Today the US Department of Energy (DOE) released new energy efficiency standards for rotary air compressors. These large air compressors power a range of commercial and industrial equipment such as manufacturing robots, pneumatic tools, and paint sprayers and use about 6 percent of all motor-driven electricity consumption in the industrial sector. Today’s new standards set minimum efficiency requirements for lubricated rotary compressors, which account for most compressor energy use. DOE did not set standards for reciprocating compressors or unlubricated rotary compressors.
DOE estimates that compressors meeting the new standards will save 0.16 quadrillion BTUs by compressors sold over 30 years, or about 15.6 billion kilowatt hours, resulting in net savings of $200 to $400 million for compressors purchased over this period. This reduction in energy consumption will also prevent the emission of an estimated 8.2 million metric tons of CO2 over the same period. To put this in perspective, this energy is equivalent to the annual electricity consumption of 1.3 million US households, and the CO2 emissions are equivalent to what 1.7 million cars in the US put out in one year.
Manufacturers, who generally supported the efficiency levels adopted when originally proposed by DOE earlier this year, can meet the new compressor standards by incorporating readily accessible, proven technologies into their products including improvements to the design, engineering and surface finish of the basic compressor components. Other improvements that can be used to meet the new standards include multiple compressor stages with intercooling and improvements to the efficiencies of filters, dryers, and other auxiliary components.
These energy efficiency standards are the culmination of nearly three years of analysis and development at DOE, beginning in February of 2014. DOE followed the normal, in-depth analysis path considering technology options, manufacturer impacts, and consumer and societal effects to develop the proposed rule released in May of this year. The new standards will first come into effect in 2022, giving compressor manufacturers and the market ample time to adjust.
Although these new standards are an important step for compressor efficiency, DOE could have gone further. The new standards only cover lubricated rotary compressors, which are the type of air compressors that tend to have the largest rated output. High output air compressors account for less than 1 percent of annual compressor shipments, but they represent an estimated 80 percent of total annual electricity consumption by air compressors. The majority of air compressors sold are reciprocating compressors, which tend to be smaller and not to run as many hours per year. However, there are also high output reciprocating models that are not covered by the new standards. The European Union is currently working on compressor standards that are expected to also include reciprocating technology and DOE should also address it in the future.