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British Army engineer argues huge carbon and cost savings could be achieved if military adopted green technologies In an era when budgetary cutbacks are leading governments to seriously reassess their military spending, you might imagine that the bean-counters had quickly identified improving fuel efficiency as a key area where savings might be achieved. The fact that so many modern wars seem to include access to oil reserves as a motivating factor should also act to sharpen their attention, too. But, according to a British Army engineer writing in the latest edition of the Royal Electrical and Mechanical Engineers Journal, the UK’s current government is ignoring the potential benefits – in cutting both costs and carbon emissions – of developing more fuel-efficient military technologies. Staff Sergeant Graham Thornton, who is currently attached to 3 Yorks Regiment as a fitter section artificer and is a member of the Institution of Mechanical Engineers , argues that the Ministry of Defence should be looking at how the “civil domain” is starting to embrace “hybrid/green technologies” to reduce fuel use. The changing nature of warfare also demands a rethink on fuel use, he says: Recent warfare has seen highly mobile land battles that utilised a large amount of equipment and a considerable amount of fuel to maintain manoeuvre. This placed a high demand on the logistical chains and stretched resources, sometimes to breaking point. A standard 2:21 Battle Group consists of 120 A vehicles and 96 B Vehicles, and can hold up to 12,000 litres of fuel in their tanks. This alone, when burnt, can produce over 31 tonnes of CO2. Furthermore, the amount of fuel that is stored in varying quantities throughout the entire supply chain places a large burden on lift assets and also requires a considerable amount of real estate on the battlefield. Modern warfare is more asymmetric and therefore sees less movement of land equipment. Subsequently a greater use of air equipments (both manned and unmanned) is being seen. The idea of hybrid tanks roaming the battlefields of the future is one suggestion put forward by Thornton. He notes that the UK defence firm QinetiQ is already working on an electric drive transmission called the E-X-Drive . But far more radical is the idea of a “wireless charge system” to power vehicles and equipment and, thereby, reduce the use of heavy batteries, which are, he says, becoming a growing burden on a military increasingly reliant on electricity as a power source, as opposed to diesel. One area where this could prove most practicable is the use of unmanned drones: Unmanned Aerial Vehicles (UAV) and Unmanned Combat Air Vehicles (UCAV) are most at risk during takeoff and landing, where a skilled operator is needed to land them safely. As the main power plants are turbo-fan propulsion (as used in the BAE Systems Taranis) and also conventional combustion plants (Hermes 450 uses a Wankel engine) they require refuelling and this is done on the ground. Some UAV/UCAV are fitted with batteries and these require charging or the use of a combustion engine to provide charge which increases the weight and limits the capability of the UAV/UCAV. Some trials have commenced with solar-powered UAV/UCAV and ‘Lighter than Air’ (LTA), but these technologies are bulky, expensive and fragile with a minimal payload and limited operation envelope. The use of batteries with a wireless charge system could be the answer. A Laser Charge system would enable long-term sorties to be flown and the only required downtime would be for the essential maintenance. A laser transmitter converts the power from the primary source (generator, battery or AC source) into a monochromatic beam of light. This is then collected by a specialist photovoltaic (PV) cell on the UAV/ UCAV and then converted to power as is conventional for the PV cell. This technology can be used to provide the electrical power to charge the batteries and if the receiver is replaced with a suitable alternative the laser can be used to provide power to provide heat to air and thus create thrust for an engine. This technology can be used to provide power for static Intelligence, Surveillance, Target Acquisition and Reconnaissance (ISTAR) missions (quadricopters and similar), multi-mission flights or unlimited patrolling. The only limit is the charge capability, the UAV/UCAV could return to a base location for charging meaning a lighter storage system is needed or for longer missions larger batteries could be used. The technology could be used in conjunction with a portable AC generator on a vehicle that sets up a mobile charging station. The potential for this technology to provide power, via satellite or mirrors, to outlying posts and patrol bases can be seen. Generators can use a substantial amount of fuel and local power options could be intermittent at best. The power offered by this could be used at certain times to charge large capacity batteries which in turn would provide power for the electronic equipment. There could also be scope for soldiers on the ground to use this technology in a similar manner to the UAV/ UCAV and have lighter/less batteries. Some immediate questions spring to mind. First, would this improved fuel efficiency really lead to a reduction in military spending? Or would it, according to Jevons paradox , just end up increasing the amount of unmanned drones used in warfare? Second, are the fuel savings really so great? The diagram used (above) by Thornton as an example for a drone describes a 4,000W input producing DC power equal to 1,000W. Is a generator on the ground used to power such a laser more efficient than a conventionally powered drone when you factor in this transmission loss ? A Seattle-based company called LaserMotive is very active in this technology, but it doesn’t seem to stress fuel savings as a key advantage of ” power beaming “, rather that it is far less costly than conventional ways of distributing electricity, namely, down copper wires. (I have asked LaserMotive to provide its thoughts on this point. When it responds, I will post below.) Thornton appears downbeat that this technology will get support from the current government due to the defence industry being “reluctant in the current financial climate to risk disfavour associated with fighting for the funding to introduce greener technologies”. I suspect he is probably right. But, in future years, it is highly likely that military technologies will be developed that help to reduce the carbon “bootprint” of armies, as well as, ultimately, our own civilian carbon footprint. This might not sit well with those environmentalists who are instinctively repulsed by the ” military industrial complex “, but history teaches us that many technological advances have been born under the shadow of war. Power-beaming might end up being one of them. Energy efficiency Leo Hickman guardian.co.uk