The wind farm is the terrain

?rsted recently announced they have revised down the expected internal rate of return and capacity factor for their offshore wind farm portfolio. 

At Black & Veatch we understand the reasons why estimates of the lifetime load factor of offshore projects in operation or under development might be revised. For many years our professionals have been observing, modelling and developing a detailed understanding of complex wind conditions offshore, and the way these interact with and are modified by offshore wind power assets, including blockage and wake phenomena. Our professionals have been at the forefront of pioneering investigations, and their insights have been shared across numerous platforms, with, for example, potential impacts of 2-3% reported in 2014

This announcement has been viewed in some quarters as a wake-up call. These issues provide a specific example of more general challenges facing the wind industry. Black & Veatch are exceptionally well placed to help our clients with short to medium term concerns, but also recognise an industry-wide approach is required in the medium to long term to address the methodological discrepancies of established procedures. We are keen to contribute to a collaborative approach engaging a wide variety of stakeholders to overcome the limitations of the industry’s legacy of received wisdom, of which these issues are artifacts.

Standard approaches to wind flow modelling assume unrestricted flow. While this approach describes the circumstances of a single turbine operating in isolation, it does not accurately describe an array, where flow is partially restricted by the presence of a large number of obstacles. Blockage is not a problem. It is simply physics. The problem is the failure of standard models to fully accommodate the real-world physics of wind farms.

Once we, as an industry, adopt modelling that takes this into account, it is not surprising that lifetime load factor needs to be adjusted. However, the industry has not moved on awareness of these issues until now because of the way project life-cycles are divided into silos, raising the possibility that organisations engaged in delivery of one aspect of the project may carry the can unfairly. The issue can be described in terms of how it compromises established procedures for wind resource assessment, for power performance testing, and so on. All these descriptions are fundamentally equivalent and interchangeable, in that they are all manifestations of the simplifications and silos we, as an industry, have inherited, and can all be resolved by the same evolution in our methodology. A full life-cycle perspective is needed to achieve progress and prevent all the risk being allocated to a single area. (I have discussed this previously here, here and here.)

In general we need to move beyond the methodologies we have inherited from our predecessors, and the issues being discussed in relation to recent announcements offer us a stimulus and an opportunity to make improvements in our procedures. Unrestricted flow in simple terrain was once a convenient simplification, but it prevents us from fully appreciating that there is no such thing as simple terrain, when we take the effects being discussed into account. The wind farm is the terrain. It modifies the conditions that determine production in a way that is an emergent property of the whole array that is only present post-construction. Pre-construction measurements cannot fully represent post-construction resources that are influenced by these phenomena. Methodologies based on the assumption that they can fully represent the resource introduce the discrepancies being discussed.

Fortunately, developments in the broader context of the Energy Transition provide a basis for moving forward. There are efforts to digitise ecosystems so that progress towards sustainable development goals are measurable. This in turn lets us to embed our digitally integrated infrastructure in ecosystems in a way that allows their environmental impacts to be assimilated by our business models. We are moving from the Internet of Things, characterised by connectivity, toward the Internet of Impacts, characterised by analytics that allow us to embed integrated and digitalised infrastructure solutions sustainably in the environment and couple them effectively with adjacent economic sectors. 

Effectively we, as a society, are achieving sustainability by ensuring externalities are no longer overlooked and are accounted for in the costs we calculate. The fully integrated approach this entails, in which digital workflows give us the earliest possible access to the best possible insights about future performance, like an early warning system that enhances the visibility of risks and so facilitates their effective mitigation, requires us to radically de-silo our projects. This means we must develop the full life-cycle perspective in the wind industry described above in which these issues are resolved. 

The wind industry already has many open transparent initiatives underway which, in combination, may show the way ahead: IEA Wind Tasks 25 (integration), 31 (wakes), 32 (lidar, for digitising wind conditions in a manner compatible with sophisticated models), 36 (forecasting), 37 (systems engineering), and 43 (digitalisation), WindEurope task forces on digitalisation and security, the RECAST project (accelerated resource assessment in complex terrain), CFARS (the consortium for the acceptance of remote sensing), AWAKEN (the American wake experiment), and so on. In the broader context we see initiatives such as the UN Working Group in Big Data and Frontier Technologies also providing a forum for these topics, and there are many other initiatives underway that can contribute to the progress we need to see. 

As we in the wind industry investigate the ways in which to lessen the effects of blockage and wake, we are drawing upon both our wind energy expertise and beyond. For example, can our approaches to optimised wind farm control - currently used to reduce intra-array wake losses – yield any inter-array benefits? What can we learn from tidal energy experts who are routinely modelling restricted flows? Our understanding of every point in asset life-cycle, and ability to pull-in expertise from many sectors, is helping create a more complete solution to the challenge of optimising wind array performance.

Looking ahead this type of approach – seeing beyond traditional silos – is a way in which we can start to fulfil the potential offered by the digital revolution to enhance all infrastructure creation and management projects. A sector and technology agnostic approach will help bridge data gaps allowing us to revise and improve performance forecasts; and help us move from the Internet of Things to the Internet of Impacts – where we are accounting for the complexity of real-world interfaces by aggregating data from the fullest possible range of sources. 

Eventually it should be possible to develop procedures for "dynamic energy yield assessment": just as, in health and safety, dynamic risk assessments are undertaken, which acknowledge our information is incomplete and our conclusions need to be continuously revised to accommodate new information as it is made available, so, by analogy, we can better protect the "health and safety" of our investments by formulating a similar living document to describe our anticipated production and expenditure, and benefit from the "earliest possible access to the best possible insights" as these are made available by our integrated digital workflows. 

If we assume we have complete information, and base the confidence we have in our production estimates on that assumption, then when new information does become available, such as, for example, 

• Measurements of complex wind shear offshore, 
• Leading edge erosion, 
• Improvements in our appreciation of the interaction between our wind power assets and the variable, intermittent, uncontrolled and unregulated resource they exploit through better understanding of blockage and wakes, 

then this assumption requires us to control the narrative to support confidence before we correct our calculations. 

However, if we accept that our information is incomplete, that there is always more to learn, that our uncertainty budgets must be continually revised because one cannot assign a likelihood to the unexpected (by definition), then every new revelation immediately provides us with a chance to improve our models, enhance our procedures, and increase the accuracy of our estimates.  

And Black & Veatch, as a provider of digitally integrated infrastructure solutions in energy, water and transport, stands ready to participate in the common endeavours that will deliver the progress we need.