Bob Mobach, a managing consultant in the infrastructure consulting unit at systems integrator Logicalis Group, helped the NCTD redesign its data center. He says a key to realizing an ROI with alternative power is embracing virtualization. The NCTD had to become more efficient before installing alternative power sources, he explains, and to become more efficient, it turned to virtualization. The agency's data center is now around 80% virtualized, and that's a primary reason why the solar arrays have become such a successful power source.
"Virtualization was critical for so many reasons," says Miller, noting that the new setup is "way more efficient," makes better use of hardware, gives the data center a smaller footprint and is easier to manage with fewer people. "My actual physical footprint went from not having any more slots in the racks available to having only half of the racks occupied, and yet we've increased our applications this year," she says.
But there is a catch, Miller says: "If you want to realize savings, you had better monitor and tune performance. Otherwise you are just propagating the same mistakes."
Analysts laud efforts like NCTD's while warning that solar power isn't for every data center by any means. "The level of efficiency you can get out of solar energy is dictated by the location of the data center," says Doug Washburn, a Forrester Research analyst who covers alternative power. "If you are in an area where the sun shines more frequently, you can take advantage of a solar investment."
One reason why solar may not be the best data center power source is the fact that data centers use 10 to 100 times more energy per square foot than a typical office complex, he says. Moreover, resiliency and uptime are so crucial to a data center's operation that "it's a critical risk and maybe even foolhardy to think you could power the majority of your data center from solar," he adds.
On the upside, Washburn does note that solar can be viable for data centers located in places where it's sunny all day. And solar is a "visible" power source, so installing solar arrays is a way demonstrate to the surrounding community that you're committed to renewable energy and sustainability. Washburn agrees that virtualization is key to the success of a solar project. Increasing the number of hosts per machine, consolidating storage and decommissioning equipment that has been virtualized can make a data center more efficient even before an energy switchover, he says.
Natural gas turbines at Syracuse University
Christopher Sedore, the CIO at Syracuse University, says the upstate New York school spent about $12 million to build a data center that uses natural-gas-fired microturbines from Capstone Turbine Corp. to generate power on site. Microturbines are essentially jet engines that run on natural gas and provide power to generators. The turbines produce about a half a megawatt of power for the university's data center and another 200 kilowatts for other uses; among other things, they power an adjacent building.
The turbines enable the university to have a cogeneration setup, meaning they can help generate both heat and power for the data center or nearby buildings. The university can also sell any extra power the turbines generate back to the local power company.
The turbines drive two 150-ton absorption chillers that turn the heat exhaust from the turbines into chilled water that cools the data center. In the winter, the university uses cold outside air for data center cooling and hot water generated by the turbines is used to heat an adjacent building.
Sedore says he considered several factors in determining the ROI for the gas turbines, though he declined to specify the ROI. One factor was that he partnered with IBM, which is using part of the main building as a research facility, and the vendor helped pay for parts of the facility -- although Sedore declined to specify what IBM's investment was. He also compared the cost of generating power to the cost of purchasing power to see the big picture.
Before cogeneration using natural-gas-fired microturbines becomes an attractive option, local power has to cost at least 12 cents per kilowatt-hour and natural gas prices "have to be reasonable," says Sedore. In New York, the price of natural gas is about $16 per thousand cubic feet, which is much lower than the prices in, for example, Florida or California. "Climate is a factor because for cogeneration you need to have alternative uses for the byproduct heating [in winter] and cooling [in summer] to make it viable," Sedore says. That blend of heating and cooling is ideal for many states, but users in locales with warm year-round climates would not realize the benefits of the heating.