Mobile broadband drives up carbon emissions

The global expansion of broadband networks is likely to cause a rise in carbon emissions, despite efforts by mobile phone operators such as Vodafone and O2 to decouple growth from emissions.

A global roll-out of mobile broadband networks is set to increase energy consumption and carbon emissions. Wireless technology firm Actix has forecast that high-speed, next generation services (3G/4G) – which can be used to watch video clips, send emails and access information from mobile phones – will see network energy use double to about 120 billion kilowatt hours by 2011 and reach about 449 billion kWh in five years.

Most of the increase is expected to come from more base stations which send radio signals between mobile phones and mobile or landline networks. Higher frequency radio waves for 3G services mean these base stations cover smaller areas than 2G sites. Actix estimates that each base station produces nearly 10 tonnes of CO2.

But Vodafone group environment manager Lucy Connell disputed the figures, arguing there is “a huge variation between base stations of different types and sizes, and the 2G and 3G networks operate side by side, so there is not necessarily a linear increase in energy consumption and emissions”.

Emissions per base station also vary according to coverage requirements and usage density. For example, a small base station located in an office will use less energy than a large site on a hill covering a wider area.

Vodafone is striving to make its network more energy efficient so emissions do not grow at the same rate as traffic.

Its focus is on improving energy efficiency in network equipment. Vodafone aims to reduce network CO2 emissions per unit of data transferred by 40% globally from 2005/06 levels by 2011. The company claims that data transmissions increased 25% in 2006, but CO2 network emissions were down 12%, equating to a cut a 29% per unit of data transmitted.

Vodafone suppliers have already met a target to provide new equipment which is 25% more energy efficient than that available in 2005/06. The target has now been raised to 33% to be achieved by March 2008. Vodafone says this pressure on suppliers has led to a breakthrough which will allow dramatic reductions in energy use by dynamically matching energy supply with demand.

Air conditioning to cool base stations accounts for about 25% of network energy use and this is being replaced with “free cooling”, which uses about 77% less energy. Power controls installed in air conditioning units at 2,000 base stations in 2005/06 have reduced energy used for cooling by about 14% at each site.

Vodafone is also installing on-site renewable technologies such as solar panels, fuel cells and wind turbines in some countries, and energy from renewable sources totalled 17% of global energy use in 2006.

In the UK, Vodafone, O2, Hutchison 3G UK, Orange and T-Mobile have licences requiring them each to provide 3G services to at least 80% of the population by the end of the year.

By the end of 2006, the UK had 49,000 mobile phone base station sites. The number could reach 51,000 by the end of 2007.

Vodafone UK and nine other operators have taken on targets to cut energy use and emissions, or to maintain levels of emissions despite expanding networks and usage.

Vodafone UK aims to cut energy use by 12.5% against 2005/06 levels by March 2009. It claims to have cut energy use by 4% in 2005/06 and reduced base station emissions from 112,100 tonnes of CO2 in 2004/05 to 69,400t in 2005/06.

Vodafone UK uses renewable electricity to reduce its climate change impact. “Our contract with British Gas Business covers 90% of our electricity needs and has helped to reduce our CO2 emissions by 60%,” says the firm’s corporate responsibility report for 2005/06.

But these claimed reductions are questionable as British Gas keeps the renewable obligation certificates (ROCs) associated with the electricity, allowing the double-counting of emissions reductions (ENDS Report 384, p 11 ).

While efficiency measures can help curb emissions in mature markets like the UK, rapid growth in developing countries like India will increase emissions.

Vodafone claims its overall global emissions dropped from 1.31 million tonnes of CO2 to 1.23MtCO2 in 2007, but the reduction is largely from the disposal of its Japanese operation.

The company admits that after sales and acquisitions, its energy use rose 6%.

Some 86% of emissions were from its network, which have risen from about 0.9MtCO2 in 2005/06 to almost 1MtCO2 in 2006/07 (see figure 1).

Vodafone predicts emissions from base stations will rise to more than 1.15MtCO2 by 2010 (see figure 2).

Average CO2 emissions from mobile operator O2’s base stations rose from 9.5 tonnes each in 2004/05 to 10.5t by the end of 2006, although it says more efficient 3G sites emitted about 8.1t on average in 2006.

The number of O2 base stations globally increased from 24,648 to 33,388 in the same period, largely because of its 3G network roll-out, and global CO2 emissions from base stations rose from 163,599t to 233,189t.

O2 claims that buying electricity from renewable or low-carbon sources such as combined heat and power means emissions have in fact “remained almost static”. But its own data reveals that, even when taking these sources into account, CO2 emissions rose from 220,763t to 337,445t.

O2 plans to use more efficient equipment, buy more renewable energy and offset emissions so its carbon footprint does not increase in line with growth. It aims to develop a carbon neutral strategy by December.

In the UK, O2 plans to have 4,317 3G sites by the end of the year, up from 4,173 in August.

Eon supplies renewable energy which will account for about 22% of O2’s electricity consumption in the UK this year. But Eon keeps the ROCs associated with this supply meaning O2 cannot claim any carbon reduction benefits from the contract.