Regularly Performing Compressed Air Energy Audits Can Boost the Bottom Line
A focus on sustainability coupled with the rising cost of electricity has made energy efficiency a top priority for industry. Unfortunately, improperly designed and maintained compressed air systems can be major energy hogs. As a matter of fact, the U.S. Department of Energy’s Compressed Air Challenge found that in a typical industrial facility, approximately 10% of the total energy consumed is used to generate compressed air and, for some facilities, compressed air generation may account for 30% or more of the electricity bill. Further, compressed air is one of the most expensive sources of energy in an industrial facility and the overall efficiency of a typical compressed air system can be as low as 10% to 15%.
What does this mean for your facility? Simply put, if your compressed air system is working harder than it needs to, it is using more energy than it should be while the associated utility costs quickly – and unnecessarily – escalate. Fortunately, performing an air energy audit on a compressed air system can help determine the ways in which efficiency can be improved, helping to reduce energy consumption and boosting your bottom line. Additionally, the Compressed Air Challenge’s best practices manual states that air energy audits can help manufacturers save up to 50% of the energy currently being used to run compressed air systems.
What is an Air Energy Audit?
Consider an air energy audit as a tool that helps determine whether the existing compressed air system is performing as efficiently as possible by discovering areas of loss and providing recommendations for correcting inefficiencies. Not only can this process reduce energy costs and provide a better understanding of how your system is operating, but it can also improve compressed air quality, catch issues before they require major repairs and increase life of the system and its components.
Compressed air energy audits can be performed on any budget and usually without disrupting production. A basic, walk-through audit can be accomplished at a very low cost, or possibly for free, while a more expensive, full-system audit conducted by a professional will include leak detection, data logging, power and flow rate measurements, air quality assessments and suggestions for improving efficiency and maintaining the system going forward.
The most basic audit is essentially a walk-through conducted by in-house personnel or your compressed air equipment/service provider and involves a simple visual inspection of the compressed air system. Basic audits can be used to detect leaks, inefficiencies, improperly sized or malfunctioning equipment and areas where performance is lacking, which can help you correct efficiency losses and boost productivity at a low cost.
Next level auditing includes the use of data logging equipment, which provides a more detailed, in-depth audit than a walk through alone. Data logging measures the performance of the compressor system over the course of seven to ten days, which can help determine whether the compressor is properly sized and operating at an optimized level. Often, local utility providers offer rebates and incentive programs for data logging audits.
Finally, there is the option of a full-system audit performed by professionals. While this service can cost thousands of dollars, it is very thorough and may provide significant savings – potentially slashing 10% to 50% percent of the electricity costs – if recommended actions are put into place. Utility providers often offer rebates and incentive programs for professionally performed audits, sometimes including rebates for recommended equipment as well.
What is Involved in An Air Energy Audit?
Depending on the complexity of the audit you’ve elected to conduct, it will likely include a site assessment, measuring and analyzing data, recommendations for improvements and a follow-up visit to determine how much efficiency has been gained by implementing suggested improvements. The audit can and should take place while the facility is up and running in order to get a real-life, real-time view of operations.
During the site survey, the auditor conducts a walk through to determine the layout of equipment, components and piping in the facility’s compressed air system, how components interact with each other and potential areas for improvement. Following the site assessment, measurement devices, such as amp loggers or kW loggers, will be placed on the air compressor(s) to measure amps, volts and power factors of the incoming power, while pressure loggers will measure compressor discharge pressure, pressure after the filtration and dryer, and downstream plan pressure. Other measurements may include air flow, air pressure, temperature and dew point. The measurement period should be at least seven to ten days and should include nights, weekends, or other downtimes to identify non-productive demands.
Once the data is collected, it should be analyzed using software that finds key patterns and inconsistencies. This information can be used to create reports containing performance indicators such as air flow demand throughout the plant, compressed air system costs, system efficiency and whether the use of compressed air is necessary for all the applications to which it is applied. Thorough analysis will pinpoint the areas of inefficiency and loss, incorrectly sized equipment and potential maintenance issues.
Recommendations for improvements are made based upon these findings and often include repairing leaks, replacing incorrectly sized air tanks with appropriately sized tanks, curbing over-pressurization within the system, installation of flow control valves, replacing faulty piping and components, eliminating unnecessary system components, replacing compressors and air dryers with models that have more efficient control methods, eliminating inappropriate usage, monitoring system equipment and improving maintenance activities. Obviously, action should be taken on the recommendations in order to remove inefficiencies and improve performance of the system, but, ultimately, the user decides which actions to implement.
Typically, a follow-up visit from the auditor after the appropriate changes have been completed will again measure system performance and determine the achieved reductions in energy usage and improvements in efficiency. Often, it is determined that taking recommended actions provides a return on investment of one to five years.
How Often Do I Need an Audit?
All compressed air systems should go through regular audits every three to five years to ensure the system is running at peak efficiency and optimized levels; however, if the system has been adjusted by adding, replacing or removing equipment or the plant has changed its productivity levels or experienced shift changes, it may be time for an audit. Additionally, if you notice efficiency dropping, unexplained spikes or dips in energy bills, frequent or unpredictable pressure fluctuations, system leaks or frequent repairs or maintenance on the system or components, it may be a good time to perform an audit.
Regularly performing compressed air energy audits will help identify how the system is operating and where it can be improved to increase performance, efficiency and reliability, which will ultimately boost your bottom line. For more information on compressed air systems and efficiency, please contact a JHFoster specialist.