How to Calculate Your Compressed Air Energy Costs

As we discussed in our Compressed Air Costs: 7 Expenses That Every Manufacturer Should Track blog post, the total cost to own and operate a compressor is generally organized into three groups – the initial capital investment or purchase price, energy usage and maintenance costs. The cost of energy is the single largest expense facing manufacturers who operate air compressors and can account for up to 75% of the compressor life-cycle cost. Because of this, understanding what you are spending to run your compressor is critical when looking for potential savings.  

Calculate Your Compressed Air Energy Costs 

To calculate the cost to produce compressed air at your plant, use the formula below. 

• Rated Power – The horsepower rating of the motor powering the air compressor; this is located on the motor nameplate.
• Service Factor – This is how far above the rated horsepower a motor can operate without damaging the motor; this is located on the motor nameplate. 
• Running Hours – The number of hours the air compressor operates on an annual basis. Continuous running machines typically operate 8,000 hours per year.
• Energy Rate – The current cost of energy from your local power supplier. For reference, the average power cost per kW is .12 cents in the USA and .33 cents (USD) in Germany.
• Full Load Time – If your compressor is fully running this would be a 1; if it is less than full time, use the percentage that it is running.
• Percentage of Compressor Loaded – This is the percentage that your compressor is operating. 
• Motor Efficiency – This is the operating efficiency of the motor found on the nameplate.

Example

Let us assume you are running a 200 hp compressor with a rated power of 215 that operates for 8,000 hours annually. It is fully loaded 85% of the time with a motor efficiency of 95% and unloaded the rest of the time (25% full-load and motor efficiency of 90%). The electric rate is $.12/kW. 

The cost when your compressor is fully loaded: $137,766.57/year

The cost when your compressor is partially loaded: $6,415.60/year

Save Time with AirCompare – Compressor Life-Cycle Cost Calculator

Now that you understand the formula for calculating your energy costs let us do the work for you. We invite you to run the AirCompare compressor life-cycle cost calculator to find out what you are spending at your plant. You may elect to receive a full report at the end of the tool to see a more comprehensive analysis of your energy costs and maintenance spending. 

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