WORKWEEK

What comes to mind when I say ‘Fast cycle vs. slow cycle?’ Maybe your mind drifts off to images from your weekend bike ride. Or you get annoyed thinking about the clothes sitting unwashed in your laundry machine.

However, when the team at Running Tide thinks about fast cycle and slow cycle dynamics, they’re cutting straight to the core of the company’s carbon removal thesis. Which is precisely what Bradley Rochlin and Jordan Breighner did a few months ago when we first connected. 

Running Tide raised an undisclosed amount of funding in its Series B last year. It has more than one hundred employees and has sold carbon credits in advance to customers like the Chan Zuckerberg Initiative and Shopify for millions of dollars. Its investors include top-tier climate funds like Lowercarbon Capital. 

The business initially focused on restoring shellfish populations; shells can serve as a carbon sequestration method. And they still run shellfish farms (I can confirm, their oysters are good). 

Then, they started growing kelp on hemp lines in the ocean. 

Now their approach uses wood as a substrate. Coated in limestone and seeded with macroalgae, wood could support kelp growth in the open ocean. And once mature, the kelp, along with the wood, should sink to the bottom of the ocean, sequestering carbon under massive amounts of pressure. Ideally, between sinking the kelp, the wood and adding in ocean de-acidification benefits from calcium carbonate in limestone, this approach could become a triple threat carbon removal solution.

Today, let’s dive deeper and look at the company’s perspective on carbon removal. On Thursday, we’ll look at what challenges lie ahead and their open ocean demos, coming soon.

From fast to slow

Fast and slow cycles are two distinct parts of the global carbon cycle. We’re all more familiar with the ‘fast’ cycle, as it’s more observable in our lifetimes and recent memory. A good example is when we fill our gas tanks at the pump (EV adopters, avert your eyes). When we drive off, the car engine burns that gasoline and produces carbon dioxide emissions, some of which enter the atmosphere. There, the carbon dioxide might linger for decades or even hundreds of years before some natural process—CO2 dissolving in the ocean or a plant performing photosynthesis—draws it back to Earth.

In this above example, the release of CO2 is undoubtedly very ‘fast,’ but its eventual reabsorption, even if it takes a few hundred years, is relatively swift, too. At least in relation to how the carbon in the gasoline assumed its fossil fuel form.

So how did a bunch of carbon transform into the fossil fuels that power societies today? Over millions of years, dead, dense organisms (like plants or plankton) fossilized and mixed with other compounds to form ‘fossil’ fuels like coal, gasoline, and natural gas. This process constitutes the ‘slow’ carbon cycle. 

Absent ‘unnatural disruptions,’ fossil fuels largely stay where they are, often sequestered in deep geological formations. Over additional millions of years, there are ways they might reenter the atmosphere. For instance, melting permafrost might release age-old natural gas. But it would take a long time, cementing the ‘slow’ moniker for this cycle. 

What happens if the ‘slow’ cycle is disrupted, however? I.e., when humans come, dig up fossil fuels, and burn them, releasing the carbon inside of them? 

As we’ve seen this year, moving carbon out of the slow cycle and into the fast cycle can profoundly impact the Earth’s environment. Over the past two hundred plus years, human activities have raised the concentration of CO2 in the atmosphere from ~300 ppm to ~420 ppm, a 40% increase. The last time the world had that much CO2 in the atmosphere, sea levels were tens of feet higher, and average global temperatures were a few degrees C warmer.

The speed of the change from 300 ppm to 400+ ppm is also unprecedented. Whether you look at floods in Pakistan or heat waves in Europe and China, erratic climate change symptoms render places where many humans settled inhospitable. The magnitude and speed of these changes point to how drastically we’ve unbalanced the fast and slow carbon cycles.

The solution? It’s simple. Move mass back from the fast carbon cycle to the slow carbon cycle. 

But simple doesn’t mean easy. Reverting to an atmosphere with 300 ppm of CO2 will require moving massive amounts of carbon. The latest IPCC assessments put the figure at around 660 gigatons of carbon. That’s 660 billion tonnes, mind you. And since scaling will take time and global emissions will continue in the interim, the figure could end up pushing 1,000 gigatons, or one trillion tonnes. 

