Conversation: Hybrid Drive for Underground Mining?

Since the turn of the year I have been catching up with as many people from within the mining technology sector as my schedule allows. I have been chatting with Martin Boulton since November but recently met him for a coffee on St Georges Terrace in Perth. We continued on from our prior phone conversations and discussed multiple areas of the mining cycle, Martin’s experience and the development of this website.

A large part of my recent content has been based around the electrification of the underground mining environment – primarily through the adoption of battery electric vehicles (BEVs). Martin and I discussed some of the infrastructure and development requirements that this adoption will require, something that can be brushed past in discussions with mining vendors.

The discussion then turned toward the use of the potential use of hybrid drive vehicles in the underground mining environment. For me this was a eureka moment – which hit me in the face! Why had there been a dramatic leap from diesel to full electric drive within the industry?

The automotive sector alternatively had trodden a different transition from fossil fuel, to hybrid drive (petrol/electric) and then now was exploring and delivering fully electric drivetrains. So why has the underground mining industry not taken similar early gains through adopting a diesel/electric hybrid drive system for underground vehicles?

I decided at this point to complete some research online to see there were any hybrid drive underground vehicles available to the market. Komatsu released their hybrid underground loaders in 2018 with two different load capacities (Komatsu WX18H/Komatsu WX22H – with the ‘H” denoting Hybrid drive). Two units were trialled by Byrnecut at Prominent Hill in mid-2018. They utilise Switched Reluctance (SR) style electric generation units for active recharge when utilising the complimentary diesel drivetrain. It could be perceived at the Toyota Prius of the underground environment!?

It is worth noting at this point the success of the hybrid drivetrain for Toyota, a business which has become synonymous with hybrid consumer vehicles. In 2020, 26.5 % of all Toyotas sold in Australia were hybrid. The original Prius, which is regarded as the first mass produced hybrid car, was released in the year 2000. Further to this, consumer on road driving moves forward into new phases of more advanced hybrid cars and improved infrastructure for fully electric cars. Could underground miners look to this proven technology for early wins in the race to reduce diesel particulates and reduce costs?

A quick search on google showed this paper from The Southern African Institute of Mining and Metallurgy Narrow Vein and Reef 2008. This brief but detailed document (The “SCOOP” ON THE WORLD’S FIRST HYBRID MINING LOADER – Sylvie Poirier, Roger Lacroix, Sylvain Ouellette) outlines testing conducted in Canada using a hybrid electric-diesel underground loader. This was trialled at the CANMET test mine and then run at four different local underground operations.

The conclusions of this report highlight savings in both ventilation costs due to both lower diesel emissions and heat generation. This is coupled with heavily reduced diesel consumption when compared to fully diesel loaders. With this information in hand it seems a compelling case for a hybrid drivetrain underground loader or truck.

So why has this technology been bypassed and most mining OEMs generally are racing to full electrification? There are possibly several factors which could include lack of marketing/exposure of the systems, mid 2010s downturn in the mining market (and resulting new machine purchase) and lack of experienced maintenance personnel. 

It will be interesting to further watch the underground market as it moves toward greener technologies. Hybrid drive seems to have clear advantages to full electrification in the near term – mainly around infrastructure install at depth & maintenance requirements. This is particularly true with the larger loaders and trucks which have huge energy requirements to operate. Komatsu could be on to something with their Joy Hybrid range – watch this hybrid space!