Compressors are machines that reduce the volume and increase the pressure of gases. Compressors are used to compress air for a variety of uses, to compress natural gas for distribution, and to compress refrigerants for use in residential and commercial HVAC equipment.
There are currently no national minimum efficiency standards for air or natural gas compressors. DOE issued a request for information in August, 2014 and held a subsequent public meeting to study whether natural gas compressors should be included under the ongoing air compressors rulemaking. Based on the information provided by various stakeholders, DOE decided to consider natural gas compressors separately from air compressors, and initiated a new natural gas compressor rulemaking. Refrigerant compressor efficiency is addressed indirectly through HVAC equipment efficiency standards.
In May 2016, DOE proposed to cover rotary air compressors ≥ 1 and ≤ 500 horsepower, driven by brushless electric motors, and with operating pressures ≥ 31 and ≤ 225 pounds per square inch gauge. The scope of the rulemaking covers bare compressor, driver (motor), equipment associated with the driver, and other ancillary equipment. In December 2016, DOE completed a final rule although they did not publish the final rule in the Federal Register so it is not in effect. Several organizations filed a lawsuit to compel DOE to publish the rule.
California, Colorado, Vermont, and Washington adopted the final DOE standards as state standards with a compliance date of January 1, 2022.
Industries use compressed air for many purposes including driving pneumatic tools, powering paint spray booths, and operating automated equipment. Many manufacturing industries also use compressed air or other gases for operations such as oxidation, cryogenics, refrigeration, filtration, dehydration, and aeration. According to DOE, technology options for improving the energy efficiency of compressors include improved controls, improved cooling fan efficiency, high efficiency motors and variable speed drives and inclusion of multiple-staged compressors.