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The ongoing need to compress energy usage

19 July 2013

The challenge to manage precious energy resources is ongoing, with legislation and voluntary initiatives being introduced to help improve efficiency within industry. As a result, compressor manufacturers, like many other manufacturers, are working hard to squeeze the last ounce of energy efficiency from their packaged products. Greg Bordiak, technical officer at BCAS, comments


The EU has put in place legal provisions to control the efficiency requirements of all equipment that uses energy. The focus of the EU’s attention recently turned to compressors, which under the umbrella of the Energy Related Products Directive, are to follow electric motors down the path of reducing energy usage.


How is it measured?

The EU has appointed a Consultant, VHK from the Netherlands, to produce a report and recommendations on what and how the energy efficiency requirement is to be identified for compressors.


VHK has been liaising with the compressor industry representative – PNEUROP – in which BCAS is actively involved. Part of the report that VHK is required to produce is a study to establish the size and energy usage of the market. An estimate for the energy usage of the total compressor market in the EU produced a result in the region of 240TWh for all compressor technologies.


The PNEUROP working group is developing an argument to restrict the scope of the eventual legal provision so that the appropriate resources can be focussed on identifying the most beneficial sector of the compressor market that can show real energy efficiency savings.


The identity of a basic compressor configuration will have to be representative of the market sector. This then takes the discussion back to what the customer wants in the form of the packaged compressor configuration. The question needs to be asked as to whether a basic compressor configuration can be reconciled with the wants of the customer.


PNEUROP is struggling to find a solution to this configuration, which in itself is reducing the scope of what will eventually become the legal provision. A basic configuration for oil flooded rotary compressors is evolving and one for reciprocating compressors is being identified.


The PNEUROP working group met almost once a month during 2012 to provide assistance to VHK so that an industry acceptable proposal for the coming legislation can be put forward for EU agreement.


Its important to remember that although a compressor is deemed efficient, it could still be installed into a system that may not be configured to take advantage of this improved performance. This overall system does not currently have an energy efficient statement of its own.


Setting the standard

However, an energy efficient statement for the overall system can soon be obtained using standardised methods and procedures within the ISO 11011 "Compressed air — Energy efficiency: Assessment". The ISO working group led by BCAS met in November 2012 to discuss the comments during the last voting phase where it received 100% support, enabling publication of ISO 11011 in 2013. 


While not intended to replace existing compressed air audit activities, ISO 11011 is designed to create a framework for the assessment process, which can then be embedded into other specific ISO requirements that exist around the globe.


The new standard considers the entire air system, from the energy inputs to the task performed and classifies compressed air in to three subsystems: 

•   Supply which includes the conversion of the primary energy resource to compressed air energy

•   Transmission which includes the movement of compressed air energy from where it is generated to where it is used

•   Demand which includes the total of all compressed air consumers, including productive end-use applications and various forms of compressed air waste


Assessing system efficiency

In compressed air systems with very large runs of pipe work and little control over system pressure, it can be difficult to manage air usage. The ISO 11011 assesses compressed air use, critical production functions and poor system performance. This assessment should help to identify and quantify energy waste, the balance between compressed air supply and demand, energy use and total compressed air demand. 


One of the key features of ISO 11011 will be the establishment of a 'baseline' performance of a compressed air system. The purpose of base lining is to establish the current performance levels and costs of a compressed air system, and to correlate the results with the plant’s present production levels. 


As improvements are made to the compressed air system, it will be possible to estimate improvements by comparing the new measurements with the original baseline.

 

In addition, ISO 11011 addresses any ‘wasted’ compressed air. This goes beyond, but doesn’t ignore, obvious leaks, which can contribute up to 35% of the generated compressed air. The standard also analyses any 'inappropriate use', such as when compressed air is be being used unnecessarily for cooling, when a simple fan would be more efficient. 


Is the focus right?

The question that remains is what level of energy saving can be achieved by compressor technologies to satisfy the upcoming legal provision from the EU, and how much energy can the customer expect to save from their system?


A 10% improvement in energy efficiency for a compressor package may not be possible, but savings of over 10% are certainly possible when it comes to the complete compressed air system.


So, has the EU focussed on the right area with machine efficiency, or should the efficiency of the complete air system be the subject of the coming regulation?


 
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