In this ClimateGenn episode I am speaking with Professor David Beerling about his rock-breaking research that could help to regenerate agricultural soils, while also enhancing their capacity as vast carbon sinks.
Carbon dioxide removal (CDR) is a controversial topic and yet it is also embedded within many national plans for carbon reduction. David Beerling is the leading researcher in this field of Enhanced Rock Weathering, and here he shares a wide range of insights about the potential for deployment, effectiveness and scaling to meet our global challenges.
Obviously no one is suggesting that this can replace carbon emissions reductions. The transition to renewables is the critical societal evolution of our times. Even this obvious statement sounds controversial at a time when powerful state-backed corporations are doubling down on fossil fuel production and profiteering.
These are tough times for anyone who understands the science of climate change and rate of ecological destruction, as we see the rise of corruption and actions of psychopaths that have long-term impacts on all our lives.
With Europe having no choice but to propose hundreds of billions of euros be invested in a new arms race for defence in human conflict, we collectively appear blind to the threat posed by mother nature, a far mightier enemy of our own creation.
In future episodes we’ll be exploring many related themes and also looking for ways to stay engaged in issues that matter without becoming psychologically exhausted.
Thank you for listening, please do like and share and, if you can, become a member of ClimateGenn to support future episodes.
A quick note – David uses the acronym, MRV – this stands for the Monitoring, Reporting and Verification in greenhouse gas removal discussions and is a critical topic.
“A crucial step in persuading government is really to get the Committee on Climate Change on board, as they advise the government on their carbon budgets.”
Professor David Beerling
Interview with professor david Beerling Transcript:
[Nick Breeze]
David, it’s great to see you. Thank you very much for taking the time to speak to me. Can you start by just giving us a brief description of what enhanced rock weathering is and just the process by which it absorbs or sequesters carbon?
[David Beerling]
Thanks for the invite to be here and have a talk about enhanced weathering. Terrestrial enhanced weathering is really the application of crushed silicate rocks to agricultural landscapes. The minerals within the rocks contain elements like calcium, magnesium that are slowly released.
And then as they’re released in the soil, they capture carbon either in a soluble form as bicarbonate, which then drains through the soil and eventually makes its way into rivers and the oceans where it’s stored for thousands of years. There’s different rocks you can use to do this. The one that’s most commonly proposed is basalt, which is a very common or the most common surface rock that’s available, mostly left over from ancient volcanic eruptions.
And I think there’s some important co-benefits for enhanced weathering that some of these other carbon dioxide removal technologies don’t have. So I guess foremost would be that as the reactions occur in the soil between the rocks and the water and the roots, you generate alkalinity and this helps reverse soil acidification. Acidification of agricultural soils is a major issue globally because mainly caused by overuse of fertilisers.
But as the soils become more acidic, then it limits the ability of crops to take up nutrients and so limits yields. And that’s why farmers typically apply lime or limestone to reverse that soil acidification. But if you apply crushed silicate rocks like basalt, then you get carbon capture and you get that liming effect for free.
And then there’s other elements in basalt as well, like potassium and phosphorus that are important for fertilising crops. And micronutrients like iron and silica, manganese and molybdenum are also important for healthy crops. So there’s a whole suite of benefits both to food security and soil health come along with doing enhanced weathering as well as the carbon capture.
[Nick Breeze]
In the recent study that you produced looking at US agricultural soils, I mean, that’s a large assessment. Did you have to take into account all the different soil types or is it a uniform sort of deployment?
[David Beerling]
The main growing areas in the US is the US Corn Belt, which is about, I don’t know, 60 million hectares. And it’s one of the most intensively managed agricultural regions in the world. So it has the infrastructure to deploy rock weathering monitoring and so on if it was found to be attractive.
And the way we did it was using a kind of set of process models and underlying soil types and hydrologies that help us understand spatial variability in the efficiency of carbon dioxide removal. And the way that we did it was couple the deployment onto the crop lands with the provision of basalt from the mining states. And so if you like, it was kind of two modelling studies in one.
The first one was modelling how could basalt production from existing mining states increase? And the second would be if it increased, then what would be the effects on the soils if you deployed it on areas of the Corn Belt to capture carbon?
[Nick Breeze]
The other part that I was interested in is in the same study, you have ranges of the quantity of CO2 sequestered. And the sort of longer term one is from 250 million tonnes to 500 million tonnes, so sort of quarter to half a gigaton by 2070. Can you talk a little bit about the pathway to that?
