It is not a revelation to anyone in the industry that energy is the largest operating expense, accounting for the majority of utility costs. With increased energy prices, it’s important that we look at energy efficiency improvements in more detail, especially as investing in energy efficiency can provide real savings, ensure superior process performance and real financial outcomes.
In manufacturing processes using compressed air, air compressors consume approximately 12% of the total electrical energy. Over the lifespan of an air compressor, 80% of the cost is energy use and 20% is the cost of the unit, including maintenance.
Energy consumption reduction targets across the Europe are scheduled to be achieved by 2030. The revised EU Energy Efficiency Directive (EU) 2023/1791, published in September 2023, will accelerate energy efficiency across the European Union, requiring EU countries to collectively reduce their energy consumption by 11.7% by 2030, relative to the 2020 reference scenario.
Additionally, EU countries will have to achieve new annual savings of on average 1.49% of total energy consumption from 2024 to 2030. Embracing energy efficiency practices is much more than compliance. It is also the right thing to do.
Decarbonisation of heavy industrial processes is central to reaching targets combatting climate change. With the industry being the third-largest carbon contributor after energy production and transport, energy efficiency measures in industrial processes have enormous decarbonisation potential.
Liaising with an expert
Whether you’re considering a new air compressor or planning to upgrade the existing system, working closely with a subject matter expert capable to design or redesign your compressed air systems, one that could then remain as your service provider, is critical. This will ensure you get the true picture of all areas that need to be addressed when aiming at improving the energy efficiency of your operations.
The aim is to strike the right balance in technical and economic choices - in compressor units, capacities, operational parameters, energy efficiency, planning for future air demand changes, and considering all energy costs.
Assessing the load type of your air compressor
When choosing an air compressor, assessing the load type is also critical. For example, a screw air compressor does not shut down immediately and goes into unload state to limit too many motor starts and stops. This unloading process consumes up to 30% of energy, increasing the company’s operating costs. When selecting the unit for your facility, duty cycle, operating pressure and airflow demand should be some of the key considerations.
The duty cycle, referring to the operation cycle or the time the compressor runs to provide compressed air at a consistent pressure and specific flow rate, is one of the critical parameters that help decide if a fixed speed drive or a variable frequency drive (VFD) is required.
Manufacturers can choose from a wide range of air compressors equipped with or without a VFD based on the variation in airflow demand. The VFD air compressor greatly benefits industries andapplications with largely varying airflow demands. However, it’s not a given that a VFD compressor is the better technology in all cases. It’s important to look at the size of the air receiver that provides a certain buffer capacity. Therefore, there is a good consideration to be done when auditing and changing eventually the system after an audit.
Reducing high-pressure drops
One of the other factors to look at is the overall design of the system and reduction of pressure drops – the reduction in air pressure from the compressor discharge point to the application point of usage.
High-pressure drop in the distribution system and the hoses, pipes, and joints results in lower operating pressure to the user and thus results in additional pressure generation and a significant increase in energy consumption. The most typical areas where “Pressure drop” occurs include the pressure vessel, aftercooler, air treatment equipment like dryers, filters, check valves, and the piping system itself. Additional generation of pressure will also lead to additional storage capacity and increase the cost of equipment.
Air pressure optimisation, and minimising differentials in all parts of the system are important criteria for efficient operation and saving energy.
If a certain side application requires a much higher or lower pressure, it is advisable to use a separate compressed air system for that pressure rather than expanding or boosting the compressed air from the central system in a factory. The ROI of a separate system will be economical compared to the overall energy savings that the plant would generate by optimising pressure requirements.
Optimising air filtration
Atmospheric air contains moisture, particle contaminants, microorganisms, and gases. When it is compressed, the concentration of these elements increases by 6 to 10 times. When it is compressed by an air compressor, oil, and metal traces get added during the compression process.
Reliable filtration solutions remove contaminants from the compressed air providing assurance of purity before it is used for any application. The filter element enables high contaminant removal with low-pressure drop, also resulting in energy savings.
Heat Recovery Systems (HRS)
Heat Recovery Systems enable to recover up to 78% of the heat generated during the process of an oil-injected air compression and are available for operations of all sizes. This heat can be used to heat water, which can be useful in the production process, boiler feed, or for domestic water usage.
A high return on investment brings immediate cost savings and more importantly, saved energy contributes to carbon emission reductions and helps you in lowering the company’s net carbon footprint.
