Mobile base stations can create large amounts of heat. Credit: Telstra
In one of the hottest summers on record, Telstra and Optus relied on fresh air cooling and high-efficiency air conditioners to keep their mobile networks going, officials from the companies said last week.
“Almost half of our energy use is air conditioning,” said Telstra energy and greenhouse general manager, Brian Hennessy.
Use of fresh air cooling in data centres, mobile sites and other network facilities has been the most effective and cost saving energy-reduction initiative at Telstra, he said on a panel at the Smart Power for Smart Communication Networks conference in Brisbane.
Optus also uses fresh air cooling, and has implemented system based on it in about 4000 base stations nationally, said Michael van der Lit, senior project manager of national mobile deployment and support services.
Mobile base stations “do a lot more than they did in the past,” he said. “As a system ... there’s a lot of heat that comes off a base station.”
Heat at Optus base stations have increased since the telco signed an mobile site-sharing agreement with Vodafone Hutchison Australia, said van der Lit.
“The heat loads that we’re experiencing now are predicted to tip around 10kW,” he said. “We’re having to review our cooling system there.”
Optus has no plans to follow what SingTel operators in Asia have done and replace equipment shelters with outdoor cabinets, he said.
“We find that those sorts of facilities are very limiting in terms of being able to be upgraded in the future,” he said.
“We have an alternative that’s a bit more vendor agnostic, and we seem to get reasonably good power utilisation ... using fresh air cooling and more efficient types of air conditioners once the fresh air cooling kicks out at a certain temperature.”
Fresh air cooling systems can fail and therefore require constant monitoring, noted Hennessy.
“The problem we’ve got is we’ve got electromechanical devices and they will fail at some time,” he said. “And what we don’t want them to do is to fail ... on a 43 degree day in Melbourne.”
High heat in Melbourne resulted in a three-hour outage on the Vodafone network earlier this summer.
In 2011, Telstra invested $43 million in a five-year energy reduction program, Hennessy said. Telstra spent $9 million last year on energy efficiency improvements and plans to spend $14 million this year and another $6 million the year after, he said.
Meanwhile, Optus has a target of reducing power consumption by 20 per cent by 2015, said van der Lit.
Telstra requires its employees to report the energy impact of every initiative, Hennessy said.
“What we put in place a number of years ago is a process where every project is assessed to determine what we can do to save energy.”
Telstra also has a team of regionally-based energy managers who inspect network sites for anomalies and faults, and fix any problems they may find, he said.
Van der Lit said Optus’s agreement with Vodafone to share some mobile sites adds some complexity to measuring electricity costs. Each telco pays only for what they use, and the telco who owns the site charges the other telco.
“It makes it more complex because the cost of running that site” is shared between the two companies and they must track the actual electricity usage at each site by each telco, he said.
“But there are also significant savings” in capital expenditures since the telcos are sharing the costs of network deployment, he said.
Rising energy costs predicted
The amount of energy consumed by networks is only going to increase with the rise of the Internet of Things, Centre for Energy Efficient Telecommunications (CEET) deputy director, Kerry Hinton, said in an earlier session. The future convergence of wireless, cloud, machine-to-machine (M2M) communications and IPv6 will result in great amounts of energy consumed, and the current energy efficiency improvement rate is not fast enough to keep up, Hinton said.
There will be “billions of things talking to each other,” with estimates ranging between 2.1 billion (Analysys Mason) and 50 billion (Ericsson) M2M connections by the year 2020, he said. “All of this requires energy.”
The rollout of IPv6 addresses will result in billions of machines communicating over the Internet, he said. That means more Internet traffic and as a result more energy used, Hinton said.
Adding to the problem, most of the machines will likely connect to the Internet wirelessly, an approach that is more convenient but “quite energy inefficient,” he said.
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