Gest. Prod., São Carlos, v. 26, n. 4, e3928, 2019 Original Article https://doi.org/http://dx.doi.org/10.1590/0104-530X3928-19 Energy planning and management during battery manufacturing Planificación y gestión energética durante la fabricación de baterías ISSN 0104-530X (Print)ISSN 1806-9649 (Online) Eliana Noriega Angarita1  Juan José Cabello Eras1 Hernán Hernández Herrera2 Vladimir Sousa Santos1 Milen Balbis Morejón1 Jorge Ivan Silva Ortega1 Alexis Sagastume Gutiérrez1 How to cite: Noriega Angarita, E., Cabello Eras, J. J., Hernández Herrera, H., Sousa Santos, V., Balbis Morejón, M., Silva Ortega, J. I., & Sagastume Gutiérrez, A. (2019). Energy planning and management during battery manufacturing. Gestão & Produção, 26(4), e3928. https://doi.org/10.1590/0104-530X3928-19 Abstract: The aim of this study is to improve energy performance at a battery factory in Colombia by introducing the energy management approach defined in ISO 50001. In the study, the main energy consumptions were identified in the battery formation, the compressed air system and the large electric motors. An energy review was performed in the factory using measurement equipment and statistical techniques. Different actions were proposed to improve energy performance. As a result, a 3.48% reduction in electricity consumption was achieved during the implementation of the proposed measures. Keywords: Energy planning; Energy efficiency; ISO 50001. Resumen: El objetivo de este estudio es mejorar el rendimiento energético en una fábrica de baterías en Colombia mediante la introducción del enfoque de gestión energética definido en ISO 50001. En el estudio, los principales consumos de energía se identificaron en la formación de la batería, el sistema de aire comprimido y la gran red eléctrica motores. Se realizó una revisión energética en la fábrica utilizando equipos de medición y técnicas estadísticas. Se propusieron diferentes acciones para mejorar el rendimiento energético. Como resultado, se logró una reducción del 3,48% en el consumo de electricidad durante la implementación de las medidas propuestas. Palabras clave: Planificación energética; Eficiencia energética; ISO 50001. 1 Introduction Since the late 20th century, energy issues have consumption (Fawkes et al., 2016). However, it been a top priority at all levels of discussion. This is is also one of the areas with the greatest potential because energy consumption is growing faster than in terms of savings, estimated at around 20% of the population, and the use of primarily fossil fuels consumption, equivalent to a reduction of 974 million is an evident cause of climate change, which poses tons of oil equivalent (mtoe) (Chan & Kantamaneni, a major threat to sustainability (Kaygusuz, 2012; 2015; Fawkes et al., 2016). One of the main paths to Camioto et al., 2015; Castro et al., 2015). realizing such potential is through energy efficiencies Manufacturing is one of the activities that most (EE) achieved through improvements in energy consumes energy, accounting for 29% of total global management (EM) (Abdelaziz et al., 2011). 1 Grupo de Investigación en Optimización Energética – GIOPEN, Departamento de Energía, Universidad de la Costa – CUC, Calle 58 No 55-66, Barranquilla, Colombia, e-mail: enoriega2@cuc.edu.co; jcabello2@cuc.edu.co; vsousa1@cuc.edu.co; mbalbis1@cuc.edu.co; jsilva6@cuc.edu.co; asagastu1@cuc.edu.co 2 Facultad de Ingeniería, Universidad Simón Bolívar, Carrera 59 No. 59-65, Barranquilla, Colombia, e-mail: hernan.hernandez@ unisimonbolivar.edu.co Received Apr. 26, 2017 - Accepted Nov. 24, 2017 Financial support: None. 1/14 Noriega Angarita, E. et al. Gest. Prod., São Carlos, v. 26, n. 4, e3928, 2019 EM is defined by Abdelaziz et al. (2011) and The primary objective of this study is to improve Cabello Eras et al. (2016) as a set of activities carried energy performance through the implementation of the out to minimize the costs and environmental impacts energy planning process described in the ISO 50001 of energy use without affecting production levels and standard at a Colombian battery factory (ISO, 2011). quality, which involves the continuous improvement The study also aims to lay the foundations for the of energy performance through control, monitoring, implementation of an Energy Management System, planning and development of actions and strategies to which over the medium term