Carbon Management

An Update on Carbon Removal & Direct Air Capture

When making the case for net zero, climate experts often refer to the “bathtub analogy.” The atmosphere is like a bathtub that’s slowly filling up with water. (In this case, the water is carbon dioxide (CO₂). Even if we slow the flow of water — or CO₂ — to a trickle, the tub will eventually fill up and water will come spilling out onto the floor. What makes this process even more complex and challenging is that there are multiple spigots — electricity, transportation, buildings, manufacturing, agriculture — so you can’t simply turn one knob. That’s why it will be extremely difficult to shut off all the water before the bathroom floods. So in addition to turning off the spigots, we also need to mop up the spilled water on the floor.

That’s where carbon capture, storage, and removal come in. Most of this report focuses on how to reduce our emissions by switching to renewable energy, decarbonizing steel and cement, and fostering innovation in technologies like hydrogen and fusion and other promising technologies. But that still won’t be enough to completely avoid disaster, because there’s already too much carbon in the air .

A bathtub overflowing with water

Before we go any further, we need to make one thing clear: Carbon capture is not an excuse to keep emitting greenhouse gases (GHGs).

Many climate experts worry that this technology gives people the wrong idea: Why stop emitting carbon when we can suck it out of the air? This is neither practical nor economically efficient. But over the last decade it’s become abundantly clear carbon capture is one necessary tool, in a larger tool kit, we can use to achieve net zero.

There are many ways to capture or remove CO₂ from the air. The oldest technological capture method is called point-source capture, which involves new builds or retrofitting industrial sites and power plants with special devices that capture the CO₂ before it even reaches the atmosphere.

A carbon removal facility

Direct air capture (DAC) is a new method, which can remove CO₂ from the air anywhere, not just at the site of emission.

Of course, engineered removal methods are not the only option. Nature offers avenues as well. Natural carbon removal includes planting trees, preventing deforestation, and managing croplands more efficiently.

Finally, there is a hybrid option that brings together the benefits of engineered and natural carbon removal strategies. This involves burying biomass that would otherwise decay and emit carbon.

While point-source capture has been around a long time, these devices are expensive to buy and operate. And unless mandated by law, companies have little incentive to use them.

We’ve seen some progress in lowering the costs and carbon footprint in this space. Companies like Mantel , a BE Fellow, have found innovative ways to do point-source capture using less energy and less heat than typical methods, lowering the cost of this technology.

The most promising advancements in this space, however, have come from the carbon removal methods. In addition to preventing CO₂ from entering the atmosphere, we can remove CO₂ already in the air. All three of the aforementioned removal strategies, which we will discuss in detail below, are vital to reducing CO₂ in the atmosphere and reaching our climate goals.

But cost remains the biggest barrier. Today several companies are pursuing practical direct air capture; some of those approaches could have cost entitlements below $100/ton. Yet, while there is some market for carbon capture and sequestration at those levels, widespread willingness to pay is likely significantly lower than that. That means we need more options for carbon removal.

The Taking Tree

Nature-Based Carbon Removal

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There are several natural ways to remove CO₂, from planting trees and preventing deforestation to managing soil more efficiently and seeding algal blooms with iron. Currently, these methods remove about 30% of annual emissions. They’re relatively inexpensive, globally scalable, and have added co-benefits like increased crop yields.

Aerial view of a forest damaged by fire

But nature-based removal has some challenges. For starters, it’s not permanent. Forests and croplands are prone to wildfires and other natural disasters, which would quite literally send all the carbon they trap up in smoke and back into the atmosphere.

Nature-based removal is also hard to measure. How do we know that what is happening is actually additive? Would a tree have grown naturally in a similar spot even without sending someone to do it? What’s to stop people from taking money in exchange for protecting forests in their area that they were never planning to cut down in the first place?

Pachama's forest mapping helps bring transparency to carbon markets

These problems have plagued nature-based removal strategies for years, inviting skepticism from climate experts and investors. But new tools and technologies are resulting in far more rigorous monitoring, reporting, and verification.

Pachama , a company BEV has invested in, uses remote sensing and satellite mapping to develop forest carbon projects and ensure the credibility of carbon credits, harnessing the power of AI to build a modern, scalable, and transparent carbon market.

Soil carbon sequestration has shown great promise as well, but it also struggles with inaccuracies and transparency. Another company we’re working with, Yard Stick , deploys handheld probes and spectroscopy for nearly instantaneous carbon measurement reporting verification. The cost-effectiveness of this method allows for a significant increase in the number of samples taken. This helps address the signal-to-noise challenge that’s been inherent in soil analysis.

Preventing deforestation is also critical to limiting our emissions. Carbon credits are one way to disincentivize deforestation. But what if the deforester you’re dealing with is Mother Nature? Data Blanket , a BEV company, uses AI drone technology to give firefighters an upper hand against wildfires and prevent even further destruction and carbon release.

Layers of soil

Nature-based carbon removal is the only tool we have that’s scalable today, and we need it in order to manage land use change emissions over the next decade.

And yet, for all its affordability and scalability, it doesn’t provide the permanence of engineered solutions. Nature-based solutions can be a stopgap, but we need advanced engineering and technology to take us the rest of the way.

Direct Air Capture

Engineered Carbon Removal

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The concept of engineered direct air capture (DAC) is simple: We take carbon directly from the air and store it safely underground permanently. No risk of wildfires or tornadoes coming along and reversing all of our progress. And unlike nature-based removal, the benefits of DAC are highly quantifiable; in other words, we know exactly how much CO₂ we’re pulling out of the air.