[David Beerling]
Yeah, sure. So just sort of go back to the two studies sort of idea. The first one is really, you know, the amount of carbon you capture is really governed by the amount of basalt you can supply to the croplands.
And we modelled this for each of the I think there’s 15 states on the east coast and more states on the west coast, or the west coast states are too far from the Corn Belt to be a great utility for this. But the east coast states, we modelled it what’s called a kind of logistic curve, which is basically a sort of S shaped sigmoidal curve. So basalt production starts really slow for a number of one or two decades, and it ramps up quickly and then it reaches a limit and stays at that limit.
And what we did is we developed these supply curves for each of the individual states, constrained by historical rates of increase in production, and also capped by the maximum, what we think was the maximum rate of production that they could have. And so in order to get to that quarter or half gigaton of carbon removal, what you have to consider is that there are lag times in the production of basalt that can go down onto the croplands, you know, typically one or two decades before the production increases. And then as your production increases, then you can put a rock down over a larger geographical surface area, and that captures more carbon.
It’s very tightly constrained by the amount of rock that’s available. And in the study, what we did was sort of look at sort of low and high options to sort of bracket what the potential might be. The context for the work was really that the Biden administration had produced a pathways to net zero plan for the US.
And it was almost entirely focused on direct air capture, industrial process of carbon removal, or bioenergy with carbon capture and storage, and with a little bit of enhancing natural carbon sinks as well. But they hadn’t really done anything about enhanced weathering. And it seemed to us this was kind of both a challenge and opportunity to try and understand, okay, so the US government, federal government has overlooked enhanced weathering because there hasn’t been enough research done.
We’ve got the modelling tools and the expert team, the team to kind of really address this issue in detail. And so that was what kind of prompted us to get into it in detail.
[Nick Breeze]
Just to touch on it, because I think it’s super important. It’s about quantifying and verifying the carbon. Once you’re doing this, how do you do it?
How reliable is it?
[David Beerling]
Yeah, that’s, you know, that’s crucially important point is hot topic. It’s important to say that our study was basically numerical simulation study using the best tools that were available. But then, you know, there are companies in the US like Lithos Carbon, which are doing very extensive deployments, they are facing this issue about, okay, so how do you do MRV on these sites?
So there’s a couple of different ways that you can do MRV. One is you can apply geochemistry techniques that tell you how much of that basalt you’ve mixed in with the soil is actually undergone weathering, how much of it is chemically dissolved in the soil after a year or two years or three years. And if you know that, then you can figure out how much calcium magnesium is released.
And then because those are positively charged ions, you know exactly how much carbon dioxide you must have captured. But the drawback of that, of course, is that some of those calcium magnesium ions get stuck on sticky sites in the soils like clays and organic matter, and they’re not washed out. So you don’t get that charge balance straight away.
So there’d be a time lag in the delivery of the carbon dioxide removal. So there’s pros and cons. So that’s one way.
And then the other way is to actually instrument the farm with what are called lysimeters, which are sort of tubes that enable you to sample the soil moisture or the soil water at depths. And then you recover the soil moisture under vacuum, and you can do chemical tests on that. And it tells you how much carbon you’re capturing.
So in an ideal world, you’ll do both, because you know, one gives you sort of instantaneous snapshot of carbon capture as it’s happening. And the other one gives you kind of carbon dioxide removal on a promise. And then you have to think about how you rationalise those two in terms of carbon credits for the carbon market.
[Nick Breeze]
You’ve talked about at the beginning, a few of the benefits that can come to the soil from this. Overall, does this align with the sort of rise in attention being focused on soils with regard to things like regenerative agriculture? Does it fit that framing?
[David Beerling]
I think it does. You know, our cultural soils, as I said earlier, are severely degraded by intensification of agriculture and use of chemical fertilise, repeated monocropping. And they are depleted in many micronutrients and also soil organic matter, which is sort of crucial to soil health.
And there are studies that suggest that if you do enhance weathering because of the release of the calcium magnesium ions, then they can kind of interact with the organic matter and increase the soil organic carbon content, which is a crucial feature of regenerative agriculture is improved soil organic carbon. Some of the issues with regenerative ag is that, you know, if you change your land use, then you can potentially release the carbon you’re trying to capture. And you can also saturate the sinks as well, the soil organic carbon sinks.
These tend to be issues that you don’t encounter with enhanced weathering. So I think there is a lot of scope for thinking about how you would combine the two actually.
