It’s human nature to be tempted to bury our heads in the sand and wish our problems would go away by themselves. Some smokers, choc-o-holics and even some compressed air system operators choose to go by the old axiom “What you don’t know won’t hurt you.” They’re attempting to negate the consequences of their actions by avoiding the facts entirely and staying uninformed. But the consequences speak for themselves; problem avoidance and lack of awareness can hurt your plant budget and profitability big time — in higher energy costs and lost productivity.
What are your costs?
Compressed air system equipment is notoriously lacking in cost-related instrumentation. Most systems include only an indication of system pressure and a few compressor temperatures. Missing are measures of compressed air flow and power consumption. This is much like automobiles used to be, when all you knew was how fast you were going and how much fuel remained, with a few idiot lights thrown in for good measure.
Nowadays, you have a fighting chance. Often, an on-board computer calculates instantaneous and cumulative fuel economy. Lacking that, it’s easy to do a quick tally of the odometer and the number of gallons on the pump, and you quickly have your efficiency number. But, in most compressed air systems, energy readings are missing, leaving you scratching your head in wonder. However, in these days of higher energy prices, it has become essential to be able to know how much your system is costing to operate.
|Measure||Percentage of Potential Savings|
|Add, Restore, Upgrade Compressor Controls||30|
|Reconfigure Piping to Reduce Pressure Loss
|Add Compressed Air Storage
|Install or Upgrade Distribution Control System||20|
|Rework or Correct Header Piping
|Modify or Replace Regulators (Controls at the process)
|Replace or Repair Air Filters
|Install or Upgrade (Ball) Valves in Distribution System
|Not Otherwise Specified||10|
|Replace or Upgrade Condensate Drains||5|
|Replace Current Compressor with More Efficient Model||2|
|Add Small Compressor for Off-Peak Loads||2|
|Add, Upgrade or Reconfigure Air Dryers||1|
|Improve Compressor Room Ventilation||1|
The annual cost savings are calculated from the annual energy savings using $0.05/kWh as the unit cost. The unit cost is based on information contained in the table: “Electric Utility Average Revenue per Kilowatt-hour to Ultimate Consumers by Sector, Census Division, and State” prepared monthly by the Energy Information Administration, U. S. Department of Energy. The payback of the energy savings is calculated as the ratio of the capital cost to the energy cost savings from the measures.
What’s at stake?
How much can the average industrial plant gain by knowing its operating costs? One way to answer this question is to consult a research document titled “The Assessment of the Market for Compressed Air Efficiency Services” (Compressed Air Market Assessment), commissioned by the U.S. Department of Energy (DOE) with technical support provided by the Compressed Air Challenge (CAC). See the sidebar for links to supporting documents.
The Compressed Air Market Assessment found that compressed air systems account for 10% of electricity and roughly 16% of motor system energy consumption in U.S. manufacturing industries. Seventy percent of manufacturing facilities in the United States have some form of compressed air system to drive a variety of equipment, including machine tools, paint booths, material separators and material handling equipment. The assessment indicated that recent experience in a variety of “system optimization programs” and the experience of consultants in the field show that more than 50% of industrial plant air systems harbored opportunities for large energy savings with relatively low project costs.
The DOE Industrial Assessment Center program conducted energy audits of small- to medium-sized industrial facilities and identified measures that had average projected compressed air system usage savings of 15% and simple paybacks of less than two years. And many case studies conducted for system optimization programs identified savings in the range of 30-60% of initial system usage. In addition to energy benefits, optimized compressed air systems frequently exhibit corresponding improvements in reliability, product quality and overall productivity.
Customer awareness of and concern for compressed air efficiency is low. Only 9% of customers interviewed for the program identified controlling energy costs as the primary objective in compressed air system maintenance and management. Only 17% mentioned efficiency at all as a system management objective. This low level of interest and knowledge was echoed in findings from the regional studies and interviews with compressed air system efficiency consultants.