Manufacturers should concentrate on five areas that could have the greatest overall effect on their facilities’ energy efficiency, according to Paul Stiller, director of energy management at Summit Energy Services, a subsidiary of Schneider Electric.
Writing for Industry Week, Stiller said many manufacturers waste hundreds of thousands of dollars a year on unnecessary energy spending. He proposes the following “New Year’s resolutions” for eliminating energy waste.
1) Use free cooling: In the winter, companies can use a heat exchanger to take advantage of cool outside temperatures, to chill water, valves and control modifications.
2) Waste heat recovery: Excess heat from cooling towers, exhaust and boiler flue gas can be used for space or process heat. Such heat can often be recovered using a simple air duct and summer/winter damper, Stiller said.
Heat recovery provides an enticing opportunity for industries using gas compression processes, according to a recent story in Sustainable Plant. About 50,000 Btu/hr of thermal energy is available to be recovered for every 100 cfm of air provided during compression.
3) Reduce peak energy use: Companies should record their electric loads at one-minute intervals, than average the power use over 15-minute periods to determine their peak loads and re-time operations accordingly.
4) Be careful with air compressors: Air compression machines are an inefficient means of delivering energy. To optimize their efficiency, companies should base-load all but one compressor. This “swing machine” maintains system pressure. Manufacturers should also avoid increasing operating pressure above 100 psig. Equipment issues can usually be resolved, instead, by changing distribution piping or adding receiver volume.
5) Turn off equipment when not in use: Monitor equipment for a week to see when it’s not being used. Stiller suggests monitoring in 15-minute intervals for electrical equipment and 30 minutes for gas-powered. Gas flow meters can be expensive, but companies can instead use data loggers on related electric equipment. Robust data loggers are available for about $200.
When hunting hidden energy costs it is often unnecessary to invest in permanent metering, as less expensive, temporary data loggers can obtain the same information, according to a recent best practice guide by Onset, a firm that manufactures such devices. According to the guide, loggers can be used to test the efficiency of air compressors.