Why electric mining vehicles are starting to take off

Regenerative drives built for rugged mining vehicles are enabling better total efficiencies and reduce cost and emissions.

Regenerative drives built for rugged mining vehicles are enabling better total efficiencies, helping mine operators achieve savings in energy consumption, heat and gas emissions, and ventilation systems.

You probably know that the mining industry is today facing difficult challenges due to depressed prices for its products. Looking further down the road, however, a lot of progressive companies are seeing big potential in fully-electric or hybrid-electric vehicles, such as trucks, front loaders, drill rigs and excavators. OEM vehicle producers as well as mine operators have realized that, when used as part of a long-term strategy, electric mining vehicles can offer many advantages.

The bottom line, of course, is the bottom line – electric vehicles can bring significant cost savings to mining companies. And in times like today, when profitability is extremely squeezed, every possible cost saving helps mine operators. But even when the market is up, electric vehicles have the potential to further improve the healthy margins. Numerous factors have converged in the past few years to lead OEM vehicle manufacturers to introduce models with hybrid-electric or even fully-electric functionality. And the mine operators are paying attention.

Greater efficiencies in many areas

The specific reason for this is efficiency – concerning toxic emissions, waste heat generation, energy use and costs, and expenses associated with constructing and running ventilation systems

Frankly speaking, the capital investment required for electric vehicles based on batteries can be significantly more than the present diesel technology. But even if you consider this, payback times of one to two years are feasible, and immediate payback is even possible in some cases.

Diesel engines are the traditional industry standard for mining, but at the same time they are inherently very inefficient at converting energy input into movement output. In the best case, they can achieve about 45% efficiency, with the rest of the energy lost to waste heat. Electric drive trains, on the other hand, can easily reach an energy efficiency of 90% or more.

Requirements: Robust for a tough environment

Until now, the diesel engine driven drive train has been the dominant technology for mining, and there are good reasons for that. The mining environment is very tough and the diesel engine driven system is robust enough to withstand challenging conditions. These include high ambient temperatures, constant vibration, violent shocks, harsh start/stop load cycles, corrosive acidic liquids and gases, aggressive pressure washing and other unforgiving treatment.

With these facts in mind, and in close cooperation with mining-vehicle OEMs, ABB Drives and Controls has recently been developing drives which effectively control electric motors in low/no-emission mining equipment. Starting with a blank sheet of paper, the strategy has been to design a new tailor-made drive from the ground up. We’re not simply repackaging standard products, but instead designing rugged and purpose-built drives. As a global player with the largest market share in variable frequency drives, ABB judges this to be the best way to catalyze faster growth in electric mining vehicles.

Regenerative energy captured

The regenerative function of drives is a critical factor, as it allows braking energy from the motor, and even from hydraulic pumps, to be captured and then stored in a battery or super capacitor. The drive acts to control the flow of energy, and transform any kinetic or potential energy back to electric energy.

Ventilation is a big issue, and cost

Ventilation and air circulation are also key drivers . . . and big cost items in underground mines. Since electric vehicles greatly reduce both waste heat and emissions generated, the ventilation requirements for electric vehicles are lower compared to diesel driven engines. On a daily basis, this can drastically reduce the cost of energy needed to circulate air to meet health and safety requirements, saving millions of euros per year. And, when a mine expansion is being considered, the reduced heat and emissions from electric vehicles means dimensioning of the ventilation system can be significantly smaller and therefore much cheaper.

Reliability and maintenance advantages

Maintenance costs and reliability are other important issues you need to consider. Many OEMs have realized, as they have been working closely with electric vehicles and drives, that the maintenance cost for electric is much less due to fewer wearing parts. For example, there is no gearbox, and no oil lubrication system is necessary.

Diesel-electric combinations are also possible, to extend the vehicle range. In series-hybrid technology, the diesel runs a generator which feeds electricity to the motors to drive the vehicle. Besides greater range, a further key benefit is that, instead of using diesel for the maximum peak power, the dimensioning of the diesel engine can be smaller to cover the average power demand.

Solutions based on proven drive technology

Considering all these requirements for electric mining vehicles, and based on careful listening to the market, ABB’s has developed the new purpose-built HES880 mobile drive. This is a totally different design from anything available previously, although it is established on the well-proven ACS880 all-compatible drive technology, which mine operators and OEMs are already familiar and comfortable with.

In addition to being robust and compact, this electric-vehicle drive is a modular product, based on a single design model and three different firmware. The single-design model can easily be tailored to specific applications simply by installing the appropriate firmware. These software options can control the motor and generator, the power grid connection, and power flow to and from the energy storage. So the hardware is the same whatever the application, allowing you to simplify stocking of equipment based on interchangeability of parts.

Due to the compact size of the drive, vehicle layout becomes much more flexible. As opposed to diesel, where the engine and power train are very fixed in the positioning in the middle of the vehicle, electric drive lines can be more flexibly placed to allow the driver a greater field of view in the workspace. As the electric vehicle technology develops, this could well mean more user-friendly and safer equipment.

Pioneers are making progress

The mining industry, like many other older established sectors, is inherently conservative about adopting new technology. So although it has taken some time electric vehicles to gain acceptance, the growing list of advantages is clearly starting to get noticed by the progressive pioneers at OEMs and mining companies.

Considering the large potential cost savings and efficiencies that electric vehicles offer, as well as the short payback times, ABB has decided to invest resources in this technology to catalyze these trends. Based on ABB’s global expertise and reach with respect to drives, new mining-vehicle solutions like the HES880 drive have the potential to create both a stronger market pull from the mining operators and a greater market push from the OEMs that will be very beneficial to the mining industry.

The future for electric mining vehicles has already started.