will complement the increase EE (Bunse et al., 2011; Aragon et al., 2013). Integrated Management System at the company, which Even though many countries have made substantial holds certifications in ISO 9000 “Quality Management progress in implementing EM (Cabello Eras et al., System”, ISO 14000 “Environmental Management 2015; Christoffersen et al., 2006; Gielen & Taylor, System” and ISO 45001 “Work Health and Safety 2009; Hens et al., 2017; Palamutcu, 2010; Posch et al., Management System”, contributing substantially 2015; Rudberg et al., 2013; Vine, 2005; Weinert et al., to improving overall performance at the company 2011), it is widely acknowledged that there is still a (Cañizares et al., 2015). long way to go in terms of optimizing the potential of EM and EE for reducing energy consumption and the 2 Material and methods environmental impact of manufacturing (Bunse et al., 2.1 Lead-acid battery manufacturing 2011; Cagno & Trianni, 2014; EC, 2014; Giacone & Mancò, 2012; ISO, 2014; Ospino-Castro, 2010; process Weinert et al., 2011). Figure 1 represents the lead-acid battery manufacturing Electric batteries are essential components in process and its main energy inputs. numerous applications. The most widely used type In the cell manufacturing process, the raw material is the lead-acid battery, of which three types are is a lead alloy. The cells are manufactured by means produced: starter, traction and stationary batteries. of casting in book molds, or through continuous These are used in motor vehicles, electric vehicles processes such as stamping, extrusion or continuous and energy storage applications, respectively. casting with subsequent rolling. In this process the The bulk of production is in starter batteries, of most widely used energy carrier is heat, which is used which close to 41.5 billion dollars were sold in 2012 to melt the lead, and is usually generated from LPG (Miloloza, 2013). Manufacturing of such batteries or oil, followed by electric power for the machines is highly energy-intensive, as the process uses large (Jung et al., 2016). quantities of electricity and other energy carriers Lead oxide is the main active component of the (Pavlov, 2011; Report Buyer Ltd., 2015; Rydh, 1999; batteries’ positive and negative electrodes and it Sullivan & Gaines, 2012). According to (Rydh & is used to coat the cells. They are produced using Sandén, 2005), each kilo of battery production consumes high purity lead, which is molten in a container and between 15 and 34 MJ, depending on whether the stirred rapidly with a rotating paddle to bring it into raw materials are recycled or virgin. The production contact with an air stream. During this stage energy process accounts for 30% of such energy, primarily is consumed primarily in the form of heat to melt in machine operation, heat-based processes for the the lead, followed by compressed air and powering transformation of materials, battery assembly, and of machines.During the pasting process the cells are filled and ancillary systems such as compressed air. The stage covered with the lead oxide paste. During this stage of the process that consumes most energy is battery electricity is used to power the machines. Afterwards formation (Jung et al., 2016; Pavlov, 2011; Sullivan they are cured in a temperature-controlled room during & Gaines, 2012), during which batches of batteries 32 hours; during this phase heat is used to prepare are charged simultaneously for the first time. This is the paste and to control the room’s temperature a critical process, as the useful life and performance (Jung et al., 2016). of the battery largely depends on the manner in which In the assembly process all the battery components this process is performed. are fitted into the body; once the battery is sealed it Heat energy is used primarily in the lead melting is ready to receive the electrolyte. During this stage process involved in manufacturing battery components. energy is consumed primarily in terms of electricity According to (Rantik, 1999), the most widely used and compressed air to power the machines and the energy carrier is electricity (4.8 MJ/kg of batteries), devices involved in the assembly (Jung et al., 2016). followed by heat (1.68 MJ/kg) and liquefied petroleum The battery formation process consists in charging gas (LPG) (1.3 MJ/kg). the battery for the first time; it