A Royal Marine refuelling a vehicle during Exercise Green Dragon 2016 (Picture: Royal Navy).
By David Hambling, technology expert
The military is not an obvious place for green technology.
Jets screaming down valleys and tanks belching diesel are more a petrolhead’s fantasy than an environmentalist’s dream. But the military are starting to deploy some surprisingly eco-friendly hardware, and the trend is set to continue.
For example, US military research agency DARPA has come up with hybrid dirt bikes with electric and fuel engines for special forces use.
The Silent Hawk bike produces 40 horsepower in electric mode and glides along producing no more noise than a conversation. The bikes can be used for stealthy cross-country transport and quiet reconnaissance missions.
This is not just an American trend. Russian arms-maker Kalashnikov has also introduced an electric motorcycle for the military. Few details have been released, but the bike has a range of 150 kilometres.
Work on hybrid vehicles is dwarfed by the effort put into biofuels. Much of the work in this area has been in the US, because the Pentagon is one of the world’s biggest fuel consumers.
The US Navy uses some five billion litres of fuel a year, while the US Air Force consumes a staggering nine billion litres.
A slight increase in the price of crude adds a billion dollars to the defence budget, and a larger shift, like the dramatic spikes in 2008 and 2011, can have more serious effects.
Hence the desire to run military kit on biodiesel derived from vegetable oil, farm straw and other waste.
The US Navy’s ambitious 'Great Green Fleet' program, announced in 2009, aims to cut consumption of fossil fuels in half by 2020.
This has included showpieces like the 2012 RIMPAC exercise in which every ship was powered by biodiesel rather than conventional fuels.
The Italian navy has its own version of the program, the 'Flotta Verde' (Green Fleet), and has operated offshore patrol vessels and submarines on biofuel since 2015. Use is not yet widespread, but the indications are that vessels can switch green fuel with no ill effects.
The US Air Force has similarly been experimenting with alternative fuels, with the first flight on an A-10 Thunderbolt using an alcohol-derived jet fuel blend.
This is a cellulose-based fuel which can be made from wood, paper, grass or other plant material. The new fuel is reportedly comparable to standard JP-8, and improvements will make it indistinguishable.
“You won't be able to determine the difference and you won't care, because all perform as JP-8," said Jeff Braun, chief for the Air Force alternative fuel certification division, in a press release.
Other aircraft, including F-15 Eagle and F-22 Raptor fighters, and C-17 transport planes, have also been flown on new biofuels.
The Royal Netherlands Air Force is taking a lead in this area, with all RNLAF F-16s at Leeuwarden Air Base flying on biofuel since the start of this year.
The fuel, in this instance, is bio-kerosene recycled from cooking oil. Apparently, the only difference is the exhaust smells less sulphurous.
The Netherlands has also experimented with converting its Apache attack helicopters to biofuel.
This year, the Indian Air Force has revealed plans to run its transport fleet on biofuel derived from locally-grown Jatropha seed.
The switch to biofuel is not just about potential cost savings, it is also about fuel security.
“It keeps… fuel from being used as a weapon against us,” the US Secretary of the Navy Ray Mabus told Reuters news agency in 2016.
So far, the British military has made only modest use of biofuels for road transport.
Another area where green options are coming into play is ‘expeditionary power’ – providing electricity for troops deployed in the field.
The problem was highlighted in Afghanistan, where fuel for generators at remote bases had to be flown in or transported by road in convoys were prone to attack by IEDs. In some cases, the total cost of getting fuel to bases was over $400 per US gallon or £80 a litre.
This has led to the development of alternatives which do not require fuel. Since 2009, the US Marine Corps has had the Ground Renewable Expeditionary Energy System (GREENS), a mobile solar power system to power communications and computing devices.
In 2016, the US Army tested a larger solar array to power a Forward Operating Base. Fuel consumption dropped by 80%, and generators were run three hours a day instead of 24.
Solar power is also becoming increasingly common at military bases.
The US Navy’s Naval Air Weapons Station at China Lake has a 47-hectare solar site providing 30% of the base’s power, claimed to save $13m a year.
Biofuels, solar power and electric vehicles may all be popular with the eco-lobby, but that is not what drives their adoption by the military. The environmental benefits are secondary.
They simply represent a better way of getting the job done.