How can I reduce the running costs of a compressed air system?
There are a number of things you can do to reduce the running costs of your compressed air system. Some of these are easy to achieve with little or no incremental costs, some are more complex and strategic which require planning and investment. All should be built into your business plans and company regular maintenance procedures. In this article we are looking at the lower cost approaches that will definitely help you save electrical costs. Click here to see the second article in this series that looks at the more complex, costly and strategic approaches
So lets look at the low cost fixes
Check and fix air leaks in your pipework / attached equipment
This sounds a completely obvious fix but practically every compressed air system over a year old will have some degree of leaks. The leaks may be in the pipework or may be in the fittings connected to the pipework or may be within the machines that use the compressed air.
There are lots of ways of checking pipework for leaks. One of the best methods is using an ultrasonic tester which listens for the sound of an air leak. There are also systems that use leak detection fluid (a bit like putting a bike inner tube into a bucket of water) and looking for bubbles. However, the key is that even a very small leak, maybe a leak that is too small to hear with your ear will be wasting several cfm.
See our compressed air leak chart below
Leak noise level (dB) Sounds like leak size (cfm @100psi) approx cost (per hour)
10 normal breathing 0.5 £0.01
20 mosquito 0.7 £0.01
30 whisper 1.3 £0.03
40 domestic fridge 1.5 £0.03
50 quiet office 2.5 £0.05
A typical small compressed air system that is several years old will have between 10 and 30 separate leaks equating to a cost of leaks of between £2 and £7 per day.
Air Equipment can come and do a ultrasonic leak test on your compressed air system to identify and repair the significant leaks in your compressed air system. The cost of this can easily be saved in a few months by the energy saved.
Turn off your compressor when it is not in use
Again an obvious one, simply turn off your air compressor when you are not using any compressed air. As we know, almost all compressed air systems have some level of leak (see above). Leaving your air compressor turned on when you are not using any compressed air is basically just feeding the leaks in your system.
Reduce the air compressor working pressure
Keep the working pressure of the compressor to the minimum you can that still meet your process needs. Many people set the pressure to a higher level than is actually needed based on the ‘better safe than sorry’ principle. This uses more energy to compress the air to an unnecessarily high pressure. It also makes the effect of leaks worse, and also amplifies the effect of pressure losses through pipework and other auxiliary equipment.
Keep your compressor room well ventilated
This may sound a little odd, but keeping the temperature of the air entering your air compressor low improves energy efficiency. A 4’C rise in ambient temperature of your compressor house will result in 1% more energy usage.
Use the heat generated by your compressor for space or water heating
This is a slightly different approach to saving energy costs. You compressor creates a lot of heat as part of the compression process. Typically over 80% of the energy used in the compression process is given off as heat. For our 11KW compressor this means about 9KW of the input energy is given off as heat, this heat is usually released to the atmosphere and wasted. It is usually easy to duct this heat into a building to help keep the building warm. This reduces the amount of other heating required, saving energy costs.
Alternatively it is a relatively easy add a heat exchanger to the air compressor cooling system and then this can be used to pre-heat water for the central heating system, showers or warm process water etc. Again this is a relatively low cost approach that can save money used for heating elsewhere in the business.
The British Compressed Air Society (BCAS) the UK trade body for Compressed Air Manufacturers and Distributors have produced a white paper on saving energy costs on compressed air systems. Click here to download the BCAS efficiency white paper