Bind CO2 with stones?: “That would be mining as big as the coal industry”

The US climate startup Vesta wants to suck CO2 out of the atmosphere by accelerating the natural weathering process of rock. A tempting idea, with prominent financiers: Google, Facebook, Shopify and Stripe, among others, belong to a climate alliance that started in spring one billion US dollars invested in startups like Vesta. Magic? Even more fantasy says Mark Lawrence in the “Climate Laboratory” by ntv. “None of these technologies will make a significant contribution to achieving the goals of the Paris climate agreement.” Nevertheless, the scientific director of the Institute for Transformative Sustainability Research (IASS) in Potsdam for researching this and other methods, because this is the only way we can find out how we can actually remove large amounts of CO2 from the atmosphere in the second half of the century. But industrial weathering in particular has a major catch: we would need a huge new mining industry.

ntv.de: There are some ideas in the fight against the climate crisis that sound like magic. One startup, for example, is called Vesta. There they want to reverse or reverse climate change by accelerating the weathering process. What does that mean?

Mark Lawrence: There are a great many ideas and suggestions as to how CO2 could be removed from the atmosphere. This is nothing new, it has been researched for about 30 years. As far as we know, there is currently no technology that could make a significant contribution to the Paris climate agreement’s two degree goals – be it accelerated weathering or something else. This is fantasy.

Then you have directly disenchanted the magic trick.

Yes, but even if none of these techniques will help in the next 20 or 30 years, it is absolutely essential that they are explored. Because we will need this knowledge if we want to sensibly extract large amounts of CO2 from the atmosphere in the second half of the century.

So should the companies pumping a lot of money into such technologies refrain from making overly big promises? Would the money be better spent elsewhere in the short term?

I see that mixed. It’s absolutely right that companies are getting involved, trying to discover new markets and exploring how the infrastructure might work. However, it can be harmful when companies make promises that they cannot fulfill or that contradict what research knows about resource, material and energy requirements or about complexities with other natural or social systems. When people hear over and over again that these ideas will save the Paris Climate Agreement, they might think: why give up my SUV, my vacation or my meat consumption when this technology exists?

Vesta writes on its website that the “Trying to capture the power of the oceans to pull CO2 out of the atmosphere”. That’s probably the kind of big promise you find risky.

If they put it like they’re going to pull a lot of CO2 out of the atmosphere over the next decade, I think that’s really risky. When they say that we are researching techniques so that in 30 or 40 years we will know, ready for the market, which ecosystems are suffering, how they interact with other market sectors and so on, then it is reasonable.

Unfortunately, no timetable is given. That would probably have made it harder to find investors.

That’s the problem.

Nevertheless, can you explain what this tempting-sounding idea is all about? It’s about the weathering process that always takes place in nature anyway and binds CO2. It should be accelerated. What does that mean?

In fact, CO2 is being removed naturally from the atmosphere through weathering processes – at a rate that is just under one percent of our annual anthropogenic emissions.

So, each year, through weathering, nature removes about one percent of the CO2 that we put into the atmosphere?

Yes. And the idea is to speed up this process. That in itself is a reasonable thought as to how CO2 could be further removed from the atmosphere. But to speed up this weathering, you have to do mining because you have to extract substances like olivine.

basalt also called.

The CO2 from the atmosphere reacts with them in a natural way. These substances must be dug up, pulverized and spread over large areas.

To speed up the weathering process, do you need friable rock?

In a natural weathering process, the CO2 reacts with the receiving surfaces, be it basalt, olivine or something else. If you want to speed up this process, you have to increase the area with which the CO2 can react: the reaction rate is related to the area. The more surface we have, the more CO2 can hit it, the more will be absorbed. This can happen both on land and in water. Vesta is attempting to introduce such substances into the water. But if you want to speed that up, you can’t just put a couple of big stones there because they don’t have much surface area. You have to pulverize them first.

So you could try to hollow out the Alps to enlarge the rock surface of the earth?

About as. But if we consider how much carbon would have to be removed from the atmosphere with this technology in order to be relevant to the climate: we emit 40 billion tons a year. That’s 1000 tons of CO2 per second or, for comparison: That would be a balloon filled with CO2 the size of a football stadium – per second!

A nice illustration.

Our current emissions correspond to about 0.5 degrees of global warming every 15 years. If we took 10 percent of our current annual emissions from the atmosphere, it would take 150 years to cool the earth by 0.5 degrees. For me, that would be the lower limit for a technique to be “relevant”. And with this 10 percent we are talking about four billion tons of CO2 per year. That would be a tremendous amount of rock to dig up and pulverize. We’re talking about a mining project that would be about the size of the coal industry.

Is the rock the central problem? Could we even mine that much?

We can, we also have the coal industry and a lot of other mining. The main problem is the infrastructure. The coal industry was not built overnight. If you want to set up a mining project of a comparable size, we’re talking about decades. And that would be a process that would have to be tested again and again and checked for its environmental impact. We don’t want to replace problem A with problem B and use this technology to destroy huge areas of land or pollute water.

The rock would probably have to be blasted out of the Alps or somewhere else with explosives? Otherwise the yield would probably be far too low.

I’m no mining engineer, but at the volumes we’re talking about, I can’t think of an alternative. In chemistry there is stoichiometry the ratio of two substances that react with each other. For carbon taken from the atmosphere, the ratio is roughly one to one. If we want to bind 4 billion tons of CO2, we would need a comparable amount of rock. There is a case for researching this technique because it is a near-natural process that is expected to be accelerated 100-fold. But there is no point in loudly promising that this technology will help us to reach net zero.

The question would also be whether you want this new mining. It’s not necessarily the “healthiest” industry for the environment and those who work there.

Hence my concern when such promises are made. Sure, it’s entirely possible that we can meet 100 percent of our electricity needs with renewable energy. Point. No problem. However, we have to accept that wind turbines and solar cells will then cover a significantly larger area than at the moment.

So in the end it might be better if we invested a billion US dollars in wind turbines. Because we actually have enough technologies that we know very well that they can help and make a very big contribution. But there is often a massive lack of investment there.

This is the key point: It is important that we research how we will effectively remove CO2 from the atmosphere in the future. Because with the current development of our emissions, we will end up with about three degrees of global warming in 2080. It is understandable that we as a global society want technologies that can do this. But we need to understand which of these make the most sense – scientifically and economically. What would it cost to remove a ton of CO2? What impact would that have on the environment? This research needs to be done. But of course you’re right: Every cent that goes into this research is not being used to research more effective solar cells or more powerful motors for wind turbines. Unfortunately, this is often a zero-sum game in science funding.

Talked to Mark Lawrencen Clara Pepper and Christian Herrmann. The conversation has been shortened and smoothed for better understanding.