Driving down industrial energy consumption

Energy consumption is becoming ever-more important and variable speed drive technology is helping industrial firms around the world to control their energy use without compromising performance or production efficiency.

Energy efficiency is a guiding principle of industry – and with good reason. Around 40 percent 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 percent between 2015 and 2040.

Recognizing 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 percent 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 optimize the pumping of water and other fluids, but they also achieve energy savings in conveyor systems that transport 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 percent drop in speed of a pump can reduce consumption by half.

How are the most innovative industries addressing energy efficiency?

There are opportunities for energy savings in every industry where drives are used to control electric motors, from heavy industries such as mining, metals and oil and gas, through process industries, manufacturing and food production, all the way to environmental controls in office and commercial buildings.

Squeezing the most out of energy

One niche motor manufacturer has integrated ABB variable speed drives (VSDs) to help oil field operators to save running costs by reducing their use of energy, which is their single largest operating expense.

General Magnetic (GM) of Calgary in Canada has developed a specialist permanent magnet motor for the progressive cavity pumps that operators use to pump challenging fluids such as heavy oils or oils containing a high quantity of sand or gas. While permanent magnet motors have a higher purchase cost than more commonly used induction motors, permanent magnet motors use significantly less energy.

By twinning its motors with VSDs, GM has reduced the motors’ energy demand even further. ABB’s ACS880 industrial drive allows the motors to run at full torque across all motor speeds from 30 to 450 rpm, meaning that they operate at optimum energy efficiency. Crucially, the ACS880 was proven to run reliably throughout the entire speed range, producing none of the vibration that was experienced with an alternative drive at low speeds.

“There is a need for the energy industry to up its game, and I'm excited that General Magnetic can make a significant, long term bottom line impact while also lessening the environmental footprint. When you consider electrical energy consumption, that's the biggest single operating cost for energy companies trying to get oil out of the ground,” says Al Duerr, GM founder and CEO.

Reducing energy consumption in pulp and paper

An alternative method for energy saving is to adopt an energy-efficient motor-drive package like ABB’s synchronous reluctance motor (SynRM) technology.

Packaging firm Stora Enso is making use of this approach at its pulp and paper mill in Nymölla, Sweden following a comparison of the technology with an existing drive-motor package in 2013. The packages were installed on a pulp pump and their power consumption was measured with a standard Dranetz PX5 power monitor. Stora Enso measured energy savings in excess of 25 percent, which could lead to significant savings in the energy-intense pulp and paper industry.

SynRM package lowers energy cost for plastic extrusion facility

A SynRM motor and drive package has also produced major benefits for a plastic extrusion company with up to 15 percent lower energy use, a significant reduction in motor maintenance costs and a drop in audible noise.

Radius Systems’ plant in Derbyshire, UK, houses 14 extrusion lines together with an injection-moulding facility making associated fittings for use by utility companies for gas and water transfer. Eight lines are powered by DC motors, many of which are over 20 years old. However, Line 12 had a particularly high utilization rate and yet the 182 kW DC motor was regularly failing, leading to an increase in downtime and rising maintenance costs.

ABB’s authorized value provider Inverter Drive Systems (IDS) carried out ‘before’ and ‘after’ monitoring of the DC motor, which estimated that potential energy savings from a SynRM package for Line 12 would be in the range from 8 to 15 percent, with a return on investment within two years. In addition, in excess of $2,500 cost avoidance is estimated with the removal of DC motor maintenance. “SynRM has given us a reduction in noise in the production hall which is a benefit we had not expected,” says Rob Betts, Engineering Manager at Radius Systems.

Eighty percent energy savings at Swedish board mill

Sweden’s Fiskeby Board achieved 80 percent energy savings after adopting an ACS880 industrial drive. The mill produces Europe’s strongest recycled paperboard and is the only site in Scandinavia that can recycle the board used in milk and juice cartons.

According to Magnus Johanson, the mill’s energy efficiency expert, the ACS880 was installed on a dilution water pump on the filter unit. Control of the pump was previously achieved by running the pump at full speed and tightening the valve on the pump outlet to throttle the flow.

The VSD has enabled Fiskeby Board to run the pump at variable speed depending on the level of the tank it is feeding. It now operates at much slower rates than previously, which has reduced energy consumption by around 120 MWh, equivalent to $6-7,000 a year. This gave a payback period of less than two years.

Since the success of its trial, Fiskeby Board has installed the ACS880 on several other pumps.

Investment decisions based on total life cost

Drives also have a major role to play in maintaining the right environmental conditions, whether creating the right environment for storing foodstuffs or perfect working or living conditions.

One example is UK-based Ellison AC, which supplies packaged plant rooms for applications such as heating, ventilation and air conditioning (HVAC) and hot and cold water supplies to a wide range of customers from defense to data centers and leisure or business facilities. Ellison’s customers make purchasing decisions based on the whole life cost of the plant and equipment.

According to Ellison, VSDs have an important role to play in its plant rooms, particularly in HVAC applications, where ABB’s ACH550 HVAC drive is enabling Ellison’s customers to achieve up to 50 percent power saving from a 20 percent reduction in motor speed.

Forty percent energy savings for South African farmer

One of the largest expenses for South African firm Riecor Farming is the energy used to operate its irrigation system. The country’s electricity prices have grown at more than 20 percent per year in recent years and the method for controlling the flow of water was not energy efficient as it called for farm workers to manually tighten valves to limit flow rates.

Pump start-up operations were also time consuming as they required manual opening and closing of valves. Each of the six pumping stations required an hour of an operator’s time for start-up and with up to three power outages per day meant that start-ups became almost a full-time job.

Farm owner Tiaan Riekert decided to test ABB VSDs on one pumping station, with dramatic results. ABB worked with a local systems integrator to supply six VSDs for pumps with motors sized 45 to 75 kW. The new VSDs led to a 40 percent reduction in consumption for just one pumping station, equivalent to $19,700 per year, or a payback period of only seven months. His experience led Riekert to place a repeat order for a second pumping station.

The first drinking water company to apply a SynRM and drive package

Evides Waterbedrijf provides reliable and pleasant tasting drinking water to 2.5 million clients in the Netherlands. It has a progressive philosophy to lower its carbon footprint and look for energy savings in innovative ways. That is why Evides is the first drinking water company to apply ABB’s energy-saving synchronous reluctance (SynRM) motor technology, controlled by ABB ACS880 industrial drives.

To increase redundancy in the drinking water supply in the province of Zeeland, Evides has built a new ‘two-street’ pumping station that has replaced several older stations. Each street has three large 250 kW motors that pump purified water from three buffer-water storage reservoirs with a total capacity of approximately 12,000 m³. The efficient KSB pumps are equipped with ABB’s motors and drives that ensure energy efficient operation.

The water sector is known to be very careful about taking any risks that might disrupt water supply. “We wanted to be the first in the Netherlands to experience the benefits that the SynRM motor offers in combination with variable frequency drives,” says Toine Rijsdijk, an Evides Process Automation Engineer who worked on the project. “We saw that the potential benefits included significant energy savings, as well as cooler and quieter operation. And after two years of running we have not had any problems.”

Energy savings achieved with the motor-drive solution are estimated to be around 20 percent compared to induction motors used in the old stations.

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 labor 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 industry, 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.