Put your data centre on an energy diet

Sal Azzaro, director of facilities for Time Warner Cable Inc., is trying to cram additional power into prime real estate at the company’s 22 facilities in New York.

“Its gone wild,” says Azzaro “Where we had 20-amp circuits before, we now have 60-amp circuits.” And, he says, “there is a much greater need now for a higher level of redundancy and a higher level of fail-safe than ever before.”

If Time Warner Cable’s network loses power, not only do televisions go black, but businesses can’t operate and customers can’t communicate over the company’s voice-over-IP and broadband connections.

When it comes to the power crunch, Time Warner Cable is in good company. In February, Jonathan Koomey, a staff scientist at Lawrence Berkeley National Laboratory and a consulting professor at Stanford University, published a study showing that in 2005, organizations worldwide spent $7.2 billion to provide their servers and associated cooling and auxiliary equipment with 120 billion kilowatt-hours of electricity. This was double the power used in 2001.

According to Koomey, the growth is occurring among volume servers (those that cost less than US$25,000 per unit), with the aggregate power consumption of midrange ($25,000 to $500,000 per unit) and high-end (over $500,000) servers remaining relatively constant.

One way Time Warner Cable is working on this problem is by installing more modular power gear that scales as its needs grow. Oversized power supplies, power distribution units (PDU) and uninterruptible power supplies (UPS) tie up capital funds, are inefficient and generate excess heat. Time Warner Cable has started using Liebert Corp.’s new NX modular UPS system, which scales in 20-kilowatt increments, to replace some of its older units.

“The question was how to go forward and rebuild your infrastructures when you have a limited amount of space,” Azzaro says.

With the NX units, instead of setting up two large UPSs, he set up five modules — three live and the other two on hot standby. That way, any two of the five modules could fail or be shut down for service and the system would still operate at 100 percent load.

Other approaches

Some users are trying innovative approaches. One new way of approaching the power issue is a technique called combined heat and power, or cogeneration, which combines a generator with a specialized chiller that turns the exhausted waste heat into a source of chilled water.

Another new approach is to build data centres that operate off DC rather than AC power. In a typical data center, the UPSs convert the AC power coming from the mains into DC power and then back into AC again. Then the server power supplies again convert the power to DC for use within the server.

Each time the electricity is switched between AC and DC, some of that power is converted into heat. Converting the AC power to DC power just once, as it comes into the data center, eliminates that waste. Rackable Systems Inc. in Fremont, Calif. has a rack-mounted power supply that converts power from 220 VAC to -48VDC in the cabinet and then distributes the power via a bus bar to the servers. On a larger scale, last summer the Lawrence Berkeley lab set up an experimental data center, hosted by Sun Microsystems Inc., that converted incoming 480 VAC power to 380 VDC power for distribution to the racks, eliminating the use of PDUs altogether. Overall, the test system used 10 percent to 20 percent less power than a comparable AC data centre.

For Rick Simpson, president of Belize Communication and Security Ltd. in Belmopan, Belize, power management means using wind and solar energy. Simpson’s company supports wireless data and communications relays in the Central American wilderness for customers including the U.K. Ministry of Defence and the U.S. embassy in Belize. He builds in enough battery power — 10,000 amp hours — to run for two weeks before even firing up the generators at the admittedly small facility.

“We have enough power redundancy at hand to make sure that nothing goes down — ever,” Simpson says. So even though the country was hit by Category 4 hurricanes in 2000 and 2001, “we haven’t been down in 15 years,” he says.

Belize Communications equipment all runs directly off the batteries and UPSs from Falcon Electric Inc. in Irwindale, Calif. Mains power is only used to charge the batteries.