involves chemical Despite the high energy-intensiveness of the lead-acid processes in the grids that transform them into battery manufacturing process, only a handful of active positive and negative electrodes. This process studies in the specialized literature address this topic. is crucial for the battery’s performance and useful 2/14 Energy planning and management… Gest. Prod., São Carlos, v. 26, n. 4, e3928, 2019 life, and consequently it is performed based on involves the identification of the areas that have the pre-established patterns regarding voltage and current most effect on energy consumption; forecasting and (Pavlov, 2011). In starter batteries, the formation planning of energy consumption; identification of process is performed in special facilities called battery potential savings, and action plans to achieve such charging units (BCU), which perform the process savings. The standard describes a four-stage process: in batches. This is the process that consumes most energy policy, energy planning, implementation and electric energy in the starter battery manufacturing verification, all as part of a continuous improvement process (Jung et al., 2016). cycle (Soto et al., 2014). The energy planning phase and the activities that 2.2 Methodology form part of it are considered the core of the EMS. Approval of the ISO 50001 standard in 2011 was This phase sets the foundations for the development a fundamental step in the development of EM at the of energy performance improvement strategies by international level, because it established the general setting specific and attainable objectives and by requirements for Energy Management Systems (EMS). establishing measures to ensure their fulfillment. Among other aspects, application of this standard Figure 2 provides a schematic view of this phase. Figure 1. Lead-acid battery manufacturing process. LPG = Liquefied Petroleum Gas. Figure 2. Energy Planning. 3/14 Noriega Angarita, E. et al. Gest. Prod., São Carlos, v. 26, n. 4, e3928, 2019 In line with what is established by the ISO 50004 In five of the months it was observed that the (ISO, 2014) standard, the methodology used in this behavior of electricity consumption and production study has 6 steps: were not proportional: In February 2011, May 2012 and November 2014 battery production increased but 1. Analysis of energy consumption and use; electric power consumption dropped because most 2. Finding the energy baseline and goal line; of the batteries produced were of lower capacity. In November 2011 the number of batteries produced 3. Developing energy performance indicators fell and electric power consumption dropped only (EPIn); slightly because most batteries produced were of greater capacity. In March 2014 production decreased 4. Identification of areas with significant energy and power consumption increased because during use; that month a technical shut-down of the plant took 5. Identification of opportunities to improve energy place over several days, during which energy was performance; consumed but no batteries were produced. Despite these exceptions, overall we find that electric power 6. Implementation and evaluation. consumption is proportional to the number of batteries produced. The relationship between these two parameters is to be used as the energy performance 3 Results and discussion indicator (EPIn) at the factory. The study was carried out at a Colombian battery factory whose production has increased at a rate 3.2 Finding the energy baseline and goal line of 14% per year between 2012 (742,600 batteries) and 2015 (1,110,900 batteries), in an assortment of The energy baseline (EBL) is used as a benchmark 168 battery types. The study reviewed consumption against which to measure progress and shortcomings and production data between 2011 and 2014; the in the organization’s energy performance. It establishes proposed improvement measures were implemented the status of energy use at the beginning of the in early 2015, and the results were assessed during intervention. the same year. In order to find the EBL, correlation analysis was performed between monthly electricity consumption 3.1 Analysis of electricity consumption and monthly battery production from 2011 to 2014; the results are displayed in Figure 4. Figure 3 displays monthly battery production and All the points included in the correlation analysis electric power consumption between 2011 and 2014, reflect actual operating conditions at the factory; indicating that consumption has risen in line with statistical analysis of consumption values produced production, which implies that improving energy a standardized bias of 0.49 and standardized kurtosis efficiency is an important priority given its high of 0.24. Because the values are within the range of incidence on production costs. -2 and +2, we can assume that the data are normally Figure 3. Monthly behavior of production and electricity consumption. 