Energy Efficiency of Electric Motors
Electric motors are extensively used in both the pharmaceutical and chemical industries. They drive pumps that circulate water, solvents, and feedstocks; fans that move air through HVAC systems and process vents; and compressors that generate pressurized air or gases. In a typical chemical plant, motor-driven systems can account for 60–70% of total electricity use, while in pharmaceutical manufacturing they dominate utility loads such as cleanroom HVAC, chilled water distribution, and compressed air. Because of their ubiquity, improving motor efficiency is one of the fastest and most cost-effective routes to lower energy consumption.
The levels of motor efficiency is defined by the International Efficiency (IE) classification (global standard IEC 60034-30). The efficiency levels are the following:
IE1 (Standard Efficiency): Outdated motors still found in older facilities; significantly less efficient, with higher operating losses.
IE2 (High Efficiency): Long considered the minimum standard in many countries, but now largely superseded.
IE3 (Premium Efficiency): Now the legal minimum in the EU, U.S., and many other markets for most industrial motors. IE3 motors are about 2–4% more efficient than IE2, which may sound small but is substantial given motors often run 8,000+ hours per year.
IE4 (Super Premium Efficiency): The current best commercially available standard, with efficiencies up to 10% higher than IE2 motors. They achieve this with improved materials, reduced electrical losses, and optimized design. While initially more expensive, IE4 motors pay back quickly in high-use applications.
IE5 (Ultra Premium Efficiency): Emerging technology, not yet widely adopted, but expected to be the future benchmark.
For example, a 100 kW motor running 8,000 hours per year at IE2 efficiency might consume ~700,000 kWh annually. Upgrading to IE3 could cut consumption by ~20,000 kWh, while IE4 could save 40,000–50,000 kWh. Considering today’s industrial electricity costs, tens of thousands of euros in lifetime energy cost savings per motor can be achieved.
Variable Speed Drives (VSDs)
Beyond motor efficiency classes, the way motors are operated has an even larger impact. Many motors are oversized or run at full speed constantly, even when the process only requires part-load operation. Variable Speed Drives (also called Variable Frequency Drives, VFDs) adjust the motor’s rotational speed to match demand.
For example, in HVAC systems in pharma cleanrooms, fan motors often run at maximum capacity to ensure airflow, even when occupancy is low. A VSD can reduce fan speed by 20%, which according to the affinity laws can cut energy consumption by nearly 50%. Similarly, in chemical plants, pumps circulating solvents or water can often be slowed when full flow is unnecessary, achieving 30–50% savings compared to throttling with valves.
Benefits for Pharmaceutical industries
In pharma facilities, motors and VSDs are critical in HVAC systems, chilled water pumps, and air handling units. Since HVAC can represent 40–60% of total site energy use, improving motor efficiency and adopting VSDs directly reduces the largest single energy load. Replacing legacy motors with IE3 units and adding VSDs to cleanroom air handling fans can reduce electricity consumption by more than 10% across a pharmaceutical facility.
Benefits for Chemical industries
In chemical plants, motors power large compressors, agitators, and pumps in continuous processes. These loads are often high and steady, making them ideal for high-efficiency IE4 motors. The absolute energy savings per motor can be very large. For example, upgrading a single 500 kW pump motor from IE2 to IE4 can save the equivalent of several households’ annual electricity use. Adding VSDs to centrifugal pumps in distillation units or to compressor systems in ammonia or polymer plants can yield 10–20% electricity savings plant-wide.
Energy Savings Potential
Motor and drive efficiency improvements are considered one of the most mature and reliable efficiency measures. The combined effect of upgrading to IE3/IE4 motors and integrating VSDs is typically a 5–15% reduction in site electricity consumption for both pharmaceutical and chemical industries. Since electricity is often the second largest cost after raw materials, the payback time is short (often less than two years). Additionally, these measures improve process control, reduce wear and tear, and extend equipment lifetime.