The push for net zero is fundamentally reshaping government agendas and many of our key industrial sectors. And that includes the world of defence, where energy sustainability is becoming an increasingly important focus both in terms of minimising the sector’s impact on the environment and ensuring that it is resilient to current and future threats.
Earlier this year, in partnership with defence giant BAE Systems, The Engineer brought together leading voices from across industry to explore the importance of carbon reduction to the defence sector and examine some of the innovations that are helping it rise to this challenge.
The following report examines some of the key topics explored during this discussion, which was live-streamed to a registered audience.
Meet the panel
Cathy Davis- Head of Strategy, Sustainability, Simulation & Synthetics, BAE Systems
Lieutenant General (Retd) Richard Nugee CB, CVO, CBE - Defence Non-Executive Director for Climate Change
Paul McNamara - Technical Director, Williams Advanced Engineering
Steve Austen- Engineering Director, SC Group & Supacat
Dave Smith - Director of Technology, Rolls Royce
Why sustainability matters to defence
Opening the session, Lieutenant General (Retd) Richard Nugee put forward a compelling case for why the defence sector must embrace “the green energy revolution”.
Nugee - who has been key to shaping the MOD’s strategy on climate change - told delegates that the adoption of green technologies will lead to significant improvements in military capability.
The ability to produce our own energy and adopt energy that’s not reliant on imports will - he said – insulate our armed forces from the volatility of global energy markets and also help overcome some of the logistical challenges presented by getting fuel to bases or conflict zones overseas. Taking Adghanistan as an example Nugee said. “It costs in the region of £250 a gallon to get diesel to Helmand, and it costs in lives in terms of the logistics resupply - the most senior British officer killed in Afghanistan was killed on a logistics resupply patrol.” The deployment of solar generators in Helmand would, he said, have vastly reduced the logistical and human costs of the operation.
The push for energy sustainability also creates the opportunity to significantly improve the performance of equipment, he added.
One example is the MOD’s ongoing evaluation of a hybrid version of the Jackal high-mobility weapons platform which, he said, could have some compelling operational advantages over a conventionally powered vehicle. “You can sneak around the battlefield without emissions from the engine, without heat emissions and without noise emissions, it is just a better way of getting about the battlefield.”
Whilst the push for net zero creates opportunities to introduce a host of new technologies – from lightweight, stealthy unmanned tanks and aircraft through to new ways of independently generating power on the battlefield - another key challenge for the defence sector will be finding ways to improve existing platforms, many of which will be in service for decades to come.
Here, said Nugee, the development of sustainable fuels will be critical. “I’m not a great fan of retrofitting….we’re not going to change the engines on the aircraft carrier - it’s due to last at least 40 years - so what we must do is look at new fuels and ways of capturing the carbon that comes off them without changing the engines.”
We’re not going to sacrifice our capability for just being green, because if you come second in a war but you’re the greenest military you’ve still come second in the war
Lieutenant General (Retd) Richard Nugee
There are clearly some key challenges ahead, but with the energy revolution in the wider world gathering pace doing nothing is not an option, he said. “If we don’t move with this we will be left behind. If we insist on diesel engines in 2050, the net result will be that we will get either antiquated equipment or we’ll get 2050 technology but it will be bespoke and unbelievably expensive. Neither of these are good for our military capability.”
To meet these challenges, he said, the sector must work with other areas of industry, and become what he terms “a fast follower”. “As soon as industry has come up with a solution that fits then we should jump on that and scale it as fast as possible.” There are already positive signs that the sector has the appetite for the change that’s required, he said. “I have been both surprised and delighted by industry’s embracing of this in the defence sector”.
Nugee wrapped up by returning to his opening theme, stressing that the aims of military effectiveness and energy sustainability are complementary and not – as one viewer suggested - mutually exclusive. “Let’s be in no doubt, we’re not going to sacrifice our capability for just being green, because if you come second in a war but you’re the greenest military you’ve still come second in the war. That doesn’t work for us. We’ve got to do it in tandem of being as effective and efficient as we can be and being as emission reduced as we possibly can be. But we still need to be able to win the war.”
An industry view
After Nugee’s stirring introduction, it was time to hear how the UK’s biggest defence company, BAE Systems, is responding to the net zero challenge.
Cathy Davis, who heads up BAE’s sustainability strategy, explained that energy sustainability is vitally important to the company, which earlier this year confirmed a target to achieve net zero greenhouse gas emissions across its operations by 2030
She explained that a major area of focus has been improving the sustainability profile of many of its key UK sites.
