Electric Motor Energy Efficiency - By the Numbers

Introduction

Today over 24 trillion kWhs of electricity is consumed worldwide. This is projected to grow to 39 trillion kWhs by 2040. There are over 300 million motors in use in industry, infrastructure and large facilities which consume over 6.75 trillion kWhs or a little over 1 out of every 4 kWh generated in the world is consumed by electric motors in large commercial facilities and industrial operations. Typically, motors consume in excess of 60% of an industrial sites’ electrical energy (approx. 30% in commercial facilities). For many industrial facilities it can be even greater. In primary manufacturing, process loads predominate and motors may constitute more than 90% of a site’s electrical consumption. The motor driven consumption will continue to increase proportionate to the electricity consumption projections and is represented in the 30 million electric motors sold annually for replacement and new applications, which as a market, is projected to grow at 19.67% over the next 5 years. Conservatively by 2040 we will be looking at over 600 million electric motors in use in the Commercial and Industrial (C&I) sectors consuming over 13.5 trillion kWhs. At $.1 per KWh this is equivalent to $1.35 trillion per year. Of this motor-driven equipment consumption D.O.E estimates that 15% to 80% of the energy consumed is wasted (Fig 1).

Motor-driven assets must be a major focus of attention in any program to reduce energy and CO2 emissions and within the industrial sector particularly, a cornerstone of any efficiency program.

Motor Efficiency Standards & Regulations

The International Electrotechnical Commission (IEC) introduced standards for classification of motor efficiency. The IEC requirements do not mandate particular efficiency levels, but they are used by governments around the world to legislate minimum efficiency performance standards to address energy independence and the ever- increasing environmental concerns. In the U.S. for example the National Electrical Manufacturers Association (NEMA) established IE3 equivalent (NEMA Premium) is mandatory. In Europe a program (EU MEPS; European Minimum Energy Performance Standard; IEC 60034- 30) is legislated to get to IE3 by 2015 for all motors between 7.5 kW to 375 kW and IE2 only in combination with a variable speed drive. And by 2017 that is expanded to IE3 for all motors between 2017 from .75 kW to 375 kW and again IE2 only in combination with a variable speed drive. Add to this that IE4 super premium efficiency levels were declared in 2012 and motors meeting this standard are now becoming commercially available presenting a whole new set of compliance, economic, and efficiency opportunities to consider. Fig. 2 summarizes the motor efficiency rating standards in place today.

The standards specify electrical efficiency classes for single-speed, 3-phase, 50Hz and 60Hz, cage- induction motors that have:

• 2, 4, or 6 poles (3,000; 1,500; and 1,000 RPM at 50Hz),
• rated output between 0.75 and 375 kW (.5 to 280 hp), and
• rated voltage up to 1,000 V.

These standards exclude motors made solely for inverter operation and motors completely integrated into a machine (pump, fan or compressor) that cannot be tested separately from the machine. These will be addressed in forth coming Asset Sustainability @ Work LLC Knowledge Briefs.
For 60Hz operations minimum full load efficiency values are virtually identical between NEMA (USA) and IEC. NEMA, however, does specify different full-load efficiency values for motors with Fan-Cooled and Open-Drip enclosures. The IEC minimum full-load efficiency standards are higher for 60Hz than for 50Hz. This is because as long as motor torque is constant winding resistance losses are the same for both. The motor output power, however, increases linearly with speed, increasing by 20% when the frequency is increased from 50 Hz to 60Hz. In general the 60Hz efficiency is about 2.5% to 5.0% better than 50Hz values.
To demonstrate compliance with these efficiency standards, motors must be tested in accordance with IEC 60034-2-1 testing protocol which produces results compatible with the North American IEEE 112B and CSA 390 testing methods. In both cases the standards require that the motor efficiency class and nominal motor efficiency be labeled on the motor nameplate and given in motor catalogs and OEM product literature in the following format; IE3 94.5%.
Based on the U.S. Department of Energy data, it is estimated that the NEMA premium efficiency motor program adoption would save 5.8 terrawatts of electricity, or the equivalent capacity of 725 800 megawatt power plants, in the next 10 years. From an environmental perspective this is equivalent to preventing the release of 80 million tonnes of carbon into the atmosphere.

Motor Life Cycle Management

Commercial and Industrial companies, Non Gov’t Organizations as well as Gov’t Agencies, whether they have a dozen unique motor- driven equipment or thousands, should adopt a motor life-cycle efficiency strategy, based on the convergence of objective, detailed energy information and intelligence with their motor management operations to include:

• Maintaining a comprehensive inventory of all motors, name plate data, specifications, OEM data, pricing, operating and maintenance history (e.g. installation, rebuild and rewind), previous application performance by motor and location, available rebates and incentives, and applicable regulations,
• Selecting the appropriate motor energy efficiency class based on regulations and efficiency performance requirements,
• Understanding within operating & maintenance context a motor’s energy performance and benchmark against inter and intra company and market current high efficiency performance standards,
• Ensuring power supply quality standards are maintained to meet motor rated efficiency and performance levels. Particularly harmonic distortion and voltage unbalance.
• Prioritizing motor maintenance and replacement efforts and resources with highest run times and potential operational, financial, and environmental impact,
• Identifying motor efficiency upgrade opportunities and determining repair vs. replace economics, and planning for future capital appropriations based on alternative’s market availability, pricing, and life-cycle operating costs,
• Identifying power quality and motor’s non-conformity performance, and notify the right person at the right time at the right place to mitigate the non- conformity,
• Documenting, verifying and validating energy efficiency measures taken and results attained,
• Manage available spares for energy efficiency and not only emergency repairs and uptime,
• Applying applicable preventive (PM) predictive (PdM) and condition based (CdM) maintenance strategies based on both direct and indirect moto energy efficiency determinants.

