Sustainable drive systems

Sustainable drive systems throughout the entire life cycle

Sustainability is a popular word in today’s dictionary. In our opinion this is very good as long as the efforts are sincere and it is not just marketing. Variable frequency drives (VFD) help reducing energy consumption, especially in variable flow applications such as fans, pumps or compressors. This benefit shall be well-known and you would find plenty of literature on the internet and in other sources (see also our previous articles [1]). Therefore, VFDs contribute to more sustainable usage of electric power. However, this is just one part of the solution for future. We can and shall do much more in terms of sustainability. This article is a short polemic about possibilities of responsible manufacturers of sustainable drive systems.

Variable frequency drives are widely used and the energy savings are quite impressive. For instance, the installed base of ABB drives saved about 515 TWh (terrawatt hours) in 2017, equivalent to the consumption per year of more than 130 million households in EU.

"If all fans and pumps were equipped with energy-efficient drives, the savings would equal the entire power generation capacity of the EU."

ABB Energy efficiency - the fast track to a sustainable energy future

There is a variety of tools to calculate energy and cost savings when using variable frequency drives in your specific application. Alternatively, you can contact us for your energy savings assessment [2].

True sustainability shall apply throughout the life cycle of the drive components. Let’s explore some ideas and already existing practices to support the vision of sustainable drive systems.

Sourcing of material

It all starts with sourcing of material. Electric drives (VFD), transformers and motors contain, apart from other materials, steel, aluminum, copper etc. Interestingly, the same drive systems are used to produce these raw materials. The sourcing shall be responsible with regards to the social responsibility of local employees or impact on environment.

There is lot of copper inside a large capacity variable frequency drive as shown in figures below.

Variable frequency drives are used in mining and metals industry reduce the energy consumption while producing these precious metals. For instance, there are many variable frequency drives in Latin America used for extraction of copper ore or in Sweden for processing of iron ore. In this way, VFDs help to reduce environmental impact in that part of the manufacturing chain.

Manufacturing

Manufacturing of certain parts and components may be energy intensive. The manufacturer of a sustainable drive system can reduce the internal energy consumption by optimized processes and innovative technologies. He might also be able to influence the energy mix being used. Factories open up opportunities to install photovoltaic panels on the roof or use other renewable sources of energy.

A great example is the ABB factory in Helsinki. Although Finland is not a photovoltaic paradise, this installation of 181 kW peak power is expected to produce 160’000 kWh of electricity per year. The solar system supplies battery chargers of forklift trucks and other loads within the factory area [3].

Not only the shop floor consumes power. The offices with their computer load, lighting or HVAC are non-negligible either. Smart building automation and proper insulation helps to reduce that part of energy bill.

Transport and logistics

Transportation in general accounts for large portion of worldwide consumed energy. Moreover, it is a considerable source of pollution. Minimizing the transport routes is the best way to reduce the environmental impact. Unfortunately, this topic has too little focus and global manufacturers often ship components across multiple countries until the product (e.g. VFD) reaches the final assembly and testing and is ready to be shipped to its end user destination. Absurd examples are known from food processing industry, but also in VFDs we could find such examples: components manufactured in countries A, B and C, shipped to country D for sub-assembly. Modules are then transported back to country A for final assembly and from there dispatched to final destination E. Companies exercising such practice call themselves eco-friendly or energy-saving, issuing regularly sustainability reports. Isn’t it a bit of hypocrisy?

Using railway as alternative to road transport typically also contributes to the reduction of carbon footprint. Combining rail and road transport might be a good option contributing to more sustainable drive systems.

A complementary option is to use electric driven trucks (E-trucks) for short and medium distances. Such solutions are already available and for instance ABB is using light E-trucks since the beginning of 2020.

We have reported about such electric truck solutions in our E-mobility series (see [4 and 5]).

Efficiency in operation [6]

Variable frequency drive systems have design lifetime of at least 20 years. Through proper service, maintenance and upgrades the lifetime can be extended to over 40 years. That being said, it is important to strive for best possible efficiency. VFDs can save significant amount of energy per default through their working principle. However, the user shall still compare different solutions very carefully.

Almost every medium voltage VFD requires an input isolation transformer. Make sure that this transformer has reasonable efficiency and low losses [7]. Transformer optimized for footprint will save the end user some space and weight, but will not reach the best efficiency. We encourage you to make your own math how much an extra kW of losses is going to cost you over the next 20-25 years.

VFD itself has losses depending mainly on topology, type of semiconductor or switching frequency. The difference in efficiency between products on the market can make up to 2% for specific power rating. Unfortunately, too many users still make their decision based on initial investment and operating expenditure might be missing in the equation.

