Biochar Carbon Sequestration vs Direct Air Capture

The clock ticking on dealing with climate change forces us to consider which carbon removal methods will have the most impact on CO₂ levels in the atmosphere.

(See: How Does CO₂ Cause Climate Change?).

Tried and tested biochar is popular in the carbon removal market, favoured by up to 80% of CDR buyers as it’s affordable and the technology is mature. In actual CO₂ captured, biochar represented 86% of delivery volume in 2024 [World Economic Forum].

Although biochar is thriving in the carbon credit/offset markets, is it the most effective method or is a technology like Direct Air Capture (DAC) a better choice to pursue?

Let’s have a deeper look at each approach.

Direct Air Capture (DAC)

On the Showdown: Biochar vs Direct Air Capture by CDR Policy, Martin Freimüller, Co-Founder and CEO of Octavia Carbon, mentioned three reasons DAC is an excellent option for carbon removal :

“1. DAC’s cost curve is steeply negative. DAC is not expensive; it is early stage and like all tech it needs to come down the cost curve, and DAC’s costs are falling really quickly.

2. Historically biomass-based climate solutions haven’t scaled like engineered ones. Today, the engineered solutions are dramatically ahead (EV vehicles vs bio diesel and solar vs bio energy), and I don’t see any inherent reason why the trend should be any different for carbon removal.

3. DAC is safe and reliable at gigatonne scale.”

Pros of Direct Air Capture

Direct Air Capture (DAC) offers several notable advantages. (See: How Does Direct Air Capture Work?)

One key benefit is that it does not compete with agriculture for land. Unlike bio-based approaches, DAC facilities do not require fertile land and can be installed in non-arable areas. This gives it a distinct edge in terms of land use.

Additionally, DAC provides precise CO₂ removal by specifically targeting carbon dioxide directly from the air, regardless of the original source of emissions.

The technology also supports durable carbon storage. When the captured CO₂ is stored in geological formations, it can remain there for thousands of years, offering long-term storage potential, and permanent storage if it is mineralized (See: What is CO₂ Utilization?)

DAC plants are modular in nature, meaning they can be built incrementally and expanded over time as needed. This allows for gradual scaling based on demand and resources.

Another advantage lies in the flexibility of location. DAC can be deployed in a range of environments, including urban and industrial areas. This flexibility makes it possible to build facilities close to CO₂ storage sites or near renewable energy sources.

Furthermore, captured CO₂ has potential industrial uses, such as in Sustainable Aviation Fuel (SAF), chemicals, or building materials such as storing CO₂ in concrete.

DAC systems also have a high potential for large-scale carbon removal. They are not reliant on specific feedstocks or land types, making it possible to deploy them globally.

Finally, while DAC remains an emerging technology, it is already operating in pilot and early-stage commercial settings. Technological developments are progressing quickly, which suggests promising growth in the near future.

Injecting Captured CO₂ into Concrete

Challenges Facing Direct Air Capture

One of the most often mentioned challenges is the cost, which ranges between $300 and $1,000 per tonne of CO₂. However, costs are expected to decrease with future technological improvements.

The technology also uses a notable amount of energy for running the fans, regenerating sorbents, and maintaining system operations. Efficiency and overall effectiveness in carbon removal is dependent on access to low-carbon, renewable energy.

Infrastructure needs also present a barrier. DAC requires support systems, including pipelines, storage facilities, and appropriate regulatory frameworks for geological injection of CO₂.

Only a few commercial-scale plants are currently in operation, and the pace of deployment falls short of what’s needed to help meet global climate targets. Although the technology holds promise, it remains in its infancy and expanding it to a useful scale will require large investments in both infrastructure and technical development.

Biochar

Sebastian Manhart, Senior Policy Advisor at Carbonfuture and a Board Member of the International Biochar Initiative, commented on the Showdown: Biochar vs Direct Air Capture by CDR Policy:

“Biochar has proven itself to be the most ‘shovel-ready’, durable carbon removal technology available. DAC is not ready now to deliver whereas biochar has everything it takes to scale today.

Biochar turns forests, municipal and agricultural waste into a highly valuable product. And it powers its own process while also producing biofuels as well as renewable heat and electricity, displacing fossil fuels in the process. Biochar can remove mega tonnes of CO₂ this decade.”

