Achieving Military Advantage for the British Army Through Energy Transition

In his response in late 2023 to the House of Commons Defence Committee Special Report - Defence and Climate Change, the former defence secretary missed the key point that advancing the ‘green’ agenda and improving military capability are not mutually exclusive. Conversely, Defence must pursue environmentally sustainable developments in technology to realise the tactical and strategic advantages, regardless of the contribution toward a net-zero target. Civilian industrial research and development on decarbonised platforms and equipment provides evidence for potential military advantage, from improved strategic resilience and operational sustainment to greater tactical manoeuvrability and survivability. 

The British Army Approach to Battlefield Electrification outlined the planned research and development to 2035 that supported the March 2021 paper on the Ministry of Defence Climate Change and Sustainability Strategic Approach. Both documents underline the requirement for UK Defence to be a ‘fast follower’, specifically ‘of new developments in the commercial sector, making sure it can embrace and install new technologies as early as is practicable’. Since 2021, advances in several technologies relevant to the field including micro-grids, hydrogen fuel cells, alternate fuels for combustion engines and micro-nuclear reactors have enhanced the military use case for such technology. This is not an argument about the potential to conduct carbon-neutral military operations, but rather the incidental benefits that offer significant military advantage.

Conscientious hydrocarbon use for military advantage is not a new concept. A 2014 commentary studying the campaign in Afghanistan encouraged US Marines to consider their use of fuel in an operational context where 52% of casualties were sustained maintaining lines of communication and conducting resupply, and tactical initiatives to generate electricity from solar power were employed at the point of need in patrol bases. If it took around 27 litres of fuel to get one litre of fuel to a patrol base in Southern Afghanistan, as recalled by a former staff officer in Task Force Helmand, then alternatives to avoid the associated operational and strategic risk to vulnerable logistic supply lines needed to be considered.

The Defence and Climate Change Special Report highlights the tactical and operational benefits case for decarbonised military equipment, including the potential to reduce logistical supply solutions and the increased electrification of vehicles to enable silent mobility and surveillance, as well as increased onboard power to serve increasingly complex electrical systems. Reducing tactical emissions by switching to electric from combustion-powered systems offers an obvious advantage in the sensor-saturated modern battlefield. Although electromagnetic emissions still require employment of counter-surveillance mitigation, there is significant reduction in acoustic signature. Those with long memories will recall the FV101 Scorpion, a tracked reconnaissance vehicle brought into service in the 1970s, which was powered by a ‘quiet’ petrol engine that enabled recce by stealth. In a tactical environment in which vehicle acoustic signatures can be detected and identified 10 km away, silent running is again key to survivability.

The amount of electrical power demanded by contemporary platforms and equipment has increased in concert with the exponential development of digital technology. Furthermore, the equipment carried by a frontline soldier such as GPS, situational awareness and communication systems, weapon sights, and electronic counter measures all requires batteries. Latest-generation fully digitised vehicles such as AJAX offer exquisite surveillance capabilities, but the sensors and data processing systems all require electric power. There will be a limit to how long batteries can provide sufficient power before the noisy and hot combustion engine must be started to recharge depleted batteries.

Static locations also present an opportunity for alternative power sources to hydrocarbon generators. Like modern vehicles, the power demands on headquarters have increased in concert with increased sensor arrays, digitised access to information, and digital support tools to aid command and control. Tactical headquarters and their subordinate and logistics nodes routinely provide the recharging point for batteries needed to power everything from dismounted radios to increasingly common unmanned aerial systems.

Being able to recharge without giving away one’s position through acoustic or other signatures has obvious applications at the sub-tactical echelon; consider the reduction in resupply requirements if an observation post or forward defensive position could recharge batteries silently at the point of use. Anticipated benefits from the British Army's TD6 project to analyse the performance of a selection of wheeled vehicles converted to hybrid and full battery electric vehicles (BEV) include improved offroad performance, ease of operation, and reliability compared to diesel-powered equivalents. Fewer moving parts equate to reduced supply chain demand, and reduced noise and vibration are better for crew welfare. Although beyond the scope of this commentary, tactical advantages through technology built for an increasingly electrified world may also be found in the Sea and Air domains. Consider the not-so-innovative technology that gives nuclear-powered naval vessels a proven advantage over fossil fuel-powered equivalents.

