The magic dust that could help fight climate change – 06/27/2023 – Environment

In a quarry surrounded by the noise of heavy machinery, Jim Mann crouches down and picks up a handful of tiny black stones.

“This is my magic dust,” he says with a smile, rubbing them gently between his fingers.

He’s holding chunks of basalt — a hard volcanic rock that is neither rare nor particularly remarkable.

But through a process known as “accelerated weathering,” it could help cool our overheated planet.

UN scientists are now clear that reducing greenhouse gas emissions alone will not be enough to halt dangerous levels of warming. They say it will take some carbon dioxide removal, that is, actively taking it out of the atmosphere.

Planting trees is the most natural way to do this, but it has its limitations: Captured CO2 is released when wood rots or burns — and there are limits to how far trees can be planted.

Direct Air Capture (DAC) technology, meanwhile, mechanically sucks CO2 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?

Accelerated rock weathering is somewhere between the natural and the artificial. It takes the natural but very gradual weathering process and turbocharges it to remove carbon faster.

I went to a quarry across the Firth of Forth estuary from Edinburgh, Scotland, to chat with Jim Mann, whose accelerated weathering company, called Undo, has just secured £12m investments and intends to expand its operations.

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

But the small pieces of basalt that remain are prized by Jim’s company. They have a useful property—when weathered by rain, they remove carbon dioxide from the atmosphere.

For millennia, volcanic rocks and cliffs have slowly removed carbon as they are weathered by rain.

Accelerated weathering uses tiny bits to increase the amount of contact between rain and rock—and thus the amount of weathering and carbon removal.

Whether on a cliff, or piled up in a quarry, basalt undergoes the action of weathering very slowly. To maximize carbon removal, it needs to 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 trapping 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 being spread in a field.

This does not require specialized equipment. A bucket on wheels is loaded with 20 tons of basalt and then it is towed up and down by a tractor — a rotating wheel at the back of it spreads out the small stones.

“It’s free, which is very important for a farmer,” says John Logan with a laugh, as basalt is laid in his field. He had seen Undo tests at a neighboring farm.

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

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

“CO2 reduction needs to come first,” says Jim, as the GPS-guided tractor drives up and down the field.

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

Mathematics, it must be said, is scary. Undo scientists calculate that it takes four tonnes of basalt rock to capture one tonne of CO2.

With the average Brit’s CO2 emissions estimated at around 7 tonnes a year, that means that each of us needs approximately thirty tonnes – or a bucket and a half of basalt to be spread annually just to reach a break-even point.

Undo has plans to rapidly expand its operation in the coming years and has attracted strong supporters. Microsoft has agreed to pay for 25,000 tonnes of basalt to be spread across UK fields. As part of the agreement, Microsoft will also help audit the project and verify that it is working as intended.

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

“Measuring how much CO2 would be taken out and where it goes is one of the main challenges, and there is no standardized system at the moment.”

Ultimately, Smith thinks the idea could end up just being a standard step in the way the land is farmed.

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

There are still many questions about how scalable it is. Undo’s projects use by-products from the local quarry—but if this is scaled up considerably, the energy and emissions needed to crush and then transport and spread the basalt will need to be taken into account.

“Right now, there is no downside, it’s a win-win for everyone involved.” evaluates Jim Mann.

This year, Undo plans to spread 185,000 tons of basalt — and expects by 2025 to have removed one million tons of CO2. It’s still a drop in the ocean compared to emissions. In 2022, it is believed that the world released around 37 billion tons of CO2 into the atmosphere.