The British Compressed Air Society’s 10% Taskforce - as the name suggests - aims to reduce the energy that compressed air systems consume by 10%. Hitting this goal will help industry to save £147.5 million in electricity costs and prevent over 411,000 tonnes of CO2 emissions.
“Energy and carbon footprint have long proved a hot topic for users of compressed air, as it represents as much as 30% of a site’s total electricity bill,” states Vanda Jones, executive director of BCAS.
“We started looking at establishing an energy taskforce just before the pandemic. Unfortunately, we parked the project to concentrate on helping our members through the trials and tribulations of COVID-19. Then, no sooner did we refocus our efforts on the 10% Taskforce, the energy crisis hit, which heightened demand for a proactive strategy with almost immediate effect. The green message was always important, but when you start talking about the cost to industry, it focuses minds in a different way.
“From our members’ perspectives, the 10% Taskforce is proving to be one of the most in-demand campaigns we’ve ever launched.”
The good news when it comes to saving energy by reducing compressed air consumption is that there are many simple improvements which do not require huge investment but which can add up to big savings.
“There is often the assumption that measures of this type require large capital investment in the shape of a new compressor or pipework circuit,” says Jones. “Frequently, however, taking small, incremental steps can have a considerable impact on energy consumption. In the main, our advice is about good practice and good processes, not capital investment. And yet, when modest capital investment is required, payback is typically fast. For instance, until recently the payback on a compressor heat-recovery system that can power boilers or industrial processes might have been three or four years, but with higher energy prices, we’ve seen cases with a return-on-investment of five to six months.”
As much as 95% of the energy consumed by a compressor converts to heat and, unless captured, will be wasted to atmosphere. The retrofit of a heat-recovery system can therefore pay notable dividends.
Of course, recovering heat is just one example. Avoiding wasteful practices and fixing pipework leaks are among further tips put forward by the 10% Taskforce. According to a report entitled ‘Compressed Air Systems in the European Union’, when assessing the most important energy-saving techniques available to compressed air users, “the energy savings amount to 32.9%, achievable over a 15-year period”.
To provide a breakdown, this total includes the following system installation or renewal initiatives: improvement of drives with high-efficiency motors (0.5% energy saving); improvement of drives with variable-speed drives (3.8%); upgrading of compressor (2.1%); use of more sophisticated control systems (2.4%); recovering waste heat for use in other functions (4.0%); improvement of cooling, drying and filtering (0.5%); better overall system design, including multi-pressure systems (4.5%); reducing frictional pressure losses (1.5%); and optimising certain end-use devices (2.0%). Also included are system operation and maintenance initiatives like reducing air leaks (16%) and more frequent filter replacement (0.8%).
“The highest potential saving clearly comes from reducing leaks, which is where we are seeing a shift in approach,” says Jones. “If a plant has an oil or water leak, it typically gets addressed immediately, but the view with an air leak is that it’s only air, so it gets ignored. Attitudes are slowly changing now because of the alarming energy price hikes. An ongoing leak test and repair programme will save you money: just one 3mm hole could cost plants over £600 a year in wasted energy. A leak survey can help to identify the scale of the issue so that you tackle the largest leaks first and start generating savings in the shortest possible time.”
ENERGY EFFICIENCY
Simple, regular maintenance will help to retain low leak rates and the reliability of equipment. Plants should also consider a policy which specifies the purchase of energy-efficient options when replacing equipment, whether it is a basic drain valve or the actual compressor itself.
For those considering upgrading their existing compressed air system, the BCAS advice is to speak with an expert. BCAS members can recommend the best equipment and system for the specific requirements. The solution could include incorporating fixed- or variable-speed drives, or a combination of both, as well as efficient downstream equipment. Where suitable, sophisticated control systems may also prove beneficial in proactively managing the supply of air.
A compressed air system is just that: a system, and every element of it impacts upon energy consumption. When discussing efficiency and the potential savings available, it is important to take a full system approach – from generation, through air treatment and distribution, to point of use.
BEST BEHAVIOUR
Many energy-saving actions will, of course, require elements of maintenance or equipment/system upgrade, but it is important not to overlook the human behavioural element. Plants can make substantial efficiency improvements by implementing new processes and encouraging staff to use compressed air more efficiently and safely. As Jones points out, sweeping down the shop floor with compressed air at the end of the shift is not good safety practice and has a financial cost. Reducing pressure at point of use and installing energy management systems can also help to deliver improvements.
“These tips don’t just apply to large manufacturing and process plants, many smaller businesses such as garages, body shops and wood yards can also take advantage,” says Jones. “They can make gains by simply looking at their usage policy, making sure their compressor is not running unnecessarily and checking their pressure is appropriate. For instance, if they are not changing their filters regularly it can lead to pressure drops that call for more energy.”
BCAS has a dedicated website for the 10% Taskforce containing simple ways to reduce the consumption of compressed air energy: see www.is.gd/ebilab. Free, downloadable guides are available, along with an area highlighting real case study examples of energy-saving measures.
“At the time we launched the campaign in April 2022, we could not have predicted the huge rises in wholesale gas and electricity prices that have since ensued,” concludes Jones. “Our original estimates of wasted electricity across industry have risen two- or even three-fold. Initially, our savings calculations were based on an energy price of 12.49p per kW, but today we hear of some plants paying over 100p per kW. By using a BCAS member to conduct an audit, plants will learn about the potential energy reductions and the choices available to lower their consumption of compressed air. I guarantee there will be options to save money and boost environmental performance.”