The ‘magic dust’ that could help fight climate change

United Nations scientists are now clear that reducing greenhouse gas emissions alone will not be enough to halt dangerous levels of warming. They say it would take some CO2 removal – that is, actively removing it from the atmosphere.

Planting trees is the most natural way to do this, but it has its limits: captured carbon dioxide is released when wood rots or burns—and there are limits to how far you can plant trees.

Meanwhile, Direct Air Capture (DAC) technology mechanically sucks carbon dioxide out of the atmosphere and stores it underground; It’s permanent—but does it make sense to invest in such an energy-intensive process when we’re trying to wean ourselves off fossil fuels?

The accelerated weathering of rocks is somewhere between natural and artificial. It takes the natural but very gradual process of weathering and turbocharges it to remove carbon faster.

I went to a quarry across the Firth of Forth estuary from Edinburgh, Scotland, to speak to Jim Mann, whose precipitating weathering company, UNDO, has secured £12m of investment and intends to expand its operations.

All around us, the black slope is constantly being eroded, scraped by huge bulldozers to make concrete and asphalt for the roads. a vibration It’s more post-nuclear apocalypse than saving the planet.

But the remaining small pieces of basalt are appreciated by Jim’s company. It has one useful property – when affected by rain, it removes carbon dioxide from the atmosphere.

For thousands of years, igneous rocks and cliffs have slowly shed carbon as they are weathered by rain. Accelerated weathering uses small particles to increase the amount of contact between rain and rock – and thus the amount of weathering and carbon removal.

Whether it is on a slope or accumulated in a quarry, basalt undergoes weathering very slowly. To maximize carbon removal, it must be spread over a larger area.

And that’s where local farmers come in, who help the planet while getting free fertilizer in return. In addition to sequestering carbon, basalt has been shown in tests to improve crop yields and pasture quality.

Half an hour’s drive from the quarry, I see basalt spread out in a field.

This does not require specialized equipment. A bucket is loaded on wheels with about 20 tons of basalt and then dragged up and down by a tractor – small stones are spread out with a spinning wheel at the back of it.

“It’s free, which is very important to the farmer,” John Logan says with a laugh, as the basalt is laid out in his field. He had seen UNDO’s tests at a nearby farm.

“It looks like it’s going to improve the grass, so it’s only going to be good for the cattle because they’ll be eating better grass.”

Some experts worry that decarbonization technologies like this could distract people from the more urgent priority of reducing emissions — and even be used as an excuse to continue living our carbon-intensive lives.

“Reducing carbon dioxide emissions has to come first,” Jim says, as the GPS-guided tractor moves up and down the field.

“But we also need to develop these technologies that can do removal on a large scale. The nice thing about what we’re doing with the accelerated weathering of rock is that it’s permanent.”

It must be said that mathematics is scary. UNDO scientists calculate that it takes four tons of basalt rock to capture one ton of carbon dioxide.

With Britain’s average carbon dioxide emissions estimated to be around 7 tonnes per year, this means that each of us would need nearly thirty tonnes – or a bucket and a half of basalt to be distributed annually just to break even.

UNDO has plans to rapidly expand its operations in the coming years and has attracted strong backers. Microsoft agreed to pay 25,000 tons of basalt to be distributed across UK fields. As part of the agreement, Microsoft will also help audit the project and verify that it is working as intended.

“The underlying chemistry of this makes sense,” says Steve Smith, a carbon removal expert at the University of Oxford in the UK.

“Measuring how much carbon dioxide will be removed and where it goes is one of the main challenges, and there is no standardized system at the moment.”

In the end, Smith believes the idea could just be a standard step in the way land is cultivated.

“It’s something that can factor into how we use the land right now, and it offers a decarbonization benefit along with other benefits in terms of how we use the land for food and crops,” he says.

There are still many questions about scalability. UNDO projects use by-products from a local quarry – but if this is to be scaled up significantly, the energy and emissions required to crush the basalt and then transport and saw it must be taken into account.

“For now, there is no downside, it’s a win-win for all parties involved.” Jim Mann resides.

This year, UNDO plans to scavenge 185,000 tons of basalt – and by 2025 it expects to remove 1 million tons of carbon dioxide. Still a drop in the ocean compared to emissions. In 2022, the world is believed to have released around 37 billion tons of carbon dioxide into the atmosphere.