2011-2014. 4/14 Energy planning and management… Gest. Prod., São Carlos, v. 26, n. 4, e3928, 2019 distributed. The t-test yielded a P-value of 0.0012, electricity consumption and the number of batteries indicating that the mean is different from 0. produced at a 95% confidence level. According to the specialized literature on studies The lineal correlation found for EBL has a of this type based on actual operating data, if the coefficient of determination R2 = 0.7519; since it is coefficient of determination (R2 > 0.6), a baseline greater than 0.6, according to the specialized literature and EPIn model can be developed with good results, (Becken et al., 2001; Bohdanowicz & Martinac, 2007; and if the coefficient is greater than 0.8, very good Deng, 2003; Matson & Piette, 2005), the relationship results can be expected (Deng, 2003; Matson & Piette, between batteries produced and energy consumption 2005; Becken et al., 2001; Bohdanowicz & Martinac, may be used to develop an EPIn, and the baseline 2007; Castrillón et al., 2013; Yanes & Gaitan, 2005). equation can be used for electricity consumption planning and evaluation purposes. Figure 4 displays the results of the correlation A reasonable and attainable goal is for energy analysis performed to find the baseline. The R2 statistic consumption to approach the values that are below indicates that the adjusted model explains 75% of the EBL. Similarly, the points that are above the the variation in electricity consumption compared to EBL can be used to estimate possible worsening of the number of batteries produced. The P-value in the energy consumption under current plant conditions if analysis of variance was 0.0004 for estimation of the no action is taken. Figure 5 shows the goal line (GL) slope and 0.0001 for estimation of the intercept; the calculated based on the points whose performance is fact that both values are less than 0.05 indicates that better than the EBL, and the worsening line calculated there is a statistically significant relationship between based on the energy performance points that are Figure 4. Energy baseline. Figure 5. Baseline, goal line and worsen line. 5/14 Noriega Angarita, E. et al. Gest. Prod., São Carlos, v. 26, n. 4, e3928, 2019 above the EBL and which tend to affect EE and to behavior of the GL indicator, the possible worsening of worsen performance. the indicator and some points reflecting actual months The potential for savings without changes to the of operation at the plant. The points below the EPIn equipment is calculated based on the difference control curve have satisfactory energy performance, between the area under the EBL straight line and and the points above have deficient performance. the area under the GL straight line. It is equal to 8% Through the implementation of the energy savings compared to current consumption, which would actions at the company, energy performance is expected produce savings of 75,200 kWh per year. Possible worsening is calculated in a similar manner, yielding to approach the goal line indicator, indicating an a result of 13%. improvement in energy performance. 3.3 Construction of the EPIn. 3.4 Identification of the main areas of energy use The objective of the EPIn is to follow up on, monitor and control the company’s energy performance. In order to identify the main areas of energy use, The company’s performance indicator is obtained simultaneous measurements were taken of overall from the baseline Equation 1, as follows: electricity consumption at the plant and of the ( ) areas and equipment that presumably have greatest Electricity consumption kWhEPIn = (1) Number of batteries produced consumption. The measurements were taken using a portable Fluke model 435 II class A network analyzer. Figure 6 displays in graphic form the behavior of Figure 7 displays the Pareto diagram of the main EPIn vs monthly battery production, as well as the energy users. Figure 6. Monthly control chart of the EPIn. Figure 7. Pareto chart. 