ELECTRIC MINES

POWERING THE SHIFT TO ELECTRIC MINES

According to a 2020 McKinsey report, the global mining industry is responsible for between four and seven per cent of total greenhouse gas emissions, so any technology that contributes to the sector’s decarbonisation is valuable. For decades, diesel-powered machinery and vehicles have dominated mining. Its long success is down to the fact diesel engines can handle the extremely harsh conditions of underground mines, enabling access to once unreachable depths.

THE PROBLEM WITH DIESEL

Diesel’s power doesn’t come without problems. From an environmental perspective, the use of diesel engines doesn’t support mining’s decarbonisation agenda.

However, there is another reason why moving away from diesel is a good idea — its negative impact on worker safety. According to the International Labour Organisation, despite only employing one per cent of the global labour force, mining is accountable for eight per cent of fatal workplace accidents.

Two major sources of hazard in underground mining are ventilation and noise, which are both worsened by the use of diesel-powered machinery. The emissions from diesel mining equipment are a large contributor to the toxic gases found in underground mines, which require vast, comprehensive ventilation systems to clear the air for workers to breathe. In addition, the noise produced by large diesel engines adds to the noise pollution, which is already significant, and can lead to noise-induced hearing loss.

THE MOVE TO ELECTRIC

EVs eliminate the noise and emission problems associated with diesel power systems. However, currently only 0.5 per cent of mining vehicles are fully electric, and many mines are reluctant to make a complete shift due to performance concerns.

The same worries holding automotive consumers back from changing to an electric car hold true for mine operators, who are reluctant to move away from diesel’s reliability due to concerns around battery capacities. 

With operations taking place hundreds, or even thousands, of metres below the ground, underground mining vehicles need to consistently perform well. Equipment failure in underground mines can not only result in huge repair costs and significantly impact production, but it can also risk health and safety, so it is critical that electric mining vehicles can meet the demands of this application.

THE REGENERATION GENERATION

Underground mining equipment encounters some of the harshest conditions out there — unseen holes, tight tunnels and uneven terrain can all place stress on automated equipment. Therefore, vehicles must be designed with these conditions in mind.

An essential component of any EV is its dynamic braking resistor (DBR). Heavy duty applications like mining require heavy duty components to withstand the tough operating conditions they face.

When a mining vehicle brakes, using the principles of regenerative braking, the first option is to store the excess energy produced in the vehicle’s battery for reuse, improving the energy efficiency of the vehicle and keeping the system operational for improved safety.

However, when the battery is close to its full charge, this is not possible. A dynamic braking resistor is the simplest, most reliable and cost-effective solution to this problem as it dissipates the excess energy as heat, allowing the EV to stop when required. This is particularly useful in mining applications, where operational efficiency and reliability are crucial.

Cressall’s EV2 water-cooled DBR has a unique design, meaning it takes up just ten per cent of the volume and 15 per cent of the weight of a conventional air-cooled DBR. Units can be combined in up to five-module assemblies to meet high-power requirements.

Mining techniques have evolved many times throughout its rich history. With increased pressure to decarbonise, mining EVs will play an essential role in bringing the industry into the 21st century, making operations efficient, reliable and safe.

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Powering autonomy 

POWERING AUTONOMONY

ENERGY-EFFICIENT BRAKING CRUCIAL TO SUCCESS OF AUTONOMOUS VEHICLES

When a self-driving Uber crash led to a fatality in 2018, to many, it seemed that the autonomous vehicle revolution was over before it had chance to gather speed. If autonomous vehicles are to make it onto our driveways, braking systems will be crucial to minimising accidents.

One year after the Uber crash, the National Transportation Safety Board (NTSB), an independent US government investigative agency, concluded that a major factor in the collision was a misjudgement by the vehicle’s safety operator — or, the human that sits in the vehicle and monitors the autonomous driving system.

While it seems that human error will never go away, manufacturers have not given up on the concept that the right technologies can help autonomous vehicles steer away from disaster. Automotive giants, like Jaguar Land Rover (JLR), continue to invest in autonomous technology. JLR’s Project Vector concept aims to have an “autonomy-ready” and “multi-use electric vehicle” on the road by 2021. 

While it’s clear that the future will be self-driving, how will manufacturers avoid the accidents of the past — and what role can advanced braking systems play?

FOLLOW THE ROUTE

Operating from March 2018 to June 2019, the Route 12 driverless bus concept successfully provided Schaffhausen, Switzerland with a driverless bus system over a year. Big cities can learn a lot from the small Swiss town and, last year in Germany, Berlin’s public transport company, Berliner Verkehrsbetriebe (BVG), also tested out its own autonomous buses.

Autonomous transport offers many benefits to towns and cities alike, not least in terms of safety. The UK’s Department for Transport reports that 27,820 people were killed or seriously injured in reported road traffic accidents in the year ending June 2019. Leading causes for these accidents included speeding, lack of focus or driving under the influence — all of which are results of human error. 

Programmable driving systems should eliminate these unsafe human habits, of course. In addition, driverless vehicles can also reduce traffic congestion by following fixed routes that are simpler to handle than the various and complicated routes along which a taxi or car usually travels. 

REGENERATIVE BRAKING

Choosing the most effective system for an autonomous vehicle goes beyond merely bringing the vehicle to a stop. As most autonomous vehicles in the future are expected to be electric vehicles (EVs), braking systems will also play a crucial role in optimising energy consumption.

This applies to EVs used for public transport, where multiple stops and starts along a single route are an energy drain. When these stops occur, and because the electric motor behaves like a generator under these conditions, the EV releases energy that is fed back into the drive system. This energy needs somewhere to go, so heads towards the EV’s battery as part of a process is known as regenerative braking. 

If the battery is full, and the EV has no other means to dissipate the excess energy, then the speed of the vehicle might be limited in order that the mechanical brakes can safely bring the vehicle to a stop without the possibility of causing brake fade or failure. 

To remedy this, a braking resistor, such as Cressall’s EV2, can dissipate excess energy when the battery does not accept the charge. This type of braking is known as dynamic braking. Wherever possible, braking should be regenerative rather than mechanical. This creates the possibility of storing and re-using braking energy, rather than just dissipating it as waste heat. 

Furthermore, many public service and heavy goods vehicles are fitted with auxiliary or endurance braking systems that work in tandem with the service brakes. The EV2 is an ideal substitute to these mechanical, hydraulic or magnetic systems. 

Heating also plays an important role in making use of this regenerated energy. The EV2 is a liquid cooled resistor. Specifically, it is cooled by pumping the cold liquid that comes into one end of the system, which then absorbs the heat generated by the resistor. This heated liquid can be pumped through a radiator, then used to provide heat to the cabin of the vehicle for a more comfortable passenger experience. 

This method of heating reduces the amount of energy required from the battery, and uses heat that would otherwise have been wasted.  

While the wide-spread adoption of autonomous transport has yet to become a reality, it’s not difficult to imagine the day when cars will brake on their own, as commanded by autopilot. After all, electric steering systems already perform a similar function. Braking technology can’t change the mistakes of the past, but it can be a huge driver in delivering energy-efficient autonomous transport. 

To find out more about Cressall’s EV2 for electric vehicles, click here

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