Regardless of the scope of the challenge, it’s one Running Tide wants to ‘sink’ its teeth into.

A shipping company meets a sinking company

There are myriad ways to remove carbon dioxide from the atmosphere. You can plant trees, which absorb it to perform photosynthesis. You can alter agricultural practices to retain more organic material in soil, helping sequester it. You can operate a giant, expensive fan that sucks it out of the air and chemically binds it to different materials (direct air capture). 

All these approaches vary across several factors, such as how engineered they are and how long they sequester carbon for. Some are nature-based solutions that don’t require engineering. Others, like direct air capture, are almost entirely engineered. They also vary regarding their ‘permanence,’ or what happens to carbon once removed from the atmosphere. 

Not all of them necessarily move carbon out of the fast cycle, either. Some remove it more temporarily, while other sequestration approaches can store it for thousands of years. 

Considering Running Tide’s focus on moving carbon from fast cycle to slow, permanence is a critical consideration. Many nature-based carbon sequestration solutions are cheaper and relatively easier to scale (at current). Still, they often aren’t as permanent and run the risk of reversal (e.g., what happens if a newly planted forest burns?) 

Other solutions can be more permanent but may come with higher costs. The core challenge for Running Tide thus becomes designing a durable process (low risk of reversal) that is permanent and efficiently moves mass. Here’s how Jordan described his thinking:

Our job in carbon removal is to build a logistics operation that moves from fast to slow. We’re essentially a shipping company. We ship things. Our leverage point is natural systems. Our job is to create the logistics infrastructure and the operation and combine that with science and engineering to nudge nature forward in the right direction.

Kelp forests can be excellent carbon sinks and are critical for ocean ecosystems. Vast carbon forests are a frontline defense against climate change; globally, seaweed already stores nearly 200M tonnes of carbon. Just like growing more trees is often touted as a solid palliative for climate change, growing more kelp, which performs photosynthesis like plants, would help remove carbon from the atmosphere.

The permanence quotient is more complicated. Kelp forests aren’t inherently permanent carbon sequesters. To move carbon from slow cycle to fast, growing more kelp alone won’t cut it. That kelp also needs to end up somewhere where, under the right conditions, it stands a chance of staying put for the long haul. Like Charm Industrial, a company that converts terrestrial plants to bio-oil and injects that oil underground, Running Tide wants to turn carbon into fossil fuels again. They’ve just chosen the ocean as their reservoir – there’s not much in the world that’s deeper!

Is sinking kelp the next best carbon sink?

Growing kelp and sinking it to the bottom of the ocean is no small feat. Growing kelp directly on the coast isn’t ideal because the ocean isn’t that deep. So you have to get out onto the open ocean, which involves transportation and complicates monitoring. Plus, sinking the kelp only once it’s mature depends on several factors.

While Running Tide considered developing fancy newfangled technologies, in our conversations, Bradley noted a high-tech approach is less viable the further out into the ocean you get:

Folks who have been on the water a long time know that things you put in the ocean tend to break when exposed to huge swells. As a result, we intentionally leverage natural systems like ocean currents, gravity, photosynthesis, to be able to do the work.

Running Tide wouldn’t be scalable if it used scarce materials in its removal process. As a result, the materials in Running Tide’s process aren’t ‘high-tech’ per se. As Jordan noted: 

We looked at glass buoy factories and developing glass buoys for our kelp and realized we’d be building the world’s largest glass buoy factory. Then we realized if we wanted to grow kelp on hemp lines, we’d have to significantly increase the amount of hemp growing globally [to reach gigaton carbon removal potential].

Instead, Running Tide uses abundant and cheap wood waste to build the buoys their kelp will grow on the open ocean. Wood has ideal qualities for this operation: It can float while the kelp grows and eventually sink under the right conditions. Plus, it’s carbon-rich, so there’s more mass movement from fast to slow cycle when it does sink and stay. Running Tide also coats the wood with limestone, which provides an additional carbon removal pathway via ocean alkalinity enhancement. The buoys themselves are seeded with macroalgae to grow the kelp. 