6/14 Energy planning and management… Gest. Prod., São Carlos, v. 26, n. 4, e3928, 2019 3.5 Main electricity users At each circuit, the drop in tension and current As shown in Figure 7, the area of greatest electricity between the connection points was measured, and consumption is the battery charging unit (BCU), which losses were calculated based on Equation 2. accounts of 42% of the factory’s consumption, followed P =V ⋅ I (2) by the compressed air system, which accounts for 9%, and large motors, accounting for 8%. where: V = Difference in measured tension (V); I = Measured current (A); P = Power (W). The above power is also calculated as: 3.6 Identification of opportunities to improve energy performance. P = I 2 ⋅ R (3) At each of the main energy usage areas the energy where: R = Resistance of circuit elements (Ω). review procedure displayed in Figure 2 was performed, Equation 3 indicates that the losses are directly in order to identify savings opportunities that may proportional to electrical resistance, given that the improve energy performance. demand for current is constant for all types of battery. Resistance in turn depends on the conditions of the 3.6.1 Identification of savings electrical conductors and points of connection. opportunities in the BCU At each circuit the power consumed was measured at the conductors and at the contact points between The energy review focused on assessing the the cables and the battery terminals, based on technical conditions of the charging tables and on which power consumption was measured using identifying deficiencies or operating problems during Equation 2. Taking into consideration the time the the formation process that produce energy losses and process takes, total energy losses were calculated consequently worsen the energy efficiency indicator. (Wh) at the conductors and contacts of each charging During the study, measurements were taken of electrical circuit. Figure 9 shows the average of such losses parameters related to losses and a thermographic at the circuits, indicating those with best and worst survey was performed for all the battery charging energy performance, finding a significant difference circuits. Figure 8 displays the arrangement of the of approximately 2000 Wh, which indicates that the battery charging circuit connections. technical conditions of the conductors and contacts Figure 8. Battery formation circuit chart. Figure 9. Energy losses at the circuits with best and worst energy performance. 7/14 Noriega Angarita, E. et al. Gest. Prod., São Carlos, v. 26, n. 4, e3928, 2019 represent an opportunity for improvement of energy • Implement cleaning programs for connectors performance in the formation process. and other devices; The incidence of the technical conditions of the conductors and contacts was confirmed by the results • Implement systematic inspection with thermography of the thermographic survey, which is displayed in to assess the quality of the process from an Figure 10, showing that conductors and contacts in energy perspective; good conditions operate at 45°, whereas in others • Establish protocols for the manual connection the temperature rises as high as 95 °C. of circuits; Another source of inefficiency that was identified was the high level of tension of supply for the • Implement a frequent maintenance in the area formation process, with an average for all circuits to ensure cleanliness and good conditions of of 17.6 V; this is higher than the recommended 16 V fixed contacts; (Kiessling, 1992; Pavlov, 2011; Prout, 1993). Since energy is proportional to tension, in a scenario of • Re-design the connectors; constant current (Equation 2) this causes substantial • Set voltage supply in the batteries formation over-consumption of energy, as well as an increase in section at 16.4 V according to the possibilities Hydrogen and Oxygen emissions during the process of the transformer. (IEC, 2000; Pavlov, 2011). 