New U.S. Solar Hydrogen Generator Powers Long-Endurance Drones

A new trailer unit developed by Sesame Solar produces hydrogen fuel where it is needed, shrinking the supply chain to nothing and enabling refueling of long-endurance drones at the front line.

The Surveillance and Drone Refueling Nanogrid Solution includes a solar-powered hydrogen generator, two Heven AeroTech Z1 drones, satellite communications, edge computing and radar. This mobile self-supporting drone system can provide 24/7 aerial coverage for extended periods.

“Continuous drone surveillance is important, and hydrogen is the best way to do it,” says Lauren Flanagan, CEO and Co-Founder of Sesame Solar.

The Hydrogen Advantage

A hydrogen fuel cell effectively burns hydrogen to create water and electricity. The technology was invented back in 1839 by Sir William Grove and packs in more energy per ounce than any battery. But while batteries can be recharged, a fuel cell needs to be refueled with hydrogen. So while hydrogen fuel cells look ideal for small drones, resupply has left the idea on the ground.

“These drones, with an endurance of four or five times as much as battery-powered drones, have been around a while but the hydrogen fuel chain has been the primary roadblock,” says Flanagan.

For example Lockheed Martin’s original battery-powered 2006 Stalker drone had flight time of 2 hours. In 2013 the company launched the Stalker XE version with a fuel cell which flies for 8 hours or more. The drone has reportedly patrolled the U.S. Southern border, an environment where laboratory-grade gas can easily be purchased and shipped. But it has had less traction in expeditionary settings, where soldiers put up with the shorter flight time of batteries in exchange for not having to cope with the logistics challenge of pressurized hydrogen.

Sesame Solar’s Nanogrid solves the supply problem by producing hydrogen on the spot, literally out of thin air, and storing it in convenient form to easily recharge fuel cells.

1920s Technology Meets Modern Storage

The first stage of the process requires water, which the Nanogrid produces with an atmospheric water generator, sucking moisture out of the air. The water is then split using electricity from solar cells, yielding oxygen and hydrogen. This is not a new way of making fuel; JBS Haldane proposed a similar scheme in 1923. The clever part is how the hydrogen is stored.

Hydrogen is notoriously dangerous, as seen when the airship Hindenburg turned into a giant fireball as the hydrogen-filled envelope ignited. Liquid hydrogen occupies less space than gas but is also hazardous. Solid metal hydrides offer a safer option.

The Nanogrid hydrogen storage units are essentially metal sponges. When exposed to hydrogen under pressure, the metal surface absorbs hydrogen, creating metal hydride. This can be kept for as long as needed, at relatively low pressure.

“It’s safely stored at less pressure than a spray paint can,” says Flanagan

The solid hydride yields hydrogen gas to recharge fuel cells simply by changing the pressure. But while in solid state it does not present the risks and challenges associated with hydrogen gas or liquid.

“The stored metal hydride is non-combustible,” says Flanagan. “It’s not going to explode like the Hindenburg.”

Sesame Solar recently acquired the solid-state storage technology, having previously been a customer, and have integrated it efficiently into their hydrogen systems. The solar-powered Nanogrid effectively provides an endless source of hydrogen. It is more than enough to keep two drones refueled, so they can maintain a permanent aerial presence with at least one drone always in the air.

Flanagan says their official claim is that the system can operate in the field for at least six months, but the reality may be significantly longer. Future systems will run for years. Nanogrids are suitable for extremely cold climates where systems struggle.

Drone Base Station

The Nanogrid is built into a trailer and can be deployed rapidly in the field, taking less than fifteen minutes go from the road to fully operational. Sesame see it is much more than a refueling station, equipping it with communications, computing and other facilities in the same unit.

The Surveillance and Drone Refueling Nanogrid Solution comes with two Heven Z1 drones. These take off vertically, and have a flight endurance of at least ten hours. The Nanogrid generates enough hydrogen to keep at least one drone in the air at all times. The Z1 carries a 10-pound payload, enough for a variety of sensors, and has a takeoff weight of 55 pounds.

The concept resembles previous Drone Hive solutions for deploying numerous drones from a trailer, the big difference between that the Sesame system also provides refueling for months on end. At present the Nanogrid still requires human involvement for the refueling process, but as others have shown, this could be automated in future iterations.

Flanagan says they are already talking to potential customers and partners interested in the system’s potential to fuel not just aerial drones but also ground robots. These are limited by the short lifetimes provided by batteries, and fuel cells would greatly increase their scope of operations. It also does not take a great leap of imagination to see the potential for hydrogen-powered FPVs with ranges several times greater than the 12 miles or so of battery-driven models.

The Future of Expeditionary Energy

Expeditionary power supply is a growing issue with increasing numbers of uncrewed vehicles and other units deployed to remote areas. The traditional solution of generators supplied by a fuel logistics chain, sometimes involving flying barrels of diesel to forward bases in helicopters for $400 a gallon. Proposed solutions include such off-the-wall projects as miniature nuclear reactors for U.S. military bases.

We have already seen improvised solar power solutions for drones in Ukraine, but the Nanogrid is on another level. The Nanogrid offers a supply of fuel with high energy density as close to the front line as needed, in a form well suited to small drones. Flanagan says the Nanogrid is available now, and production can be scaled up rapidly as needed to meet demand.

Switching to hydrogen will not make sense for all drones, but the technology opens up a lot of new possibilities when the fuel can be so easily available.

“By removing reliance on fuel supply chains, we’re making military operations more efficient,” says Flanagan.