All these materials can help move carbon from fast cycle to slow. This also underscores Running Tide’s focus on creating a negative carbon supply chain; the more materials used in your process you can involve in mass transfer, the better. Cultivating a negative carbon supply chain also means considering the embedded carbon of materials in your supply chain, not just their abundance. If it’s made of carbon, it better be part of the sink!

Nor is that thinking confined to materials. It also extends to things like transportation. For example, when Running Tide operates a ship to bring its wood out into the water, it won’t just have to think about the dollar cost of that operation. It will consider the carbon price of burning bunker oil to power that ship. Running Tide aims to sell carbon credits for hundreds of dollars per tonne. That also means the company has a super high internal cost of carbon; it’s worth hundreds of dollars to them not to emit CO2 in the same way that it’s worth hundreds of dollars to them to remove one tonne of CO2. 

Note: We’ll write more about negative carbon supply chains and internal costs of carbon in the future, because they’re critical concepts for climate technologies and decarbonization.

Sink or swim

There are several technical and operational challenges facing Running Tide. Most of the significant open questions involve what will happen with the kelp: 

• How do you best support kelp growth out on the open ocean?
• What’s the ecological impact of sinking massive amounts of it? 
• How do you accurately measure and model all of the above?

The latter open questions point to a common tension in carbon removal between evidence and implementation. There’s a significant need and desire to scale and iterate, even as there’s a lot to learn concerning the efficacy and safety of techniques like Running Tide’s. Here’s Jordan’s perspective: 

We often hear, ‘There’s still uncertainty in this, so we should wait. In our opinion, we need to move forward so we can reduce uncertainty over time. There’s uncertainty in everything, including global system climate models. What’s important is scaling solutions, not to 100% perfection or removing all uncertainties throughout the system. The way you remove uncertainties is acting, learning, collecting data, and refining models.

The measurement, reporting, and verification (‘MRV’) side of this may prove even harder than proving efficacy in general in tests and demos. Running Tide notes they’ve invested considerably in MRV technology, and whether and how reliably these technologies perform on the open ocean is also an ‘open’ question. 

The ocean alkalinity enhancement component won’t be directly observable; it’ll be modeled based on empirical testing in a lab. Measuring how much calcium carbonate dissolves in the ocean and measuring the ocean conditions where it does allows you to calculate the theoretical carbon drawdown via calcium carbonate chemistry formulas. 

Ideally, other companies will also recognize the opportunity in ocean MRV tech and accelerate innovation. Still, with three different carbon removal pathways, Running Tide’s measurement needs are significant.  

What’s next?

Whichever challenge described above looms largest in your mind, the next step for Running Tide remains the same: They’re ready to conduct a large-scale pilot in open waters this fall. 

They’ve done several deployments on smaller scales already, focusing especially on measurement and verification. Their next major deployment in Iceland this fall will ideally prove that the removal process itself works end-to-end and help identify areas for optimization. 

Jordan told me they have thousands of tonnes of waste wood (that would otherwise have been burnt) ready to coat with limestone and seed with microalgae. They have a ship ready to take that wood out onto the open ocean. 

Kelp growth won’t even be the primary focus of this deployment. They will still seed wood with macroalgae, but Jordan noted that much more agronomy work is needed to optimize around questions like which kelp types will work best for different seasons. Another lever Running Tide is studying is testing different wood form factors to support kelp growth. 

Rather, for these first open ocean deployments, Running Tide is most focused on the wooden substrate and ocean alkalinity enhancement. In their words, this will be the biggest ocean alkalinity experiment ever. Which, again, comes with a lot of questions to study. Will the wood travel to the part of the ocean Running Tide ‘wants’ it too to promote maximum depth post-sink for sequestration? Will the wood float long enough to dissolve ideal amounts of calcium carbonate from the limestone over a widespread area? Long enough for kelp to grow?

That’s the beauty of getting out of the lab and onto the ocean. If nothing else, the tests and deployments should yield ‘tons’ of valuable data and, ideally, thousands of tonnes of carbon sequestration from the wood that sinks to the bottom of the ocean. Which isn’t to say it’s riskless. No one has done a test like this ever before. That comes with unknown unknowns. 

We’re excited to see and report on the result and hope it’s a successful sink 🤞!