Creating a carbon-neutral mine site

Hydrogen fuel cells have proven a popular topic on The Intelligent Miner blog, so when I read that Anglo American was teaming up with energy services company ENGIE to make hydrogen-powered mining trucks a reality, I had to find out more.

The agreement was signed on October 10, by the two companies aboard the Energy Observer, during the London stop of its round-the-world voyage.

The hydrogen fuelled catamaran is nearly halfway through a mammoth six-year journey to promote clean energy technology as an enabler of the next industrial revolution; a fitting place then for such a high-profile announcement.

The project is part of Anglo American’s technology-led sustainable mining programme, FutureSmart Mining, and Anglo is working with a number of partners to develop the necessary systems.

The pilot will involve the conversion of a 300 metric tonne haul truck to run on hydrogen for operation at Anglo’s flagship platinum group metal (PGM) operation in South Africa, Mogalakwena.

ENGIE will provide the hydrogen generation solutions and Anglo American the truck. The modifications required include replacing the diesel tank with hydrogen tanks and replacing the engine with hydrogen fuel cells and a battery pack.

The hydrogen will be provided by the solar power generation capacity at the mine, and a spokesperson for Anglo told me that the hybrid hydrogen power plant is being developed in-house.

In the press release, the companies said that ‘first motion’ of the truck is expected in 2020, followed by testing and validation at Mogalakwena. If that is a success, then the technology will be rolled out to other Anglo American open-pit operations.

Operational performance of the converted truck is expected to be the same or better than the original diesel model, with the additional benefits of fewer emissions, less noise and lower maintenance costs.

“It [the prototype] is being constructed now and will be ready for trials next year,” an Anglo American spokesperson told me. “The trial will start at the end of Q2 2020 and will continue to the end of the year.

“We are developing a power module that is a combination of fuel cells and battery that will drive the electric motors on the haul truck. Due to hydrogen’s energy density and light weight, it allows us to operate our haul trucks in the same fashion as diesel powered trucks do today.”

How do hydrogen fuel cells work?

Hydrogen fuel cells transform chemical energy into electrical energy by converting hydrogen gas and oxygen into water. Both elements are readily available in Earth’s atmosphere, and it’s also possible to produce more hydrogen from the electrolysis of water using solar or wind energy. Securing supplies is therefore no trouble and can also be carbon emission-free.

Anglo explained the process in a blog post earlier this year: to turn hydrogen and oxygen into electricity, every fuel cell needs an anode, a cathode and an electrolyte membrane. Hydrogen enters the fuel cell at the anode, and oxygen at the cathode.

When pressurised, hydrogen enters the fuel cell at the anode and the catalyst, which usually contains platinum, separates it into protons and electrons.

The protons travel through the electrolyte membrane towards the cathode where electrons are diverted to an external circuit that generates an electrical current. The electrons then move towards the cathode to combine with the oxygen and protons forming a water molecule which is the only by-product.

The development of reliable, high-performance fuel cells is critical to a achieving a low-carbon future.

While the proportion of electric vehicles sold annually across the globe – both battery electric and fuel cell electric – is currently less than 5%, this is forecast to increase to more than 50% for both light-duty and heavy-duty vehicles by 2050.

Given that Anglo American is a leading global PGM producer, the sustainability of its business stands to benefit in more ways than one from the expansion of the fuel cell market.

It’s therefore no great surprise that the company has chosen to go down the fuel cell path for its own low-carbon mining technology investments.

Working towards carbon neutrality

Commenting on the ENGIE deal, Anglo American’s technical director, Tony O’Neill, said that the company is very excited about the project.

“We look forward to developing and implementing this step-change technology. As part of our Smart Power Project, where we analysed our mine site power requirements and applied a unique decision process on how we look at renewable energy systems and their benefits, we came up with a mix that allows us to be carbon neutral and have a very different footprint.

“This is part of our plan to create a smart energy mix that moves us closer towards our carbon and energy targets for 2030 and, ultimately, our vision of operating a carbon-neutral mine.”

Creating a carbon-neutral mine site is quite a feat given the scale of the footprint today’s operations have, but if any mining company can achieve it, it’s likely to be Anglo.

The company was one of the first to formalise its efforts to tackle climate change, introducing a dedicated policy in 2011 which is now updated annually.

As part of this, it is currently working towards delivering an 8% improvement in energy use and a 22% saving in greenhouse gas (GHG) emissions by 2020 against its projected ‘business as usual’ consumption.

Anglo was also one of the first mining companies to link its achievements in carbon and GHG reduction to its executive long-term incentive plan, a move that was announced in 2017.

Kudos where it’s due, the company’s hard work is paying off.

In the 2019 update of its climate change report, Anglo reported that the 440 energy efficiency and business improvement projects it had implemented had saved more than 6 million gigajoules of energy, and its GHG emissions savings in 2018 amounted to 6.1 million tonnes CO₂ equivalent.

And, hydrogen fuel cells aren’t the only innovative technologies that Anglo has in store for its mines… Carbon capture and storage technologies will also play an important role in the creation of carbon-neutral sites.

Capturing carbon with kimberlite

For some time now, De Beers, a subsidiary of Anglo American, has been working on a programme called Project Minera. This aims to harness the inherent properties of kimberlite – a diamond bearing ore – to remove carbon from the atmosphere.

It works on the premise that when kimberlite is brought to the Earth’s surface and crushed it acts like a sponge, absorbing carbon dioxide from the atmosphere and locking it into stable, non-toxic carbonate minerals.

“These carbonates form naturally in our processed ore, and our research is looking at ways of speeding up that process,” Anglo said in its climate change report. “Together with experts from the University of British Colombia, the University of Alberta, Trent University, the University of Queensland and Bond University, we are testing different mineral carbonation technologies (carbon dioxide injection, cation exchange and biotechnology) in laboratories – and we will soon be moving to mine sites.”

The intention is that the technologies will operate under ambient conditions at low costs. Scientists estimate that the carbon storage potential of kimberlite tailings produced by a diamond mine every year could offset up to 10 times the emissions of a typical mine.

De Beers is hoping to implement field trials at the Gahcho Kué mine in Canada in the near future and Anglo said that, together with its efforts to improve energy efficiency and switch to renewable energy sources, mineral carbonation has the potential to help its mining operations become carbon neutral.

With projects like these in the pipeline, it’s pretty exciting to think how different mining operations could look in just ten year’s time.