Industrial Motor Systems

In many industrial processes electrical energy is transformed into mechanical power to drive machines, pumps or belt conveyors [1]. Also compressed air, fan and pumping systems include motor systems, in total accounting for about 60 percent of energy consumption in manufacturing processes [2]. The manufacturing sector is growing, together with energy demand, especially in countries where wages and resources are inexpensive compared to welfare states. Most of the needed energy still is generated from fossil fuels, which leads to increasing greenhouse gas emissions as well. It is estimated that industrial motor systems will account for 7 percent of global carbon emissions by 2020 [1]. Exclusively considering China, this number can be assumed to be 10 percent [3].

There is a classification scheme for motor systems based on energy efficiency, which was established by the European Commission and the CEMEP , ranging from EFF1 (high efficiency) over EFF2 (medium efficiency) to EFF3 (low efficiency) [4]. Sales figures show that in 2005 only 4 percent of purchased motor systems were classified EFF1, while the major part of motors sold was EFF2 (87%) [5]. By now the classification scheme has been changed to new international efficiency (IE) classes, where IE1 stands for standard efficiency (consistent with EFF2), IE2 stands for high efficiency (consistent with EFF1) and IE3 stands for premium efficiency [4]. Due to technological progress the low efficiency class EFF3 is not considered anymore.

As in vehicles, optimized engineered and controlled motor systems can provide energy and emissions savings as well as long-term cost reductions in production processes. Such motor systems are controlled and optimized by microelectronics. Basically there are three different possibilities to improve the energy efficiency of motor systems:

• Replacement of existing motor systems by high efficiency systems: The potential for improvements by using motor systems of the highest efficiency classification grade is estimated at 10 percent [5]. 
• Equipment of motor systems with electronic rotation speed control: Such motor systems are called variable speed drives (VSD) [1] and are controlled and optimized by microelectronics, to adjust rotation speed and power consumption to match the required level. This minimizes energy losses due to over-sized motor power. It is assumed that electronic speed control could account for efficiency improvements of 30 percent [5]. 
• Optimization of mechanics: Improvements in gears, belts, bearings and lubricants can significantly increase decrease friction and losses and therefore increase energy efficiency. The improvement potential is estimated at 60 percent [5]. 

The role of ICT in the optimization of motor systems is to enable improvements by electronic rotation speed control, accounting for significant efficiency gains. In this context the main principle of optimization is to apply highly efficient frequency converters, as it is necessary to convert the electricity from energy grids to make it applicable to motor systems [5]. The conversion of electricity is always accompanied by energy losses of a certain extent, which can be optimized by microelectronics. Another possibility to improve energy efficiency is to use frequency inverters, which convert direct current (DC) to alternating current (AC) and can there- fore minimize energy losses in acceleration and breaking applications, due to the adjustment of frequency to rotation speed [5]. It is assumed that the efficiency of industrial motor systems can be increased by 30 percent, considering all of the existing options. If this technology is applied at 60 percent of industrial motors this would lead to global savings of 0.68 GtCO2e in 2020 [1].

References

[1] The Climate Group. Smart 2020: Enabling the low carbon economy in the information age. Technical report, The Climate Group on behalf of the Global e-Sustainability Initiative (GeSI), 2008.

[2] United Nations Industrial Development Organisation (UNIDO). Motor systems efficiency
supply curves, December 2010.

[3] G. Philipson. Ict’s role in the low carbon economy. Technical report, Australian Information Industry Association (AIIA), 2010.

[4] European Committee of Manufacturers of Electrical Machines and Power Electronics (CEMEP). New efficiency classes for low-voltage three-phase motors (IE-Code). http://www.cemep.org/index.php?id=53. Accessed: 2013-03-06.

[5] Bio Intelligence Service. Impacts of information and communication technologies on energy efficiency, final  report. ftp://ftp.cordis.europa.eu/pub/fp7/ict/docs/sustainable-growth/ict4ee-final-report_en.pdf, September 2008. Accessed: 2013-02-12.