[LINK] NBN may increase Greenhouse Gas Emissions

Richard Chirgwin rchirgwin at ozemail.com.au
Fri Apr 10 17:29:30 AEST 2009

Tom Worthington wrote:
> The government's $43B National Broadband Network plan has 
> implications for greenhouse gas emissions. An example of a negative 
> effect is that higher bandwidth devices use more electricity and will 
> therefore cause more greenhouse gas emissions. Also the digital 
> devices connected to the network tend to use more power than old 
> fashioned analog devices.  

Perhaps the impact won't be so severe. Looking around for GPON devices (there
aren't many), I found Motorola CPE that has a 20 watt maximum power requirement
(I suppose less if it's idle).

A Netgear ADSL2+ gateway with voice needs 12 watts.

On the surface, that says the fibre CPE needs twice the power - but it may be
offset in the distribution side.

The Motorola ASX1800 optical line terminal (ie, the exchange-end kit) uses a
maximum of 1500 W and can be split to 64 subscribers per line - so its head-end
power consumption per subscriber (maximum) is about .42 watts per subscriber.

It wasn't easy to find numbers for DSLAMs, but this one uses about 2.5 watts per


So there may be considerable savings at the exchange to offset the higher CPE power.

While there is a general case that higher speed = more power, it doesn't hold
true when comparing different technologies (ie, optical is more efficient than
wired, so the speed - consumption relationship is different).


A positive effect will be if more access
> to teleconferences results in less business travel.
> The ACS Victorian Branch conference this year is on the theme 
> "Greening ICT towards Sustainability" 15 to 16 May 2009. I am 
> facilitating a session on The Carbon Footprint and was thinking we 
> might look at the environmental implications of the NBN in the 
> workshop: <http://www.acs.org.au/vic/2009conference>.
> Tom Worthington FACS HLM tom.worthington at tomw.net.au Ph: 0419 496150
> Director, Tomw Communications Pty Ltd            ABN: 17 088 714 309
> PO Box 13, Belconnen ACT 2617                      http://www.tomw.net.au/
> Adjunct Senior Lecturer, Australian National University  
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