Japan’s telecommunications company, NTT, has announced the development of drones that can use changes in electric field strength to induce and guide lightning strikes, thus reducing damage to buildings and people, and ultimately enhancing public safety. These drones are equipped with Faraday cages to prevent losses from lightning strikes.
According to a press release issued by NTT on April 18, lightning strikes are one of the most destructive natural phenomena affecting human society. In Japan alone, the annual losses due to lightning strikes are estimated to be as high as 100 billion to 200 billion Japanese yen (700 million to 1.4 billion U.S. dollars).
Despite implementing various lightning protection measures for critical infrastructure, including telecommunications facilities, damage related to lightning strikes continues to occur. Therefore, drawing on their long-standing expertise, NTT is currently dedicated to developing drone technology aimed at eliminating losses from lightning strikes on infrastructure and urban areas.
Traditionally, lightning protection has heavily relied on lightning rods, which have limited protection range and may be impractical in certain situations, such as outdoor activities. The new method developed by the company utilizing rapidly advancing drone technology allows drones to fly to optimal positions beneath thunderclouds with higher electric field intensity, actively inducing lightning and channeling the current away from vulnerable areas.
From December 2024 to January 2025, NTT conducted drone-induced lightning experiments at an altitude of 900 meters in the mountainous area of Hamada City, Shimane Prefecture. Researchers used a device called a field mill to monitor the electric field on the ground. When the electric field intensity increased as thunderclouds approached, researchers deployed a custom-built Faraday-caged drone in an attempt to induce lightning.
On December 13, 2024, as thunderclouds neared, the field mill detected an increase in ground electric field intensity. Subsequently, a drone equipped with a conducting wire flew to 300 meters altitude, and by activating a switch on the ground, conducted electricity through the wire. Researchers observed a significant amount of current flowing through the wire and noticed a marked change in the surrounding electric field intensity.
Prior to the lightning strike, researchers confirmed a potential difference of over 2,000 volts between the wire and the ground. The rapid increase in local electric field intensity resulted in the lightning strike on the drone, making this the world’s first successful case of inducing lightning with a drone.
At the moment of lightning generation, researchers heard a loud burst and saw a flash, causing partial melting of the drone’s Faraday cage. However, the drone remained stable and continued flying after this lightning strike.
NTT stresses that merely flying drones under thunderclouds is insufficient to attract lightning. To successfully induce lightning with drones, they must possess active triggering technology and maintain operation after being struck by lightning. This is due to the two key technologies of the Faraday cage and the current-guiding wire apparatus.
Researchers conducted artificial lightning tests on drones equipped with Faraday cages, showing that the system can withstand up to 150 kiloamperes (kA) of artificial lightning – five times higher than the average current in natural lightning strikes – without affecting the drone’s core functions, effectively handling over 98% of natural lightning strike scenarios.
In order to increase the success rate of inducing lightning with drones, NTT will continue research and development in two key areas: high-precision lightning position prediction and a deeper understanding of lightning mechanisms.
Furthermore, their objective extends beyond inducing and guiding lightning to harnessing its energy. Future efforts will concentrate on developing technologies to capture and store lightning energy for subsequent applications.