Green Solutions for Defence: Current International Activities and Potential Technology Options

By Magnus Clausen

Green Solutions for Defence: Current International Activities and Potential Technology Options

In recent years, many states have developed and implemented green solutions for defense. Yet the military is currently engaged in an extensive undertaking to improve its sustainable energy use by reducing demand and developing renewables in its multiple roles as a war fighter, a landlord, a first user of precommercial technologies, and a potential high-demand consumer. The military is undertaking such actions not only in response to parliamentary directives and executive orders, but also voluntarily in response to its internal battlefield and national security needs.

Building on these initiatives NATO formulated the NATO Green Defence Framework in 2014. The framework provides a basis for increased knowledge-sharing and research coordination, which can support the development of cheaper and more effective green solutions for defense—solutions capable of addressing a number of contemporary and emerging security challenges, in particular energy security, global climate change, defense spending, and the logistical challenge of getting energy to the battlefield.

One aspect of the debate on climate change and the military has been that it has directed a spotlight on armed forces as a major producer of greenhouse gases. While there are no reliable estimates of the global greenhouse gas production by militaries, it is likely that their shares in global greenhouse gas production are similar or higher than the shares of military expenditures in global income because of energy intensive activities such as transport and flying. By far, the largest consumer of energy and producer of greenhouse gases in the world is the US military. Its size, global spread and military action in places distant from most major installations, such as Afghanistan during the military intervention there, make the Pentagon’s agency in charge of supplying the largest single customer of energy in the world with energy, buying more than USD 17 billion worth of energy in financial year 2011. By their own account, the US armed forces have seriously begun to take energy considerations into account for the full spectrum of their activities. They have defined energy-saving goals and objectives in operations, including combat operations, as well as acquisitions. One of the objectives is the increased use of alternative energy. Substantial amounts of money have been invested in solar and wind energy on military bases, as well as the adaptation of systems, such as aircrafts and warships, to use biofuels.

Contemporary war-fighting platforms on land, sea and air are continually evolving, becoming more agile and deadly. But despite their increasing performance, one factor remains unchanged, that of a near-total dependency on oil. Oil, processed into a range of refined liquid hydrocarbon fuels, is the primary source of mobility energy for almost every combat and utility platform in any modern military force. As a consequence of this dependence, military organisations are frequently burdened by increased operational and training costs during peacetime, while the requirement for copious quantities of fuel to sustain military operations on the battlefield creates significant logistical issues which degrade performance.

Technological solutions—in the form of alternative energy and propulsion options—are emerging but a number of challenges will need to be addressed before such technologies can be fully exploited. These challenges range from the technical—such as the immaturity of emerging technologies and their unproven operational performance—to psychological barriers preventing military leadership from effecting change to established oil-based infrastructures.

Land combat platforms

Land combat platforms are required to have high mobility to operate in difficult terrain with superior high-speed characteristics. At the same time, high reliability, crew protection and offensive capabilities are also fundamental requirements of all platforms used in combat, increasing weight and incurring further energy penalties. It is, therefore, not surprising that these conflicting requirements are difficult to satisfy in practice and the result is that military combat platforms are often very fuel-inefficient. The greatest challenge, therefore, is for land platform designers to reduce fuel consumption without sacrificing firepower, performance and protection.

Today’s platforms are a complex “system of systems” which feature advanced offensive and defensive subsystems, enhanced electronic and communications equipment all working in synergy to support the warfighter.

DARPA’s Ground X-Vehicle Technology (GXV-T) with electric hub drive is improving the survivability of ground-based armored fighting vehicles by increasing vehicle agility.

First, weight reduction is the most basic way to increase fuel efficiency for land platforms. The greatest potential savings in platform weight can be achieved through the use of modern materials and design, such as employing lightweight, high-strength material as carbonreinforced composites and space-frame construction principles. Second, alternative propulsion technologies may present some viable options. The Hybrid Electric Vehicle (HEV) concept has demonstrated great potential for reducing oil dependency on the battlefield. While hybrid propulsion systems promise significant improvements in operational fuel economy, they also provide a ready source of electrical power for the increasingly wide range of sensors and next-generation armaments. At the same time, they offer other tactical benefits, such as reduced signatures, stealth, greater vehicle design flexibility, and even enhanced diagnostics and prognostics

At some juncture in the future, military organisations will have to consider the strategic and economic viability of legacy vehicles and systems that are reliant on oil at a time when new propulsion systems may mature sufficiently to have military utility, and alternative sources of energy may become more cost effective and environmentally acceptable.

This consideration will have significant implications for military organisations, although some platforms and systems will continue to remain oil dependent owing to their highly specialised and demanding circumstances, and may have to be specifically designated as prioritised oil users until technology allows a practical alternative. Thus, in the near future, energy transformation may be evolutionary rather than revolutionary due to the legacy of, and investment sunk in, current and longestablished methods of oil-based energy conversion, as well as the remaining, accessible oil stocks that are yet to be claimed from underground.

