Compressed air energy efficiency

The cost of using compressed air is many times greater than that of other energy sources. So it makes sense to only use compressed air where appropriate, and to use cheaper alternatives whenever possible.

Do you need to use compressed air at all?

Compressed air is commonly used for some operations that could be carried as out as effectively - and with far less energy consumption - using an alternative method. For example, compressed air is often used for 'pick and place' applications where the air is used to generate a vacuum that lifts an item and takes it from one place to another. But a vacuum pump would generate the same volume of vacuum for a fraction of the energy.

It's a good idea to take a critical look at all the processes where you currently use compressed air and work out on a case-by-case basis to determine whether there is a more cost-effective alternative.

Switching air compressors off

An idling compressor can still use between 20 and 70 per cent of its full load power. So you can save a significant amount of energy if you turn compressors off when they are not needed. It might be appropriate to have a switch-off procedure for each compressed air process, which you could automate using time-operated solenoid valves or interlocks. These only allow a compressed air line to operate if another piece of equipment is already running.

Controlling air pressure

Regulating the air pressure to the requirement of the particular device being powered can result in significant savings. By comparing the device manufacturer's recommendations with the actual pressure used on site, you can find out if you're using more compressed air than is necessary due to the higher pressure. If you are, you can fit a pressure regulator that's local to the device and will deliver only the correct amount of pressure.

Similarly, it's a good idea to make sure that the system is delivering the air in the most efficient and effective way. For example, many blow guns are just open-ended pipes. Fitting a venturi-type nozzle to these delivers the same performance for up to 30 per cent less air.

It's also very important to keep the distribution system pressure drop as low as possible, typically below 0.2 bar, because a large pressure drop across the distribution system increases energy consumption due to the compressed air having to be generated at a higher pressure.