Key Takeaways

— Vesta is conducting the very first trials on coastal carbon capture, a promising carbon dioxide removal methodology, whereby alkali sand released on beaches to reverse ocean acidification and so re-increase the ocean’s CO2 sequestering capacity.

— Initial results suggest that the methodology is inherently scalable, affordable, boasts important co-benefits and does not come with any adverse environmental effects.

— On the 12th of December 2022, Finnish start-up Puro.earth has approved enhanced weathering as an accredited carbon removal methodology, marking a new developmental stage for the technique

In the first part of our series on novel natural carbon removal technologies, cCarbon is speaking to Tom Green, founder and CEO of Vesta Corporations, a public benefit company promoting enhanced weathering in marine environment, an emerging method of carbon dioxide removal. Tom, a biologist by training, has a busy career behind him which saw him work for various different organisations in the fields of financial services, technology and consulting. He also holds an MBA from Harvard Business School.

Coastal carbon capture is a way to harness the power of the oceans to accelerate the Earth’s natural long-term carbon dioxide removal process and enhance coastal resilience. Its potential has been recognised in decades’ worth of scientific research. Vesta was founded to bring together the necessary multidisciplinary team, government support and funding to turn the theory into reality.

We were eager to learn more about it from Tom.

Protocol Introduction

cCarbon: Hi Tom, thank you very much for agreeing to talking to us. To get us started, would you mind telling us a little bit about what compelled you to found Vesta?

Tom: It all started in 2019 when, after working for 20 years for various large corporations, I took a step back to think about what I wanted to do with the next phase of my career. I decided that since the climate crisis was upon us, I could apply my skills and background from my original biologist’s training to have a real impact.  So, I ended up co-founding Vesta. We do coastal carbon capture which is a way to accelerate the Earth’s natural geological carbon removal process, which has been working for billions of years.

cCarbon: How does the process work, in ‘enough’ detail?

It works as follows: when rain falls on certain types of rocks it causes a reaction called weathering. Weathering results in CO2 entering rainwater, which then flows into the ocean. There, the CO2 in inflowing rainwater is used by animals like corals to form the calcium carbonate in their shells. When those organisms die, the shells and skeletons form marine sediment on the seabed eventually hardens into limestone and is subducted into the Earth’s crust.

Therefore, this is a natural way of turning atmospheric carbon dioxide into rock. This process has kept the carbon concentration of the atmosphere in balance over time. But it is a very slow process. So, the question is: how do we speed it up?

A possible answer came 32 years ago in the form of a letter to Nature suggesting that one way to do it is by transporting certain types of minerals, specifically silicate minerals, to the ocean or grinding them up into sand on the beaches where they would dissolve in the ocean water and accelerate this process. From that point on, intense scientific research started looking at the different aspects of this process and exploring its feasibility. By the end of this investigation, all research papers were calling for field trials.

We at Vesta answered that call and started doing field trials. What we do is take an extremely common igneous silicate minerals called olivine, grind it into sand and transport it to the ocean in coastal areas. There, it gradually dissolves in the seawater and adds alkalinity to the seawater in the process.

This is an extremely important co-benefit of coastal carbon capture as it addresses a massive environmental issue: ocean acidification. Today, the planet’s oceans are 30% more acidic than they were before the Industrial Revolution because they have absorbed about a third of the extra carbon dioxide that we have emitted in that time. Adding silicate minerals to seawater makes atmospheric CO2 dissolve in the water as bicarbonate which the ocean stores for roughly 80,000 years. Bicarbonate is alkaline; therefore, it counteracts has the potential to counteract ocean acidification.

Additionality and Quality Evaluation

cCarbon: Is the storage of bicarbonate by the ocean not a problem? Does this not cause any knock-on effects?

Tom: It is nothing problematic. There is a lot of bicarbonate in the ocean already and the percentage increase of bicarbonate in the ocean following enhanced weathering would be extremely small. Plus, coral reefs are being hurt by thermal and acidity stress. From this perspective, there is a potential that carbon capture, if done correctly, could alleviate some of the environmental pressures and could bring some benefits to coral reefs.

cCarbon: Great. The next thing I wanted to ask you about is a very interesting hypothesis that I have been introduced to. It is a theory suggesting that as carbon is being removed from the atmosphere, the oceans start emitting the same amount of carbon back into the atmosphere to maintain the former concentration atmospheric CO2. If we accept this hypothesis, then, supposedly, knowing for sure that a certain amount of carbon that would have been released was not released (i.e., emission reduction) is better than ineffectually capturing carbon. Do you recognise this emission effect as well? If so, how is Vesta different from other stipulated carbon removal technologies in which this danger is inherent?

Tom: It is certainly an interesting area of research though there is definitely more work that needs to be done. Nevertheless, the conclusion that emission reduction should be favoured over carbon capture does not, in my opinion, follow. This is because if the ocean indeed compensates for a reduction in atmospheric carbon dioxide, then, compared to a business-as-usual scenario it does not matter whether the relative CO2 levels lower because of emission reduction or carbon capture.

Potential Scale

cCarbon: All clear. So what stage are you at with your trial and what is its initial scale like? When can the methodology be expected to be implemented?