It’s also permanent. Once we inject CO₂ into things like concrete or underground reservoirs, it stays there. Or in climate terminology, it’s “durable.”

Climeworks’ DAC+S facility “Orca” in Iceland

So what’s the problem? Well, there are a few. DAC isn’t cheap.

In fact, it’s some of the most expensive technology out there, coming in at above $1,000 per ton of CO₂ for individual buyers and more than $750 per ton for corporate or bulk buyers. That’s partly why at the moment, there are only two commercial-scale facilities in operation in the world, one in Iceland and run by a company called Climeworks (which is not part of the BEV portfolio) and another that was just opened by Heirloom in November 2023. But like point-source capture, no matter how much the cost of direct air capture comes down, it will always cost more than doing nothing. Without policy intervention, there is little incentive for companies to pursue it.

DAC is also highly energy intensive. And no nation wants to take precious clean electrons to remove carbon instead of providing power to its people and businesses.

Then there are the legal issues. To put things in the ground, you need to go through siting, permitting, and other regulatory hurdles that can take years.

A close-up of dark gray stone

The SOLUTION

Heirloom , a San Francisco-based company, is trying to get around some of these obstacles. Heirloom uses a process called carbon mineralization. They grind up limestone, put it on larger baking-esque sheets, and let it passively pull CO2 out of the air. Once it’s fully saturated with CO2, they put it inside an electric kiln, heat it up to release the CO2 that was absorbed, and put the carbon underground (or sequester it in cement, which they sometimes do via another BEV portfolio company, CarbonCure). Because of the limestone’s passive properties, this method uses significantly less heat and power than traditional direct air capture technologies.

Once you capture carbon, however, you need a place to store it. Companies like 44.01 work with DAC companies to do exactly that. 44.01’s process takes captured CO₂, combines it with water, and injects it deep underground into a rock called peridotite.

CO₂

Because this rock in particular is very reactive with CO₂, it accelerates the process of mineralization, turning CO₂ into a solid in a matter of years, compared to traditional CO₂ storage, which can take thousands of years to mineralize.

These innovations hold a lot of promise and potential, and direct air capture may well be the way of the future. But for now, most DAC options are just too expensive, energy intensive, technologically complex, and regulatorily fraught to scale globally.

The Hybrid Way

Carbon Casting

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There is a third option, a hybrid of the first two we’ve discussed that combines the strength of nature-based approaches with the lasting impact of engineered removal.

Graphyte is one company exploring this area. Incubated by Breakthrough Energy Ventures, Graphyte has developed a carbon dioxide removal approach that is permanent, affordable, and immediately scalable.

Inert carbon blocks created by Graphyte to store biomass.

Foresters and farmers already capture billions of tons of CO₂ each year in the form of timber and crop residues that are left to decompose into CO₂ and methane. But what if carbon-rich biomass can be transformed into permanently sequestered carbon?

That’s what Graphyte does with its Carbon Casting technology. This process dries the biomass to remove microbes and the water they depend on, then creates inert carbon blocks protected by an impermeable barrier to ensure the biomass decomposition does not restart. These blocks are stored in monitored, underground storage sites that provide a further layer of protection and enable robust long-term monitoring.

This new technology provides an immediate pathway to low-cost carbon removal with durability over 1,000 years. Combining photosynthesis with practical engineering enables Graphyte to meet long-term cost targets in the near term, whereas other approaches hold the promise of achieving these targets over many years, contingent on future innovations.

The Carbon Casting process preserves nearly all the carbon stored in the biomass while also consuming less energy than other removal approaches (an order of magnitude less than the leading direct air capture solutions). In addition, the use of a purpose-built sequestration site enables comprehensive monitoring of the sequestered carbon, making Graphyte’s approach the only permanent negative-emissions technology that can be monitored directly.

By making high-quality carbon removal affordable to companies and governments today, Graphyte accelerates progress toward the billions of tons of carbon removal needed to meet the IPCC’s projected path. It also broadens the opportunity to areas in the Global South that are rich in biomass but simply can’t afford expensive and energy-intensive DAC solutions.

Graphyte collaborates with farmers and foresters who sustainably manage agriculture and timber lands across the world, and turns their unused biomass into permanent carbon removal. As we work to accelerate the clean energy transition, climate leaders should consider this important addition to the toolkit to deliver higher volumes of permanent removals at an affordable price today.

Policy and Persuasion

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Innovation is key, but we can’t scale these technologies without proactive policy. This past summer, the United States saw a major breakthrough on that front when the Department of Energy announced its first round of Direct Air Capture hubs awards, the single largest investment in the history of DAC. These hubs can bring together multiple DAC companies within the same facility to access shared infrastructure so they can scale their technology faster and do it at a lower cost.

A visualization of a rural direct air capture facility

Policy isn’t the only tool in our arsenal. We also need to increase understanding about these technologies. For example, direct air capture remains relatively unknown among the public. But when people understand it better it gains support, especially when they learn about its potential to create jobs and address emissions.

Again, carbon removal shouldn’t be an excuse to keep emitting. We must continue our efforts to decarbonize every sector of the global economy. In other words, we still need to turn off the spigot, even if we can drain some of it.

But the bottom line is, carbon management needs to be an option that remains on the table. Despite its drawbacks, it’s a vital tool for the future. And no one’s ever solved a problem faster with fewer tools at their disposal.

State of the Transition 2023

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