We have all seen the movies – highly sophisticated robots rumble across battlefields, deploying advanced weapons and sweeping all before them. With AI in war having entered the mainstream consciousness decades ago through films like The Terminator that showcased what futurists thought drones and other unmanned vehicles might look and operate like, we are now increasingly in a world where glimmers of that future are now in the present. Of course, we are still a long way away from totally autonomous machines roaming the theatres of war and conducting a business that was once exclusively the domain of humans. In the meantime, there are significant plans being put into place by advanced Western powers, including the UK, to revolutionise the conduct of war through increasing digitisation. However, these plans will be through more iterative steps that are perhaps more of a logistical revolution than an operational one that will throw out all the current doctrinal rulebooks. Indeed, it may be that the most iterative step of all is the weaning off of the reliance on fossil fuels in favour of renewable energy, and in particular the electrification of tactical and combat vehicles.

Self-sufficiency is security

Yet, and unlike the drive for commercial and urban electrification, it is not environmental concerns that are likely to be the primary motivating factor behind this drive. After all, the kinds of munitions deployed by militaries around the world are not only incredibly destructive, but can also be catastrophically toxic, as in the case of Iraq where the US-led coalition was well-known to have used depleted uranium rounds extensively, leading to ongoing environmental and health crises.

Rather, the primary motivation behind this drive for electrification appears to be the reduction of the West’s reliance on fossil fuel producers, many of them having interests divergent from or directly in opposition to Nato and the world order that has been in place since the end of the Cold War. This is particularly true in the Russian example, whereby President Vladimir Putin has repeatedly made moves to punish Western attempts to curtail his ambitions by using his country’s control over vast fossil fuel resources and numerous gas and oil pipelines to dampen supplies and increase prices.

“We have now experienced the effect of a disrupted [energy] supply chain, and budgets have been affected by unstable costs,” says Dr Sarah Ashbridge, research fellow in military science at RUSI. “By moving to self-produced, renewable power sources, we reduce our dependency on a supply chain which can be disrupted to such an extent [as imposed by Russia] and minimise our dependency on adversaries like Russia.”

Energy security is no minor matter and can deeply impact states’ national security. With even oil-producing giants such as Saudi Arabia and the United Arab Emirates – who have themselves been moving into China’s orbit in the wake of Beijing brokering deals between Riyadh and its Iranian foe in Tehran – drifting away from fossil fuels and investing billions in renewable energies, so too must Western powers move away from being reliant on a fuel supply largely dominated by ever-mercurial and increasingly independent powers.

This is a point Ashbridge makes rather succinctly. “Defence can’t have operational security without energy security, especially as we become increasingly digitised,” she says. “We know critical national infrastructure can and will be targeted by an adversary like Russia, so defence has to find ways to operate which can be self-powered where national energy infrastructure is affected – whether in the UK or in the countries we may fight in.”

Running under our own power

So, assuming the UK and its Nato allies can move away from dependency on the likes of Russia, what are their plans for the electrification of typically energy-hungry military vehicles? What would the military applications of such vehicles be, and just how effective could they be in any future conflict? After all, no one wants an environmentally friendly armoured personnel carrier that cannot deliver troops to battle.

To address some of the possible defence applications of electric propulsion, a white paper prepared by Bryan Munce from the British Army’s Armoured Trials and Development Unit in November 2022 laid out how hybrid electric drive (HED) vehicles could change the way the British armed forces conduct wars in the future. In that paper, entitled ‘Electric Propulsion: What are the benefits?’, one of the key advantages identified was the reduced noise signature of such vehicles, allowing mounted units to close in on enemy formations without being detected to maintain the element of surprise.

Similarly, minimising thermal signatures was another area of significant interest, “as thermal optics are no longer the privilege of peer forces”, the white paper explains. In existing vehicles powered by diesel engines, heat signatures from hot engines and exhaust fumes can be seen at great ranges and allow enemies to prepare for an incoming attack or to identify the kind of vehicle that they will have to engage. With electric or even hybrid vehicles, however, the thermal profile could be significantly reduced.

Electric propulsion vehicles also cut a more svelte figure, allowing for up to a 20% reduction in size and weight as compared with their internal combustion engine counterparts. This has a direct military advantage, as there is not only less load, but it also means that the physical size of these vehicles can be reduced. Crucially, this means that more of these vehicles can be transported into theatres on air or sea frames – as the white paper identifies, this could potentially mean that some airframes could double their capacity of combat and tactical vehicles.

The value of Dstl defence sector contracts, including for electrification, as of May 2022.

A work in progress

While the aim is for full electrification, the current steps appear to be more along what is already commercially available in the civilian sphere, and that is to study how HED vehicles can conceivably work in a military setting. In that vein, the UK Ministry of Defence’s Defence Science and Technology Laboratory (Dstl) has been working with industry partners on the Technology Demonstrator 6 (TD6) project for the development of HED vehicles.

The maximum percentage of fuel savings demonstrated in TD6 trials.

So far, research involving TD6 have indicated that HED vehicles can increase fuel efficiency by up to 20%, improve automotive performance, better manage thermal and sound signatures, and can even act as portable power generators themselves, allowing vehicles to feed one another and other devices.

The cost per gallon of fuel used by US forces in Afghanistan.
US Congress Appropriations Defense Subcommittee

Dstl is keen to stress that, currently, no nation has a HED military vehicle in service. This demonstrates that, despite more money being poured into the research and development of HED vehicles, the concept is still very much in its infancy and this is the case globally due to a number of logistical constraints that need to be addressed by smart technological solutions that simply do not currently exist. This has an impact on the logistical burden faced by armed forces, with a Pentagon report to the US Congress indicating that each gallon of fuel transported to Afghanistan cost an eye-watering $400 – clearly making the case for a more advanced electric propulsion solution.

There are a multitude of ways that this could look like on the modern battlefield, but each of those requires logistical solutions. “Realistically, I expect there will be a mix of hybrids and full electrics,” Ashbridge explains. “We can’t depend on full-electric realistically until we have concrete plans for deployable infrastructure – which is something that [UK] defence is working on.

“Of course, deployable infrastructure suitable for EV charging to support these hybrid or fully electric vehicles must still be transported into theatre, so there is a logistical burden, but this burden is offset by the reduction in current pressure upon the logistics supply chain to maintain a supply of conventional fuels at the scale currently required. These benefits will be felt for the duration of a campaign or operation.”

Clearly, though, not all battlefields are created equal. However much the military brass may try to hardwire contingencies into their plans, it can often be impossible for even the most high-tech deployable energy infrastructure solution to be used. “In certain environments, domestic electric infrastructure may not be accessible, and deployable infrastructure may not be appropriate. Here defence will defer to conventional fuels,” Ashbridge says, adding that, “Defence has the task of finding solutions for deployable infrastructure whilst also making decisions about which platforms will continue to be powered by conventional fuels as a means of minimising any risks to operability until that solution is found.”

Given that most military platforms are developed with an eye to them being in service for extended periods of time and not updated every single year like commercial vehicles, it is clear that the shift from conventional fuels to HED or fully electric vehicles will be a long work in progress. However, with all the benefits of electrification in the military domain in terms of maintaining more agile, leaner forces that are not dependent on fuels controlled by adversaries, it is becoming increasingly clear that there is little choice in the matter.