Do Wind Turbines Light Up At Night?

As wind energy continues to expand as a sustainable source of renewable power, more wind turbines are being installed across the landscape. This has led some communities to raise concerns about the visual impacts of wind farms, especially at night when turbine lighting can cause annoyance and disrupt sleep patterns.

Understanding whether wind turbines use lights at night, and what factors determine their lighting schemes, is important for assessing the potential effects of new wind projects. Light pollution from wind farms can impact wildlife that is sensitive to artificial light at night. It also affects the night sky views that some feel are an important part of rural character. Balancing these concerns with safety requirements for aviation obstruction lighting on tall structures requires nuanced solutions.

This article provides an overview of the issues around wind turbine lighting, regulations that guide their use, technologies to minimize nighttime impacts, and ongoing debates over how best to implement turbine obstruction marking systems. The goal is to objectively cover the topic so readers can make informed conclusions about the trade-offs involved.

Safety Regulations for Wind Turbine Lighting

Wind turbines are required by the Federal Aviation Administration (FAA) to have aviation warning lights for the safety of airplane pilots. This is to ensure pilots can see and avoid the tall structures at night or in poor visibility conditions. According to the FAA, wind turbines that are over 200 feet tall need to have synchronized red lights installed on the nacelle (the part of the turbine that houses internal components). Turbines shorter than 200 feet may also need lighting if they are within a certain distance of an airport.

The FAA lighting requirements include specifications on the color, flash pattern, intensity, and placement of the aviation warning lights. The red flashing lights on wind turbines must be visible for 3-5 miles during the night. These regulations are intended to maximize turbine visibility while minimizing visual impacts on the surrounding areas.

In 2016, the FAA updated their guidelines with new recommendations to reduce the impact of wind turbine lighting on nearby communities. These included using light mitigation technologies, selecting lights with optimal flash patterns, and implementing curfews to turn off turbine lighting during certain nighttime hours when aviation activity is low.[1]

Turbine Lighting Systems

There are several different lighting systems used on modern wind turbines to meet aviation safety regulations. The most common options include:

• Flashing red aviation obstruction lights – These pulsating red lights are placed at the highest point of the nacelle and flash around 20-40 times per minute. They ensure visibility for passing aircraft.
• Medium-intensity flashing white lights – Mounted on the turbine tower below the nacelle, these lights flash intermittently to identify the structure.
• High-intensity flashing white lights – Used on particularly tall turbines, these bright strobes provide enhanced visibility from a distance.
• Aircraft detection lighting systems – With these, the lights only activate when aircraft are detected in the area, reducing light pollution at other times.
• Obstruction lighting control systems – These can adjust lighting intensity based on visibility conditions, dimming lights on clearer nights.

The number and placement of lights depends on turbine height and location. The lighting systems are designed to provide maximum visibility and safety, avoiding distracting or blinding effects. New technologies continue to emerge to make systems more efficient.

Sources: https://dataintelo.com/report/global-wind-turbine-lighting-market/

Lighting Color and Brightness

Wind turbines are required by the Federal Aviation Administration (FAA) in the United States and Transport Canada to have obstruction lighting in order to make them visible to aircraft. The lighting color and brightness standards are outlined in FAA Advisory Circular 70/7460-1L and Transport Canada’s Obstruction Marking and Lighting Standards (https://www.tc.gc.ca/eng/civilaviation/opssvs/obstmark-7012.htm).

According to FAA regulations, wind turbines are considered to be obstruction lights of high intensity. For heights below 200 feet, the typical lighting color is medium intensity red. For heights above 200 feet, high intensity white strobes are required during daytime and twilight, and red obstruction lights are required for nighttime (FAA Advisory Circular 70/7460-1L).

The brightness and intensities of wind turbine obstruction lights are precisely defined. Medium intensity red obstruction lights must have a minimum intensity of 32.5 candelas. High intensity strobe lighting during daytime has an effective intensity of 270,000 candelas (FAA Advisory Circular 70/7460-1L). At night, high intensity red obstruction lights must have a peak intensity of 2,000 candelas.

These bright lighting systems are intended to maximize visibility and safety for passing aircraft. However, concerns have arisen about light pollution and impacts on wildlife, which has led to development of new technologies to minimize lighting when possible.

Impact on Birds and Wildlife

Wind turbines can have negative impacts on birds and wildlife if not properly designed and operated. One concern is that lighting on wind turbines can attract and disorient migratory birds and bats.¹ Birds use stars and moon for navigation during migration. Bright steady-burning or flashing lights on wind turbines can cause confusion, leading to collisions.²

Studies have shown that lighting, especially red and white lights, increase collision risk for migrating birds and bats. The FAA recommends using flashing strobes instead of steady-burning lights to mitigate this risk. Proper lighting color, duration, and placement can help reduce harm to wildlife.³ New technologies like aircraft detection lighting systems can also help by turning off turbine lights except when needed for aviation safety.

Overall, wind energy impacts less birds than other structures when properly sited and lit. With thoughtful design and regulations, wind turbines can provide clean energy while also protecting local birds and bats.

