Meet Neil Dalvie – Bacteria that rock!

Continuing in our efforts to foster dialogue about genetic technologies as tools for addressing climate change, Connecting Genetics to Climate is hosting “Bacteria that Rock!” as part of the 2024 Cambridge Science Festival.

During this interactive discussion, to be held at the Cambridge Public Library on Monday September 23 at 6 PM, we’ll be joined by Dr. Neil Dalvie to talk about the scientific and societal implications of his work.

Neil is a chemical engineer in the Silver Lab, part of Harvard University’s Wyss Institute. His current work focuses on bioweathering, a novel carbon capture technique with the potential to help reduce atmospheric greenhouse gas levels. We talked to Neil to learn more about his research and his passions.

 

This interview has been edited for length and clarity.

Let’s start with the basics- what is rock weathering?

Neil Dalvie: Rock weathering is a natural process where, very simply, rocks on the earth’s surface are exposed to the elements, dissolve into water and ultimately wash into the ocean. This is part of the rock cycle, where rocks weather, go into the ocean, eventually sediment, and then undergo metamorphosis in the earth and form new rock.

What do people mean when they talk about enhanced rock weathering with respect to climate change?

Neil Dalvie: Carbon is captured through the process of rock weathering from the atmosphere. The carbon goes into the ocean, where it’s stored for a very long time before being incorporated into new rock.

The rock cycle happens on a scale of tens of thousands to millions of years. If you could speed up rock weathering into more human time scales (~10-50 years) from what’s usually geologic time scales, you would capture carbon at a faster rate, potentially to offset our own carbon emissions.

How much carbon is currently pulled in by the rock weathering cycle?

Neil Dalvie: The natural weathering rate captures approximately 0.1-0.2 gigatons/year of carbon dioxide (CO₂). If we’re going to stop climate change, we need to capture ~10 gigatons of CO₂ from the atmosphere every year. To capture a gigaton of carbon from CO₂, you would need to dissolve a gigaton of rock. Which is a lot of rock.

That being said, humans right now every year dig up and use 50 to 100 gigatons of rock for mining, construction, and building our civilization. So we do move gigatons of rock. We dig that out, grind it up, put it in a truck and move it somewhere else. A one gigaton amount of rock is incredibly large, but it is possible.

What are some of the benefits to enhanced rock weathering in addition to carbon capture?

Neil Dalvie: The biggest ecological side benefit is that it would counter ocean acidification . The oceans are acidifying because we emit CO₂ into the atmosphere. If we expand the capacity of the ocean to hold that CO₂ by rock weathering, the amount of acidification would go down, which is good for ecosystems.

The hope is that this technology, if it’s scaled appropriately, would also be an alternative for mineral processing companies to deal with mining waste. This waste is sometimes disposed of using things like acid treatment that are environmentally harmful. This is a potential alternative to use mining wastes substrates in a more eco-friendly way.

You work in the bioweathering space. Can you explain what that is and how it relates to rock weathering?

Neil Dalvie: What we mean by bioweathering is using biotechnology to accelerate rock weathering. Specifically, what we’re working on is engineering microorganisms that you could grow alongside or with rocks. The microbes can make molecules or themselves dissolve the rocks and increase the weathering rate, which subsequently would increase the carbon capture rate.

What are the challenges to implementing both enhanced rock weathering and bioweathering?

Neil Dalvie: For abiotic enhanced weathering, that is an environmental question. Is it safe to put large amounts of rocks in the ocean? We know it’s safe on a global level, but is it safe to do it all at one beach?

The biggest risks would be the impact on the marine ecosystem in a local area. There are field studies going on to assess whether the plankton and the local marine life are OK if we increase the alkalinity. The data that’s come out so far from field studies in this area has been pretty positive. Organisms aren’t affected that much by rock weathering, even at medium scales.

For bioweathering, the barrier is cost and scale. We need organisms or biocatalysts that will grow in cheap substrates. Processing of the water would add a lot of costs.

An additional challenge to any kind of carbon capture is measurement and verification. If you dump alkaline water or rocks in the ocean, how do you know how much carbon you’ve captured? There are technologies like buoys that would detect how much carbon goes into the water. An important field of science right now is how to measure this.

You mentioned costs and scale. What are the economies of scale for this process?

Neil Dalvie: We have to start small—can we take existing waste streams and create a process that’s economical so that a company or a government would be incentivized to pay for it? If I’m a mining company with a fixed amount of waste, is it worth it for me to pay to use that waste to capture carbon?

People will pay you about $100 per ton of CO₂ you capture ($0.11/kg), so your process has to cost less than that. Bioprocesses typically don’t get cheaper than about $1/kg of product. So 1 kg of our bioproduct needs to capture 10 kg of CO₂. It’s not impossible, but it’s going to require some innovation.

What is the time scale for putting any of this into action?

Neil Dalvie: Rock weathering in general is moving fast. There are companies that do field studies now at pilot scale and even medium scale.

Bioweathering is several years behind. There’s more development work to be done to understand the cost and the potential benefits. How much biology can accelerate the weathering rate is not yet known. We’ve seen that it could be three to ten times faster, but that’s not the maximum. That’s one thing that the research community should figure out in the next few years.

What role do communities play in the development and application of these technologies?

Neil Dalvie: The engagement with communities to enable long-term studies has been an essential part of being able to set up field studies. Field researchers need years of measurement of the local ecosystem and permission to do that in a safe way. The answers here are not very clear sometimes, especially at the beginning.

Bioweathering will take a combination of industries. Massachusetts is an exciting place for biotech. It’s certainly going to take the innovation in that space to do a process like this alongside the mineral processing industry. The interest and the amount of financial resources devoted to this is growing, but I think both of those industries are not fully there yet.

Turning more personal, what got you into this line of research?

Neil Dalvie: I kind of stumbled into climate change. I’m a chemical engineer and in my last job I studied drug manufacturing, high-cost bioprocesses. When I was looking for my next step, I was interested in what else bioprocesses could be applied for, specifically bigger scale environmental things.

I got a Schmidt Science Fellowship, which encourages you to take a hard pivot in your research and do something risky and learn a new field. I learned that applying biotechnology to environmental problems is very hard and not really figured out yet.

Now that I’m here, I appreciate the complexity behind any new technology. We’ve had to develop a lot of new techniques and lab experiments that no one’s ever done before. It’s intimidating, but the need for change and impact is very obvious, so it’s easy to stay motivated.

Let’s end on a high note. When thinking about climate change, what gives you hope?

Neil Dalvie: There are two sources of hope for me. Since starting this work, I’ve learned a lot about the ways Earth keeps things balanced naturally. Our climate has been stable for a long time and that’s because of natural processes that have feedback on each other and keep the climate relatively mild on this planet. It’s exciting to think about how we could leverage those processes to keep the climate in check.

The second thing is that in the last few years in the scientific community and in the government, you can feel the energy and the funding that’s coming for this type of research, which is really important. So that’s moving in the right direction too.

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Join Neil and Connecting Genetics to Climate at this year’s Cambridge Science Festival at 6 PM on Monday September 23 at the Cambridge Public Library.

Click here to register!