For instance in Samlesbury - home to manufacturing operations for the Eurofighter Typhoon, and the F-35 Lightning II - the old runway has been repurposed as a solar farm which provides a fifth of the site’s peak electric consumption, and has so far saved £300,000 in energy costs. Another key site operated by BAE, the Portsmouth naval base, has used a range of measures including solar energy, heat containment, battery energy storage, and a switch to onsite electric vehicles to drive a 65 percent reduction in carbon emissions.
Alongside the sites and facilities, the challenges posed by climate change are also having a profound impact on both current and future products added Davis. “Climate change will continue to affect temperatures and create extreme weather conditions, and for us it’s important to understand these challenges so that we can design systems fit for operation in these future environments.”
Activities here fall under three broad areas beginning with electrification where – she said - the company is particularly keen to tap into some of the breakthroughs being made in other sectors. A case in point is BAE’s collaboration with Williams Advanced Engineering on the potential combat aircraft applications of battery management technologies originally developed for motorsport.
This is an area that needs collaboration across the defence community and wider industry
Cathy Davis - BAE Systems
Another key area of BAE’s electrification work is around energy optimisation where, for instance, the company has been collaborating with engineers at Oxfordshire aerospace firm Reaction Engines on novel heat exchangers for next generation aircraft. This technology could, said Davis, potentially be used to recycle excess engine heat for powering integrated high energy weapons or computing systems.
Other areas of focus include an emphasis on improving design and manufacturing processes by, for example, exploiting the use of additive manufacturing techniques to produce lightweight parts and, lastly, a concerted effort to reduce the use of fossil fuels, whether it’s through the adoption of virtual training techniques that negate a requirement for fuelled training platforms or the use of new sustainable synthetic fuels.
The integration of new fuel types will, she said, be particularly challenging, and significant levels of R&D will be required to both meet demand and bring down the costs (sustainable fuels are between 3 and 14 times more expensive than diesel. “This is an area that needs collaboration across the defence community and wider industry…if we are to transition to net zero for large platforms,” she said.
From race-track to the battlefield
With both Nugee and Davis stressing the need for collaboration with non-defence companies, our next speaker - Technical Director of Williams Advanced Engineering (WAE) Paul McNamara – discussed how some of the lessons learned in motorsport - particularly with regard to electrification - can be applied to challenges in defence.
Electrification is a key area of expertise for WAE, which has been heavily involved in the development of batteries and powertrains for electric racing competitions including F1’s electric cousin FormulaE, and the ExtremE off-road racing series. Its experiences in these competitions, which regularly push electric systems to their limits, have – said McNamara – delivered defence-relevant solutions to some of the key challenges presented by electrification: particularly around ruggedisation, refueling, and – critically - engineering new products around electric powertrains. “What motorsport is trying to do with lightweight electrification has a lot of overlap into defence,” he said.
You have to look at the engineering of the entire product – how to you configure the whole system
Paul McNamara - Williams Advanced Engineering
When considering the challenge of developing an electric vehicle, the key issue is energy density. Batteries – said McNamara - are much heavier than the equivalent bit of diesel. “Kilogram for kilogram diesel is storing about 50 x as much energy. When you to take account of the fact the engines etc. are pretty heavy and not terribly efficient you still end up with a factor of around 20. You have to look at the engineering of the entire product – how to you configure the whole system.” WAE’s understanding in this area is – he said – already feeding into the defence sector.
In terms of ruggedisation, the ExtremeE competition (where vehicles are pushed to the limit in extremely rough terrain) is also generating useful knowledge. “That is a key area of collaboration between us and defence,” said McNamara.
He added that motorsport is also helping to drive forward the practical understanding of how to optimise batteries for different cycles. This is another key challenge for the defence sector, where different types of vehicle require different amounts of power at different points. Here, he said, advances in hybridisation of batteries - where the battery itself has multiple different chemistries tuned for particular parts of the cycle - could prove particularly attractive to defence.
Finally, McNamara turned to the work that WAE has been doing on refueling and explained that the introduction of pitstop refueling for electric racing cars is driving development in rapid battery charging that will have significant military relevance.
Electrifying land vehicles
Picking up the electrification baton, and expandong on some of the benefits discussed by other panelists our next presenter, Supacat engineering director Steve Austen, took a deep dive into the challenges and benefits of electrifying military land vehicles.
