ALTERNATIVE ENERGY: BATTERIES oemoffhighway.com/21521607
BATTERY POWER and the Future of Deep-Level Mining There are several battery and charging technologies which need to be considered when transitioning to electromobility in underground mining. contributed by Xavier Iraçabal, Mobility Product Manager, Saft
B
attery-powered mining vehicles are ideally suited for underground mining. Because they do not emit exhaust gases, they reduce cooling and ventilation requirements, cut greenhouse gas (GHG) emissions and maintenance costs, and improve working conditions. Almost all underground mine equipment today is diesel powered and creates exhaust fumes. This drives the need for extensive ventilation systems to maintain safety for workers. Moreover, as today’s mine operators are digging as deep as 4 km (13,123.4 ft.) to access ore deposits, these systems become exponentially larger. That makes them more costly to install and run and more energy hungry. At the same time, the market is changing. Governments are setting environmental targets and consumers are increasingly willing to pay a premium for end products that can demonstrate a lower carbon footprint. That is creating more interest in decarbonizing mines.
SAFT
28
OEM Off-Highway | AUGUST 2021
Load, haul, and dump (LHD) machines are an excellent opportunity to do this. They represent around 80% of the energy demand for underground mining as they move people and equipment through the mine. Switching to battery powered vehicles can decarbonize mining and simplify ventilation systems. This requires batteries with high power and long duration—a duty that was beyond the capabilities of previous technology. However, research and development over the last few years has created a new breed of lithium-ion (Li-ion) batteries with the right level of performance, safety, affordability and reliability.
Five-year expectation When operators buy LHD machines, they expect a 5-year life at most due to the tough conditions. Machines need to transport heavy loads 24 hours a day in uneven conditions with moisture, dust and rocks, mechanical shock
and vibration. When it comes to power, operators need battery systems that match the lifetime of the machine. The batteries also need to withstand frequent and deep charge and discharge cycles. They also need to be capable of fast charging to maximize the vehicle’s availability. This means 4 hours of service at a time, matching the half-day shift pattern.
Battery-swapping versus fast charging Battery-swapping and fast charging emerged as the two options to achieve this. Battery-swapping requires two identical sets of batteries—one powering the vehicle and one on charge. After a 4-hour shift, the spent battery is replaced with a freshly charged one. The advantage is that this does not need high power charging and can typically be supported by the mine’s existing electrical infrastructure. However, the changeover requires lifting and handling, which creates an extra task. The other approach is to use a single battery capable of rapid charging within around 10 minutes during pauses, breaks and shift changes. This eliminates the need to switch batteries, making life simpler. However, fast charging relies on a high-power grid connection and mine operators may need to upgrade their electrical infrastructure or install wayside energy storage, especially for larger fleets that need to charge simultaneously.
