Compressed air is one of your most expensive utilities
Only 15% of the energy that produces compressed air is put to work, while the rest is converted to waste heat. Consider whether compressed air is the right option for any new or existing application. You may be able to eliminate the use of compressed air equipment with electrically driven motors or valves. If not, investigate areas to potentially reduce demand.
Where is your compressed air going?
Check to see if these common problems are making your compressed air system less efficient:
- Air leaks - 20%-30% of compressed air demand can disappear this way. A well-managed system will have less than 10% leakage. Repairs almost always have a very short payback period.
- Unnecessary use - includes using high pressure air for cleaning, using it when low pressure air would be fine, or using it in mechanical applications where an electric drive is used.
- Fluctuating demand - large fluctuations in demand from equipment attached to a system can cause large pressure drops across that system.
- Pressure drops in the air network – check for rust, undersized pipes or pipe constrictions and unnecessary deviations, and partly-blocked filters.
These can help you avoid wastage:
- Pressure regulators - minimising supply pressure needed for air-driven equipment can cut demand.
- Measuring flow and pressure - use the equipment specification and use profiles of each piece of equipment to estimate the network airflow demand.
Optimise your supply
Compressors need to accommodate the pressure and flow requirements of the network. It’s important that your compressors are correctly sized to meet demand on the system. Other factors influencing supply-end efficiency include:
- Controlling multiple compressors - arranging ‘run order' to match air supply to demand and make sure machines are operating at their optimum efficiency. For example base demand could be met with a fixed speed machine and any peaks in demand supplied with a variable speed compressor.
- Variable speed compressors - variable flow compressors match air supply to demand (eliminating off load running) and are typically more efficient than fixed flow machines where air demand is variable.
- Compressor supply pressure - for every 1 bar the compressor is set over the required pressure, the system loses about 7% efficiency.
- Drier selection and sizing - over-drying the air wastes energy. A faulty drier can cause excessive pressure drops.
- Environment and maintenance - air compressors are often installed in service areas with boilers, pumps and chillers. Radiant heat affects air compressor efficiency, generally by 1% for every 3°C the intake air is above outside ambient air temperature.
Recover wasted heatAbout 85% of energy used to run an air compressor turns into heat. Explore ways to use it, such as ducting the hot air from the air compressor cooling vents to heat work spaces or using a heat exchanger to heat water.
Co-funding for compressed air systemsIf you spend more than $200,000 a year on stationary energy, you may be eligible for co-funding for an audit of your compressed air system, system optimisation or installing a monitoring and targeting system. Larger energy users can also be co-funded for industrial design advice.