Naval platforms

Contemporary naval surface vessels are commonly powered by a combination of diesel and gas turbine engines, because such systems offer excellent fuel economy at low to medium speeds and offer tremendous power in a compact and light package. However, because contemporary ship designs utilise propulsion systems that are directly coupled to the prime mover, up to 90 per cent of a typical naval platform’s available power is locked into its propulsion system. The present arrangement limits the power available for other functions of the ship, such as weapon, sensor and auxiliary support systems and thus requires additional generators which reduce platform design flexibility, adds complexity and limits future upgradability.

Although fuel supply is generally less of a problem for naval vessels than for land or air platforms, naval platforms can nevertheless increase their war-fighting capabilities through reduced and more efficient use of fuel. For example, reducing energy use in naval platforms can reduce fuel costs and increase cruising range. Increasing cruising range can improve operational flexibility by increasing the time between refuelling and the distance that the ship can operate away from its next refuelling point

Furthermore, this has also the potential to reduce hot exhaust emissions and thus reduce its infrared signature. First, hull design improvements on platforms can lead to substantial fuel savings and are easily retrofitted onto existing platforms. Second, alternative propulsion options are available for naval surface platforms in the form of hybrid-electric drive systems. Compared to the traditional mechanical-drive propulsion system with two separate sets of turbines—one for propulsion, the other for generating electricity to power the weapon, sensor and auxiliary systems— on most current surface vessels, an integrated electric-drive propulsion system can reduce fuel consumption by operating the single combined set of turbines to be run more often at their most fuel-efficient settings. The hybrid-electric concept is similar to equivalent systems for land platforms, where the primary engine generates electrical power for vehicle subsystems and electric motors that provide locomotion.

A quiet electric propulsion system will allow Type 26 frigates to hunt submarines more effectively without being detected.

Type 26 frigates will use the electric motors for patrolling and cruising at lower speeds.

Royal Navy Type 26 Global Combat Ships use advanced electric propulsion motors and drive systems.

In addition, electric drive systems enable the use of innovative propeller configurations that can reduce ship fuel consumption due to their improved hydrodynamic efficiency. Alternative energy sources based on hydrogen fuel cell systems are another option for reducing oil dependency for surface platforms. Other potential advantages of fuel cell technology include reduced maintenance costs, greater stealth through reduced emissions and acoustic signature, and finally, greater ship design flexibility.

Air combat platforms

Contemporary military air combat platforms are designed to maximise performance through the combination of jet turbine propulsion which generate high thrust ratings, and aerodynamically optimised, lightweight airframe designs. However, the penalty associated with the emphasis on performance is great fuel consumption. As a result, propulsion systems and fuel payload typically account for 40 per cent to 60 per cent of gross takeoff weight of the aircraft itself, and the performance of the propulsion system has an enormous effect on flying performance.

Unlike land and naval platforms, alternative propulsion technologies directly applicable to air combat platforms are non-existent today, chiefly due to the fact that the jet turbine engine, which powers many of today’s air combat platforms, remains vastly superior to other forms of propulsion systems in all performance characteristics. Despite the unavailability of alternative propulsion options for air combat platforms, there are still a number of technological options that may assist in reducing oil dependency.

First, air platform design efficiencies appear to provide the most fundamental step to achieving improved fuel-economy. Second, jet turbine design improvements can potentially reduce fuel consumption while providing superior performance characteristics. Third, alternative fuels are being investigated, and have already been tested on a number of front-line combat platforms. Finally, unmanned air platform systems offer the potential to drastically reduce oil dependency as a result of their pilotless designs. This section explores some of these options. For military aircraft, design efficiency appears to be the most promising method to reduce oil dependence for air forces. Air platform design efficiencies can be pursued in the areas of structural design and configurations, as well as weight reduction. Advances in materials and design processes will enable the design of stronger, lighter aircraft with simpler, unified structures that are easier to manufacture.

XV-24A LitheningStrike developed within DARPA’s Vertical Take-Off and Landing Experimental Aircraft (VTOL X-Plane) program.

Composite materials, in particular, will allow bonded joints and reinforcement technologies for complex loads. Lighter weight structures based on advanced materials and computer-aided designs enable significant fuel savings without compromising performance or structural integrity. Such fuel savings extend to a number of air force platforms such as combat, transport and tanker aircraft, and potentially even helicopters. Platform configurations can be modified to reduce aerodynamic drag from skin friction.

Soldier Systems

The modern soldier is equipped with advanced technology devices designed to increase safety and enhance his combat ability. However, this inevitably increases the demand for more power and energy. A Third Generation urban warrior is expected to need more than 30 watts to power his devices. To sustain this equipment in continuous autonomous team operations, heavier and more advanced batteries are needed. The additional energy required, which is typically supplied by batteries, adds weight to the soldier and impedes his mobility.

