As Data Centers Grow, Innovators Search for Green Cooling Methods
As web services remain a growth area, the number of data centers – large facilities that house web servers and other back-end IT systems – continues to spring up at a brisk pace. This is causing a dilemma, as data centers chew through between 100 to 200 times more energy than typical offices do while the companies that own them seek to meet U.S. environmental mandates. This has opened a new market for green data centers.
As a company that runs a data center can commonly shell out nearly half of its budget for energy, green data centers are designed to run at maximum efficiency and use the least amount of power. Many companies keep track of a number called the PUE, or power usage effectiveness, ratio, to measure the efficiency of their data centers. The biggest factor in driving up PUE ratios is cooling, which is necessary to keep servers running at optimal efficiency. While temperatures go down, PUE numbers trend up; most data centers operate with a PUE between 2 and 3.
Green-minded companies, however, are taking steps to suppress this number. Facebook’s recently launched data center in Oregon reportedly has a PUE of 1.07 and consumes about 38 percent less energy than a typical center. GE runs an ultra-efficient data center that boasts a PUE of 1.63. One of the features these green data centers share is a series of innovative cooling methods.
Liquid Cooling Can Eliminate Air-Conditioning
An Austin, Texas-based startup called Green Revolution Cooling recently introduced a liquid cooling system that it says can bring down the temperature of data servers for a fraction of the cost of air-conditioning. The company’s CarnotJet Dielectric Fluid Submersion (DEF) Cooling System allows servers to be inserted vertically into slots in a specially designed enclosure that is filled with a coolant that resembles mineral oil.
Green Revolution Cooling says its system allows customers to operate their data centers without the need for traditional computer room air-conditioning (CRAC) units. This negates the need for raised floors or chillers, according to Data Center Knowledge.
While cooling with a mineral-oil-like substance isn’t new – Cray Research used mineral oil as a coolant in its Cray2 supercomputer in the 1980s — Green Revolution Cooling says its DEF coolant goes beyond other fluids and can support heat loads of up to 100 kilowatts per 42U rack, which far exceeds average heat loads of 4 to 8 watts per rack and high-density loads of 12 to 30 kilowatts per rack.
Green Revolution Cooling’s GreenDEF recently completed a high-profile test run at Intel. The chip maker used the system to achieve a PUE ratio of between 1.02 and
1.03. According to Green Revolution Cooling officials, the system reduced power consumption for cooling for Intel’s data center by as much as 95 percent, which resulted in a 50 percent reduction in energy use.
Outside Air Cools a Modular System
Toshiba and Nanyang Technological University (NTU), in Singapore, are currently collaborating on a new cooling technology for data centers that the organizations say can cut energy use by 30 percent. A data center in Singapore is using Toshiba’s air-cooling technology in concert with NTU’s advanced info-communications technology. The savings are derived from the unique shape of the setups – container-sized modules that can either stand alone or be combined – coupled with a smart cooling system, according to the website Phys.Org.
The system makes use of outside air for cooling purposes whenever possible. To keep the heat generated low in the first place, the data center optimizes server capacity by consolidating multiple applications from different servers into one server. When additional servers are not needed, they go into sleep mode, which saves both electricity and the need for cooling.
While everyone knows that wind can cool on a hot day by removing heat, the same is true for heat-generating equipment. Canadian firm SMi Group International is using wind and air flow in a new cooling method that can reduce costs and energy use by as much as 50 percent, reported Green Tech Media. SMi’s technology basically lifts the heat off of the servers:
“We said, let’s try to remove equipment and simplify the equation,” said Jean-Simon Venne, head of the company’s energy efficiency division.
First, the company uses precooling, which isn’t new and has demonstrated the ability to cut energy use by only about 10 percent. To bump up the energy savings, SMi engineers determined that by combining precooling with a technology that pressurizes the space inside the server enclosure and blows air over the equipment before heat has a chance to build up (essentially putting it into a wind tunnel), they could effectively cut energy use in half. The new technology also comes with an unexpected green bonus: SMi says the space-efficient configuration of its solution means companies can reduce the size of their facilities. The result, apparently, could be a PUE ratio as low as 1.1 for a new facility and 1.3 for a retrofitted facility.
Make Less Heat To Begin With
Many data centers are finding energy savings in a new way of converting AC power to more power-sipping DC. Normally, high-voltage AC power from the grid is converted to DC and back again as many as five times to decrease the voltage before it’s used by servers. Each time it’s converted, however, it loses power, says Green Tech Media. Converting AC to DC just once at the power gateway can cut energy use by 10 percent over a typical AC data center and more than 20 percent over a traditional center. Additional savings can come from the use of DC equipment, which is cheaper and requires less cooling. In addition, a DC data center can be between 25 to 40 percent smaller, since the equipment can connect directly to backup batteries without the need for uninterruptable power supplies (UPS), which take up space.
Companies achieving savings today with DC data centers include JPMorgan, Sprint, Bank of America, Boeing and SAP, all of which have reported lower energy costs with their installations.
While a company may not want extra heat in the server room, that heat could be useful in other parts of the building. For this reason, many data centers are harnessing the heat they draw off servers and delivering it elsewhere.
This method will be used by a new hybrid supercomputer being built for the U.S. Department of Energy’s National Renewable Energy Laboratory, which has partnered with HP and Intel to create both the machine and an energy-efficient data center to house it. Heat from the as-yet-unnamed computer, which will be located in a facility in Golden, Colo., will be harvested and delivered to other parts of the building. This, in conjunction with other cutting-edge cooling methods such as component-level water cooling inside the server (a process that is still in beta stages by HP and not yet commercially available), will result in a petaflops-class computer that uses no mechanical chilling.
The design developed by HP and Intel is reportedly capable of reducing server heat by 90 percent, leaving the remaining 10 percent to be dealt with by evaporative cooling.
As companies go greener yet need to launch more web services and store ever larger blocks of data, green data centers are expected to thrive. As these facilities currently use about 2 percent of the power consumed in the U.S. , it is not hard to envision a near future in which they will consume 5 percent or more of all energy. For companies that develop the “magic bullet” in low-energy cooling, the future is very cool.