Industrial Utility Efficiency

# University of Manitoba Bannatyne Medical Campus Saves 15% Annually in Energy Costs

Interestingly, the analyses compared a similar sized oil-free fixed speed air compressor from the same manufacturer to the VSD variant of the air compressor. It predicted that the VSD air compressor would consume about the same power due to drive losses and lower overall internal compression element efficiency. However, because the VSD unit operates at a fixed-target pressure, with a setting lower than the load/unload pressure band of the fixed-speed type, the savings due to the lower pressure was estimated at about \$1,100 per year. In addition, the prediction showed the HOC dryer would save about \$4,600 per year in electrical costs. As a result, the utility was able to offer about \$13,500 in incentives toward the project. ### Conclusion The project was verified after installation and the compressed air load was found to be lower than expected, making the savings higher than predicted. Instead of the expected 148 cfm the actual facility flow was calculated at 130 cfm. The compressor energy was measured at 292,000 kWh costing \$17,800 per year to operate, which represents a 15% savings in annual energy costs when compared with the original compressed air system that cost \$21,000 per year to operate. Importantly, the use of VSD air compressors and HOC drying – instead of the 75 HP fixed-speed air compressor with heatless desiccant drying – resulted in an energy cost reduction of 28 percent when compared with the new base case of \$24,600.

##### Figure 6: A histogram in the air compressor control panel shows the air compressor remains loaded at its most efficient point, but has additional capacity for future changes.

In the final analysis, the use of waste heat and the reduction of pressure saved energy over and above the fixed-speed variant with heatless dryer. As a result, a substantial utility incentive was gained and, ongoing annual energy savings achieved for years to come.

In addition to energy savings, the installation of the VSD air compressor with an internal HOC dryer allowed the University of Manitoba Bannatyne Campus to renew its air compressor system, improve their air quality and upgrade its compressed air capacity. The compressed air system now has enough capacity that further increases in compressed airflow can be accommodated without the need to purchase another air compressor or experience low pressure. The new air compressor system also saves valuable floor space because the compressor and dryer are all in the same package.

For more information contact Ron Marshall, Marshall Compressed Air Consulting, tel: 204-806-2085, email: ronm@mts.net.