Electrification of Mobile Mining Equipment Can be Cheaper than Diesel

By Florian Güldner

Over the last years, an increasing number of mining companies have committed to ambitious CO2 targets.  This is a good thing due to environmental reasons, but as publicly listed companies they need to justify their investments.  So, this raises a question:  Why? How can electrification of mobile mining equipment be cheaper than using a good old diesel engine?

First, there are a couple of reasons, which root in a broader context:

  • There is social pressure from local communities, which increasingly protest against the impact of mining.  This forces mining operations to partly go sub-surface and also adopt more environmentally-friendly technology.
  • Mining, like many other industries, is challenged to attract well educated workers.  Millennials are more ecologically sensitive, becoming carbon-neutral can be critical.

Second, there are direct economic reasons for going electric:

  • Diesel itself holds dangers.  Leakage in the mine, as well as the threat of tanks spilling are causing additional expenditures.
  • Ventilation is costly, and electric vehicles lower the demand for ventilation.
  • Cost of diesel itself.  Mining trucks regularly carry 3,000 to 5,000 liters of diesel and consume around 300 to 400 liters per hour while travelling up a 17km ramp in half an hour (for all Americas, this is as little as a mile per gallon). (Source ABB)
  • Mining trucks need gas-stops like all vehicles do.  Using trolley systems, the downtime can be reduced as the gas consumption of hybrid trucks is lowered by 90 percent.
  • Electric vehicles have fewer rotating parts and maintenance costs are typically lower
  • Costs are easier to forecast, as gas prices are much more volatile than electricity prices.
  • Not an economic reason, but going electric means you have nearly all torque available from the start, not unattractive, when you are going up and down a mining ramp.

What can be done?

  • Simple, but maybe not the first thing on everybody’s mind: you can use electric buses to get workers on site.  As mines are often in mountains, regenerative braking can be used going down.
  • Underground mining vehicles can be fully electric.
  • You can move from diesel to hybrid vehicles.
  • Trolleys (e.g. there is a cable over the truck, so we are not talking about giant lithium Ion batteries) can be used for mining roads
  • Modern vehicles (including trolleys) allow for regenerative braking, e.g. using in-wheel motors
  • Many mines use their own train lines for transportation, these can be electrified as well

So, while there are many reasons to actually go electric, there are a number of challenges associated with it.  First and foremost, you need to have the power on site.  This needs to be reliable, and if aiming for lower greenhouse gas emissions, it also needs to be sourced from renewable energy sources.  While co-generation is popular, especially in areas with an unreliable electricity grid and a high number of outage hours per year, co-generation typically involves gas turbines, as they can be started quickly and are reliable.  While many mines can also generate electricity from renewable sources, this is often not enough to cover peak demand and remains an add-on in many cases.

The investments in power infrastructure from E-houses, charging stations and trolley lines, to simple cabling, electricity storage, co-generation, etc. are significant.

As electric vehicles need charging, the charging needs to be scheduled to avoid peaks in power demand, which is typically quite stable in an industry focusing on 24/7 availability.  Selected OEMs of mining equipment have introduced battery swapping systems.  Under any circumstances, a well-designed micro-grid (see here Siemens and Juwi) and energy management software needs to manage the supply and demand of electric power. 

Electrification of Mobile Mining Equipment

While trolleys are certainly the best solution for surface transportation, in underground mining, battery electric vehicles are the more practicable solution.  The prices for lithium ion batteries has dropped significantly (see chart) from around 1200$/kWh to around 180$/kWh and is expected to drop further to less than 100 $/kWh in the next years.  This makes it increasingly possible to power heavy mining equipment with it.  Fortescue is working on a battery-electric/fuel cell prototype for a 240t haul truck and Kirkland works with a battery-powered Sandvik LH518B. 

Another hot topic is Hydrogen.  In March 2020, four companies - BHP, Fortescue, Anglo American and Hatch – formed the Green Hydrogen Consortium  to accelerate renewable energy-powered hydrogen production and its application to the resources sector and other heavy industries.  While the initiative is new, there are already applications in use.  Since 2015, Glencore's Raglan mine in Canada has run on a micro-grid powered by an arctic-rated wind turbine generator connected to a hydrogen energy storage unit.  In 2019, Anglo American announced the development of the world’s largest hydrogen-powered mine haul truck (290t).  Others are using hydrogen fuel cells for forklifts.

Electrification of Mobile Mining Equipment

 

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