Mobile phones long ago began conquering parts of the world that are far away from the nearest electrical substation. But the rising price of oil is exposing a problem with the networks that connect mobile handsets together.

In the far reaches of places like India or Africa, where companies such as Ericsson or Nokia Siemens Networks, a joint venture of Nokia and Siemens, are installing new cellular base stations at a furious pace, the facilities almost always get their power from diesel-powered generators. But fuel can account for as much as two-thirds of base-station operating costs. Add to that the expense of trucking diesel over poor roads to far-flung locations and protecting the valuable fuel against theft. “Getting oil or diesel to these stations is tremendously difficult,” says Mats Granryd, president of Ericsson India.

Rapid Deployment

As a result, green energy is suddenly becoming more than a feel-good project for the world’s mobile service providers. As mobile networks expand far beyond the reach of power grids, they need to find alternatives to diesel. After experimenting for years with base stations powered by wind, solar energy, or biofuel, equipment suppliers are preparing to roll out alternative energy technology in significant numbers.

“We’re starting to see this deployed globally now,” says Dawn Haig-Thomas, director of the development fund of the GSM Assn., an industry group. “It’s our hottest area.” Two Asian network operators will shortly announce plans for more than 500 new base stations powered by a combination of sun and wind, Haig-Thomas says. [She declines to name the operators.]

Solving the power problem is key to maintaining the growth of the mobile industry. The number of mobile subscribers is expected to climb to 5 billion by 2015, from 3 billion today. A large proportion of those new users will be in poor, rural areas with little…