Inspenet, July 8, 2023.
Is it possible that an alternative to fight global warming is found in a hard volcanic rock and nothing outstanding?
Apparently yes and it is about basalt ; a rock that is turned through a process called “enhanced rock weathering” into the “magic dust” that could help cool the planet.
This is what Jim Mann, owner of the enhanced rock weathering company UNDO, calls the tiny and highly valued fragments of basalt, because they have the unique property of absorbing carbon dioxide from the atmosphere when worn away by rain.
This company has just received a new investment of $15.5 million, has attracted potential investors and has plans to expand its operations.
UN scientists now acknowledge that reducing greenhouse gas emissions will not be enough to halt dangerous levels of warming, and say that some carbon dioxide will need to be actively removed from the atmosphere.
Planting trees is the most natural way to achieve this, but it does have its limitations, as captured CO₂ is released when wood decays or burns, and there is a limit to the number of trees that can be planted.
Another option is direct air capture (DAC), which mechanically removes CO₂ from the atmosphere and stores it underground.
While this is a permanent solution, it raises the question of whether it makes sense to build such an energy-intensive process when you’re trying to move away from fossil fuels.
Can enhanced rock weathering help combat global warming?
Enhanced rock weathering falls somewhere between natural and man-made. It takes advantage of the natural but extremely slow aging process and speeds it up to remove carbon more quickly.
This process uses small fragments to increase the contact surface between the rocks and the rain, which in turn increases the amount of weathering and carbon removal.
For thousands of years, volcanic rocks and cliffs have been slowly removing carbon as they erode under rain.
Basalt, piled up in the quarry or forming cliffs, wears away very slowly. So to maximize carbon removal, it needs to be spread out over a wider area. This is where local farmers play an important role, as they contribute to caring for the planet and receive free fertilizer in return.
In addition to sequestering carbon, basalt has been shown in tests to improve both crop yields and grazing quality.
How is the process carried out?
A trailer is loaded with 20 tons of basalt and a tractor pulls it up and down the field while a caster wheel at the rear disperses the small rocks.
“It’s free, which is very important for farmers,” says John Logan as he spreads the basalt in his field. He had seen the tests carried out by UNDO on a nearby farm.
“It seems that it will improve the pasture, which can only be beneficial for cattle, since it represents better quality feed.”
Some experts are concerned that carbon removal techniques like this could divert attention from the more urgent priority of reducing emissions and even be used as a justification for continuing a carbon-intensive lifestyle.
“CO₂ reduction needs to be the priority,” Jim says, “but we also need to develop these technologies that can remove it on a large scale. The nice thing about what we’re doing with enhanced rock weathering is that it’s permanent.”
UNDO scientists estimate that it takes four tons of basalt rock to capture one ton of CO₂. This year, the company plans to spread 185,000 tons of basalt and hopes to have removed one million tons of CO₂ by 2025.
Microsoft has agreed to finance 25,000 tons of basalt to be spread across UK fields. You will also help audit the project and verify that it is working as planned.
“The fundamental chemistry makes sense,” Steve Smith, an expert in carbon removal at Oxford University, told me.
“Measuring how much CO₂ would be removed and where it would ultimately go is one of the key challenges and there is currently no standardized system.”
Smith thinks this idea could ultimately become a standard part of farming.
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