Wind Farms Switch Lights On, Off With Aircraft Detection System

October 17, 2023 by Shannon Cuthrell

Onshore wind farms are using aircraft detection lighting systems that operate on demand to reduce light pollution.

Danish energy giant Ørsted recently started operations at its Sunflower Wind Farm in Kansas, incorporating an aircraft detection lighting system (ADLS) designed to control the duration and intensity of lights that flash when aircraft approach the turbines. 


The 200-megawatt Sunflower Wind Farm recently started operations in Marion County, Kansas.

The 200-megawatt Sunflower Wind Farm recently started operations in Marion County, Kansas. Image used courtesy of Ørsted 


This comes after Kansas’s governor signed Senate Bill 49 into law earlier this year. The legislation requires new wind farm owners, operators, and developers with at least five turbines to secure approval with the U.S. Federal Aviation Administration (FAA) for light mitigation systems. When approved, companies have 24 months to install them. The state’s 44 existing wind farms would need to apply for FAA approval within six months of renewing their power offtake agreements. 

Wind farms accounted for 47% of Kansas’s net electricity generation in 2022, the third-highest share in the nation, per the U.S. Energy Information Administration. With an increasing share of intermittent wind generation on its power grid, the state moved to address concerns about light pollution affecting night sky views and migratory birds. 

Interest in ADLS started building in the 20th century around the dark-sky movement, a global campaign to reduce light pollution with new street light fixtures, lighting regulations, and other mitigations. ADLS rules have been adopted in North Dakota, which was the first state to mandate it for new and existing wind projects, and Colorado. 

The light mitigating technology applies to the Sunflower Wind Farm’s 76 General Electric 2.82-megawatt (MW) wind turbines. The 214 MW project will provide power to over 70,000 homes per year in the Marion County area. 


What Is ADLS?

ADLSs—also known as obstruction lighting systems—are automatic warning systems that activate blinking lights on demand when aircraft and other obstructions approach wind turbines. Sensor-based ADLS products typically consist of a surveillance radar, antenna, and light control server. The radar acts as the main sensor, monitoring the air space above and around the turbines for airplanes, helicopters, gliders, and birds. The radar sends a pulse of energy and measures the time it takes to reach the target, providing the range. The lighting system kicks on when objects enter the zone and then deactivates when the air space is clear. 

Various designs are in the commercial market today, including perimeter and in-field systems, ground-based and turbine-mounted sensors, and those with secondary sensors like aircraft transponder receivers. 

When requesting ADLS approval, the FAA requires maps showing the radar coverage area at 200 feet above ground and 1,000 feet above the tallest wind turbine. The agency’s general ADLS standards expect horizontal detection coverage prior to aircraft breaching the perimeter at a minimum of three nautical miles (NM). 


FAA-Approved ADLS Tech 

Only a handful of companies have been approved for ADLS systems in the U.S. The two most active suppliers are Terma, a Danish defense and aerospace manufacturer, and DeTect, Inc., a Florida-based radar system company. Ørsted confirmed to EE Power that it used DeTect’s ground-based installation at the Sunflower Wind Farm. 


DeTect’s HARRIER ADLS system activates turbine lights at a wind farm.

DeTect’s HARRIER ADLS system activates turbine lights at a wind farm. Image used courtesy of DeTect 


DeTect’s ground-based HARRIER ADLS provides 360-degree radar surveillance up to 18 NM and is compatible with all wind turbines, control and communication networks, and obstruction lighting systems. The system also offers continuous recording of aircraft detection and other activation events to an internal SQL database with auto-reporting. According to DeTect, HARRIER ADLS includes a solid-state Doppler processor with S- or X-band radar sensors. Its power source is a single-phase 120-240 VAC system with uninterruptible power supply (UPS) backup and power conditioning. 

HARRIER has been installed on more than 100 systems in the U.S., Canada, and Europe. In presenting its technology to Kansas officials, DeTect mentioned it analyzed over 80 U.S. ADLS installations operating since 2009 and found its average “lights off” time is about 97%. 


Terma’s ADLS lights on top of a wind turbine

Terma’s ADLS lights on top of a wind turbine. Image used courtesy of Terma 


Terma installed its first two radar-activated ADLS at wind farms in New Hampshire and North Dakota in 2020. The company says its ADLS improves wind farms’ “lights off” time by up to 95%, meaning the lights remain deactivated after the air dome around the turbines is clear. Terma’s SCANTER 5202 off-the-shelf product has been installed in over 300 locations worldwide. 

Terma’s ADLS has up to 18 NM of range with 360-degree coverage. It claims it is the only ADLS provider using full inter-turbine radar visibility for continuous aircraft tracking around wind farms and between turbine generators. It also offers full remote monitoring and integration with a range of SCADA systems and network configurations

In a presentation to the Kansas state legislature last year, Terma said the ADLS system architecture includes its SCANTER 4000/5000 series radar sensor paired with a light control system (LCS) server and a network-connected light control module (LCM) from third-party vendors.