[Nick Breeze]
How much does it cost? I mean, what’s the way in? And how do you get that going into a sort of a scale up, whereas it becomes a feasible economic proposition?
[David Beerling]
Yeah, those are good questions. And there’s about, I don’t know, 20 startups now in the enhanced weathering space. And these are exactly the questions that they’re grappling with in terms of what’s their business model for making this attractive to farmers.
And in a sense, you know, in many ways, it shouldn’t be an attractive business model, because what you have to do is invest all your money and your basalt supplies up front. And then you have to persuade farmers to put it down on the land. And then slowly, you’ll get carbon credits and recover your costs and turn a profit.
But nevertheless, despite that, as I said, there has been, I don’t know, about 20 enhanced weathering companies that have now been funded either through climate funds or venture capitalist investment, where they think these problems aren’t insurmountable. And yeah, I don’t know the secrets of their business model. I’d be interested to learn it.
They’re still going, well, they’re still going another five years, not a matter.
[Nick Breeze]
You talked about the Biden administration was a sort of spur for getting this going. Obviously, things have changed. And is there a way and we’ll just use the US as an example for a moment.
But do you think that there’s still a road to deployment despite the current political framework in the US?
[David Beerling]
Getting it supported federally is going to be almost impossible, at least in the near term. I have colleagues in the US whose USDA and Department of Energy grants that are running large scale field trials are basically frozen because of the Trump executive orders. And they’ve had to put postdocs and technicians on, you know, on notice of leave because they might lose their jobs, the funds aren’t frozen.
So I think that the federal pathway is extremely difficult, at least in the near term. So you know, that really only leaves commercial deployments for upscaling. And I think what’s going to be critical for that is finding robust, transparent, cost effective ways for doing MRV so that they can convince the carbon markets that the carbon credits they’re offering are durable and robust.
And, you know, enhanced weathering doesn’t go down the same route as say, reforestation credits with the Vera scandal where it turned out that carbon credits weren’t durable at all, because with a fire or even disease, then they will go back up into the atmosphere. So yes, I think getting the MRV right, it’s going to be crucial in terms of thinking about the commercial picture that has been the sale now of enhanced weathering carbon credits by a company in Brazil actually called Implanet, who have now sold what I believe are the first carbon credits from enhanced weathering, and they’ve yet to release their protocols. So everybody’s sort of waiting with bated breath to see exactly how they did it, and whether we all agree that it is robust and transparent.
But in terms of scaling it, at least in the US, it’s going to have to be commercial.
[Nick Breeze]
But let’s come over to UK and Europe. It seems like the assessments here could find positive policy makers or means. Have you had any interactions?
What’s been going on?
[David Beerling]
Yeah, so I also lead as well as the Leverhulme Centre for Climate Change Mitigation, which is dedicated to international efforts with enhanced weathering. I also lead the UKRI project in the UK. We have three sites in the UK, where we’re looking at this performance of lowland grazing, upland grazing and arable land.
Also as part of that project, we have representatives of the UKRI expert advisory group, and they are very excited about it. And I think, you know, really, the next step is to sort of synthesise our findings probably this year and report back to government. I think a crucial step in persuading government is really to get the Committee on Climate Change on board, who are the sort of the independent body that advises the government on their carbon budgets.
And they’re about to release their seventh carbon budget, I think, in the next few months, next couple of months over the summer. And if we can put enhanced weathering on the map there, you know, with an evidence base that’s been missing previously, then I think it’s got a chance, you know, at the same time with coming out of the EU, we’re also having this, you know, the ELMS, Environmental Land Management Scheme. And part of the remit of ELMS is public land for the public good.
But also part of that is also carbon capture. So you could imagine, you know, maybe possibly UK farmers being subsidised to do enhanced weathering if their land was of the right sort, or the soils were the right pH. And in a sense, that would provide an additional source of income.
And, you know, just very welcome for farmers right now.
[Nick Breeze]
In the US, sort of the top end by 2070, you estimated around half a gigaton, 500 million tonnes. Is there any kind of assessment for the UK or Europe or any other places?
[David Beerling]
Yes, we have done a similar similar analysis for the UK. And obviously, the figures are much lower because of the smaller land area. But I think it could meet maybe 10% of the UK’s greenhouse gas removal target by doing enhanced weathering.
