‘Electric Drive Is A Mature Technology’

Liebherr’s mining equipment division produces a number of electric machines, including the R 9200 E, a 205 tonne excavator, and the T 236, a 100 tonne class mining truck. When it comes to reducing greenhouse gas emissions for the mining sector, electric drive machines have a key role to play says the company.

Plant & Equipment: What are the potential cost savings for end users of adopting electric machines in the mining industry?

Liebherr: The potential direct cost savings come from the replacement of the diesel engine by the electric drive. Aside from the fuel itself, the other main cost reduction drivers are: engine fluids, e.g. engine oil, coolant; filters, e.g. fuel filters, oil filters, air filters and coolant filters (sometimes also air compressor filters); engine mid-life – replacement of injectors or the turbo charger, and complete engine replacement for the overhaul, as an electric drive lasts two to three times longer than a diesel engine. Indirect savings can be highlighted on the main/hydraulic components due to the smoother running of the electric drive compared to the diesel engine. Less vibration and less acceleration result in extended component lifetimes.

P&E: Looking at your range of electric excavators such as the R 9200 E, are there any environmental factors that will affect its performance, or where it will have a better performance over a similar machine with a conventional diesel engine?

Liebherr: From a pure performance perspective, the electric drive is better compared to the diesel powertrain. However, there are constraints inherent to the use of the electric excavators which have to be taken into account. This includes the power network and power distribution inside the mine site – the electric excavator can only work if the right and constant power is supplied. Any network disturbance will directly affect the machines performance which could be compared to the use of poor diesel fuel quality in diesel machines.

Also, the mine layout – due to the power cable attached to the machine, an electric excavator has less mobility compared to the very high versatility of the diesel powertrain. This requires a real mind-set change for the mine organisation if they want to change over to electric excavators. The cable management can also become a tricky point, especially for the backhoe configurations as the cable will lay on an uneven floor which could damage the cable. In the last decades, 99% of the excavators have been delivered in face shovel configuration to replace or assist electric rope shovels. This experience with the cable management has made the transition to electric excavators in face shovel configuration much easier. Now, we start to operate backhoe electric machines and for that the experience with the cable management has to be gained.

Operating electric powered excavators inside mines requires careful management of the power cable’s position.

P&E: Speaking generally, when it comes to electrification, are there advantages (e.g. technical or economic) for electrification in mining machines versus smaller machines such as in the construction equipment segment?

Liebherr: If the machine electrification is taken as a global mine objective with everybody supporting the project the answer is ‘Yes’. We know by experience that the cost savings are around 25% compared to diesel machines. The E-machines’ performance is better compared to diesel engines but I want to say it again, the win-win can only be achieved if everybody supports the project. Even though the constraints to implement electric machines are higher compared to diesel machines, the trend of opting for electrification is on the rise as they are directly linked to overall greenhouse gas emissions reduction strategies.

P&E: Apart from cost and productivity, what are some of the reasons that operators want electric machines? One trend we see globally is ESG investing, and examination of listed companies’ activities and emissions by investors. Is this a factor in mine operators sourcing electric machines?

Liebherr: Since the signatory of the Paris agreement, 188 countries are currently committed to reduce greenhouse gas (GHG) emissions. The mining industry is also an actor in this transition and has started to take environmental engagements with dedicated investments and defined calendars. The mining industry alone cannot cover the full picture; they need all the stakeholders on board to achieve their goals.

Beside all the existing solutions such as Hydrogen, Ammoniac, and Fuel Cell where there are many unknowns and a lot of challenges (e.g. storage, distribution, Health & Safety, maintenance, etc.), the electric drive is positioned as a mature technology. The electric drive has been used for more than 50 years worldwide. The technology is well mastered, including the additional CAPEX/OPEX compared to diesel machines, the difference in machine maintenance, and the skills you need to maintain it. In comparison to fuel cell or hydrogen where workforces do not exist at this stage or only for very specific cases, workforces for high voltage skills are readily available.