## Energy Answers: The Cost to Operate a Compressor (video)

How much does it cost to operate a compressor? If you can read your electric bill, a motor nameplate and understand a few simple formulas, you can quickly find the answer for your compressor, or any other motor-driven process.

Just take power in kilowatts (kW), multiply it by time in hours, and multiply that by your electricity rate in dollars per kilowatt-hour (kWh).

Every motor should have a nameplate that provides specific information about the unit. What we are looking for is the power input in kW. In this case, we are only shown 40 horsepower (HP) output. If the nameplate only shows HP output, convert it to electrical power input using the following formula:

**40 HP x 0.746/.96 = 31 kW**

Time is how long you expect to operate the equipment. Let’s say eight hours. Next, find your electricity rate on your bill. We will use $0.08 per kWh in this example. In this case it would cost about $20 to run a compressor for eight hours:

**31 kW x 8h x $0.08/kWh = $19.84**

If you are running your compressor at part load, the cost would be less, but not exactly proportional due to reduced efficient at part-load operation. This formula should give you a good idea for estimating purposes, however.

You also have to add any peak demand charges. If your demand charge is $8 per kW, for example, it would cost you an extra $248 per month to operate:

**Peak Demand = 31 kW x $8/kW = $248**

Making sure your system is efficient and used properly can make that money stretch even further.