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Compressed air & energy efficiency

23 October 2020

Compressed air is used extensively as a safe and versatile source of power. Often referred to as the fourth utility, manufacturers and processors rely on its availability to power mission critical processes 24/7. However, it is not free and generating compressed air can be very energy intensive, representing between 5-30 per cent of a site’s total electricity bill, asserts Vanda Jones, Executive Director, British Compressed Air Society (BCAS)

According to a report entitled ‘Compressed Air Systems in the European Union’, when looking at the most important energy saving techniques available to compressed air users, ‘the energy savings amount to 32.9 per cent, achievable over a 15-year period.’

The drive to cut energy

Stringent environmental legislation sets limits on carbon emissions, encouraging all users to take steps to reduce their electricity consumption to create a cleaner and greener manufacturing environment.

For example, the Government’s Clean Growth Strategy for meeting the UK’s legally-binding carbon commitments, aims to help businesses decarbonise. Part of the Strategy includes the ‘Industrial Decarbonisation and Energy Efficiency Roadmap Action Plan.’ The action plan will seek to reduce greenhouse gas emissions and become more energy efficient while remaining competitive during the UK’s low carbon transition.’

Yet, while compressed air energy consumption represents a considerable overhead for manufacturers, its performance and efficiency can often be overlooked, and improvement programmes delayed.  This can be counterproductive, because, as illustrated above, there are many simple ways that users can reduce their energy usage, without investing in new capital plant and equipment.

Simple ways to cut energy

The best place to start, when considering upgrading an existing compressed air system, is to speak to an expert. BCAS members can advise on the best equipment and system for your needs. This could include incorporating fixed and variable-speed drives or a combination of both as well as efficient downstream equipment. Where suitable, sophisticated control systems can help proactively manage the supply of air.

Equally, BCAS members can conduct a full system audit and advise on some of the simpler, low cost ways that energy usage and wastage can be reduced.

BCAS’s ‘whole system approach’ article discusses some of the specific ways that users can cut wastage and thereby improve energy performance in more detail, including:

- Fix leaks - Just one 3mm hole could cost over £600 a year in wasted energy. A leak survey can help to size the issue – and to tackle the largest leaks first

- Heat recovery - As much as 95 per cent of the energy consumed by a compressor is converted to to heat and, unless captured, will be wasted to the atmosphere. Many manufacturers offer heat recovery systems, which can often be retrofitted.

- System design - When discussing efficiency and the potential savings that could be realised, it is important to take a full, system approach. – from generation to air treatment to distribution and finally, the point of use.

- Improve control - Reducing pressure at the point of use, switching off compressors when there is no demand for air and installing energy management systems can all help you identify wastage and take action

- Manage air downstream - Excellent savings are achievable be treating all the generated air to the minimum acceptable level and improving the purity (quality) to the desired level at the usage point.

- Behavioural change - You can make substantial efficiency improvements by implementing new processes and encouraging staff to use compressed air more efficiently and safely.