TECHNOLOGY TRENDS

Operator targets: how BT and Orange are tackling emissions

BT says it has reduced the carbon emissions of its global business by 54% since 1997 and aims to reduce them by 80% by 2020 from that base year. The operator says in the UK more than 40% of the electricity it uses now comes from renewable sources. In 2009 it reduced electricity consumption by around 50 Gigawatt hours (GWh), preventing the emission of 21,600 tonnes of CO2; in all, BT says it cut CO2 emissions by 59,000 tonnes or 7% in that year (see table below). Orange aims to reduce greenhouse gas emissions by 20% by 2020. Among its energy- saving schemes in 2009 the operator says it deployed 13,037 virtual machines generating savings of 30.7 GWh of electricity—equivalent to the annual electricity consumption of 8,000-10,000 European households. It says use of 9.7 GWh of renewable energies in 2009 prevented 3,059 metric tons of CO2 being emitted. And 900 solar stations deployed by the middle of 2010 led to the prevention of the emission of more than 16,000 equivalent metric tonnes of CO2.

BT CO2 equivalent emissions CO2

e tonnes

(thousands) Scope 1

Scope 2 (gross) Sub Total Scope 3

Total emissions (gross)

Less purchase of: Renewable electricity

CHP low carbon electricity Total emissions (net)

2010 2009 2008

Base year 1997

212 249 256 414 1,419 1,448 1,407 1,631 1,698 1,663

1,682 1,742

1,156 1,569

1,627 Change

2009-2010 -15%

Change

1997-2010 -49%

-2% 23% -4%

-5% 4%

51 73 79 58 -30% -11% 1,771

3%

572 591 516 310 801

319 860

337 888

— —

1,627

-3% -3%

— —

-7% -51% Source: BT

wireless access accounts for 30% of energy consumption, followed by central offices and broadband access networks. And wireline broadband access is a contributor to rising energy costs due to growth in both data rates and subscribers. “Although the power-per-bit is coming down, overall power is rising,” says Dickerson at the ITU. Technologies such as VDSL2 and passive optical networks (PON) improve power-per-bit performance, while PON has an advantage over VDSL2 in that it is solely fibre-based. “If you consider a certain given band-

width, it is quite simple to show that fibre has the lowest power consumption [compared to copper and wireless],” says Klaus Grobe, senior principal engineer at ADVA Optical Networking. “That means we have to use fibre wherever we can.” But from an operator’s point of view that is costly in terms of initial opex (Total Telecom Plus, Fibre Economics ). The EU has introduced a code of

conduct for energy consumption of broad- band communication equipment that aims for energy reduction in the access network. These guidelines set targets for vendors in terms of Watts-per-megabit-

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per-second for their equipment to meet. Such targets are also leading to the use

of techniques such as power-saving standby modes, says Dickerson. DSL plat- forms can power down line cards during periods when broadband connections are idle at night . The ITU is looking at how to apply such modes to VDSL2 equipment , and its study group on future networks is looking at how parts of the core network can be shut down when traffic levels are lower. In addition, there are proposals for a deep-sleep mode for XG-PON, the latest 10-Gbps PON standard. Meanwhile vendors continue to enhance

their platforms as they benefit from new technologies and greater integration. Nokia Siemens Networks has improved an optical transport product using denser interfaces—four 10-Gbps interfaces on a line card compared to one—and reducing the number of optical-electrical-optical conversions. The result is a 28% power saving in 2010 compared to the platform in 2007, and that will rise to 42% in 2011, says the company. In wireless networks up to half the

power with base stations can be lost in the coupling of the radio signal to the

antenna, and the platforms also require cooling. Such factors explain why power consumption of base stations can vary by a factor of five between different opera- tors and different regions based on the age of equipment, says Dickerson. Elaine Weidman, vice president and

head of corporate social responsibility and sustainability at Ericsson, says the company sets new energy efficiency targets for each base station product generation while also continuing to work on equipment already installed. Ericsson has 2 million base stations deployed and it uses software updates to improve energy efficiency of deployed systems that switch off functions when the loading is less. Alcatel-Lucent also is making major claims for reducing the carbon footprint of wireless networks with its LightRadio products, which tackle ampli- fier efficiency and the issue of cooling in base stations (see box). Systems integration in mobile networks

similarly improves power efficiency. “In the past GSM and W-CDMA were sepa- rate boxes. Now by incorporating in one box GSM and W-CDMA we save power by integration,” says Jyrki Louhi, envi- ronmental affairs manager for network systems at Nokia Siemens Networks. But despite such system vendor devel-

opments in wireline and wireless networks, challenges remain for opera- tors. “Technology is changing so rapidly that there is always a balance between installing new, more energy efficient equipment and the effort to reduce the huge energy footprint of existing opera- tions,” says AT&T’s Schinter. For Verizon, one challenge is how to

manage equipment substitution that delivers power savings while continuing to serve its customers. “We spend a lot of time doing good analysis about what is the highest return work we can do first,” says Kimm. Determining equipment spend in terms

of timing and scale is also not simple. “The big challenge for us is to plan the capex effort such that we achieve the return-on-investment based on antici- pated energy costs,” says Tuzzolino at France Telecom. n

www.totaltele.com March 2011