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June 2009

Factory Automation

An efficiency high

Bringing efficiency up, costs down boosts businesses around the world

By Ellen Fussell Policastro

An integrated group of companies in The Netherlands, called DSM, supplies the life sciences and material sciences sectors with high performance materials, polymers, and industrial chemicals and has annual sales of $8.6 billion (€6.3 billion) and 22,000 employees in over 200 locations worldwide.

After finding repaired motors are less energy-efficient than new ones and comparing a new high-efficiency motor with an old motor, the company found the energy efficiency of the old motor decreased after it was repaired.

“When deciding whether to purchase a new motor or repair an old one, we consider the price of the new motor and how it will depreciate over the following four years,” said Peter Pieters, a company maintenance engineer.

But the benefits to buying a new motor far outweighed the price of repairing the old one. “Even the most expensive new high-efficiency motor will cost less over the long term, taking into consideration the initial investment, the life expectancy of the bearings and energy losses,” Pieters said. “We use around 20,000 motors at DSM, so choosing new high-efficiency motors will lead to a very significant annual reduction in running costs.”

Government mandates

Pieters and his peers in industries across the world are taking a stance for higher-efficiency motors to improve business, not only to meet environmental demands. But the demands from government are cracking down for those who are not as enlightened as Pieters.

A March report from IMS Research said two significant factors affecting the worldwide AC induction motor market over the next five years include rapid slowing of growth in the worldwide economy and government-led movement toward higher-efficiency motors.

First, the worldwide market is forecast to contract more than 7% in 2009. This decline is offset in part by positive, though much slower, growth in China, the report said. Europe, the Middle East, Africa, and the U.S. are seeing much slower growth.

Second, governments have introduced legislation, or encouraged voluntary industry agreements, that will dramatically shift the market away from Environmental Policy Act and EFF2 motors to higher-efficiency motors. EFF2 is the mid-range of a European motor-efficiency designation—EFF1 being the highest efficiency band and EFF3 being the lowest.

The U.S. Energy Independence and Security Act of 2007 (EISA) will now require, beginning 19 December 2010, all general purpose motors of at least 1 HP and not more than 200 HP to meet or exceed NEMA premium motor efficiency levels. Governments and trade bodies in the EU, China, Korea, and Australia have enacted similar legislation or agreements.

Swedish iron ore saves more

Take the case of a mining company in Sweden that acquires only high-efficiency motors. LKAB is an international high technology minerals group out of Luleå that supplies upgraded iron ore products and industrial minerals, and employs over 3,500 people.

The company’s main issue was the criticality of its electric motor efficiency. The company uses almost 15,000 electric motors at its mines and other facilities, accounting for 90% of LKAB’s annual electricity consumption of around 1.7 kilowatt hour, which represents 1% of Sweden’s total electricity consumption.

To address the issue, nearly 10 years ago, LKAB said it would only acquire energy-efficient motors in the future. “They are slightly more expensive to purchase, but you save money in the long run—the purchase price represents only about 1% of the total costs associated with running the motor over its service life,” said LKAB’s Lennart Mukka. By replacing its existing motors with high-efficiency motors, LKAB has achieved significant savings. At the same time, energy efficient motors provide LKAB with the operating capacity it needs without additional maintenance load.

U.K. worth its salt

And not to be outdone in the efficiency race, U.K. salt producer Salt Union had the capacity to produce around 1 million tons of salt every year at its Runcorn site. The company said its high-efficiency equipment, costing just $30,506 (£20,000), cut energy consumption by over 60%, resulting in savings exceeding $152,550 (£100,000) per year.

The main issue for Salt Union was, as part of the production process, salt is passed through dryers, which use fans to suck air in. In addition to food-grade, pure-dried vacuum salt, the plant also produces a courser granular product used in applications such as dishwashers. The dryer for this product previously used a fan to suck air through at a rate controlled by a damper. The damper was 95% closed during normal  operation, so most of the energy consumed was seeing use to suck air through the narrow constriction.

