NTT Lightning Drones: Triggering Storms To Protect People

The Cost of Waiting for Lightning

Lightning kills approximately 24,000 people annually worldwide and injures 240,000 more. It destroys power lines, damages electrical systems, and causes communication failures that cascade through entire regions. In Japan alone, annual lightning damage costs between 100 and 200 billion yen. Traditional approaches relied on lightning rods installed on buildings and infrastructure. But lightning rods protect only limited areas. Many critical facilities like wind turbines, outdoor venues, and communication towers spanning wide areas cannot practically rely on this outdated technology. What if instead of waiting for lightning to strike unpredictably, we could trigger it safely and guide it away from people? On December 13, 2024, NTT achieved this for the first time in the world.

How NTT's Lightning Drones Work

The system combines two breakthrough technologies. The first is a lightning protection cage made of conductive metal. When lightning strikes the drone, the cage acts as a shield, redirecting electrical current away from the drone's internal components. Rather than allowing current to flow through the drone itself, the cage distributes the lightning current radially outward, canceling the strong magnetic fields generated by the strike and minimizing electromagnetic interference. In testing, drones equipped with this cage withstood artificial lightning strikes of up to 150,000 amperes. This is five times greater than the average natural lightning strike. This means the system works effectively in approximately 98 percent of naturally occurring lightning conditions.

The second technology is an electric field-based triggering system. A conductive wire connects the drone to the ground, with a high-voltage switch installed at ground level. By operating this switch at precisely the right moment, NTT creates a rapid change in the electric field around the drone. This change in field strength draws lightning toward the drone, triggering a strike deliberately rather than leaving it to chance.

The World's First Demonstration

NTT tested this technology in the mountains of Hamada City in Shimane Prefecture, Japan, at an elevation of 900 meters. Scientists used a field mill, an instrument that monitors electric field strength at ground level, to detect when conditions were favorable for lightning. As a thundercloud approached and the electric field strengthened, they launched a drone equipped with a protective cage and conductive wire.

On December 13, 2024, they flew the drone toward a thundercloud at 300 meters altitude and activated the high-voltage switch on the conductive wire. This created an electrical connection to the ground. Immediately, more than 2,000 volts flowed through the wire, accompanied by a significant change in the surrounding electric field. This sudden increase in local field strength triggered a lightning strike directly at the drone. This was a world first.

The strike produced an audible crack, a visible flash, and minor melting of the protective cage. Yet the drone continued flying stably. NTT had proven that the triggering method worked and the protection technology protected the aircraft. Lightning could be deliberately triggered and safely guided.

From Protection to Energy

The immediate application is protecting communities and critical infrastructure. Power companies, telecommunications operators, and government agencies could eventually deploy these drones to absorb lightning energy from thunderclouds before it ever reaches the ground. This would prevent power outages, protect communication networks, and reduce the risk to people in outdoor environments.

But NTT is thinking further ahead. Lightning contains enormous energy. The team is developing technology to capture and store this lightning energy for eventual use as a renewable energy source. Imagine if the massive amounts of electrical energy released by thunderstorms could be harvested, stored, and distributed to communities. The same drones that protect people from lightning could simultaneously gather clean energy.

Research continues on high-precision lightning location prediction and a deeper understanding of lightning mechanisms. This includes the physics and processes behind how lightning forms. Future drones will be even more capable of positioning themselves where lightning will strike with maximum benefit.