Stereo Bird Tracking

Understanding the impact of off-shore wind farms on the local birds populace

Overview

Understanding collision risk is an important factor in managing risk in development of individual offshore wind projects and in quantifying the environmental impacts of the UK’s offshore wind industry. Many observers and practitioners in the industry have identified obtaining sound collision risk data as the most critical issue facing the deployment of offshore wind in the UK. Indeed, to date, the lack of sound data regarding collision risk is the leading factor in delaying consenting decisions, with the refusal of consent by the Department of Energy and Climate Change (DECC) for Centrica’s Docking Shoal Offshore Wind Farm (Docking Shoal) project being due to a lack of evidence to support a positive appropriate assessment under The Conservation of Habitats and Species Regulations 2010 (as amended) (the Habitats Regulations).

Unlike onshore wind farms where bird corpses can be used as evidence to quantify collision, collisions offshore are very hard to observe directly. Furthermore, in many situations direct monitoring of collisions presents a catch-22 situation where statistical significance is achieved only after an unacceptable level of mortality has been observed.

Collision risk assessments are derived from well-understood collision risk models. These models initially assume that birds are oblivious to turbines, and then apply a correction factor known as ‘avoidance rate’ to provide the final estimate. At present, determining avoidance rates is a challenge, and often a mixture of direct measurement, prior knowledge and overly precautionary assumptions have to be applied to derive a value.

Ideally, avoidance would be measured directly; although this can be done under some circumstance, e.g. using radar, there is as yet no general solution that can be applied to all species at all sites.

 

Approach

The established approach to deducing avoidance rate is to measure collision rate at a constructed site and deduce avoidance from this and the pre-construction baseline surveys undertaken at the site being assessed. A fundamental difficulty with collision monitoring is the low anticipated collision rates for many at risk species. An example of this is Sandwich tern in the Greater Wash, where the collision rate is such that even if every single collision in a summer were observed the uncertainty in the resulting estimate of collision rate could still be very large. Data which focusses purely on collisions is therefore unlikely to significantly advance the debate on collision risk unless it is gathered over several years and at several locations.

A better alternative is to study avoidance behaviour; by understanding how birds adapt to the immediate presence of a turbine, we can refine the assumptions that feed into a collision risk model leading to more accurate estimates of mortality. In this approach, rather than studying collisions in the context of population size, we propose to study birds at species level that are ‘available for collision’ (birds which cross the swept area of the rotors, plus a buffer to account for mortality due to potential rotor tip turbulence) in the context of all birds in the vicinity of the turbine.

To achieve this functionality, an ideal survey tool would capture the flight path in three dimensions of all birds entering a pre-defined “box” around the turbine. Each flight path can be tested to see whether or not it intersects the swept area of the rotors, enabling birds ‘available for collision’ to be differentiated from those that avoid the turbine. The detection box would be sized such that all birds available for collision could be identified and a significant number of paths not intersecting the rotor could also be detected.

Avoidance behaviour can then be measured by comparing the proportion of birds ‘available for collision’ with the prediction of a model that assumes no avoidance behaviour. Uncertainty can be robustly estimated using a non-parametric bootstrap technique, which can account for behaviour such as flocking by appropriate aggregation of samples.

Solution

The system as implemented is based around a pair of sixteen (16) megapixel digital video cameras equipped with fisheye lenses. The fisheye lenses give a very wide field of view enabling a single pair of cameras to cover the space up to and including the turbine blades and down to the water with a horizontal field of view of approximately 100 degrees (°). To achieve this view the cameras are tilted upwards by 45°, as shown in Figure 2. The combination of this viewing angle and the extremely wide field of view of the lenses allows the rotors to be seen clearly, while enabling detection and tracking of birds at a considerable horizontal distance from the turbine. The system can therefore detect collisions as well as monitor avoidance.

 

The baseline of the cameras was set at 1.4m which gives the system potentially good spatial resolution of up to 1m at a range of 100m and some ability to measure with decreased accuracy out to 500m. These images are then transmitted back to shore via a wireless link where they are analysed to identify the birds species and track the birds flight. This information tells us which species are in the vicinity it also shows us the impact of the turbine on the birds flight path.

The system spent a year on a turbine in a wind farm in the north sea where it was used to monitor the local tern population.

Conclusion

The developed system for avoidance monitoring at offshore wind farms, was successfully deployed for over six months at an operational offshore wind farm, without any significant faults. From the data collected, it has been possible to track individual birds and identify them to species-group or better. The data collected showed evidence of micro-avoidance behaviour, with none of the birds approaching within a blade-length of the turbine.

