Step 1 for Compressed Air Analysis: Cost distribution over the life cycle

Over the life cycle of a compressed air system, the costs are generally distributed as follows:

1. Acquisition costs (about 10-15%): Cost of purchasing and installation of the system, including equipment like compressors, dyers.
2. Energy costs (about 70-75%): Cost of electricity consumption during compressed air system operation.
3. Maintenance costs (about 10-15%): Spare parts, repairs, routine maintenance and service contracts

While exact percentages may vary depending of type of compressed air system and operating conditions, energy costs are always the dominant factor in the life cycle of the compressed air system.

The specific power in (kWh/m³) corresponds to the efficiency of the compressed air system based on the ideal adiabatic compression for air:

where:

• W = power requirement per cubic meter (kWh/m³)
• y= 1.4 (specific heat ratio for air)
• P1 = Atmospheric pressure (1 bar absolute)
• P2 = Final pressure after compression (typically 7 bar absolute)
• n = Efficiency of the compressor (typically 85-95%)

As there are various factors influencing the specific power and thus efficiency of the compressor, it should be permanently monitored. A efficient and new compressor may even work inefficiently in a system that is not optimally designed.

An efficient compressor would typically have a specific power of around 0.12 kWh/m³ or 7.2 kW/ (m³/min).