3.6.2 Actions to be implemented to 3.6.3 Identification of savings opportunities improve energy performance in the in the compressed air system batteries formation process The compressed air system is in charge of supplying air in the required conditions of pressure • Establish requirements for use of intermediate and quality to all plant equipment and facilities that conductors. Frequent inspections of their require it. The network installed throughout the technical conditions; plant is 942.6 m long with a volume of 4.12 m3; it is Figure 10. Thermographic analysis results. 8/14 Energy planning and management… Gest. Prod., São Carlos, v. 26, n. 4, e3928, 2019 divided into two main components: generation and P1 − P2 demand. The generation side consists of four modern C =V ⋅ k (4)t ⋅ P0 and efficient compressors of the KAESER make model ASD 40S, each with flow of 162 Cubic feet where: C = Air leak capacity (m3/s); P1 = Test starting per minute (CFM) and consumption of 30 kW; one pressure (Psi); P2 = End of test pressure (Psi); KAESER TF 230 drying unit with flow of 671 CFM t = Time it takes to reach the end of test pressure and consumption of 1.61 kW and one buffer tank (sec.); P0 = Atmospheric pressure (Psi); V = Total with capacity of 1.13 m3. volume of the system; k = Coefficient of correction Energy consumption measurements were taken to the normal pressure system; k = 1.25. during one week using a Fluke model 435 II class The results of the measurements and the value of A portable network analyzer, to measure energy the leaks are displayed in Table 1. consumption and start-up and idling times of the The average (Mean) value of the leaks was 34.61 compressors. It was found that total consumption and the standard deviation (σ) of the measurements is between 110 and 130 kWh, very close to its was 2.49. Measurement number 4 was excluded from maximum value. The operating regime consists of the sample because it lies outside the control range of three compressors working continuously and one the variable (Mean -σ, Mean +σ), which is between compressor working in the ON/OFF mode, depending 31.8 and 36.8, and the final average value is 33.7%. on the regulated pressure range of the system, which This average value of leaks is greater than that is set at Pmax = 108 Psi and Pmin = 100 Psi. The start-up recommended in the literature, which indicates that and idling times are between 17 and 25 seconds, it should be lower than 15% (Abdelaziz et al., 2011; which is far below the values established by the Dindorf, 2012), which implies that the leaks must manufacturer, which recommends minimum idling be corrected. time of 2 minutes for compressors of this type. If the system worked at the recommended values This behavior may the result of inadequate system of leaks of between 10-15%, it would require a flow design, substantial air leaks, or both. An inspection of 484 CFM. At this value, three compressors would of the network was performed with an AMPROVE be in operation and the other would be on standby as TMULD 300 ultrasonic detector to identify places backup. Two of the three compressors in operation with substantial leaks, links with abrupt layouts, would be in continuous operation and the other would poorly designed reductions and sealing problems. be in the ON/OFF mode, dependent of the pressure To establish the value of the leaks, the procedure in the system. Calculations were performed to make proposed by (Dindorf, 2012; Saidur et al., 2010) was the idling last 2 minutes, as recommended by the used, which consists in starting up the compressors manufacturer, finding that a storage tank of 6.53 m3 with no demand in the system, bringing them up to capacity would be required, and that regulation of the working pressure and then shutting them off to find generation system should be changed to the range of the average time it takes the pressure to fall below between Pmax = 120 Psi and Pmin = 100 Psi. This 50% of its nominal value. The value of the leaks was new system configuration would produce savings calculated based on such nominal value through the of 27% compared to the current system, which is following Equation 4. equivalent to 8,793,865.98 COP per month. Table 1. Measurement results and percentage of leaks. Measurement number P start Psi P end Psi T, sec. Amount of air leaked % leaked 1 104 52 186 207.43 CFM 32.01 2 105 52.3 153 255.53 CFM 36.43 3 104.4 51.8 189 206.59 CFM 31.88 4 104 51.7 150 258.71 CFM 39.92 5 105.2 52.1 183 215.27 CFM 33.22 6 104.6 52.5 184 210.19 CFM 32.43 7 103.8 51.4 167 232.86 CFM 35.93 8 104.3 52.4 176 218.88 CFM 33.77 9 103.9 52.1 173 222.27 CFM 34.30 10 105.3 52.4 182 215.70 CFM 33.28 Average 34.61 CFM = Cubic feet per minute. 