Aviation constraints are a huge issue for the wind industry. In 2011, EWEA carried out a survey and found that 19 GW of wind projects were blocked by radar difficulties in the UK, Finland, Sweden, Germany, Czech Republic, France, Spain, Greece and Ireland.
Many difficulties for wind farm developers come from conflicts with obsolete radar equipment and problems associated with keeping track of system upgrades over time. According to Renewable UK, for example, half of all wind farm developments in the UK will face objections from aviation stakeholders on the grounds of radar interference, obstruction or impact to low flying. However, a new promising radar technology could be one way to solve some of these problems.
Cambridge Airport in the south-east of England has signed a deal to use so-called 3D holographic radar technology. Its creators claim that the technology is the first of its kind that can reliably discriminate between wind turbines and aircraft based on differences in their behaviour.
When built in the line of sight of air traffic control radar, wind farms create interference that can adversely affect the air traffic controller’s view of what is happening in the sky. This new technology purports to clearly distinguish between the wind turbines and the aircraft. It therefore feeds only information about the position of the aircraft to the airport radar without the “clutter” caused by the wind turbines. This should give air traffic controllers a consistent and accurate view of the aircraft the entire time it is over the wind farm.
“Unlike the current generation of ATC radar that scan a narrow beam using the familiar antenna that rotates around a fixed point, holographic radar constantly looks in all directions at once,” say the inventors of the technology. Moreover, it “continuously measures the dynamic characteristics of each individual target, providing comprehensive information on all moving objects within the field”.
The difficulties faced by placing wind farms near airports have been raised on numerous occasions, not least by Finland’s Minister of Economic Affairs and Energy, Jyri Häkämies. In the September issue of Wind Directions, when trying to explain Finland’s low share of total electricity consumption from wind compared to other Scandinavian nations, he cited the apparent difference in planning laws around airports in the two countries. “When we were approaching the [Copenhagen] airport [for EWEA 2012] we noticed that there are wind generators very near to the airport so we were wondering how it is possible that in Finland they must be 15 kilometres away [from the airport]”. The research laboratory VTT has developed a simulation tool financed partly by the wind sector and partly by the Finnish Ministry of Trade and Industry to assess the potential electromagnetic interference. The tool simulates the interaction of radars with wind turbines.
Each country is obviously different and, as the UK Department of Energy and Climate Change (DECC) points out, “each area of aviation demands its own solutions” with objections raised by both military and civilian bodies. Moreover, solutions are not cheap. A full set of technical solutions to all affected radars could cost up to £100 million between now and 2020, according to Renewable UK. This is a considerable amount of money, especially in the current economic climate.
But at least having the right technology available could be a sizeable step in the right direction for some authorities. If it delivers what it claims, this new technology could help ensure significant numbers of new onshore wind farms secure planning approval in the UK and maybe beyond.
Technology developments aside, it is important to point out that wind turbines and radar can coexist. Early dialogue, meaningful cooperation and transparency between stakeholders is key to solving the issues.