In the desert city of Las Vegas, there is an exceptional focus on conservation, with water and electricity heading the list of concerns. At the Mirage, the flagship mega-resort on the Las Vegas Strip, the management team has designed an aggressive framework of green initiatives that exemplify the city’s highest objectives. No element of the Mirage operation escaped scrutiny. Their chillers, which account for approximately 30% of the facility’s electricity consumption, got special attention.

In their quest to identify the most effective course of action, team Mirage, under the leadership of operations vice president David McKinnis and energy manager John Leslie, gave serious consideration to the benefits of VFD technology. This step is consistent with the MGM/Mirage corporate-wide policy of devoting the time and resources necessary to make the Mirage the standard-bearer for energy conservation on the Las Vegas Strip and the most highly automated plant in the western United States.

Put To The Test

Six 1,320-ton Trane chillers were commissioned when the Mirage was built in 1989, and remain in service today. Since then, the Mirage has authorized the purchase of high-quality, industrial-grade sensors to create the most sophisticated data collection program in the region.

MGM/Mirage also established funding for comprehensive research into savings opportunities. A portion of these funds was earmarked for the purchase of VFDs. To bolster the potential success of this course of action, MGM/Mirage partnered with a carefully chosen team of experts.

Siemens, a long-time MGM/Mirage preferred vendor, offered the Siemens Micro Harmony VFD. This design provides an advanced method for minimizing harmonics cost-effectively.

Prior to this MGM/Mirage project, VFD retrofits were almost exclusively associated with 480Vchillers. Siemens was instrumental in developing a drive compatible with the 4,160V chillers at MGM, a pioneering step that would deliver surprising results.

Metro Mechanical, another trusted MGM/Mirage supplier, took charge of the mechanical installation. They confirmed their value to the corporation once again by providing a smooth transition, installing sophisticated equipment under unconventional circumstances.

John Leslie was involved in coordinating this unprecedented retrofit from planning to completion and beyond. After the VFDs were commissioned, he devoted a year to testing and evaluating the equipment. Determined to test the limits of the two newly retrofitted VFDs, as well as the Mirage’s four constant-speed chillers, he then contacted Efficiency Technologies, Inc. to learn more about EffTrack, their Web-based chiller monitoring, engineering analysis, and reporting program.

Maximizing Efficiency

The industrial quality sensors required by EffTrack were in place at the Mirage, and Leslie provided the necessary original design criteria to begin EffTrack chiller profiling. All systems were go for conducting a remarkable level of performance testing by MGM/Mirage. He was able to identify what he could do and what he should not do to maximize chiller performance and efficiency.

“The goal at the Mirage was not just to add VFDs and turn them on and off,” says Leslie. “The goal from concept to completion was to see what the VFDs could do. The engineering team did not assume the VFDs were saving energy and money; they went beyond routine methods to verify the results of their efforts.”

MGM/Mirage, Siemens, Nedco IMC (Siemens VFD representatives), and Metro-Mechanical engineers/technicians expected the performance testing to reveal essential insights. But they were very surprised by the extent to which testing was possible using EffTrack. Leslie was able to go to unprecedented extremes - without damaging or compromising the equipment - because he was able to merge his extensive knowledge and experience with the precise monitoring capabilities of EffTrack. He tested the chillers at appreciably reduced evaporator and condenser flow rates; extremely low load limits; and extreme basin water temperatures. The chillers achieved excellent performance standards under these conditions, and EffTrack software verified the details.

With the purchase and successful implementation of the VFD program, the MGM/Mirage can now achieve and verify a monthly energy cost reduction of $11,000 for each VFD chiller and reduced monthly greenhouse gas emissions of more than 360,000 pounds of CO2 equivalents. MGM/Mirage is now building on the knowledge gained through this inaugural trial by rolling out VFD programs throughout all of their facilities.

“We are proud of the model we’ve developed for employing VFD technology to meet our energy and cost conservation goals,” says David McKinnis. “Every part of the process - the choice of equipment and consultants, funding for research and testing - was absolutely essential to achieving our rigorous objectives. We aimed high, and the payoff will only continue to grow as we expand the program into all of our locations.”