9/14 Noriega Angarita, E. et al. Gest. Prod., São Carlos, v. 26, n. 4, e3928, 2019 3.6.3.1 Actions to be implemented to motor was performed using a method based on the data reduce energy consumption in the on the motor plates and catalogs (Hasanuzzaman et al., compressed air system 2011). The assessment considers the effects of the harmonics generated by the frequency drives, by • Establish a leak detection and correction program means of the model for losses due to the effect of harmonics indicated in the standard (ANSI, 2012). with maintenance personnel. The program will Table 2 displays the nominal data of the motors, consist of inspecting the entire compressed air the average and maximum values of the load factor system to identify leaks and eliminate them and the operating efficiency of the motors, as well as through sealing or substitution of the required the percent difference between nominal efficiency and sections. The personnel will be equipped with an maximum operating efficiency obtained in each motor. AMPROVE TMULD 300 ultrasonic leak detector The table shows that motors M2, M3 and M9 and a Fluke Ti200 thermographic camera, as are operating near nominal efficiency, whereas the recommended by (Dudic et al., 2012; Dindorf, operating efficiency of the remaining six motors is 2012; Saidur et al., 2010; Abdelaziz et al., 2011); lower. In motors M1 and M4, the lower efficiency is due to the effect of harmonics generated by frequency • Also, sections with layout design problems drives. In motors M5 and M8 the lower efficiency must be corrected; is because they work at a load factor below 50%, • Substitute the buffer tank for one with capacity whereas in motors M6 and M7 the lower efficiency equal to or greater than 6.53 m3; is due to a combination of the harmonics effect and the low load factor (Chirindo et al., 2016; Siraki & • Once the new tank is installed, increase the Pillay, 2012; Sousa et al., 2017). Motors M1, M2, M4, generation system regulation pressure to a range M6 and M7 operate with frequency drives, whereas of between 100-120 Psi, with the objective of the other motors use soft starters. reducing sudden changes in demand and pressure drops and to increase the compressor start-up 3.6.4.1 Actions to reduce energy and idling interval, thereby reducing electricity consumption in electric motors consumption and increasing useful life. Replace motors to improve operating efficiency. In order to reduce energy consumption of the 3.6.4 Identification of savings opportunities motors, the proposal is to replace the current motors for new ones that operate at a higher load factor in large electric motors and level of efficiency (Siraki & Pillay, 2012). The operating features of the nine motors with An economic feasibility analysis was performed greatest consumption were studied. Fluke model 435 II using the Simple Return on Investment method class A and Dranetz Power Visa portable network (SROI) (Hasanuzzaman et al., 2011), which takes analyzers were used to measure the monthly energy into consideration the cost of the new motor, lower consumption of each motor. The assessment of output expenses due to energy savings and the residual value power, the load factor and operating efficiency of the of the equipment to be replaced. Table 2. Output power, load factor and operating efficiency of the motors. Nominal Energy F F η η Differencec c o o Motor efficiency consumption average max. average max. ηn and ηo (%) (kWh/month) (%) (%) (%) (%) (max.)(%) M1 93.6 25,997 71.4 73.9 89.0 90.8 2.99 M2 94.1 20,028 84.4 94.7 93.5 93.7 0.43 M3 91.8 11,045 64.9 65.7 91.4 91.4 0.44 M4 94.1 17,484 68.8 72.2 87.3 88.3 6.16 M5 93.6 12,556 27.0 42.9 89.1 92.3 1.39 M6 93.0 2,642 28.5 44.3 85.3 91.8 1.29 M7 90.2 2,756 25.6 44.0 81.0 88.7 1.66 M8 93.8 3,344 6.0 26.3 33.8 91.0 2.78 M9 93.8 1,724 3.5 86.8 14.5 94.0 0.43 Fc = load factor; ηo = operational efficiency. 