Compressed air is often used in industry to drive processes that could be achieved using far less electricity. Electricity savings of up to 80% may be realized for switching from use of compressed air to direct-drive (via electric motor) for specific applications.
Compressed air is often used in industry to drive processes that could be redesigned to use far less electrical energy. Electricity savings of up to 80% may be realized for switching from use of compressed air to direct-drive (via electric motor) for specific applications, such as cooling, drying, conveying, mixing, and cleaning. This type of technology requires familiarity with the specific application, but equipment conversions can yield substantial cost and energy savings.
Energy use reductions of 40% are often identified during compressed air assessments. Compressed air assessors are taught to look for potentially inappropriate uses of compressed air in industrial plants as many applications can be done more effectively or more efficiently using methods other than compressed air. The overall efficiency of a typical compressed air system can be as low as 15% to 20%. It takes 7-8 hp of electrical input power to an air compressor to operate a 1 hp air motor. Additional potentially inappropriate uses of compressed air include: open blowing (bearing cooling, drying, clean up, clearing conveyor jams), sparging, aspirating, atomizing, mixing and agitation, padding, dilute and dense-phase transport, vacuum generation with venturis, personnel cooling, open hand-held blowguns or lances, diaphragm pumps, cabinet cooling, and some hand held tool applications.
The compressed air auditor seeks to reduce air use requirements (hourly profile) through minimization of leakage and elimination of inappropriate uses of compressed air. The supply side is then optimized to meet these reduced airflow requirements. Sometimes a compressor can be turned off, resulting in significant energy savings.
Status:
Baseline Description:
Compressed air tools are used in many applications and have varying air flow, pressure, and operational requirements. Air tools include drills, nutsetters, impact wrenches, grinders, sanders, burring tools, rammers and tampers, air motors, paint spray guns, chipping and riveting hammers, circular saws, nailers, blow guns, caulking and grease guns, concrete vibrators, jackhammers and pavement breakers, pneumatic doors, and lifts and hoists. A sander with a 9-inch pad would require 20-cfm (of 100-psig air) given a 25% usage factor (from: "Air Consumption Charts for Industrial Type Tools", from Ingersoll-Rand, at http://www.industrialairpower.com/wp-content/uploads/Air-Compressor-Consumption-Charts.pdf). Rotary screw compressors have a specific package power of about 20 to 22 kW/100 cfm, so a 20-cfm air flow requirement is equivalent to a compressor drive motor input power of 4 kW to 4.4 kW. This estimate understates potential savings as it examines end use requirements versus compressed air delivered to a wet receiver. It does not account for compressed air losses due to leaks and the purging of desiccant dryers.
"Typical" Savings: 85% Low and High Energy Savings: 80% to 87%
It takes 7-8 hp of electrical input power to an air compressor to operate a 1 hp air motor.
Simple payback, new construction (years): N/A
Simple payback, retrofit (years): N/A
Cost Effectiveness is calculated using baseline energy use, best estimate of typical energy savings, and first cost. It does not account for factors such as impacts on O&M costs (which could be significant if product life is greatly extended) or savings of non-electric fuels such as natural gas. Actual overall cost effectiveness could be significantly different based on these other factors.
EERE, 12/22/2003. Improving Compressed Air System Performance: A Sourcebook for Industry Energy Efficiency & Renewable Energy