Unbeknownst to most mobile users, the air-conditioner has always played an important – if unseen – role in their ability to make calls and send texts.

This most unassuming of devices may, however, lose its connection to the world of mobile communications thanks to an innovative British technology. An ultra-efficient device made by a small, Cambridge-based company could end the need for cooling in base stations, cutting dramatically the cost of running a mobile phone network.

The company, called Nujira, makes the little devices that turn mobile signals from data that arrive via cables at a base station into the powerful radio waves that reach out to the nation’s handsets.

Traditionally, these power amplifiers produce enormous amounts of heat which must be extracted using air-conditioning or fanning systems. These systems, bolted onto the side of cabins at the bottom of antennae, cost about £12,000 to install, £500 per year to maintain and in the process of cooling down the amplifiers – which can heat to about 150 degrees – burn more power.

All of which creates a sizeable cost headache for the networks, which between them own about 60,000 base stations across the country.

Nujira’s devices, which measure just 8cm by 8cm, increase the power efficiency of base stations to such a degree that they can be cooled using natural convection currents, removing the need for fans or air conditioning.

“Our amplifiers draw on immensely complicated physics,” Tim Haynes, chief executive of Nujira, said. “Two of the companies which make base stations are looking at similar technology, but we're the only ones taking it to a commercial level so far.”

The company, which was set up with venture capital funding five years ago, is currently under contract to trial the devices with eight of the world’s twelve base station manufacturers, and Mr Haynes anticipates that the first orders will be placed in the third quarter of this year.

Networks are increasingly looking for ways to increase their power efficiency, for financial as well as environmental reasons. "The physics of 3G means that you burn more power, and burning more power not only costs more, it means more gets dissipated in heat, which must be removed, and that costs money,” Mr Haynes said.

Vodafone has said that it spends £150 million per year to power its network – about 80 per cent of its total electricity costs – and of that about 10 to 15 per cent is estimated to go on base stations.

According to the industry analysts ABI Research, electricity consumption by phone networks is likely to grow at a rate of 24 per cent per year between now and 2011 – partly because the networks themselves still getting bigger, but also because customers are increasingly using the phones to download music and videos, which uses up more bandwidth than voice calls.

“Currently, an individual cell within a network will support five to six users each consuming 300Kb of data per second,” Stuart Carlaw, the company's director of wireless research, said. “As more and more users start to download music and video, the cell won’t be able to support that number of subscribers, so you’ll need more cells overall.”

Mr Carlaw said that this would pre-empt the rise in ‘pico-cell’ and ‘femto-cell’ technologies, which take pressure off the main network by creating subsidiary networks – or ‘cells’ – in localised environments such as the home or office.

Charlotte Grezo, director of corporate social responsibility at Vodafone, which has committed to reducing its carbon dioxide emissions per unit of data by 40 per cent in the next four years, said that increasing energy efficiency was a matter of "huge importance", both for environmental reasons and because power was such a significant cost for the company.

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