How green is green? That's always a matter of how the beholder interprets the color. But Syracruse University is very proud of its Green DataCenter, which uses trigeneration microturbines and absorption chillers to keep energy use and costs down. It hopes other datacenter designers will follow its lead.
Tom Gibson took a look at Syracruse's facility for Progressive Engineer in detail in an article that tracks its concept from its initial collaboration between Syracruse, IBM and the New York State Energy Research and Development Authority (NYSERDA) to its completion in December 2009. Mark Weldon, executive director of corporate relations at Syracruse, boasts that it's “the greenest datacenter in the world.”
After deciding to partner with IBM to design the datacenter, IBM challenged the university to build one that would cut energy use in half, and to complete it within two years. It cost $12.4 million to build the 12,000-foot facility, including 6,000 square feet of primary raised-floor space for computers and servers. IBM donated $5 million in design services and NYSERDA contributed $2 million in cash. After the design was finished, the facility was actually built in 188 days.
The datacenter is a lights-out facility with no staff, typically controlled remotely from a laptop computer. It's powered by 12 Capstone natural gas-fueled microturbines, which allows the university to relegate the grid to backup if it wants—although it usually uses the grid for power and the turbines for backup. The university uses the microturbines when the electricity rates from the grid are high. Batteries start the turbines and double as an emergency backup power system. The 300-volt battery banks can run the datacenter for at least 17 minutes at full power.
Microturbines provide electricity and heat for hot water and cooling
Capstone developed a new microturbine for the facility, the Hybrid UPS, a variation on a previous product it sells, the C65, which produces 65 Kw of power. It uses an air bearing, enabling it to spin at 96,000 rpm. That's done with a foil shaped like an airplane wing that creates a thin film of air so that the turbine shaft actually floats on air.
The center has its own direct current sub-distribution system that moves the current directly from the turbines to the equipment, cutting energy use by about 10 percent—energy that would normally be lost in the conversion from AC from the grid to DC for the equipment. The turbines still lose energy converting the gas to electricity, of course, on the order of a 30% loss.
The energy from the turbines, however, is used efficiently. They are used for cooling, heat and power, making them trigeneration devices. That boosts the energy conversion rate to 80%.
The turbine exhaust is 3070C (5850F). The exhaust from all six microturbines goes into one duct, which directs it to two heat-recovery modules. One is for hot water and another powers absorption chillers that create chilled water. One chiller generates 100 tons of cooling water for the datacenter, the other generates 200 tons for the research and office building next door. Although the chillers can cool water as low as 70C, these are set to cool the water to about 200C for both the datacenter and the office building. In the datacenter, the cool water is fed to heat exchangers at the back of the server racks, where fans blow the cool air across the servers and into the room. Sensors monitor the temperatures, and the temperature of each rack can be controlled individually.
The hot water from the microturbines is used in the office building--to run the perimeter heating system, to preheat ventilation air from the outside, and to produce domestic hot water.
But is that really the greenest datacenter in the world? After all, it still relies on the grid and gas-powered turbines. Kevin Noble, manager of engineering for campus design, planning and construction, acknowledges that flaw.“We are actually considering supplementing our DC power system with solar panels,” he says.
When the primary power system is solar, then we might really put the datacenter into contention for the greenest around--although the competition is getting fierce.