Energy saving is on everyone’s mind at the moment. With rising energy costs putting major financial pressures on us all, it’s no surprise that the compressed air sector is experiencing similar issues.
And with compressed air said to account for 10% of a site’s electricity bill, it’s no wonder that teams are working hard to design compressed air systems that are as efficient as possible.
We would recommend taking a 360 approach to air compressors, ensuring that all areas of the system are prioritised. Focusing on just one area of the system, for example, will mean that other opportunities to save energy could be missed, leading to unnecessary energy usage.
As we’ve explored in other recent blog posts on leak reduction and maintenance of air compressors, there are more important issues that need to be addressed first before looking at energy saving measures as a whole. For example, a leak in an air compressor system could result in a large amount of energy wastage, but could easily be fixed or avoided entirely.
In this blog post, we will share advice on how to design a compressed air system that can help to maximise energy savings, and, therefore, help to save you money in the long term.
Designing an energy-saving system
Your air compressor will undoubtedly be your largest energy-consuming system. But it’s also important to consider that the usage and design of your system will dictate its overall energy consumption.
Poor system design, incorrectly dimensioned distribution piping and purification equipment can lead to avoidable pressure loss, so it’s important to consider these points when designing your system. Pressure loss will, of course, increase costs with the need to generate compressed air at a higher pressure.
How to calculate your system’s annual cost
If you’re looking for ways in which to maximise your energy savings, it’s important to calculate your system’s total yearly cost. This will allow you to identify opportunities to maximise your energy saving plans.
To check on the electrical consumption of your compressor, you will need to obtain the reading by sub-metering the compressor house. This will be in kilowatt hours (kWh).
A data logging system will also help to determine the yearly cost of your compressor system. This needs to be installed for a period of at least seven days.
With this system in place, you can determine the pattern of demand, otherwise known as a demand profile, and the off-load running time when there is no demand for air. This does not account for the ‘off-load’ power consumption, when the compressor is consuming energy without generating air.
And finally, option 3 allows you to calculate the annual cost of your system by estimating the energy consumption of each air compressor.
You can do this by following this working example: a 75kW compressor operates at 7 bar. It is on load for 80% of the production time, which is 2,000 hours per year. Energy consumption of the compressor = 75 x 0.8 x 2,000 = 120,000 kWh/year. If electricity costs £0.1249/kWh, the annual energy cost is £14,988. Should production time increase to 6,000 hours per year, for example, then the annual energy cost would rise to £44,964.
With a range of options available to monitor the annual cost of your air compressor system, it’s important to also ensure that you are comparing alternatives based on ‘whole life’ cost, not just the initial capital outlay. By opting for equipment that is a higher cost but is more efficient, you will benefit from lower running costs in the long term.
For more information, please speak to a BCAS member who can assist in this area by emailing firstname.lastname@example.org. And to download a free copy of the system design guide, please click here.