Can Volvo and Skanska create the world's first ultra-low emission quarry?
For decades, Vikan Kross quarry just outside Gothenburg has been excavated for granite and aggregates, producing around 1.25 million metric tons of material each year for use in the construction, asphalt and cement industries. And, just like any other mining site around the world, a raft of diesel-guzzling heavy machinery traditionally has been used to carry out the hefty, load-bearing work.
The site is Skanska's oldest and largest quarry in Sweden, but for the past 10 weeks or so, the construction and engineering giant has been piloting new electric and autonomous machinery at the site — including excavators, crushers and load carriers — in the hope a new wave of clean technologies can cut costs, emissions and air pollution. The plan is to turn Vikran Kross into the world's first emissions-free quarry.
"This is the first time anything like this has been attempted in the quarrying industry and, if successful, it could serve as a blueprint for transforming the efficiency, safety and environmental impact of quarries around the world," Skanska Sweden CEO Gunnar Hagman said in August, just before the 10-week pilot got underway.
Dubbed the Electric Site project, it is a collaboration with transport giant Volvo which was first announced in 2015 and has been backed by $22.3 million of investment, with the Swedish Energy Agency and two Swedish academic institutions, Linköping University and Mälardalen University — also involved.
Research had suggested the project would be able to reduce CO2 emissions from the quarry by 95 percent, while also cutting total operating costs by as much as 25 percent. Three years later, the prototype machinery and equipment is finally being tested, and the early results are very promising, according to Uwe Müller, chief manager for the project at Volvo Construction Equipment.
"Based on the measurements we have seen so far, we believe we could even go up to a 98 percent reduction in CO2 emissions," he tells us. "We are not fully there with all the results, but on energy consumption, we believe there is scaling potential to reduce energy costs by up to 70 percent. On automation, too, we believe we can reduce operating costs by 40 percent. Then the third tranche of costs is the machinery, which is to be figured out. We expected to go a bit higher on machine costs, but overall with the reduction in the other two cost streams, we believe a 25 percent reduction in overall costs is doable."
"As we had so many learnings and it was going so well — plus we also had a lot of issues as it's the first time we've tried something like this — we decided to extend the testing until Christmas, so we're going to run the demonstration for four more weeks roughly," says Müller. "It will be a chance to really take full advantage as now we have everything in place, and from both sides there is a lot to learn."
Drawing on the Volvo Group's electromobility and automation expertise, the project has seen each stage of the quarry's operations electrified as far as possible, from excavation to primary crushing, and transport to secondary crushing. The companies say a "negligible" amount of diesel fuel is still required, but overall a surprising number of heavy duty processes can be electrified.
In addition to a fully electrified conveyor belt being installed at the site, Volvo developed three new prototype mining and construction machines specifically for the project. These were introduced alongside new work methods, processes and site management systems drawn up by Skanska to ensure the highest efficiency throughout operations.
Firstly, there is an electric-diesel-hybrid, 70-metric ton capacity excavator named the EX1. When connected by cable to the power source, the EX1 automatically operates in zero-emission mode, and obviously when it isn't connected, it operates in diesel mode.
The second prototype piece of machinery on site is the LX1, a wheel loader which is again an electric-diesel hybrid, although this time including both electric motors and an energy storage system with a "significantly smaller" diesel engine. Volvo claims the machine can deliver up to a 50 percent improvement in fuel efficiency, as well as significant reductions in emissions and noise compared to fully diesel powered equivalents. Moreover, it can even do the work of a wheel-loader that is one size larger, Volvo claims.
And finally, eight battery-electric HX2 autonomous load carriers ferry material around the quarry, either to the site's asphalt plant or two concrete factories, or for transport elsewhere. Using GPS, these are essentially on a constant, pre-programmed loop of the quarry, powering up once every circuit — roughly every 10 minutes — using on-site chargers. They use lithium-ion batteries and are fitted with a vision system which allows them to detect humans and obstacles, according to Volvo.
Clearly, though, with diesel fuel still being used on site, Vikan Kross is not a completely zero-emission quarry, and eradicating fossil fuels altogether at the site remains a significant challenge. Is there any hope a fully-electrified quarry mining can be delivered in the not-too-distant future?
"It depends on the situation," explains Müller. "Right now you could in theory run the loader for some time on full-electric power, but this one doesn't have breaks in the process — it is continuously running and moving around. So, if you wanted it to run full-electric for a whole day, you would need to have so many batteries that it would not be a good idea, both from a cost perspective and a load perspective, because of the additional battery weight."
Still, in additions to cost savings for Skanska, the project signals a significant commercial opportunity for Volvo. None of the machinery is yet commercially available, but the auto giant hopes in future to ramp up development of zero and low emissions mining equipment for the industry, explains Müller.
Both the electric-hybrid excavator and loader machines potentially could be brought to market fairly quickly, he says, but the complexity of the technology means the autonomous vehicles are likely to take longer.
"Here we are showing all the elements introduced together, but what I also see are the different individual elements implemented in different applications in different timeframes," he says.
However, he also admits that it could be some time before ultra-low emissions quarry mining becomes widespread. "We aren't talking about months here — there are still some years to go," Müller acknowledges.
So what next? Once the final results are in, Volvo will remove its prototype machinery early next year in order to carry out further development work, and the Vikan Kroll quarry will go back to using fossil-fuelled equipment — although the full-electric conveyor belt will stay.
"We really want to focus on the learnings right now and try to fix any issues, and then the next step would be to go towards a full commercial pilot, as this is just a research project at present," Müller says.
Mining may not have the most environmentally friendly reputation, but there is no doubt the global economy will need the materials it provides for the foreseeable future. Whether it is scaling up greener buildings, laying roads for zero-emission vehicles, or securing minerals for our increasingly digital and electrified economy, mining sits at the end of global supply chains. But equally there is no way to deliver a net zero emission economy without deep decarbonization across even this most carbon-intensive of sectors. The work currently being undertaken at one of Skanska's oldest granite mines could mark the start of a cleaner, greener future for the industry.
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