Jukka Tolvanen explains why energy consumption is becoming ever-more important and shares a practical example of how variable speed drive technology is helping a plastics moulding manufacturer to control its energy use

Energy efficiency is a guiding principle of manufacturing industry – and with good reason. Around 40 per cent of electricity is consumed by industry worldwide, much of which is used by the electric motors used in pumps, compressors, conveyors and handling systems.

According to the International Energy Agency’s (IEA’s) World Energy Outlook report, global electricity demand is due to grow by more than 70 per cent between 2015 and 2040.

Recognising that we need to use our resources wisely, governments around the world have been actively legislating to improve energy efficiency. The IEA found that energy efficiency regulations in industry, buildings and transportation grew significantly between 2005 and 2014 and now covers more than one third of the energy used by industry. Legislation is likely to become more onerous in the wake of the COP22 agreement on climate change as governments set ever-more ambitious targets to limit energy consumption and greenhouse gas emissions.

Opportunity to cut energy bills
With this in mind, now is a good time to take a closer look at practical steps to improve energy efficiency, not just to limit energy bills but also to comply with tightening regulation.

With motors consuming 28 per cent of the world’s energy, they are a clear target for energy improvement measures. Traditionally, motor speeds were controlled by mechanical techniques such as throttling the output of a pump to achieve the desired flow rate. However, this can lead to significant loss of energy as the motor continues to operate at full speed.

Adopting variable speed drives (VSDs) will not only optimise the pumping of water and other fluids across manufacturing facilities, but they also achieve energy savings in other applications such as conveyor systems transporting solid materials and products from one place to another. VSDs regulate the speed and torque of electric motors and even a small drop in motor speed can offer major savings. For example, a 20 per cent drop in speed of a pump can reduce consumption by half.

With all the electric motors there are in the world, these savings can soon add up. We estimate that just the VSDs supplied by ABB alone are saving some 490 TWh of energy per year – equivalent to the consumption per year of more than 120 million European households. Yet there is still a long way to go, since we estimate that almost 70 per cent of the world’s motors are still waiting for an energy-efficient solution.

Plastic container maker saves energy and boosts output
An excellent example of the potential for energy saving is provided by PrimePac of Northern Ireland. The company specialises in continuous extrusion blow moulding to manufacture a range of plastic bottles, containers and jars together with closures, pumps, sprays and various accessories. Recently, it faced two separate problems. First was the declining product quality of an old hydraulic blow moulding machine. The second was an urgent need to install a new all-electric blow moulding machine to produce a new type of medicine bottle, but there was insufficient power capacity available, which meant that PrimePac would need to invest on an upgrade on its power supply.

An energy appraisal service which analysed the energy savings potential at Primepac manufacturing facilities showed that the power use was erratic and consumption was high due to the hydraulic pack requiring extra torque on start up. It also indicated a potential energy saving of up to 30 per cent by replacing the hydraulic motor with a synchronous reluctance motor (SynRM) and drive package.

However, once the 55 kW, IE4 SynRM package was installed the actual energy saving peaked at 60 per cent – with an anticipated payback in under 12 months.

Such are the energy savings that PrimePac was able to avoid a £250,000 upgrade of its 600 kVA electrical supply, since there is now capacity available to power the new all-electric blow moulding machine.

Energy efficiency delivers multiple benefits
The benefits of installing VSDs often extend well beyond an immediate reduction in energy usage and complying with regulations. For example, smoother and more precise control can help eliminate wastage of precious resources. The potential for automatic startup and shutdown at pre-set times also reduces the need for manual intervention and associated labour costs. Drives also eliminate the negative side effects of energy loss, such as heat and noise, helping create a more pleasant and productive working environment.

An additional benefit of drives is that they can significantly enhance system reliability, with consequent savings in maintenance and spare parts costs. In pumping applications in particular,the slow controlled ramping up and ramping down of the motor speed eliminates mechanical stresses on the pump couplings as well as reducing impellor wear and tear and water hammering.

Whatever the application, wherever electric motors are installed, there is an opportunity to achieve multiple benefits by investing in variable speed drives. In many cases, the consequent savings in energy costs, improved control and enhanced reliability will deliver an excellent return on investment (ROI) that helps finance further investments in operational efficiency – creating a virtuous circle.

Jukka Tolvanen
Jukka Tolvanen is ABB’s energy efficiency expert.
ABB Drives is a leading manufacturer of variable speed drives – providing low and medium voltage AC drives and DC drives along with control software to various constant and variable torque applications such as pumps, fans, conveyers, winches and cranes across all industries. Variable speed drives along with high efficiency motors are the most affordable and effective way to save energy and optimise operations in a sustainable way.