As the number of wind turbines erected onshore and offshore increases, the impact of wind turbines on radar has become more evident.

Both in the UK and Europe, large onshore and offshore wind farm developments are beginning to proliferate and these large developments can have a big impact on aviation.

In this context, it is essential that impact on aviation, radar and communication systems is understood early on in the process and that feasible mitigation is identified and can be made available within the timescales of development of each wind farm site.

Tools for quantifying and predicting impact on radar and communication systems form the foundation of this process and it is vitally important that they are well validated and produce results that can be trusted.

“These tools will certainly assist with understanding the issues and options for mitigation will be relied upon further as the wind farm development environment becomes more complex as the number of projects increases,” says Clive Jackson, Lead Consultant, Wind Farm Technology, BAE Systems.

“At the same time, however, it is not enough to rely solely on such tools,” added Jackson, who is scheduled to speak during European Wind Farm Site Selection Summit, which is scheduled to take place on 1-2 April in Hamburg this year.

There are a wide variety of deployed radar and communication systems across Europe, developed by a variety of different manufacturers.

“Each of these systems will be impacted in different ways depending on their design and manufacturers are understandably reluctant to reveal too much of their own system's designs to potential competitors. Therefore, while these tools are key to taking the first steps to understanding potential issues, there is no replacement for dealing directly with the affected stakeholders to understand their issues and develop mitigation in a systematic and coherent way to help ensure that the maximum number of megawatts are released,” shared Jackson in an interview.

He further spoke about the impact of turbines on primary surveillance radar, the significance of consultation at an early stage and much more. Excerpts:

windenergyupdate.com: In the past, it has been acknowledged that the impact of turbines on primary surveillance radar or PSR is currently a roadblock to numerous developments and a technological solution mitigating this impact could potentially release hundreds of megawatts of renewable energy. How has this been taken care of to an extent?

Clive Jackson: Performance impacts on PSR within line of sight of wind farms is far and away the most common cause of concern to aviation stakeholders. These typically fall into the three categories: Unwanted turbine reports on the radar displays; Reduced probability of detecting the wanted aircraft reports in the vicinity of turbines; Tracking performance degradation.

There has been a lot of effort over the past few years to address these effects on radar. These range from very simple changes (such as simply blanking areas of radar displays), through high performance tracker designs, hardware/software modification of existing radars, fusion of data from new gap filling radars,  novel gap filling radar designs and even stealthy wind turbine designs. Of course these are things being looked at independently by various radar manufacturers, including ourselves at BAE Systems.

For example, as part of our work here at BAE Systems we are developing modifications to some of our own radar designs, which are proving feasible options and are assisting in gaining the consent of many hundreds of megawatts of wind energy both on- and offshore in the UK. At the same time, we are developing generic options, which could be added to existing radars, such as our Advanced Digital Tracking system that to a large extent addresses tracking performance degradation issues. We are also investigating the feasibility of implementing Gap Filling Radar mitigation options, which show promise in mitigating a wide range of radar / wind farm issues. Finally, with expertise developed in our Advanced Technology Centres, we are even investigating materials and designs for stealthy wind turbines

Importantly, in the UK, this sort of development is being encouraged by the BWEA and the Department of Energy and Climate Change (DECC)  who are supporting funding initiatives to bring a number of these sorts of radar technologies to market.

In terms of relevance to a given wind farm and aviation stakeholder, these options are all at various levels of maturity and the skill in finding the best option often depends on availability, timescales and precedent as much as technological complexity. 

It is particularly important for the wind farm developers to understand the timescales for the development and implementation of any mitigation since any loss of revenue from delaying power generation may outweigh the cost of a more expensive but quicker mitigation option. One of the main contributors to long timescales for aviation stakeholders are those concerned with achieving safety case certification from regulatory bodies. This is one of the main challenges facing those wishing to implement new technologies in this area, whether for wind farm mitigation or any other reason and to a certain extent tends to favour mitigation options that exploit conventional radar technology.

Another important factor is of course the cost implications for any aviation mitigation. Whilst some available mitigation techniques may be technically feasible, they may not be economically viable when considered against the size of a given wind farm development.

Finally, understanding the stage in the wind farm develop programme that any aviation planning condition is fulfilled is very important.  This will help the developer to quantify the risk in their business case.

windenergyupdate.com: What do you recommend when it comes to communicating the knowledge and data of the potential impact of a wind farm on stakeholders to ensure the most appropriate mitigation strategy is implemented?

Clive Jackson: Face-to-Face consultation at an early stage, supported by an expert/  consultant and good evidence of impact and mitigation options is the easiest approach. It helps both the wind farm developer and the aviation stakeholder come to a common understanding and to appreciate each others standpoints. If actions can be agreed at these meetings it certainly gives impetus to the process going forward too.

In terms of communicating more widely, conferences such as this one (scheduled to take place in Hamburg) are great for bringing these issues to the wider wind and renewables community, who otherwise may not appreciate the flavour of aviation concerns. The trade bodies such as the BWEA and EWEA are also key to bringing the two communities together in a constructive way.

windenergyupdate.com: How can one go about resolving objections, reaching a common understanding – and secure the go-ahead for a project with early aviation stakeholder engagement?

Clive Jackson: Really this is all about doing the analysis and opening the lines of communication as early as possible. If both sides can appreciate the issues, it is easier to move forward and develop realistic expectations. There really is no substitute for understanding the technological and aviation operational issues surrounding a wind farm development and building a relationship with the aviation stakeholder to work towards a mutually acceptable solution.

If it is determined that technological radar mitigation is required then evidence that the mitigation is achievable and timely needs to be built up in consultation with all stakeholders , the earlier this can happen the better.

windenergyupdate.com: There have been instances where techniques employed within conventional radar which attempt to exploit differences in the above characteristics are not sufficient to distinguish between echoes from wind turbines and those from real aircraft. What according to you needs to be done in this case?

Clive Jackson: This comes back to understanding the operational impact on a stakeholder, of a wind farm’s radar performance effects. It is also worth remembering that turbines can appear to be many thousands of times larger to a radar than the aircraft it is designed to detect.  Combine this with the fact that turbine blades can move at speeds comparable to small aircraft and you begin to see the challenges facing a radar system and any form of mitigation design in sorting aircraft from turbines.

In that context it would be fair to say that it is unlikely that any form of radar technological mitigation can fully eliminate wind turbine radar performance effects. This includes both conventional radar modifications and novel radar designs.

What is possible, however, is a considerable reduction in the performance effects. In my experience, such mitigation coupled with an analysis of actual stakeholder operational requirements, can identify a feasible and timely mitigation strategy that reduces the radar performance effects to such a level that they are no longer operationally unacceptable. Provided this can be agreed by both sides, this can give the aviation stakeholder the confidence to remove their objection (on the condition of implementing mitigation) and leaves the way forward for the wind farm developer to gain consent and build their wind farm.

In my experience,  with a large number of wind farm developers and stakeholders, this twin approach of technological and operational analysis and early engagement with stakeholders has been the most successful and has allowed us at BAE Systems to facilitate the granting of consent to many hundreds of megawatts of renewable wind energy.

European Wind Farm Site Selection Summit

BAE Systems’ Clive Jackson is scheduled to speak during European Wind Farm Site Selection Summit, which is scheduled to take place on 1-2 April in Hamburg this year.

For more information click here: http://www.windenergyupdate.com/eurosite09/programme.shtml

or Contact: Pete Carkeek by email pcarkeek@windenergyupdate.com