Did you realise that Australia’s retail electricity prices have risen by 72% alone in the five years to June 2012? Once seen as a relatively low fixed cost, energy is now becoming an important variable cost that impacts on company profits. The energy costs of a typical compressed air system can account for almost three quarters of its lifetime costs. In addition, depending on utilisation, electrical power can account for up to 90% of the total costs of compressed air production. It therefore pays to keep power consumption of compressors and peripheral equipment to an absolute minimum. Many existing compressed air users could be hiding an energy savings potential of 30% or more!
How could I improve the energy efficiency of my existing compressed air system?
There are a number of steps you could take to improve the energy efficiency of your existing compressed air system, starting with reviewing; usage, distribution, storage and treatment…
The initial stage in optimising the energy efficiency of your compressed air system is to identify how and where you currently use compressed air. It may sound obvious, but by simply observing and listing what you are actually using the compressed air for will allow you to identify where initial energy savings could be made. For example, are you using your compressed air supply for tasks which could be performed more cost effectively without compressed air? Using a nozzle or gun for blowing or cleaning your workshop would be an example of an inefficient and inappropriate use of compressed air.
A more in depth look into your compressed air usage would also identify opportunities for energy savings. This may include reviewing your existing and future demand for compressed air. As an example, any changes to shift patterns and production patterns will impact on your actual demand for compressed air. By measuring the systems load profile – or in other words the demand on the compressed air system over a defined period of time – you will also be able to identify how and where compressed air system performance and efficiencies can be made.
Did you know that just one 2 mm hole in your compressed air system could be costing you $2,364 per annum?* It doesn’t sound a lot as an isolated leak, but accumulatively leaks can squander up to 50% of the compressed air produced by a compressor. Now consider the cost implication to your business!
Identifying, measuring and fixing air leaks within your compressed air system could therefore play a significant role in reducing your associated all up energy costs. This can be achieved, for example, with the assistance of Ultra Sonic Leak Detection. Furthermore, implementing a leak management program, by which you make leak detection a regular part of your maintenance program, will ensure that the energy savings are long term.
In identifying your existing and future demands for compressed air you may also want to review your compressed air receiver(s). Changes in production and even, for example, the number of tools associated with your compressed air system will change the efficiency of your existing compressed air receiver. Let’s say that production and the number of tools you power with compressed air have both increased. This increases the overall compressed air supply you now require. The knock on effect may be that your existing compressed air receiver is too small to efficiently meet these new requirements. This means that the associated compressor will be running for longer than it needs to. And, running the compressor more than you need to will increase associated energy costs as well as wear and tear to the compressor.
Choosing to follow the prescribed maintenance schedule for your compressed air system will impact on its overall energy efficiency. This includes following the recommended maintenance schedule for compressed air treatment equipment, such as the; separators, dryers, filters and drains. Why is this important to the energy efficiency of the compressed air system? As an example, a blocked filter will cause the pressure to drop - essentially wasting energy.
You might also want to review the type of compressed air treatment equipment you have, for example, what type of drain valves are you using? The longer a drain is open the more compressed air that will be lost from the system. If you don’t have them already, consider installing electronic level sensing drains. These drains will optimise the amount of time drains are open for – another way to reduce energy wastage.
Additionally, assessing your compressed air dryers may highlight energy saving opportunities. There are a number of different compressed air dryer technologies out there which possess dramatically different energy efficiencies. Depending on your compressed air requirements you may find, for example, that a cycling thermal mass refrigerant dryer is far more energy efficient to operate than a non-cycling hot gas bypass refrigerant dryer. If your compressed air demand fluctuates a cycling refrigerant dryer, with integrated thermal mass, will shut down during breaks, periods of low demand or downtime for optimum energy efficiency. Whereas, a non-cycling hot gas bypass refrigerant dryer runs continuously. This may be a good option for a compressed air user running their system continuously and at full capacity. For those that don’t however, running the dryer continuously and irrespective of actual demand, will create unnecessary energy costs.
Once you have reviewed the usage, distribution, storage and treatment elements of your compressed air system, it is also worth considering the actual compressor(s) you have. Are you using the right type of compressor for your application? Has the demand on compressed air changed since you installed your compressor? Could your existing and future demand for compressed air be better met by installing an additional compressor or by replacing the existing compressor? The answer to these questions could also have a large bearing on the all up energy efficiency of your compressed air system.
There are certainly a number of areas to consider evaluating when it comes to identifying the energy efficiency of your compressed air system, some of which we have summarised above. To obtain a comprehensive overview of the potential energy saving opportunities within a specific compressed air system however, it may be worth engaging a qualified compressed a specialist to conduct a comprehensive compressed air audit.
*Example based on a compressor running 24/7 and electricity cost 15 cents/kW/hr
Australian Bureau of Statistics: 4102.0 - Australian Social Trends, September 2012
Climate Works Australia: Energy Management And Company Competitiveness, October 2014
Sustainability Victoria: Energy Efficiency Best Practice Guide Compressed Air Systems, 2009
Please note: The advice provided in this blog is general advice only; it does not take into account individual objectives or needs. For specific advice on your compressed air system, contact Kaeser Compressors today! We do not endorse any third party information or links and make no guarantees or warranties on whether the information or links are either correct or complete. You agree to use these links and third party information at your own risk.