Regulations on Light Pollution

As wind energy expands across the United States, there has been growing concern about light pollution from wind turbines that have flashing red aviation warning lights. Local governments have started passing laws to restrict light pollution from wind farms in their communities.

For example, in 2021 Texas passed House Bill 4492 which requires wind turbines built after September 2021 to use Aircraft Detection Lighting Systems (ADLS) which activate flashing lights only when aircraft are detected in the area, reducing overall light pollution [1]. Some counties in Texas have gone even further, passing local laws completely banning red flashing aviation lights on wind turbines [2].

At the national level, the U.S. Bureau of Ocean Energy Management issued new voluntary guidelines in 2021 recommending that offshore wind projects use ADLS to mitigate light pollution [3]. However, many local governments would like to see mandatory federal regulations restricting light pollution from wind farms.

Community Concerns

One of the main complaints from communities located near wind farms is the nuisance caused by wind turbine lighting at night. The flashing red aviation warning lights on top of wind turbines can be an eyesore and cause annoyance for nearby residents.

While wind turbine lighting is required by the Federal Aviation Administration (FAA) for safety reasons, many find the nighttime flashing to be disruptive, especially for those living in close proximity. This lighting can make some residents feel like they are living in an industrial zone at night.

In certain areas, local communities have voiced concerns about wind turbine lighting negatively impacting night sky viewing. The lights can create visual clutter and make it more difficult to see stars at night. This is especially true in more rural locations that previously had minimal light pollution at night.

There are also concerns that wind turbine lighting flashes could disturb sleep patterns for nearby residents. The repetitive on-and-off flashing could make it difficult to fall asleep or lead to intermittent waking in the middle of the night.

All of these factors can lead to lower tolerance for wind projects and a poorer quality of life for those living near turbines. Addressing community concerns and nuisance from wind turbine lighting remains an important consideration for wind farm developers and operators.

Sources:
https://windexchange.energy.gov/projects/community
https://energy5.com/addressing-local-community-concerns-about-wind-turbine-security

New Technologies to Reduce Lighting

Many new innovations are aiming to reduce the lighting required on wind turbines while still maintaining safety. One promising technology is aircraft detection lighting systems, which use radar technology to only activate the turbine’s warning lights when an aircraft approaches the wind farm. This allows the lights to remain off through most of the night, greatly reducing light pollution and impacts on wildlife and nearby communities. Studies have shown aircraft detection lighting can reduce turbine lighting by up to 90%, while still meeting all FAA requirements for aircraft safety. A bill in Washington would require new wind projects to install this technology, showing the growing support for solutions that mitigate turbine lighting impacts.

Best Practices in Turbine Lighting

Wind energy developers and operators aim to minimize the impact of lighting on the surrounding environment and nearby communities. According to the U.S. Department of the Interior’s guidelines, wind farms should use lighting systems that reduce nighttime impacts, yet still meet safety regulations for pilots (2021 Lighting and Marking Guidelines). Several strategies can help achieve this balance.

The color and intensity of lighting can be designed to lessen disturbances. Lights that emit warmer tones like red are preferred over bright white lighting. Red lights are less noticeable and disruptive to wildlife and nearby homes. Using lighting systems with sensors or timers to activate lights only when needed can also minimize constant illumination. Choose lighting technologies like LEDs that focus light directionally to avoid light spillage and pollution (Technostrobe Design Guidelines).

Light intensity and duration should be limited to the minimum required for aviation safety. Strobe lighting at the highest allowable flash intervals is recommended, such as strobes activating no more than 40 times per minute. Keep lights steady-burning instead of flashing when feasible. Synchronize lighting across turbines to flash simultaneously so the effect is concentrated rather than scattered (2022 Wind Energy Lighting FAA Buyer’s Guide).

New radar-activated lighting systems and aircraft detection technologies can automatically adjust lights based on proximity to aircraft. These smart lighting solutions illuminate only when needed for aviation safety rather than running all night. They help wind farms balance productivity with sustainability and community relations.

Conclusion

In summary, most modern wind turbines do have lighting systems to meet safety regulations for aerial navigation. The lighting is specifically designed to avoid endangering wildlife while still marking the turbines at night. Regulations balance the needs of the aviation industry, local communities, and environmental concerns. New technologies are emerging to minimize light pollution from wind farms when possible. Overall, turbine lighting is an important safety measure that follows strict guidelines to reduce excess glare and other negative impacts.

The key points covered include:

• Safety regulations generally require wind turbines over 200 feet tall to have synchronized red lights.
• The lighting systems are designed to avoid attracting birds and bats.
• The color and brightness follow set standards based on turbine height.
• Community concerns about light pollution are weighed against aviation safety.
• New radar and infrared technologies can activate lighting only when needed.
• Best practices call for minimizing overall glare and unnecessary lights.

Wind turbine lighting aims to balance the safety needs for air navigation while minimizing harm to the environment and communities. New technologies continue to improve nighttime turbine visibility and reduce excess lighting.