How Drones are Becoming Today’s Sustainability Superheroes

The drone is set to be one of the superheroes of the global drive towards net zero. Drones can transform logistics networks with their fast, flexible, sustainable delivery capability over the last mile, and in locations with poor existing road and rail infrastructure.

Beyond this direct role, the technological innovations that have given us drones open the door to other key sustainable transportation initiatives, notably Urban Air Mobility.

Drone technology is advancing at a rate that makes it hard to predict what the drone world of 2040 will look like, particularly in the critical area of power. While rechargeable batteries are the de facto drone power source right now, considerations around factors like recyclability, raw materials and power density mean alternatives, mainly hydrogen fuel cell-based power sources, should not be ruled out as a long-term solution.

Factors which are less important now will become critical as the number of drones increases exponentially. One report predicts 16 million drones in European airspace by 2040.

This article considers relative advantages and disadvantages of rechargeable battery versus hydrogen fuel cell power. It highlights how drones’ superhero role depends at least as much on light, strong, safe, sustainable materials as on power sources, and how Henkel are excited and proud to be in the forefront of materials technology both for autonomous logistic-drones and for manned drones in the Urban Air Mobility (UAM) market.

Drone power – Rechargeable Battery versus Hydrogen Fuel Cell

Because Drones and UAM vehicles are relatively small and light compared with larger traditional aircraft, rechargeable battery or hydrogen fuel cell technology are likely to remain the only realistic options for motive power.

In a hydrogen fuel cell powered drone, the fuel cell charges a small battery which delivers the motive power, as the time lag from direct fuel cell power makes it unsuitable for drones. A US Department of Energy article explains this in more detail,

There are some key features of rechargeable battery and hydrogen fuel cell power that could have an increasing impact on the choice of power source as the number of drones increases

• For batteries, the availability and environmental impact of extracting and processing materials such as cobalt and rare earth metals could be a significant consideration. Recycling or using alternative materials can mitigate this.
  
• Battery recyclability is a factor for commercial drones. One source quotes an average drone battery life of 100-200 charge cycles.. Realistically, a high utilization drone requires 600-800 charge cycles from a single battery, otherwise the battery will need to be changed within a week. This raises a question over what happens to the old batteries when they have to be changed? However, drone batteries can retain 80% of power capacity when they are changed, so they could be reused instead of recycled in other, less critical applications.
• For vertical take-off and landing, a superior power density and specific energy needs to be present, which favours the continuous charging capability of a fuel cell-based power source.
• Ground charging infrastructure for rechargeable batteries is much more widely established than for hydrogen fuel cells
• Power for batteries can easily be taken from sustainable sources while ‘green’ hydrogen production is in its infancy and is costly.
• Rechargeable batteries are a more efficient power source in terms of the amount of power lost between production and delivery.

These and other factors are explored in more detail in a recent article from circular materials specialists Umicore.

Both rechargeable battery and fuel cell technologies are fluid and constantly developing, so it would be risky to predict that will dominate in the long term. It is more likely that both will establish their own niche based on the specific requirements of particular use cases, such as range, payload, and operating environment.

Drones’ Superhero Status Depends on Materials as Much as Power

While drones’ role as a sustainability superhero is largely about power, materials and manufacturing methods have a big part to play too.

Being able to build much lighter, stronger and safer drones will have a direct bearing on how efficient new power sources need to be, and how those power sources can be built into drones in ways that make them as safe as possible.

Creating drone manufacturing processes that minimize direct environmental impacts and maximise efficiency and flexibility have a major role to play in the sustainable future for drones.