Compressed air — is it a sustainable power source for industry?

With the rapidly rising cost of electricity, the answer to this headline question is complicated, with many variables affecting the real efficiencies relating to cost versus application.

Most industries in Australia and throughout the world rely on compressed air as a major source of energy to operate equipment such as pneumatic controls, air tools, pumps, valve actuators, pistons and large-scale processes. Compressed air is used because it is a clean, safe and convenient energy source, but compressed air is also an expensive energy source. In fact, approximately 10% of the electricity supplied to Australian industry is used to compress air.

The continued effectiveness of compressed air as an industrial power source lies in today’s technological advances in compressor design, control methods, reticulation design and the maintenance of systems to ensure optimum operational effectiveness.

In existing installations, we need to completely and accurately review and assess the efficiencies in the compressor itself and ancillary equipment in relation to the nature of the demand. Today’s systems need to be flexible and adaptable to meet current and future requirements.

Below are some questions that should be asked in order to optimise the efficiency of your compressed air system:

Is compressed air the most efficient power source for the application?

Analysis of the cost per application needs to be determined to identify the most cost-effective and efficient method of running that process. Compressed air may not always be the optimum solution. For example, today’s rechargeable, battery-operated power tools are in many cases more convenient and cheaper to run than compressed air equivalents.

Is the system supplying the minimum appropriate air pressure for the required task?

Use of the minimum appropriate air pressure for the required task can save considerable energy as the work required to compress air is a factor of both pressure as well as volume. Many procedures do not require air at the maximum pressure that the compressed air system can produce. Delivering a higher than necessary pressure results in excessive energy use, excessive equipment wear, artificial demand and higher, long-term maintenance costs.

Are there leaks in the system?

Up to 50% of generated air is frequently lost through leaks. These leaks not only waste energy, but they can also make the compressor work harder to meet the higher demand. This can shorten equipment life, increase maintenance needs and create unnecessary downtime. A proactive leak repair and maintenance program will help to maintain system efficiency and can significantly reduce energy consumption.

Can the air be varied?

In situations where demand varies frequently and rapidly, variable speed drive control (VSD) allows the compressor to automatically adjust its output to meet demand. This minimises energy usage proportionally with demand, which can result in significant power cost savings.

Can pressure drop be reduced?

A typical system should maintain a pressure drop of less than 3% between the compressor’s output pressure and the point of use. Pressure drop occurs due to friction throughout the reticulation system and is generally a result of poor system design. Unnecessary bends and small capacity piping also cause friction. Improving the layout, increasing piping diameter and installing smooth bore piping can greatly lower friction and minimise pressure drop. Reducing operating pressure by 100 Pa will save around 8% of required input power.

Are system ancillary components doing their job?

Ancillary components such as coalescing filters, air dryers and moisture separators should be specified and installed to match the air quality requirements for the application, otherwise contaminants such as water, dust, dirt and residual hydrocarbons can cause damage to system components and can also cause product spoilage.

Is an adequate preventive maintenance program in place?

Regular checks and maintenance of compressed air systems are essential for continued efficient operation and minimisation of downtime. Like any other piece of expensive machinery, well-maintained systems will give the user many more years of operating life with lowest possible cost. Leading suppliers offer tailored maintenance programs to suit individual customer needs.

Is it time to upgrade the system?

With great advances in compressed air technology today, there is a wide choice of compressor type and size to fit every application; however, it requires expert assessment to match a compressed air system to cater for a given application and ensure it will provide for current and future demands.

New compressed air systems

Much of the criteria as applied above to upgrading an existing system must also be applied to the selection of a new system installation to fit a specific or varied task. Installing the right compressed air system for your particular application is fundamental to minimising the cost of energy. There’s a lot to consider when selecting and installing the right compressor. What volume flow rate output do you need? Should we install one or multiple compressors? Is a single- or two-stage compressor right for the task? What discharge pressure do you require? Do you have a fixed or varying demand? Do you want a compressor that will cater for future growth?

Selecting the right system or upgrading current systems to more sustainable levels of power usage can, in many cases, be cost negative when consideration is given to the energy cost savings achieved.

Southern Cross Compressors (Australia) can provide Australian industry know-how and service with the latest innovations in products covering every conceivable compressed air need. It also provides a free compressed air assessment service to recommend the right system or upgrade to achieve your specialised needs. In many cases where the existing system is running inefficiently due to leakage, restriction and or wear and tear, the company can clearly demonstrate the savings to be achieved through repair or upgrading of the system.

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