Mobile Industry on the Hunt for Lower Emissions

During the rainy season roads are washed away, and diesel has to be helicoptered to mobile base stations not connected to the electrical grid, so it's easy to understand the communications industry's growing interest in energy-efficiency and renewable energy sources.

All mobile carriers are currently investigating how to improve energy efficiency, according to Gartner analyst Martin Gutberlet.

"The main driver is to reduce the cost of running mobile networks, but then you also get to reduce CO2 emissions as a bonus," he said.

Just recently Vodafone announced it would reduce its carbon-dioxide emissions by 50 percent by 2020. The push makes sense from an environmental and business point of view, according to CEO Arun Sarin.

Vodafone started looking at energy efficiency two years ago, but as evidence has mounted of how carbon-dioxide affects the environment the company felt it was time to do more.

"Succeeding will be a big challenge, and today we don't know exactly how to do it," said Ulrich Blau, senior manager Site Infrastructure & Energy, at Vodafone Group.

The primary focus should be on the mobile base stations, since they consume almost 70 percent of all energy in a mobile network, according to Ericsson.

There are a number of ways for mobile operators to become more energy efficient.

One way is to increase the temperature at which equipment will work, which reduces the energy needed for air conditioning. Instead operators can use free cooling, which uses outside air.

Raising the temperature from 25 degrees Celsius to 40 degrees Celsius reduces required energy by up to 30 percent, according to Nokia Siemens Networks.

Another method is to reduce energy consumption during off-peak hours by adapting the energy use of the base station according to the level of calls, just like a laptop goes into sleep mode when it isn't used. A feature from Ericsson, called Base Transceiver Station Power Savings (BTS Power Savings), does just that and can lower energy use by 15 percent to 25 percent.

A more spectacular way of reducing carbon-dioxide is Ericsson's radio base station site concept Tower Tube, which looks like something from a science-fiction movie, designed to require no active cooling. It is built using concrete instead of steel, which lowers emissions by up to 40 percent.

Nokia Siemens has set a target to reduce energy use of typical GSM (Global System for Mobile Communications) base stations by 20 percent by 2010, from the 2007 level of 800W, and 3G (third-generation) base stations by 40 percent from 500W, during the same period.

In 2008 Ericsson exceeded its target to lower energy use in a 3G base station by 50 percent compared to 2005 levels. Later this year it will introduce future targets.

As the need for power decreases, the use of renewable energy, like solar and wind power, becomes more viable. A base station that needed 200 square meters of solar panels five years ago, today needs 50 square meters, according to Ericsson.

Wind and solar power have advantages and disadvantages. Wind is more efficient, if you find a spot with enough speed and wind occurrence, according to Blau.

But there is more data -- about where the sun shines, and for how many hours -- about where you can use solar power, according to Ericsson's Linda Ekener Mägi, marketing manager, Communications Expander.

At the same time, solar-power technology has disappointed in recent years -- it isn't evolving as fast as Ericsson and Vodafone had hoped.

In the end, considerations about lowering carbon-dioxide emissions and using renewable energy come down to cost. Currently any Vodafone investment needs a pay-back time of two years at the most.

Vodafone Germany was the first operator to upgrade its network to support BTS Power Savings. "I am keen to get it in other networks as well, but the software upgrade is really expensive," said Blau.

From a technical standpoint, there are also challenges. The best way to decrease carbon-dioxide emissions is to use fewer base stations. But building a network with high data speeds requires using more base stations. 

Vodafone acknowledges the paradox.

"The radio guys want to build the best network in the world, and I want to lower energy use, so we'll have to try to find a compromise," said Blau.

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