Relevant for drive system efficiency and life cycle cost is also re-cooling. 99% of all VFD panels are installed indoor, either in a “brick building” or in a pre-fabricated building (“container”). VFD dissipates losses into the ambient and such room needs to be re-cooled. Liquid cooled VFD emits very small portion of total losses into the ambient (majority dissipated through liquid cooling circuit). The HVAC demand for a liquid cooled drive is just a fraction of the one required for air cooled drive.

Motors shall be optimized for best efficiency as well. The minimum efficiency rules do not apply for large VFD driven machines so far. However, high efficiency pays off throughout the lifetime. Synchronous machines generally reach higher efficiency than their asynchronous counterparts. Always keep in mind that the energy cost summed up over the product lifetime exceeds the initial investment cost multiple times.

Long lifetime and repairability

I am sure you know it: Your washing machine or dishwasher has a fault and the shop recommends you to buy a new one rather than repairing the existing one. It does not pay off to repair the broken equipment or the spare parts are not available anymore. I remember having a side job during my studies in a DIY shop. People would bring their lawn mowers back claiming a defect. They would give their money back or get a new mower from the shelf. The defect lawn mower would be simply scrapped. No-one would ever check what the issue was. That would be too expensive.

That should not be a practice for industrial equipment, for sure not for quality products and sustainable drive systems. The components shall be designed not just for great performance, but also for maintainability and serviceability. The manufacturer shall have adequate service network and shall guarantee availability of all spare parts for a decent period of time. Scrapping equipment due to lack of spare parts or design not supporting proper serviceability is not economical. And for sure it is not sustainable, either.

Services that a reputable VFD manufacturer shall offer for economically and environmentally sustainable drive systems:

Availability of spare parts

We have seen many end users replacing their drives after 20 years, sometimes even earlier. It is not because the VFDs reached end of their life. Instead, the original manufacturer is not supporting the product anymore and spare parts are not available. For the end user this is usually too high risk leading to a decision to replace the VFD with a new one.

Luckily, there seems to be increasing awareness in this regard and manufacturers shall be pushed to support easy serviceability and long lifetime. Compliments to all those manufacturers who already live this mission and provide excellent support throughout and beyond product lifetime [8].

Disposal and recycling

Sustainable drive system is not just energy efficient. It is designed in a way allowing effective disposal. The equipment shall not contain any dangerous or toxic materials.Maximum possible parts shall be recycled or reused.

Reputable manufacturers provide end of life services as natural part of their DNA [8].

Great example of such initiative is a recently signed agreement between ABB Power Grids and Stena Recycling [9]. The cooperation agreement covers the Swedish market. When looking at the balance you get really impressed – only 1% of the old transformer ends up as scrap. Hopefully many other companies get inspired by this Nordic approach towards a sustainable society.

"Each year around 200 power transformers are sold on the Swedish market. Most of them replace an old transformer. With Stena recycling, ABB Power Grids will undertake the disposal of old transformers, reusing or recycling about 99 percent of the material as per Stena’s recycling guidelines. This will comprise 64% material recycling, 35% clean, low carbon incineration for energy and the balance 1% as scrap. Almost all the recycling will be done locally in Sweden itself."

ABB Power Grids

Circular economy

In the past everyone was talking about growth strategies. Nowadays people use the term organic growth. However, is continuous growth sustainable? Can the economy keep growing forever? Most likely not and some people start thinking of post-growth economy. The energy consumption is projected to grow sharp as the world population increases and emerging countries reach higher living standard. Therefore, the demand for energy efficient products and technologies will remain on a high level.

Instead of focusing on producing more and more we need to focus on how to make better products with higher efficiency, longer lifetime and minimum environmental impact. Such business model creates higher value for all participants and reduced energy and material consumption. It is a win-win-win for the end user, manufacturer and environment.

It shall become natural that when developing a new product the entire life cycle considerations are inherently included.

The mentioned collaboration of ABB Power Grids and Stena Recycling is a perfect example also in this regard. It is not just about recycling old transformers when replacing them with a new one. Both companies collaborate also in the development of new transformers to make them better and easier to recycle in the future.

Similar model shall be applicable also for variable frequency drives and motors. ABB drive service team offers upgrades and retrofits of drives including legacy products. In fact, they can often upgrade a VFD of another brand as well. Majority of these upgrades is economically more attractive than replacing the entire drive system with a new one. Apart from the lower capital investment the user profits from a shorter down-time. And obviously, it is more sustainable as well. Most of the hardware components can be kept and their remaining lifetime fully utilized. Transport of heavy equipment can be largely avoided.

Sustainable drive systems: Final word

This article discussed and mentioned several topics to be considered for sustainable drive systems. The goal was to stress the fact that sustainability involves the overall product life cycle. It is good to see that some manufacturers already integrate sustainability principle and even go one step further. The others might get some inspiration what to improve.