Energy intensive data centers are mission critical components of DoD Installations. An EPA report to Congress about the Energy Star Program concluded that data centers consume more than 10% of all electricity used on DoD Installations. Cooling accounts for 40% of the electricity consumed by data centers, totaling over 4.4 billion kWh per year. Because of their mission critical nature, most data centers are exempt from energy reduction goals. Subsequently, IT managers are hesitant to adopt new energy saving technologies or practices that may endanger server uptime or system reliability.
ESTCP began three data center cooling projects in FY 2013 to reduce the energy consumption for heat rejection in DoD data centers. Traditionally, servers rely on highly inefficient internal fans coupled with building AC units to cool the entire server room. The three ESTCP projects attempt to decrease the mechanical cooling required to satisfy the thermal loads associated with data center heat rejection. Though similar in intent, the three projects employ different approaches.
Lawrence Berkley National Laboratory’s Immersion Cooling of Electronics in DoD Installations cools high heat density electronics through encapsulating the system and immersing the entire unit in a dielectric fluid. Heat from the servers transfers directly into the fluid rather than heating the air in the server room. Dielectric fluids do not conduct electricity; therefore electronics immersed in the fluid can function effectively. The project team expects to demonstrate server cooling with about 50% less energy than legacy AC systems and without using evaporative water.
Partnered with Munters Inc., Brookhaven National Laboratory’s Demonstration of a High-Efficiency Evaporative Cooler for Improved Energy Efficiency in DoD Data Centers, leverages an auxiliary cooling unit called the Oasis Polymer Fluid Cooler (PFC). The system is unique in that it can operate in both wet and dry modes, as ambient conditions permit, to maximize annual energy and water savings. The innovative design of this system minimizes the utilization of water as compared to conventional evaporative cooling devices. The use of a polymer – rather than metal – heat exchanger minimizes issues with fouling and water contamination, which simplifies water treatment and minimizes maintenance. The project team expects the system to reduce data center energy costs by 50%.
Asetek’s Data Center Liquid-Cooling involves direct cooling of servers by utilizing a direct-to-chip, hot water liquid cooling system. The technique, originally developed for supercomputing and high performance gaming computers, involves a relatively simple retrofit to route plastic tubes and small heat exchangers inside the computers mounted on racks in the server room. The system cools directly instead of relying on AC units to cool the whole room. The temperatures of the system allow for cooling without the operation of a refrigerant-based chiller, which results in a significant energy savings.
The three demonstrations will occur through 2016 to show how relatively simple concepts have the potential for short payback periods. They represent a small portion of the many and diverse activities associated with the ESTCP Energy Test Bed.