10/14 Energy planning and management… Gest. Prod., São Carlos, v. 26, n. 4, e3928, 2019 Table 3 shows the maximum operating load factor 3.7 Implementation and evaluation and the maximum operating efficiency of the current motors (a) and the new proposed motors (n); estimated The proposed actions to save electricity were implemented in late 2015, producing significant monthly energy savings (ES) and the corresponding improvements in energy performance. A major SROI. For motors M2 and M9 no replacement is achievement was to reduce leakage in the compressed proposed because they have a good load factor and air system from 34.61% to 19.5%. In the battery premium efficiency; M3 has similar behavior, but it formation area, a protocol was implemented to review is of standard efficiency, so the proposal is to change the conductors and contact points of the formation it for one with premium efficiency. tables that includes cleaning and measurement of The above table shows total potential energy contact resistance. In the motors area, the frequency savings of 2.272 kWh/ month, and that the return drives of motors M1, M4 and M2 were replaced for on the investment is less than 3 months, due to the soft starters and motors M3 and M5 were replaced high potential energy savings and the high residual for motors with greater efficiency and appropriate value of the current motors. power as per Table 3. Replace unnecessary frequency drives for soft Between January and July 2016, management starters. performed monthly analysis of the company’s energy Motors M1, M2 and M4 operate with unnecessary performance. It evaluated the results of the measures frequency drives, because their load is essentially that were implemented and undertook corrective constant; consequently, the proposal is to replace the actions as required in response to deviations. Figure 11 frequency drives for soft starters. Table 4 displays shows the results of the six-month evaluation. Despite the maximum and average values of THDV, annual the significant increase in battery production and the energy losses due to the effect of harmonics calculated consequent increase in energy consumption, the energy performance indicator remained below the EBL and using the model of standard (ANSI, 2012) and the above the goal line that was initially established. SROI of the proposed change. Table 5 displays monthly energy savings, As shown in the table, THDV is above 3%, the calculated as the difference between forecast energy limit established by the standard (ANSI, 2012), consumption according to the EBL and actual energy which produces energy losses due to harmonics consumption. Over the entire period energy savings of 28,776 kWh. The return on investment in these totaled 201,934 kWh (3.48%); the highest monthly units is less than one year because of their high savings totaled 47,548 kWh (4.68%) and the lowest residual value. monthly savings totaled 16,270 kWh (1.89%). Table 3. Nominal and operating data of the motors and monthly energy savings. P P FC(a) FC(n) ηo(a) ηo(n) ESMotor n(a) n(n) ηn(a) ηn(n)(kW) (kW) (%) (%) (max.) (max.) (max.) (max.) (kWh)/ SROI (%) (%) (%) (%) month (months) M1 45 37 93.6 94.6 73.9 88.7 90.8 91.6 283.8 3 M3 30 22 91.8 94.0 65.7 89.1 91.4 94.0 306.9 1.2 M4 30 22 94.1 94.0 72.2 97.9 88.3 88.5 77.7 1.6 M5 56 22 93.6 93.6 42.9 100.0 92.3 93.3 603.7 1 M6 22 11 93.0 92.7 44.3 90.1 91.8 92.8 107.8 1.2 M7 15 6 90.2 91.7 44.0 100.0 88.7 88.9 162.8 1 M8 45 11 93.6 92.4 26.3 100.0 91.0 92.7 729.2 1 Total 2272 Fc = load factor; ηo = operational efficiency; Pn = rated power; ηn = nominal efficiency; (a) = current; (n) = new; ES = energy saving; SROI = payback period. Table 4. Result of the analysis of harmonics in motors. Motor THDV Avg. THDV Max. (%) (%) NEMA Limit Losses SROI (kWh/year) (months) M1 6.2 6.9 3 13,533 6 M4 6.9 7.4 3 12,542 8 M2 4.2 4.6 3 2,701 10 Total 28,776 THDV = total harmonic distortion of voltage; Avg = avarage; Max = maximun. 11/14 Noriega Angarita, E. et al. Gest. Prod., São Carlos, v. 26, n. 4, e3928, 2019 Figure 11. Results of the monthly analysis of energy performance at the company. Table 5. Total and monthly energy savings. Energy Month Production consumption Actual energy (Batteries) forecast by EBL consumption Energy savings Energy savings (kWh) (kWh) (%)(kWh) January 93,840 860,868 844,597 16,270 1.89 February 100,242 910,890 887,207 23,683 2.60 March 109,503 983,251 949,624 33,627 3.42 Aril 121,108 1,073,926 1,034,406 39,520 3.68 May 105,971 955,653 914,369 41,284 4.32 June 113,693 1,015,989 968,441 47,548 4.68 Total 644,357 5,800,577 5,598,644 201,934 3.48 EBL = Energy baseline. 4 Conclusions American National Standard Motors and Generator – ANSI. 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