But you know, the reality is that getting any nation to net zero is going to require more than one CDR technology, you know, you’re going to need a whole suite of different technologies, you may only need five or 10 million tonnes for enhanced weathering in the UK, and then five from direct air capture and five from VEX. What these sorts of analyses show is that enhanced weathering could be an important part of the mix for helping any particular nation get to net zero. But you know, with these co-benefits for soils and food security.
[Nick Breeze]
If they’re proven to do the job, and it’s quantifiable and verified, etc, then as these start replicating in different places, it becomes quite significant, especially if you start getting over a gigaton.
[David Beerling]
Oh, yeah, I think so. Yeah. And I think, you know, one of the areas that we’re very interested in at the moment is actually to think about how you’d use numerical models and AI to generate a new set of computational tools for MRV that are still ground truth with a kind of more restricted set of measurements on the deployment fields.
But then you could sort of generate an app or a web-based app for farmers to use and say, okay, we’ve got this application rate, this sort of rock, this much area, you know, and you run the simulations on a web-based tool, and it tells you what your carbon capture time course would be and what the uncertainties would be. And I think, you know, if we can crack that part of the puzzle, then that would really open up a lot of potential for upscaling, because it would remove the need to do thousands of expensive geochemistry measurements.
[Nick Breeze]
Are there any downsides, things that worry you about the process or the technology itself?
[David Beerling]
I think you have to do due diligence on the feedstocks that you’re using. You don’t want to choose feedstocks that are rich in heavy metals, although I have to say, you know, basalt tends not to be rich in heavy metals. That’s why, you know, some of the most productive regions in the world are, you know, which are volcanic, like around the foothills of Mount Vesuvius, also the most fertile in Italy.
You know, that’s where they grow their best tomatoes, apricots and cherries around the base of Mount Vesuvius, because of the microclimate, but also because of the soils. But I think, yeah, you do have to do due diligence, any kind of deployment prior to applying it. And then during application, you’d want to check for trace metal contamination in the soils, the edible parts of the crops and in the drainage waters and stream waters.
There is a sense as well about mining, if you had to increase the outputs from existing mines, would that be an issue for people? Or even if you had to create new mines, would that be an issue? In the US, the public engagement work that we’ve been doing, led by Nick Pigeon at Cardiff, has found that most people in the US, because they’ve got so much land, it’s not such a big issue.
But possibly in the UK, there’s more nimbyism, because we’ve got such a small footprint of land, it might be more of an issue. But you know, on the other hand, when Nick’s done public engagement workshops in areas that are used to mining, like, for example, Shropshire, they say, well, actually, mining is quite an important part of our community, the mining companies fund our football teams and our primary schools, they contribute to Fates and stuff like that. And actually, you wouldn’t mind if you if you opened another mine, or if you expanded mining production, it creates employment.
Feeds back into the community. So there’s a lot of complex issues around around mining that you need to think about.
[Nick Breeze]
Community engagement is so critical to all this and how it does impact people. This really to end on, what’s the next big thing on your horizon that we should be looking out for to do with enhanced rock weathering?
[David Beerling]
For us, it’s thinking now about sort of stacking the different CDR technologies. So one thing we’re quite excited about is stacking enhanced weathering with reforestation. This is some work that’s going on with the carbon community, which is a UK carbon removal charity.
They have a huge field site, 11 and a half hectares in Wales, where they’ve been combining tree planting with enhanced weathering. And what you find is the trees love basalt, trees grow better with basalt for several reasons, but mainly because the basalt releases nutrients that the trees love as it weathers, and so it helps the trees grow better. And so that’s one area that we’re starting to think about more and how do we stack different CDR technologies to exploit potential synergies between them.
You could also imagine that you could stack enhanced weathering with biochar, for example, and increase the potential for CO2 removal as well. So these areas that we’re looking to develop in future years.
[Nick Breeze]
Although it’s not a panacea, it is certainly something that we could really start thinking of much more ingrained within our whole agricultural system. Would you say that’s a good ambition for this?
[David Beerling]
Yeah, I think it does offer really unparalleled opportunities for sustainable agriculture. And in the UK basalt is the only soil fertiliser that’s approved by the Organic Soil Association because it’s a natural rock. So there’s great potential for making it part of sustainable agriculture going forward.
[Nick Breeze]
That’s really, really interesting. Thank you, David, for explaining it. And I hope to speak to you again when there’s been some more sort of news and development.
[David Beerling]
It’s a pleasure. Thanks. Thanks for the invite.