Tom: We deployed the first field trial earlier this year, in July 2022 on Long Island, New York. This is the first and only deployment of the technique so far. We now have a pilot live and olivine is dissolving in the water. Our scientific team is studying everything that has been happening, gathering all the data that we need for carbon approval. At the same time, we are measuring the ecological data so as to understand the safety profile of the procedure.

This initial trial involved 650 tonnes of olivine which is anticipated to remove up to 500 tonnes of CO2 from the atmosphere. Future trials will be much larger, of course.

cCarbon: So, I gather that the 500 tonnes represent the optimal scenario. What would be a pessimistic prediction?

Tom: According to existing research, the maximum for carbon removal is 1.1 tonnes of CO2 removed per tonne of olivine dispersed. Accordingly, the trial could remove 715 tonnes of CO2. However, we wanted to be conservative in our estimates. We continue measuring everything to eliminate all uncertainties from that calculation.

Looking forward, one of the great things about this process is that it is inherently a very scalable solution. The coastal nourishment industry in the US already places 60 billion tonnes of sand in the water every year to protect coastlines. The methods for moving hundreds of thousands, even billions of tonnes of sand and depositing those in coastline environments are already very well established. So coastal capture methods are not especially more complicated than what we are doing at the moment on a pilot scale. There is also a very large amount of olivine present near the surface, especially in India. And there is obviously a lot of coastlines. So, the fundamental scalability is very high and could reach the range of gigatonnes in terms of how much we could deploy. Meanwhile, the constraints are relatively limited.

This presents a great advantage of coastal carbon capture over other methods of carbon dioxide removal (CDR). These often require some kind of change in land use, freshwater or renewable energy sources which pose a difficulty to scaling. Similar difficulties persist for highly technologically engineered solutions: one needs to build a plant at each new level of scale which presents an entirely new set of engineering challenges.

Buyer Response 

cCarbon: Yes, having looked at other techniques in this space, this sounds very exciting indeed. Do investors also agree with this assessment?

Tom: When we are talking about coastal carbon capture with people what we normally hear is, first, that they like that the methodology is nature-based since we are accelerating a geological process. Second, they appreciate that the methodology is quite intuitive. It is also much valued that the method comes with significant co-benefits, particularly its ability to decrease ocean acidity but also the fact that it helps protect coastlines which, with sea-levels rising and storms getting stronger, is quite significant.

This last aspect makes the method a potential contributor to the progress being made on the issue of climate justice; the realisation that whilst the climate crisis has been predominantly caused by the rich countries, the costs are mostly being borne by lower income countries. With sea levels rising and storms getting stronger, coastal flood surges have been becoming a much higher risk and one which is only going to get worse. These risks fall disproportionately on coastal communities, particularly in the Global South where countries and communities cannot afford protection or to move away if their homes get flooded. So, the fact that coastal carbon capture could work well in the Global South — that in fact it works best in the tropics — is a very important feature. Carbon capture could, in time help lower income countries either through the addition of sand to their coast lines or through its economic benefits of having an industry around coastal carbon capture.

Market Impact

cCarbon:  Brilliant. You have mentioned that the US itself has been distributing 60 billion tonnes of sand into its water a year. Are there any other obvious places where coastal carbon capture could be swiftly and effectively deployed?

Tom: Well, the obvious places where this technique could be deployed are indeed the US and Europe. It is difficult at the moment to anticipate other global big buyers but the market in the US is growing rapidly.

cCarbon: Speaking of markets: what kind of cost per tonne of CO2 removed are we looking at? 

Tom: Our long-term target is to reduce costs to $35 per tonne of CO2 removed. That is based on analysis on what we think is possible once we reach a large scale. At the moment, because we are doing it on such a small scale, it is obviously very expensive.

Currently we are working with purchasers like Stripe who are explicitly looking to purchase carbon removal from less mature technologies which are just getting started and which still need to do their pilots and then scale. Part of the context of those arrangements is that the buyers understand not only that the projects are expensive at this stage but that there are uncertainties involved with the delivery as well. They are supporting the market and its future growth by working with newer processes like ours. In that context, we are selling at the moment at $750 a tonne of CO2 removed. But we of course expect the prices to come down relatively dramatically as we scale to eventually hit that $35 cost number.”

cCarbon: Who are your competitors? Are there any other players on the technology side of coastal carbon capture?

Tom: There is nobody else doing what we are doing or anything similar. There are a few other actors working on what is called ocean alkalinity enhancement which is the name for the broader approach which we fit into. This is an approach to carbon removal that involves adding alkaline substances to seawater to enhance the ocean’s natural carbon sink. There are also some who are trying to accelerate weathering not in marine environments but in agricultural settings, allowing the same reaction of weathering to occur in the soil.

Generally, however, when I think about the market of carbon removals, I do not really think about competitors — if there were any, that would be hugely good news, and we will need a lot of them. People need to know about carbon dioxide removal and see that it is a part of the solution to climate change.

cCarbon: Fully agreed. Many thanks for speaking to us, Tom, we hugely appreciate your time and insights.