Light infantry

A modern infantry soldier can carry up to 70kg of kit, around 25 per cent of which is the weight of batteries, powering essential equipment such as radios, night vision and gun sights. A joint EPSRC/DSTL project aims to develop combined photovoltaic (PV) and thermoelectric (TE) technology that could significantly reduce or even eliminate a soldier's reliance on batteries.

The project, in collaboration with

and involving

,

,

,

and

universities, will address how to integrate the two technologies while not adversely affecting the soldier's movement. Principal investigator Prof Duncan Gregory, head of inorganic chemistry at

, explained: 'We need to initially show that we can grow films or nanostructures of both materials on a single substrate on a small scale.

'To demonstrate that this could be part of a system, we'd start off using a battery then gradually decrease reliance on it, using energy that our new device harvests to keep the solider going and cut down battery weight. Ultimately, we may be able to remove the battery altogether.'

The energy-generating systems will initially be grown on a rigid substrate then, when the technology is proven, moved onto a flexible polymer. Eventually, this could be incorporated into the soldier's uniform or body armour.

Though PV is relatively mature technology, TE power relies on a new generation of mostly unproven materials. The two will be combined on either side of the same substrate and a method found to connect the two together. According to Gregory, the biggest challenges will be making the new nanostructured thermoelectric material and integrating it with PV for the first time. 'The idea is during the day we collect the light energy using the PV, then during the night we can use the heat from the soldier's body relative to the cooler outside temperature,' he added.

As the material is colour independent, the systems could be camouflaged to blend in with the uniform and would have the advantage of helping mask the wearer's infrared signature from observers using night-vision equipment.

The current largest consumers of energy are personal communications equipment and the electronic countermeasures, which are worn as a backpack to block electronic signals to help protect soldiers from smart bombs. They currently use Li-ion batteries, whose weight is further increased with ruggedising armour.

With analysts estimating that the power demand for infantry soldiers will increase 10-fold by 2020, mainly due to an increase in the information possible to communicate electronically, the project will also focus on power management and making the devices less power hungry.

The project runs until 2011, by which time the researchers aim to have a demonstrator to show the MoD, which could be scaled up as required. 'We could fit our technology to, say, a soldier's helmet powering his night vision, or put it on his gun to control his weapons ranging and sight,' said Gregory. 'Ultimately, we can imagine integrating in into textiles or with the body armour, which would be another challenge.'