Civilian Market Assumptions Should Not Constrain the Military Use Case

There are good reasons for civilian vehicles and infrastructure preferring direct electric power rather than alternatives such as hydrogen fuel cell electric vehicles (FCEV). Direct use of electricity is very energy efficient, and – if renewable power generation is available – relatively easy to operate as net-zero carbon. Where electrical power supply is supported by existing infrastructure in developed economies, mass market consumer preference seems to be for BEVs, for now at least. However, the needs of a civilian market should not be automatically applied to a military use case.

The problem with BEVs in a military context is that a source of electricity through civilian infrastructure is not always available. There is no guaranteed access to domestic or international electricity grids or to high-grade road networks, meaning military vehicles need to make further compensations in design to accommodate heavy batteries in order to extend their range. Although the latter issue can be dealt with, the problem of recharging BEVs and the batteries that power modern battlefield technology is a critical one to overcome.

Case Study: Hydrogen Fuel Cell Vehicles and Generators

A noteworthy omission in both the Defence Committee Special Report and the Army’s Approach to Battlefield Electrification was any reference to hydrogen, either as an alternative fuel for combustion engines or to power fuel cells that broadly offer the same benefits as electric vehicles. Hydrogen FCEVs have the added benefits of self-power generation, allowing greater range and reduced weight due to fewer batteries carried. The smaller battery in an FCEV also equates to significantly smaller amounts of rare earth metals required (as much as an 8–16 times less), thus reducing strategic vulnerability. The benefits, less those related to mobility, can also be applied to hydrogen fuel cell electric generators. To aid visualisation, consider the H2RESCUE, a zero-emission hydrogen FCEV that has a range of around 1,500 miles, or can travel 180 miles and provide 25 KW of power for 72 hours – enough for 15 homes. The disaster relief use case is clear, but such a vehicle could also be used to power a tactical headquarters with a near zero-emission signature.

UK industry has already created solutions that could have dual civilian/military use: The 2024 Isle of Wight music festival was powered by hydrogen generators that could be used to power a Divisional HQ or patrol base; JCB offers hydrogen-powered generators and construction vehicles developed for remote-access construction sites; Jaguar Land Rover Defender and INEOS Grenadier have prototype offroad FCEV variants in addition to BEV options; and Babcock will develop an FCEV version of its General Logistics Vehicle for trials.

Use of hydrogen is an opportunity exceptional to the UK – among few others – because of extant renewable energy infrastructure. The 2024 Autumn Budget announcement of funding for 11 green hydrogen generation projects means that adoption of hydrogen by Defence would be in line with the existing government direction toward net-zero targets, UK sovereign industrial prosperity, and assured power generation. 

Decarbonised Military Technology Must be Considered

If UK Defence is to be the ‘fast follower’ described in the Ministry of Defence’s Climate Change and Sustainability Strategic Approach, the British Army must invest in research and development on emerging technology like micro-grids, electric vehicles, and local renewable power generation to assure resilient networks in a contested or infrastructure-degraded environment. Commercial platforms are available today that could fulfil the power needs of static locations on UK or overseas exercises, ranging in scale to suit headquarters from sub-unit to division. Emerging lessons from research such as the British Army's TD6 that underline the significant advantages of electric tactical vehicles should lead to further development.

The British Army may not have a planned hydrogen-powered main battle tank by 2040 like South Korea, but the need to invest in research on alternatives to hydrocarbon combustion engines for generating electricity to power the vehicles, unmanned aerial and ground systems, sensor and communication systems of the future is clear.

© RUSI, 2025

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