Wind turbine owners are presented with an overwhelming range of options for turbine upgrades, including retrofit blade furniture, control system upgrades, new alignment procedures and new sensor technologies. These systems are often designed to produce an increase in the turbine performance and AEP (Annual Energy Production), improve availability e.g. through condition monitoring and predictive maintenance, or enable other operational efficiency improvements. In some cases, the upgrades are offered by the turbine OEM, and sometimes by independent suppliers. The technology offering will generally be accompanied by a business case demonstrating how quickly the cost of the upgrade will be repaid through increased electricity sales or reduced operational costs.
Given such a large range of options, all of which appear to be beneficial, how should owners decide which ones to go for? The following are some guidelines that will help.
- How convincing are the fundamentals?
- Check the technical feasibility of what is being offered. Does the technology fundamentally make sense? Are the stated functionality and benefits logical, intuitive and transparent? Be wary of offerings that include impressive claims without full explanation of how this can be possible. If an upgrade works, then it can be explained in physics and engineering terms, without the need to refer to abstract buzzwords. Of course, if claims are physically impossible (e.g. performance at levels above the Betz limit!) then ignore the offering and move on. Consider calling upon the services of an independent technical expert for a second opinion.
- Check whether the offered upgrade will work equally well on all turbine types, ages and variants, or whether there are limitations. Similarly check whether the effectiveness of the upgrade will be affected by site conditions.
- Consider whether there are any boundary conditions that may cause difficulties in using the technology at scale across your portfolio. For example, will the upgrade cause any issues for turbines under warranty, or under full-service maintenance contracts? Will there be any risk to the turbine certification? Is the participation or agreement of any third-party required, and has this been secured?
- Are there any hidden downsides? For example, increased performance may mean higher loads, increasing the damage accumulation on critical components over the turbine operational lifetime and ultimately leading to component failure, higher downtime and costs.
- Can the benefit be accurately measured?
- If the benefit of an upgrade or optimisation initiative cannot be properly quantified, then it will be difficult to justify the costs. But here, the devil is in the details. Even if a measurement technique is agreed, all uncertainties associated with the result should be considered carefully. For example, a campaign to measure and correct blade misalignment will be associated with uncertainty in the measurement, uncertainty in the correction and uncertainty in the quantification of resulting performance gains. The overall benefit (increased AEP, reduced turbine loads) should be shown to exceed the costs, even given these uncertainties.
- Specialist equipment and techniques are usually needed for accurate measurement of gains. For example, for power performance testing a nacelle mounted lidar may be needed. A lower cost option may be to use SCADA data from the upgraded turbine (and potentially also from met masts or neighbour turbines), but this must be done carefully to yield accurate results. At i4SEE we offer such analysis using our product “i4SEE Delta™”.
- A measurement campaign might take several months or even a year or more, resulting in significant delays before a decision can be made on rollout across a larger portfolio. This should be considered at the planning stage. The ideal upgrade will be easy to evaluate, and quickly provide results that can be measured with low uncertainty, so that decisions can be made about greenlighting further upgrades.
- Despite the complexity of measuring the influence of an upgrade, if the technology is sufficiently cheap, the physics make sense and a clear benefit can be expected (e.g. reduced loads, increased production, increased operational efficiency), it may still be worth introducing, especially if this can be done with minimal effort and change to existing operational processes.
- Is the business model fair?
- Generally, an upgrade offering is attractive if it will add value for the wind turbine owner that is a healthy multiple of the investment price. The bigger the multiple, the more attractive the offering.
- In evaluation of price, it should always be considered that upgrade projects usually result in internal effort and costs for the wind turbine owner. Project management, supplier meetings, coordination of service staff, training to use new tools, validation of the results …all result in costs which in some cases may be significantly higher than the price of the system purchased.
- Opportunity cost should also be considered. Most asset owners have limited human resources and time available and will need to be selective about which upgrade projects and initiatives to pursue.
- Upside share models, where the supplier of the tech earns a proportion of the gains over a defined time period, tend to be complex, difficult to quantify and may even be a potential source of conflict later on.
- An attractive offering will allow a low-commitment entry point. For example, hardware-based upgrades should be trialled on a small scale first and a clear method for evaluation of the technology should be agreed before this trial. Software trials should be offered without long lock-in periods.
The decision-making process when considering turbine upgrades is complex. What we provide here is an overview, and we hope that with these considerations in mind, fleet owners will feel more confident when faced with decisions concerning wind turbine upgrades. If further advice is needed, at i4SEE we have a team of experienced professionals who are happy to help!