NAB data centre uses trigen, saves 20k tonnes of carbon

Super heated gas cools data centre, cuts some ties with grid

Marilyn Monroe shows off cogeneration in the film The 7 Year Itch

Marilyn Monroe shows off cogeneration in the film The 7 Year Itch

The National Australia Bank (NAB) is laying claim to the title of first organisation in the country to use tri-generation (trigen) power in its data centre.

An ambitious project was launched in 2008 to supply power and cooling to its primary Melbourne data centre on site using trigen and remove half of its energy dependency from the grid.

Trigen technology introduces cooling processes into co-generation technology, which reuses heat from energy manufacture. Co-generation is the technology behind the famous New York stream system which transports heat for homes and office buildings.

The gas-powered data centre channels excess gas — heated to more than 300ºC — into the 2 megawatt trigen plant where it is sent into an absorption chiller that boils refrigerant liquid to produce cold water for cooling.

NAB data centre platform specialist, Glenn Allan, said the trigen plant was quietly switched on early this month.

“We are farming a single energy expense for multiple re-use,” Allan said.

“We are the first [to use trigen] in data centres, but you will be able to count the months until the next deployment.”

Allan said trigen power will gradually replace the data centres’ remaining energy grid dependence and will be considered for incorporation into all new NAB data centres.

“These aren’t emergency stand-by technologies — they are running the baseload power every day of the week,” Allan said.

The project design was influenced by existing trigen implementations, including the use of co-generation in the South Australia Coopers Brewery where heat produced in a power plant is used in the brewing process.

The trigen plant will save 20,000 tonnes of carbon annually, meaning NAB can spend less on carbon offsets to meet its 2007 commitment to be carbon neutral by 30 September this year. Allan said the plant was pitched on a five-year return-on-investment (ROI) which Allan said is now “significantly shorter” due to sharper than anticipated increases in the price of gas.

A carbon friendly data centre?

NAB’s primary Melbourne data centre has been a favourite of the banks’ carbon razor gang, as part of the carbon neutral initiative through which the bank has conducted efficiency assessments, bought a fleet of hybrid vehicles, switched to 10 per cent green power and slashed energy use in its 790 branches.

For Allan, the relationship between carbon reduction and cost cutting is simple — carbon reduction equals savings. There’s no need to toy with calculus or limits, he said, just establish how much you will pay per tonne to offset carbon, and you will see whether the cheap gas-guzzling option is financial viable in the long term.

“That simple model can differentiate what looks like a quick win,” Allan said. “The cheap solution could cost you more than the sleeping giant in permanent, ongoing carbon costs.”

Power and cooling costs can also be significantly reduced by replacing ordinary servers with blades and using virtualisation, Allan said. Blade servers are the staple in NAB’s data centres and, while virtualisation has been deployed extensively, he warned that the enterprise consolidation ratios may not reach some of the more optimistic predictions. Allan said the most productive uses of virtualisation are only coming out now after the “toy factor” mentality has passed.

“There is a litany of inventions in history where the usefulness is only discovered later… virtualisation could be made more useful if I could create backup application on a server, inflate it for 90 minutes then remove it so it doesn’t take up resources,” he said.

“[Virtualisation] will lower the server-to-power ratio — NAB has 16 blades to six power supplies — and if you virtualise, the ratio becomes incredible,” he said. “The case for virtualisation is off the table; everyone should do it, if not for the power savings than for the improved change management capabilities.”

The data centre uses cold and hot isle systems and Allan, who is eagerly watching research in jet impingement chip cooling, said every data centre should operate advanced cooling management models.

Allan has also considered free cooling and kyoto cooling — which replaces hot air with cool outside air via a turning wheel — but has reservations about introducing external elements into the mission-critical data centre.

“There is cause for a good deal of concern; it has been 12 months since the [Black Saturday] bushfires and Melbourne has gone through trials of dust storms and hail... it is about risk mitigation when you want to bring outside [influences] into the data centre,” he said, adding that free cooling will be first adopted by smaller or agile data centres such as Google which, unlike banks, can migrate services between centres.

NAB is systematic with its carbon cutting, taking the best ROI wins first and shelving the more difficult ones for later. “It’s the law of diminishing returns,” Allan said. “I’ll review a plan with 10-year ROI each year and put it back on the shelf — I won’t throw it out because that ROI might be halved in a few years time”.

He said the concept of the data centre as an energy hog is a matter of perception.

“Data centres account for 2 per cent of the world’s energy costs [but] take away IT and see your carbon footprint grow,” he said.

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