Ahead of the Mines and Technology Americas event in Toronto from 15-17 October 2018, the organisers spoke to Alistair Ross, Director of Mining Operations at Vale about his thoughts on moving to electric fleets – the drivers, challenges and potential.
Ross states: “The interest in battery electric vehicles comes in large part from the reduction in heat generation from a battery electric piece of equipment compared to diesel. The heat produced between a diesel fleet relative to an electric fleet is about 1/3 to a ½ in favour of electric. In areas like Coleman mine, we have relatively small but rich orebody very deep in the mine. So, we don’t have much justification to implement expensive ventilation cooling equipment where mining will be limited. In addition, if we reduce the heat generated by all mobile equipment, we can reduce the number of days we lose in a year due to heat in the summer months.”
He adds: “It is also very clear to us that carbon emissions in the form of carbon soot at the micron and even sub-micron level, is deleterious to health. In addition, catalytic converters must be put on diesel equipment to control NO2. We have to ventilate like crazy to control the breathable elements and ensure the well-being of our people. By engineering out the need to ventilate these airborne particulates, ventilation demand drops by about a 1/3. This means we can significantly cut the capital costs when looking to open new mines.”
“So that was the original plan. Even if we just prevented one day of downtime it saves a lot of money for us. In spite of Canada having formed a standard for charging, the risk we have in adopting batteries this early is that the actual battery technology itself is exploding so fast that it is difficult for us to create a battery strategy. Every piece of equipment has different duty cycles, and every duty cycle requires a different charging cycle. The way people are answering those different duty cycles and matching price constraint on purchased batteries is huge.”
“You can have a standard lithium dioxide battery that is relatively cheap, slow to charge and quite large for its energy content. Then you have the latest ones which have a combination of manganese, nickel and cobalt. They also have liquid cooling in them, so you can charge them up faster. They have more capacity for the same size. The trick for us is, how do we manage our electrical infrastructure to manage the demand of plugging in electric vehicle? This is an interesting challenge.”
“The other aspect is minimising waste. We don’t want to build a graveyard full of batteries, so one of the risks we are trying to manage is what happens when the duty cycle of the battery no longer matches the requirements of the mine. For example, today we may buy a battery that has a nominal 100% amount of capacity but somewhere in the battery life it drops to somewhere around 85%. For most cycles, that battery would no longer be sufficient, and we would then have to change it out. And with the technology there is today, that battery would have to be changed out every two years or so, which would result in a huge battery surplus in a very short time.”
“One solution is to utilise a third party that can manage a larger problem potentially more easily than a user of batteries such as us. And the producers of these batteries see a potential opportunity in this, unlike us, who see a problem. We also don’t know anything about the repair or maintenance of these batteries. We can get a handle on the charging system quickly because we manage the electrical side of things quite well. However, the vendors understand the repair and maintenance of batteries much better than we do.”
“From a safety perspective, another threat we are trying to understand is the fire risk of the batteries. Batteries, which have a relatively high capacity, have been known to catch fire. Look at the Apples, MacBooks and Samsungs that have come out – those are quite small batteries but when they explode they create a large amount of damage. If that risk was to occur with the size of the batteries we own, we are not quite sure how we would manage that. We have to make sure that none of those mistakes occur underground. We can’t afford to have people trapped behind a fire which could then spread to the tires and cause harm to our people and infrastructure.”
“The other risk concerning the batteries is that the initial technology means that people have to lift out the batteries and put them on to a charging system, and then place a new one back in. This will happen once per shift, sometimes twice per shift. These are batteries that weigh tonnes, so lifting them on a routine basis brings a lot of errant risk for the people involved. We’re interested in finding a way where we don’t have people involved or where the charge point is at such a low rate that you don’t bother taking it out of the vehicle.”
“A broader challenge is the power-demand for the equipment. You have 800 pieces of equipment and all of them are demanding power to recharge at the end of a shift. You can imagine the electricity draw if we suddenly plug in 800 vehicles to draw a megawatt each. That’s a lot of power that not only the mine system has to handle, but the district system must handle too. One thing we must manage is working closely with the electricity providers to make sure we understand the grid demand. This is the one issue that we are still figuring out as we move forward.”
“Another broader challenge is having all equipment electrified at the rate we would like it. We’re in demand for a 100% solution in electrification across the board, but this was not the case five years ago. As a result, the vendors are not able to meet the demand. This brings into question, are we ready to accept sub-optimum fleets which cater to all to achieve electrification? Or we do slow down our demand and only adopt electrification if it is the right size?”
“We are definitely talking very closely with all the vendors across the market. We would look to above the market solutions with different vendors. For example, if we are the only ones who have a demand for a certain truck, the vendor would not be inclined to rush into production only for us. So, we would then look to, for example, getting a Cat truck and then going to an OEM to electrify this.”
“Concerning power demand, we have developed a strategy where we are hoping to have our final plan to build storage approved this year. Then we would have battery storage tied to our grid and recharge when we do shift changes. We are fortunate enough to generate roughly 20% of our power from our own hydroelectric dams. In the off-peak hours when we would normally slow that down, we would instead be able to hook up the batteries and charge them up quite cheaply. Not only will we potentially lower our energy costs, we would also avoid major demand peaks on the system.”
On the future he says: “It’s hard to give it a specific time frame but I would hazard a guess, certainly within the 20 years, that it will be unlikely to run anything that is diesel anywhere. And this primarily because of the health concerns that I previously mentioned. We run a fair-sized surface fleet and we are already looking at what it may entail to go battery. It’s our intention that any mine we build from now, beyond the ones we are already building, will be battery electric.”
