The Sustainability of Electric Motors
What are the key factors necessary to assess the environmental sustainability of electric motors?
First, let’s define what we mean by an electric motor. An e-motor is a product that converts electric power into mechanical, turning power. We find them everywhere: in machines, robots, conveyor belts, cars and automation of every kind—in principle in everything that moves that is not alive.
E-motors make up to 40% of total electricity consumption worldwide or 70% of industrial electricity consumption.  If manufacturers do not improve the energy efficiency of these motors, the electricity consumption by e-motors will double by the year 2030, because more and more electric motors will be manufactured, sold and used. This growth has, and will continue to have, a huge impact on the environment.
Usually 1-5% of the impact comes from the manufacturing stage, 95-99% from the use stage and the disposal or recycling of the motor makes up the rest.
If we examine the distribution of environmental impacts within the lifecycle of e-motors, usually 1-5% of the impact comes from the manufacturing stage, 95-99% from the use stage and the disposal or recycling of the motor—its End-of-Life—makes up the rest. If you are a manufacturer, that means that your motor’s design is critical to its environmental impact, because the design defines how the motor will behave during its use and thereby the amount of energy it ultimately consumes.
Ecodesign is normally understood as the improvement of the sustainability of a single product. The standard EN50598 for ecodesign for power drive systems goes beyond a single motor and requires that you think about the entire motor system. This includes such things as frequency converters, motor starter equipment, gears, etc.
In 2018, thinkstep conducted a workshop with German electric motor manufacturers to call attention to sustainable solutions that push thinking beyond the EN50598 standard. We suggested that improvements could be realized by thinking about the best application for the demand. For example, by downscaling—scaling the size of the motor down to fulfil the motor’s demand for energy during the period in which the consumer uses the motor most—and developing a smart solution for peak demand periods.
Three Levels of Thinking
Let’s take a step back. There are three levels of thinking about or examining the challenge for how to improve the sustainability of an electric motor. We can look at it from the perspective of each individual motor, we can examine it from the perspective of the motor system and, lastly, we can assess it from the perspective of a smart solution for fulfilling the demand (or application).
To illustrate these three levels in relationship to sustainability, let’s take a simple example. Think about a ceiling fan. When ceiling fans were initially developed, they could only be turned on or off. That means they had a static operating point according to the demanded speed of the fan—the fan always turned at the same speed and the motor design defined the efficiency at a single operating point and thus the energy consumption whenever the fan turned. This is an example of the framework for examining the sustainability of a fan as an individual motor.
However, consumers wanted faster and slower speeds, depending on the changing temperatures they experienced in a room. So manufacturers introduced a resistor that consumed part of the energy such that the motor turned more slowly—the most terrible solution with regard to efficiency (energy use), because it meant the motor would consume the same amount of energy, just with less output. Here too, we are still talking about an individual motor.
A much better solution for a dynamic fan speed was then to introduce a motor system. For example, they introduced a gear or a frequency controller or other measures around the motor that could provide various speed levels at different operating points for the motor. So with this approach, you need less energy for less output. You add additional parts, but it still improves the sustainability of the motor during its most important phase, the use phase. Motor manufacturers spend a lot of their efforts engaged in this approach.
The third level is now a smart solution in which you challenge what is required to actually fulfill the consumer’s demand. Here, a manufacturer asks what the consumer really needs. In the case of a ceiling fan, how often does the consumer really need full speed? Of course, it depends on the temperature in the room. So if the highest speed is only needed for three days out of the year, during the height of summer, why not replace a single motor with two smaller motors in the fan. Each smaller motor would have less energy demand, with the optimally efficient operating point (load factor). The second motor would then only turn on during those days when the demand is highest and would mostly remain off, not consuming power at all, but ensuring that the peak demand could be fulfilled when necessary. Yes, you end up building more motors than you would otherwise, but since we know that the use stage of the fan is the most critical phase for the fan’s environmental sustainability, it is easy to calculate how much better a double-motor fan would be at delivering a solution that drastically reduces the fan’s electricity consumption, and thus its negative environmental impact.
This calculation calls attention to timing or frequency of use. Far too few manufacturers think about the various modes and their timing during the use stage of their motorized products. They lay out the motor rating to the peak demand instead of optimizing the motor system to the dominant use mode.
Taking a smart solution into consideration, designers now have to defend a higher manufacturing demand with two motors, because they know it will cause less impact over the lifecycle of the motor. Defending this kind of design necessitates accurate data that identifies how much impact the consumer causes because of a manufacturer’s business. In other words, you as a designer need to prove how much cost your product causes over the entire lifecycle for the consumer, also known as “total cost of ownership” or “life cycle costing.”
Without a doubt, in the near future, carbon will be taxed.
If users are now demanding carbon-free solutions, the highest efficiency and the lowest cost face a new challenge. Currently, manufacturers only pay directly for energy. However, that will change. Without a doubt, in the near future, carbon will be taxed. But already today, large companies are making commitments to become carbon-free businesses in the near future, often as early as 2030. That means they will need carbon footprint information for the products they sell. That carbon footprint information allows their customers to know how much CO2 is procured and how much CO2 is avoided. It tells them how much green (carbon-free) energy they need. And finally, it indicates how much of the remaining emissions have to be offset in order for the company to become carbon neural.
That means the motor system with the lowest electricity demand (during the use stage) and the lowest carbon emissions from manufacturing and from End-of-life is the best option for zero-carbon customers. These consumers will pay per kWh of consumed electricity as any other customer would. However, they may end up paying more for their energy if that energy is carbon-free electricity, and they pay for CO2 emissions that are unavoidable through offsetting. So, for example, if motors contained within a product are not manufactured carbon-free, the cost of carbon offsetting will be passed on to the customer. That points the finger back at the manufacturer, who is responsible for his or her own emissions.
If motors contained within a product are not manufactured carbon-free, the cost of carbon offsetting will be passed on to the customer.
The closer to a zero-carbon footprint your electric motor system is, the cheaper it is for customers who demand zero-free products. So as a manufacturer you have to provide all the relevant data from the product’s life cycle to your customers. That is, you have to include more than the total cost of ownership. You have to include the carbon footprint of all the life cycle stages for your system. Your customer needs this information to calculate the true cost of achieving zero carbon with your motor solutions. You can become the best manufacturer if you produce carbon-neutral motor systems on your own, providing the highest energy efficiency for the consumer’s intended application, which, ultimately, translates to the cheapest carbon-free solution.
 Waide, P., Brunner, C.: “Energy-Efficiency Policy Opportunities for Electric Motor-Driven Systems”, International Energy Agency, IEA, France 2011Waide, P., Brunner, C.: “Energy-Efficiency Policy Opportunities for Electric Motor-Driven Systems”, International Energy Agency, IEA, France 2011