Systematic Motor Efficiency

To attain the greatest potential operating, financial, and environmental benefits of a motor efficiency program the program must systematically address the following factors;

1. ensuring management commitment for placing emphasis on energy efficiency and motor energy expense as an important cost,
2. ensuring organization alignment where accountability and responsibility for motor operating performance and efficiency are one and the same,
3. focusing on integration into day-to- day business processes as opposed to looking to audits and projects to deliver sustainable benefits (this falls under my rule , “don’t kid yourself”. You will end up only funding certain projects, on average less than 30% as you compete with other business initiatives, and the results are typically not sustainable with the benefits decaying over time due to lack of maintenance), and
4. promoting benefits. Initially there will some level of disbelief that an effective motor efficiency program is achievable. To sustain the motor efficiency program inertia a cognitive approach to educating the stakeholders of the benefits being derived is a critical success factor. Therefore to address the factors outlined there is really only one practical solution, a systematic approach to motor efficiency based on the convergence of the “Motor Community”; the OEMs, Operations & Maintenance, and Energy Management, people, process, products and technology through a Community information portal. The portal provides motor efficiency analytics enabled by unlocking internally and externally stored data and information, and as an integrator and aggregator, a single gateway to make informed motor efficiency maintenance and replacement decisions within a company context.

The “Motor Community” convergence is a collaborative motor energy efficiency approach based on inter and intra company stake holder data, operating alignment, and intelligence and communication. Interdependent data, processes, and intelligence would need to ultimately be systematically integrated into a company’s day-to-day direct and indirect motor related business functions (operations & control, maintenance, procurement, environmental health & safety / sustainability, energy management, finance, and regulatory compliance). To accomplish this a Community portal front end should provide members with security clearance and information profiles designed to actively inform users of motor-driven equipment priorities and actions required by workflow processes controlled by a company’s many disparate systems throughout their enterprise.
This comprehensive “Motor Community” approach, that nobody really has and everybody needs, should be the basis for any systematic motor efficiency program.

Dollars & Sense

The motor efficiency program business case is very compelling. To illustrate we will use the following; typical observed motor efficiency is 82.5%. And let’s assume that IE3 94.5% is attainable. In this example we will use a 100 hp motor costing $10,000 with a lifetime operations expectancy of 10 years. And one last factor, electricity cost are $.10 per kWh.
So let’s do the math. The life-cycle (10 yr @ 8,000 hrs./ year) energy cost:
@ 82.5% efficiency = $723,394 = ( 100 hp * .746 kW / hp * 80,000 hrs. * .$.01/ kWh ) / 82.5%
@ 94.5% efficiency = $615,534 = ( 100 hp * .746 kW / hp * 80,000 hrs. * .$.01/ kWh ) / 94.5%
a potential savings of $91,860 by either maintaining the motor for premium efficiency performance or replacing the motor with a comparable premium efficiency motor. Now translate these potential savings for one motor to over 300 million motors.
The question is now, would you invest $3,120 over 10 years to save $91,860? It’s possible!

Conclusion

Electric motor–driven systems consume large amounts of electrical energy and can provide an opportunity for significant energy savings. Energy represents more than 97% of total motor operating & maintenance costs over the motor’s lifetime. However the purchase of a new motor or the maintenance of an existing motor often tends to be driven by price or performance, not the electricity it will or is consuming. Even a small improvement in efficiency could result in significant energy and cost savings while also reducing the greenhouse gases that contribute to climate change.

References

1. US Department of Energy; Motor Systems Tip Sheet
2. Motor Asset Management; Schneider Electric
3. Wikipedia; Premium Efficiency Electrical Motors

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About the Author

Rod Ellsworth has over 30 years of related energy and enterprise asset management experience. Prior to founding Asset Sustainability @ Work Rod lead the convergence of the energy and asset management markets, “Global Asset Sustainability”, through the first commercially available energy and asset management offering. Rod founded Asset Sustainability @ Work to develop certified Best Practice software tools to enable Customer business transformation with organizations having a focus on promoting energy conservation and sustainability by delivering the financial and physical controls for an enterprise to be in full control of their sustainability, energy consumption, and the asset and operating infrastructure that underpins them. Asset Sustainability @ Work’s initial offering is Motors @ Wok, a SaaS solution based on certified best practices for managing commercial and industrial motor-driven equipment for peak energy efficiency.

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To learn more how your Company can adopt a comprehensive electric motor energy efficient program contact:
Asset Sustainability @ Work LLC tel. +1 864.297.0211 or visit Motors@Work.