In April this year, the British Compressed Air Society (BCAS) launched its 10% Taskforce initiative to encourage compressed air users to cut their energy consumption from compressed air by 10%.

In the first month alone, BCAS members demonstrated how they had helped customers save 5,457 MWh in otherwise wasted energy – the equivalent of powering 1,800,810 homes for one hour – or 1,631 homes continuously.

Often referred to as the fourth utility, industry relies on compressed air to keep plants performing profitably and efficiently. However, it is not a free resource.  Generating compressed air can be very energy intensive, representing between 5-30% plus of a site's total electricity bill.  

Coupled with this significant overhead, poor practices and housekeeping can also contribute to unnecessary wastage. In fact, 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%, achievable over a 15-year period". 

Compressed air energy savings in context

Using figures from the recent UK Energy-related products policy study, conducted by ICF in May 2021, BCAS calculated the combined energy usage for the mid-point of all industrial compressor technologies over their lifetime at 11.71 TWh.  

When the report was first prepared, the UK average non-domestic electrical unit cost was £0.1249/kWh , which equated to £1.475bn being spent by UK companies to generate the compressed air their businesses rely on. 

Now, of course, wholesale gas prices have risen at an unprecedented rate and savings will be considerably higher.  Businesses are advised to refer to their electricity unit charge to calculate the potential savings.

Add to this the fact that over 30% of this energy is being wasted through inefficient practices and there is much that businesses can do to cut this figure significantly.

Yet, compressed air energy consumption is often overlooked, when, as we have already learnt, the potential for wastage is substantial and represents a considerable overhead, not to mention carbon footprint that could be reduced.

Top tips for compressed air system energy savings 

A compressed air system is just that; a system, and every element of it impacts on its energy consumption. Therefore, when exploring 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. 

Change behaviours

Many actions will require elements of maintenance or equipment/system upgrade, but the human element should not be overlooked. Substantial efficiency improvements can be made by implementing new processes and encouraging staff to use compressed air more efficiently and safely. 

For example, not allowing benches or equipment to be cleaned down with compressed air will save a significant amount of air being vented into the atmosphere.  It is far safer to carry out such cleaning using a vacuum system to reduce the risk of injury.

Control better

BCAS members can advise on the best equipment and system for the application. This could include incorporating fixed and variable-speed drives or a combination of both as well as efficient downstream equipment. 

For example, if a site installs the most efficient compressor available, but connects it to a system with a 30% leak rate, then all the benefits are lost. Operators should aim to improve the overall system efficiency. Efficiency in the generation of compressed air is one aspect but targeting avoidable waste in the system is even more important.

Even when off-load, compressors can consume up to 70% of their full load power, so units should be switched off overnight where there is no demand for air and running hours optimised to reduce costs.

Where appropriate, energy management systems can be installed to turn compressors off when they are not being used and to proactively manage the supply of air.

Fix leaks

Reducing air leaks can have the biggest impact on overall system efficiency. Leak rates in industrial systems are typically between 20 and 40%, meaning the compressor must work harder, and therefore consume more energy, to compensate for the pressure loss.  

A tiny leak of just three millimetres can cost more than £700 a year in wasted energy, but an out-of-hours survey can identify leaks easily. 

Recover heat

As much as 95% of the energy consumed by a compressor is converted to heat and, unless captured, will be wasted to the atmosphere. Many manufacturers offer heat recovery systems, which can often be retrofitted. These recycle this excess heat; re-directing the hot oil to an oil-to-water heat exchanger. 

Manage air downstream

Treating air to remove dirt, water and oil is necessary but can use a lot of energy. The process is likely to only need a proportion of the compressed air to be treated to a very high purity.

In these cases, excellent savings are achievable by treating all the generated air to the minimum acceptable level and improving the purity (quality) to the desired level at the usage point. 

Service and maintain

Low cost, regular maintenance will help retain low leak rates and reliability of equipment.  Operators should consider a policy that specifies that energy efficient options are purchased when replacing all equipment – whether it is a basic drain valve through to the actual compressor unit itself.  

Finally, the manufacturer's genuine spare parts should be used, instead of cheaper alternatives. These can enable significant savings in excess of 25%.

In conclusion

There are many straightforward ways to save energy consumption from compressed air systems and, implementing just one or two of the steps highlighted above can help minimise avoidable waste significantly.

In doing so, industry can make considerable overhead, and carbon footprint savings alongside a significant contribution to bottom line profitability and environmental performance. 

For further information, please visit taskforce10.bcas.org.uk

Vanda Jones is executive director, British Compressed Air Society (BCAS) 

www.bcas.org.uk

Tel: 020 7935 2464

BOXOFF

A rallying call to UK business

The 10% Taskforce from BCAS is a call to arms for UK businesses to take simple steps to cut their compressed air energy usage figure by 10%. 

Working together the industry could save over £147.5m in wasted electricity costs – and more importantly, make significant strides to improve climate change by taking the equivalent of 317 thousand cars off the road.