be thrown considerable distances at damaging velocities. Lightning can damage blades as well as turbine control and computer systems.
Battery storage facilities have also grown in parallel to renewable energy focused generation facilities, due to the need for renewable energy companies to store the energy they produce. Power generation companies need to be aware of the exposure to risk that these storage facilities create. Battery storage facilities represent a significant fire risk, due to the lithium ion battery technology utilised. Lithium ion batteries typically contain flammable electrolytes which can lead to challenging electrical fires – sometimes caused at first by manufacturing defects or by damage sustained to the batteries themselves, resulting in a runaway thermal reaction.
What can power generation companies do to mitigate the risks created by renewables? Firstly, renewable energy focused generation companies need to understand the risks they are introducing to facilities. Only when a risk is understood can it be mitigated against, through the introduction of physical changes to facilities, implementation of appropriate maintenance routines, as well as through the usage of appropriate monitoring systems for machinery.
Physical safeguards are best implemented during the design phase. Avoid combustible construction materials, ensure the local wind, hail and other environmental exposures are fully understood and allowed for, use non-ignitable control and lubrication fluids in wind turbines. Be very careful with the interplay of design return period for wind storms and design safety factors.
For existing solar arrays with combustible construction or mounting systems ensure they can be reached by fire hoses and that fires can safely be fought without fire fighters being exposed to dangerous electric shocks. If the design is deficient with respect to wind storm consider extra ballast or securement. If panels are steerable ensure there are good emergency procedures to stow them in the safest position if extreme weather threatens.
Ensure proper inspection and maintenance of wind turbine systems to ensure that they can be safely feathered when winds exceed safe limits. Condition-based monitoring systems can be used to detect incipient failures, evaluate component health conditions to support a condition-based or predictive maintenance system and to analyse the root cause of failures. The condition of blades, the tower and foundations can be monitored indirectly using low-frequency nacelle/drive train vibrations or strain measurements. Vibration and oil monitoring will help protect the key elements of the drive train i.e. the gearbox, generator and main bearing.
With regards to battery storage facilities, they should be fire separated by distance or construction from important buildings or critical utilities. Fire detection should be provided and where necessary to protect surrounding occupancy or equipment consider providing battery rooms with automatic sprinkler protection. Online condition monitoring should supervise battery room temperature and other key parameters relating to charge and discharge, capacity, internal resistance etc.
A risk renewable plants share with conventional is cyber attack. Unauthorised access to control systems might allow intruders to compromise overspeed protection on wind turbines, interfere with electrical distribution systems or deny access to systems and data. Ensuring computer and control systems are physically secure and software systems are resilient against intrusion will help mitigate this risk.
Partnering with an insurer that is familiar with the renewable energy sector is vital. An insurer with this expertise will be able to advise in detail on physical changes that would be beneficial along with adjustments to maintenance routines and procedures. The partnership will also ensure that, should a loss occur, the client will be covered for loss of revenue, something that is of paramount importance when the timescales involved in restoring normal operations can be so long – for example, the largest wind turbines can take up to two years to be procured and installed. This cover should form part of a comprehensive business interruption policy, enabling the client to gain access to vital financial and technical support in the short and medium terms, so that operations can be restored as quickly as possible. This will limit the long-term reputation damage that the operator might suffer, maximising long-term success.
The author is Allan Macpherson, Operations Chief Engineer, London Operations, FM Global.
This article originally appeared on Engineering Live. Click here to read it.