Supacat - a major supplier of high mobility defence vehicles, is now at the forefront of efforts to electrify this aspect of defence, and Austen began by identifying some of the key attractions of electric land vehicles. “It’s the capability to reduce your signature,” he said, “whether that’s through quiet or silent running, a lower thermal signature, or the ability to go on silent watch [i.e. operate in-the-field communication and nav equipment without having to turn your IC engine on]. We’ve also found through the vehicles we’ve developed that the use of electric motors gives you a great increase in controllable torque at low RPM. Suddenly your mobility at low-speed increases.”
As the commercial sector embraces electrification …the ability to support traditional IC engines and components is going to get harder for defence customers
Steve Austen - Supacat
Alongside these performance benefits, another key driver for the adoption of electric vehicles identified by Austen is the supportability of existing platforms, which will become trickier as the rest of the world moves on. “As the commercial sector embraces electrification …the ability to support traditional IC engines and components is going to get harder for defence customers,” he said.
However, despite the advantages, there are also some big challenges: electric vehicles bring with them infrastructure requirements around charging and maintenance; low torque high RPM motors present some significant cooling challenges; and there are also important safety considerations around the use of HV electrical systems on the battlefield. “There’s a lot of work to do to ensure that your electrical components can continue to operate reliably in theatre,” said Austen.
Until recently, there have been relatively few electric vehicles to trial so that these issues can be properly explored, but as Austen explained Supacat is now at the heart of efforts to explore the practicalities of the technology, through its development of a prototype hybrid electric variant of the Jackal HMT which is now being evaluated by the MOD at the Millbrook proving ground in Bedfordshire.
Looking further into the future, Austen said that given the rapid advances in different methods of energy storage it will be important to be power agnostic when thinking about electrification. “If we can make it so that the driveline and overall vehicle remains the same then we can take advantages of improvements in power sources as they come along and avoid the risk of built-in obsolescence.”
Civil aviation’s low carbon push
Our final presenter, Rolls-Royce’s director of central technology Dave Smith turned his attention to aviation, and looked at how the trends and technologies shaping the civil aviation sector might affect the world of defence.
The civil aviation sector’s rapid drive to net zero, and the development and deployment of new technologies, presents both risk and opportunity for the defence sector, said smith.
It’s a risk - he said - because the design and manufacture capability for engines is going to diminish as the civil word adapts and fuel availability is inevitably going to change. “We won’t be using kerosene in the future as we do today in civil aviation in 2050, so the current fuel we have designed platforms around will not be available and that is going to be a challenge to military combat operations.”
You can either choose to be an early adopter or you can go very late, but one thing you can’t do is ignore it
Dave Smith - Rolls-Royce plc
However, if the defence sector can tap into the advances being made in the civil sector, the prize in terms of operational improvements could be huge, he said.
Echoing fellow panellist Richard Nugee, Smith said ignoring these developments is simply not an option. “The world’s energy needs will be met by civil energy suppliers using new forms of energy, engine and fuel. You can either choose to be an early adopter or you can go very late, but one thing you can’t do is ignore it, because it’s going to happen. And you need to work with suppliers of that new technology because you want to influence and understand their roadmaps and understand all of the different energy sources that will shape the future.”
Smith said that many of the different technologies coming through – from lightweight fully electric vertical take off and landing (VTOL) vehicles, through to hydrogen fuel cell powered aircraft – could have a useful role to play in the military airspace, but the most significant area of development will, he argued, be the use of sustainable aviation fuel (SAF), a clean substitute for current jet fuel that can be produced from sustainable resources.
“This is technically better than kerosene,” he said. “It has slightly more energy per kg per litre; it has better thermal properties, it is a better fuel.”
There are also, he added, multiple different pathways to producing it. “You can make it from crop residue, or from municipal waste and you can make it from green electricity. We think nuclear is a very good route to doing that and we’re looking at microreactors and SMRs and integrating them into a fuel production plant to produce this net zero sustainable fuel. It’s potentially a means of having self-sufficiency for operations wherever they are.”
SAF is currently expensive, but as the industry gears up towards producing the volumes that will be required by the civil aviation sector (500 million tonnes by 2050 according to Smith) prices will come down, and this monumental scale-up is already underway. “Available SAF in Europe will be ten times more in 2024 than it is today,” said Smith.
“The green energy transition is not a threat to defence,” concluded Smith, “it’s overwhelmingly an opportunity. But we do have to respond and understand it and work with people we probably haven’t worked with before to make sure we get the get the full potential of this massive civilian investment in technology. ”