The evidence gathered as part of this study indicates that the data provided by the system will enable micro-avoidance to be quantified.

 

The system has shown to offer:

  • Continuous and autonomous operation over many months
  • Tracks birds in 3D and records flight paths
  • Reduces the risk of changing animal behaviour by human presence

 

The capability developed here may have significant benefits in other fields, such as UAV detection.

matt

Matt Mellor, Managing Director

Matt Mellor started his career as an academic working in research and development at Oxford University where his specialist field was in computer vision and robotics with medical application. But in writing papers, which he says were mainly “read by other academics so they could cite it in their research”, Matt could see there was a vital component missing.

“To turn that research into a product I learned that you have got to make that happen yourself to ensure others recognise the value of it,” said Matt. “That started me on an odyssey to learn about the full process of technological development. That means not just learning about technology, but also about business, people, finance – all the parts you need to make something happen which is going to make a positive change in the world.”

With that in mind, Matt moved to Cumbria and joined REACT Engineering. “REACT put the emphasis on entrepreneurship and I joined the company to apply what I had learned in nuclear medicine to nuclear engineering.” In particular, Matt was able to apply his knowledge in medical imaging to provide smart, technological solutions to the nuclear clean-up industry.

In 2007, Matt was the technical lead in setting up REACT’s own spin-out – aerial surveying company, Hi-Def, which gave him valuable experience of the process involved in setting up a spin-out business. Hi-Def went on to be a sustainable, successful business in its own right and in 2016 became part of the BioConsult SH group. Meanwhile, Matt set up Createc in June 2010, and as CEO has led the company to achieve impressive growth ever since.

Createc started out with just three members of staff – Matt, Alan Shippen and Pete Rodgers. The company’s mission was to create a profitable business out of computer vision and robotics research and development, demonstrating the value such a service adds to industry. Building on technological expertise in the nuclear sector learned from REACT Engineering, Createc developed its N-Visage® technology which went on to be used in the clean-up following the Fukushima Daiichi accident in Japan.

Closer to home, Createc used its intellectual property in computer vision to build a business opportunity and set up spin-out company, Sportlight. Earlier this year, it launched a second spin-out from its robotics expertise creating Createc Robotics.

Looking ahead, as society and industry move out of a Covid-19 lockdown, Matt sees robotics playing an ever more important role – but warns those who think it will be an overnight change, to be more patient. “Society has always overestimated what technological development will take place over a two to five-year period. But it has always underestimated what development will take place over 20 years,” said Matt.

“Technological development is an accumulation of small goals which build on top of each other. It creeps forward so that over a 20-year period people then look back and are amazed at how much the world has changed. In 20 years’ time we are going to have a lot more robots, and we will have improved collaboration between human and machine. In some areas that might involve helping to remove people from having to carry out tasks in hazardous environments. In other areas it might be giving people more senses and more capabilities.”

Createc applies its thinking and technologies to any problem to find a solution, and takes a flexible approach when doing so. This means that it can adapt for a range of industries and a range of situations. “We look at the way we can do something, not where we can do it,” said Matt. It’s an approach which has seen its solutions applied in a range of industries and settings, including nuclear and defence, rail and security. Among future growth areas for Createc are heavy engineering, major industrial and general construction.

Createc has received two Queen’s Awards in recent years, one for International Trade and one for Innovation, recognising the company’s success in developing technology. The company is also proud to have won awards for innovation from The Institution for Engineering and Technology (IET), The International Atomic Energy Agency (IAEA) and Nuclear Decommissioning Authority (NDA).

Createc’s strategy as it moves beyond its 10-year anniversary is to concentrate on research and development to launch a series of further spin-out companies. Two things Matt is keen to influence in the wider economy to help support the company’s ambitions are funding and leadership. “We need to make sure that the UK is more start-up friendly. And we need more entrepreneurs who want to come and run these businesses,” said Matt. “To me an entrepreneur takes complete ownership and picks their way forward and proceeds confidently in the face of doubt.”

“We have had a sustained growth rate of 40 per cent, and we are focused on continuing to grow at this rate. In the first ten years we have grown from a company with three people turning over £180,000 to 30 people turning over £3.5m. To sustain that level of growth by the end of the next ten years we would have 300 people turning over more than £60m.”

Matt has a clear vision of how the company will keep driving forward, and his motivation and appetite to lead the company to further success is clear. “My motivation comes from bringing something completely new to life which results in the world being a better place,” he said. “Seeing all the pieces come together and creating this thing which creates an economic benefit and also has a positive impact on the world is really satisfying.”