Variable speed drives (VSDs), are certainly nothing new. They’ve been around for quite a while and their benefits within industrial applications has been well documented. However, while their numbers are on the increase, their deployment is by no means universal – which is something of a surprise as industrial organisations are feeling the pressure to reduce carbon emissions and improve energy efficiency – with both financial and reputational penalties lurking should anyone neglect their responsibilities.

Parties in the know have been banging the VSD drum for some time now, yet it seems that many organisations are still oblivious to the advantages that VSDs can bring as they are still not exactly banging down the door of the VSD providers. Therefore, while some may feel like they are suffering from VSD fatigue, Atlas Copco Compressors feel that it’s a story worth retelling – particularly at a time when the economy is starting to grow again and organisations are more willing to talk about investment.

Atlas Copco Compressors is the UK sales and service operation of the Atlas Copco Group, providing oil-free and oil injected stationary air compressors, gas and process compressors, turbo expanders, air treatment equipment and air management systems. And, with ten percent of industry’s energy consumption being spent on compressed air, the company is well positioned to champion the case for VSDs. Add to that the fact that over 70% of a compressor’s lifecycle cost is spent on electricity and that the use of VSDs in such applications can yield an energy saving of up to 35%, it is indeed puzzling as to why people aren’t falling over themselves to have them installed.

It is true that, when it comes to air compressors, energy savings are a challenge to accurately measure, simulate and realise, and are viewed as something of a dark art. However, Atlas Copco has a methodology (verified by the Carbon Trust), to measure the usage and compare VSDs to demonstrate potential savings. The company also offers a full range of VSD solutions (5-900kW), as one size does not fit all.

The environmental impact of using VSDs cannot be underestimated. Based on the number of VSD compressors Atlas Copco supplied to UK industry last year, over 16 million kWh have been saved (based on an average 25% saving in electricity and 4,000 running hours per year), along with approximately nine million kg of CO2. To put that into context this equates to around 50 million air miles.

Taking those figures into account, one might ask the question, ‘why aren’t all installations VSD?’ Well, it should first be pointed out that not all applications would benefit from VSD technology. Where constant flow / constant pressure is required, VSDs would have little use. However, likewise there are many applications where VSDs would yield significant savings in terms of pounds on the bottom line and energy. However, for many organisations, it’s a simple case of a lack of education. Many just don’t have the information to hand to make an informed decision regarding VSDs, which again is somewhat surprising as the benefits of VSDs have been shouted from the roof tops for some time.

Obviously, with purse strings still tight for many companies, a lack of capital can also be sighted as reason why VSDs are not more commonplace. It is true that VSD technology and equipment does come at an additional cost – one that many finance directors may find hard to justify. However, Atlas Copco claim that this is a very short term view that focuses on initial purchase price rather than the total cost of ownership. The company claim that in many instances it can demonstrate that VSDs will realise significant savings for the client within one or two years. In addition, there is funding available through organisations such as the Carbon Trust and the ECA, and Atlas Copco themselves offer its 0% finance scheme.

One Atlas Copco customer (a printing company), witnessed first hand the full benefits of VSDs. Its 26kW application used a fixed speed 30kW compressor, operating a 16 hour shift, five days a week. Due to the varied power demand of the application, the VSD (which came at an additional cost of £5,250), achieved a 25% saving. This totalled £3,232 per year meaning the VSD would pay for itself in 1.6 years.

So, in the right application the advantages of installing VSDs are clear. Their money saving potential is there for all to see, as is their impact on the environment. In addition, there is funding available for those organisations that are concerned over the initial short term outlay.

While it may feel like VSD fatigue for some, it is certainly worth reiterating the point as Paul O’Neill, divisional manager, oil-free air, Atlas Copco, explained, “As manufacturing picks up it’s a perfect opportunity to retell the VSD story as people look to reduce operating costs. Three years ago UK plc was solely focussed on survival but, now things are growing again, there’s no better time to reinvestigate this subject.”