Malone Engineering Group.
Compressed Air Opportunities
Compressed air is often regarded as the fourth utility (along with water (steam), electricity and gas) in manufacturing and process environments. It provides force for simple and powerful mechanical solutions. It drives pistons/ cylinders used in lifting and moving. It powers the opening and closing mechanism and valves. It offers relatively low capital costs and is quick to install. However, it has the highest energy cost of any utility and is prone to leaks. In the UK, compressed air accounts for approximately 10% of industry’s electrical consumption. Given that many estimates put the percentage of the input energy converted to usable compressed as low as 7-15%, it is no surprise that changes in how we use compressed air could lead to substantial energy savings for manufacturing in Ireland.
Compressed air systems offer low cost solutions to solving mechanical movement issues in manufacturing and process facilities. It is fast acting, easy to install, understand and repair. It has no real ATEX issues when used with non-metallic components so in many ways it is an idea utility. However, it is, in most facilities, a massive energy cost and energy waster. Statistics from the UK seem to indicate that 10% of the industrial consumption of electricity goes on compressed air systems (CAS). In Ireland, industry uses approximately 9.3million MWh per annum (based on 2013 data). If we assume that Ireland, which doesn’t have as big a manufacturing base as the UK, only uses 5% (and this is a low estimate) of this figure for compressed air generation then factories and other process industries are using just over 460,000MWhr per year. To put this into perspective, this is equivalent to same electrical consumption as 85 thousand houses or the entire domestic electrical demand of Galway County. Conservatively, 90% of this is wasted in the process of generating the compressed air and is generally lost as heat. A further 10-50% (averaging around 20%) of the compressed air produced is then lost in the system through leaks, before it able to do any work. This represents a huge loss, in financial terms to Irish Industry. If the price paid for electricity is, say 14c/kWh then the cost to Irish industry, running standard compressed air systems, is €60 million across the industry each year.
A reduction in system pressure, repairing of leaks, an element of heat recovery at the generation stage and smart use of the system could save Irish industry millions per annum.
It is prudent to ask if compressed air is required or if another, albeit possibly higher capital cost, solution offers a better lifetime cost. It is also important to ask if systems are being run when they are not required as this is wasting energy, money and resources when there is zero return. Can the heat of generation be utilised in some way to reduce the overall loss. For instance this “waste” heat could be recovered and used to preheat air for air conditioning systems, to preheat water etc. Leaks within the system could be detected and repaired on an ongoing basis. Companies can address these items now even on existing systems. Another fundamental question that needs to be asked is ‘ Does the system need to run at 6bar or higher?”. A reduction in 1 bar in operating pressure would reduces losses through leaks and also reduce energy consumption by 7% according to Atlas Copco, a leading compressor manufacturer.
Compressed air systems are costing industry millions of Euro. Some remedial work and investment in existing systems will pay off handsomely in reducing energy bills.
About Fergus Whelan:
Fergus is the Group Engineering Director at Malone Engineering Group. They specialise in full service project delivery in the Food & Drink and Pharmaceutical sectors. They are an international company, operating in Ireland, UK, Poland and Canada currently. Much of thier workload involves energy recovery or reducing energy losses within utility systems (e.g. steam or compressed air).
Prior to joining Malone Group, he worked as a project engineer, project manager and contract manager in the renewable energy sector.
He was involved in the design, planning, installation or construction of numerous large and small windfarms throughout Ireland.
He is a Chartered Engineer with a masters degree in renewable energy.