Solar-panel backpacks.

The additional weight is a key challenge; it should not exceed one-third of the soldier’s weight. The disposal of used batteries is a logistical problem. They can harm the environment and compromise the soldier’s position. Spent batteries are thus carried as dead weight. Extended operations require soldiers to carry even more load, as the availability of resupply during a mission can be unpredictable and the lack of sustainablesupplies could jeopardize the survivability of the force. To enable soldiers to overcome the weight of batteries, alternative energy and power solutions could harness energy from the soldier as well as from his surroundings. For example, nanotechnology researchers at the Georgia Institute of Technology are developing an energy-harvesting shirt that converts the wearer’s physical movement into electricity.

Known as the “piezoelectric effect,” energy is harvested through mechanical loading and agitations produced by everyday activities such as heartbeats, footsteps and light wind. The researchers have estimated that the nanogenerators can generate adequate power for personal electronics and scaled-down defence applications.

Industrial R&D

In many ways the defense sector is increasingly reliant on the private sector, supply chains, and market competition for green innovations. For example, a solar panel may be freely available on the market, but the adaptation of solar technology for the purposes of, say, powering unmanned aerial vehicles and/or armored vehicles or devices that transform air moisture into drinking water for troops, require defense firms’ expertise. In this regard, projects that contribute toward increasing military capabilities have the highest chance of being realized and convincing militaries that greening is a worthwhile strategy.

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Working with industry for defense-led energy innovation requires treading a fine line. Advocates of military demand pull for energy innovation need to understand the critical tasks facing specific military organizations, meaning that they have to live in the world of military jargon, strategic thinking, and budget politics. At the same time, the advocates need to be able to reach nontraditional suppliers who have no interest in military culture but are developing technologies that follow performance trajectories totally different from the established military systems. More likely, it will not be the advocates who will develop the knowledge to bridge the two groups, their understandings of their critical tasks, and the ways they communicate and contract. It will be the prime contractors, if their military customers want them to respond to a demand for energy innovation. However, the operational energy efforts may face other problems, as the demand for energy-efficient equipment to use in the field introduces new performance metrics into defense acquisition that are unfamiliar to the established defense industrial base, especially at the prime contractor level. The new performance metrics are likely to require some significant changes in industry structure – drawing on new technology companies. In past waves of military innovation, the defense prime contractors have successfully drawn in new technologies through mergers and acquisitions, joint ventures, and subcontracting relationships, building on the primes’ core competency in understanding and responding to the desires of their military customers.

Defense firms are currently developing military equipment that is lighter and more energy efficient than the capabilities currently being used, and MoDs are seeking ways to improve the efficiency and sustainability of camps, logistical processes (water, food, and fuel supplies), and above all else, troop safety

Environmental management is a key element in ensuring positive environmental performance of an organization. The integration of environmental management into military activities has become a growing concern for defence sectors internationally. At present, an Environmental Management System (EMS) is one of the most widely used environmental management tools throughout the world.

For the defense sector in Europe also (self-)regulation has become an important component of greening efforts. Defense corporations have developed corporate sustainability strategies to improve their own energy efficiency and to decrease carbon emissions. Several European-based defense companies have also adapted business practices to regulation, with many of them receiving ISO 14001 certification—meaning that such firms are internationally recognized for adopting environmental management system standards related to waste, resource, and energy consumption. Companies such as Airbus Group, Thales Defence & Security, Safran, DCNS, Dassault Aviation and Rheinmetall Defence are either fully ISO 14001-certified or they voluntarily implement the standard in a number of their factories.


The integration of environmental and sustainable development considerations into policy sectors and economic activities is one of most challenging targets at an international level. Creating a winwin situation for all stakeholders to opt for responsible solutions is essential, especially in a domain like defence and crisis management where climate, energy and environment are not necessarily core business

The integration of environmental and sustainable development considerations into policy sectors and economic activities is one of most challenging targets at an international level. Creating a winwin situation for all stakeholders to opt for responsible solutions is essential, especially in a domain like defence and crisis management where climate, energy and environment are not necessarily core business.

While the Green Defense concept sounds like something to strive for in times of security and prosperity, green defense solutions have proven their ability to increase operational effectiveness and limit operational costs. The concept also holds much promise with regard to energy security. Diversification in energy sources and reduced consumption of energy will be key elements in forming a policy response to future energy security challenges. NATO’s Green Defence Framework should therefore not be forgotten in times of tension and great power politics. Military forces and societies will be more resilient if they have developed and implemented viable green solutions.


Magnus Clausen
Senior Researcher

Dr. Magnus Clausen joined the Eyvor Institut in February 2017 as senior researcher. Magnus Clausen studied physics at Humboldt University, Berlin and received a PhD in geophysics from Stellenbosch University. His research is focussing on technology foresight methods and its application for underpinning strategy building and innovation processes.