The solution for this British brine master was an energy audit from Central Electrical to determine the potential for energy savings. The original fan motor had a rating of 337 kW, but Central Electrical’s calculations showed 132 kW should be sufficient to create the draft the dryer needed. “That’s a huge energy savings when you think we run the unit for about 8,000 hours a year,” said Dave Mullin, the auditor’s electrical plant improvement engineer. “In fact, it’s equivalent to over 1,600 MWh per year,” he said.

The reason the original fan was significantly oversized traces back to a previous process. The dryer formerly saw use to process vacuum salt crystals, which are much smaller than the spherical, 2-3 mm diameter particles in granular salt.

The resulting energy savings now average $13,724 (£9,000) a month, or $152,550 (£100,000) per year. “The fan was probably on the generous side to start with. Years ago, it was common for engineers to add a safety margin,” Mullin said. “But once the duty changed, it became grossly oversized.”

Ken Tym of Central Electrical said this type of problem is common: “Industries and processes change, but there are a lot of areas that manufacturers don’t seem to consider. Sometimes the main task is to inform end users about the energy savings that are achievable.”

U.S. high-efficiency standards

Any application that runs 2,000 hours or more per year should be using NEMA Premium motors, said Kitt Butler, director of the motors and drives division at Advanced Energy, a national firm that focuses on industrial process technologies, motors and drives testing, and applied building science in Raleigh, N.C.

The National Electrical Manufacturers Association (NEMA) is a U.S.-based association that sets standards used in electrical products, and helps to develop and promote the International Electrotechnical Commission’s standards in the U.S.

“When you look at the lifecycle cost of a motor, the initial purchase price typically represents 3-5% of the total ownership. The other 95-97% is mostly the cost of energy to run the motor. This assumes a 10-year life for the motor. Having the highest efficient motor you can buy pays dividends every moment it is spinning,” he said. “Pumps, fans, compressors, and conveyors are the most common types of applications that should be using NEMA Premium motors,” he said. Manufacturers should also employ variable frequency drives in applications that require varying output for more energy savings.”

Pulp and paper, chemical, and food all specify NEMA Premium high-efficiency motors—at least in the U.S. Some of them have active motor management programs with dedicated staff that work throughout the supply chain to make sure their motors are the most efficient they can buy and that they stay that way while running in their plants, Butler said.

These companies sometimes contract directly with a single motor manufacturer to reduce costs further and review those contracts with us from time to time by testing for efficiency in our lab. These companies also pay close attention to their motor repair vendors to make sure they maintain efficiency when repairing a motor for them. “Weyerhaeuser, DuPont, BASF, Rock-Tenn, and Cargill are companies we’ve worked with in the past,” said Butler, who offers a quality assurance program called Proven Efficiency Verification to the motor repair industry. “Companies like Cargill have required it in their motor repair specifications,” he said.

Companies with active motor management programs are claiming it reduces their energy usage 5-8%, which increases their process reliability; motor management includes a formal inventory process that identifies critical motors and makes certain good plans are in place to keep that process running, Butler said.

The inventory also predetermines the repair-or-replace decision every company has to make when a motor fails in operation, such as in DSM’s case.

“By making the decision ahead of time, they make good clear choices that do not degrade efficiency, and they make them faster,” Butler said. Butler’s company has published an HP Bulletin and Motor Survey How to Guide, which is most useful for manufacturers who want to start working on motor management or improve the policies they already have. “We also conducted research on motor ride-through, in which a motor driven system can safely ride through momentary power interruptions, reducing unplanned down time.”

Electric motors convert on average 70% and sometimes, for the large process industries, 90% of the electrical energy delivered to an industrial facility to mechanical energy. Because of this, they warrant attention, “and this is why we’ve been working at it for almost two decades,” Butler said.

The need for high-efficiency motors will remain critical as energy prices are expected to continue rising. On 19 December 2010, the new EISA efficiency levels for industrial motors will go into affect. “This only addresses the new motor population and does not require anyone to replace existing stock of motors, which is in the millions,” Butler said. Continued education, awareness, and incentives for NEMA Premium motors will be crucial, even after EISA is in effect.

ABOUT THE AUTHOR

Ellen Fussell Policastro is the associate editor of InTech. Her e-mail is efussellpolicastro@isa.org.