Pros of Biochar

One of biochar’s most appealing features is the relatively low cost, with estimates ranging from $30 to $200 per tonne of CO₂ removed, depending on the feedstock and processing method.

It also brings multiple co-benefits, especially in agricultural settings. These include improved soil fertility, up to 25% improved water retention, enhanced microbial activity, and 10%-50% increased crop yields. Additionally, it can reduce methane and nitrous oxide emissions from soils, adding to its environmental value. These co-benefits are especially welcome in areas subject to frequent droughts and wildfires.

Carbon durability is another strength. When properly produced and stored, biochar can lock carbon away for hundreds to thousands of years, making it a stable method of carbon storage.

The technology itself is simple. Pyrolysis—the process used to create biochar—is well understood and can be carried out using basic equipment. This simplicity makes it more accessible for small-scale use.

Biochar is already in use in various regions and applications, particularly in agriculture and forestry. It utilises waste biomass, such as agricultural or forestry residues, which might otherwise decompose and emit CO₂ or methane. This not only prevents emissions but also turns waste into a useful product.

The process also requires less energy compared to Direct Air Capture. Pyrolysis, which involves heating biomass in the absence of oxygen, is relatively low in energy demand. Furthermore, the energy used can sometimes be offset by harnessing by-products for heat or electricity.

Biochar production is scalable at a regional level. It can be carried out locally without the need for major infrastructure, allowing it to be tailored to local conditions.

As a mature technology with a long history of use in agriculture, biochar is well understood, with lower barriers to entry than more complex carbon removal methods.

Biochar

Challenges of Biochar

Biochar, while beneficial in many ways, also comes with several limitations.

One major constraint is its dependence on land and feedstock. Scaling up biochar production relies heavily on the availability of biomass and the logistics involved in transporting it. This presents a geographical limitation, as biochar is most effective in regions with agricultural land and accessible biomass waste.

Furthermore, large-scale biochar production may require significant land, which could conflict with food production or efforts to conserve forests.

Despite its effectiveness at sequestering carbon in soil, biochar has limited global potential. Theoretical estimates suggest a maximum of around 1 to 2 gigatonnes of CO₂ removal per year—far below what is needed to meet broader climate targets. The need for suitable biomass and available land further limits the overall scale at which biochar can contribute.

The permanence of carbon storage in biochar is inconsistent. Not all biochar is equally stable, as stability depends on the type of feedstock used and the conditions under which pyrolysis occurs. Carbon sequestration can vary based on soil type, climate, and how the biochar is managed.

There is also competition for biomass feedstocks. The same materials used to produce biochar could instead be used for energy, compost, or animal bedding. This means there is a trade-off in how biomass resources are allocated.

Monitoring the long-term effectiveness of biochar adds another layer of complexity. Measuring carbon storage across diverse soil types and climates is challenging, and ensuring permanence over decades or centuries is not straightforward.

Transportation costs also pose a problem. Gathering and moving biomass to production facilities can become expensive, especially if the feedstock is not sourced locally.

Direct Air Capture vs Biochar Summary Table

	Direct Air Capture (DAC)	Biochar
Basic Principle	Machines extract CO₂ directly from ambient air	Charred biomass stores carbon in a stable form in soil
Carbon Removal Mechanism	Captures CO₂ gas, which is then stored or used.	Stores carbon in solid form, often buried in soil
Feedstock/Input	Air (contains ~0.04% CO₂)	Organic waste (e.g., wood chips, crop residue)
Co-benefits	Can supply captured CO₂ for industrial use	Improves soil health, water retention and crop yields
Challenges	Energy demand, cost, and infrastructure requirements	Competing land uses, consistency in carbon stability
Best Use Case	Areas with access to cheap renewable energy and suitable storage/utilization sites	Rural/agricultural areas with biomass waste
Current Cost	$300–$1,000/tCO₂ but expected to drop with scale	Lower ($30–$200 per tonne of CO₂) but depends on local feedstock and logistics
Carbon Storage Duration	1,000+ years with geological storage. Very durable/permanent if CO₂ is injected underground and mineralized or used in long-term storage e.g. in concrete	100–1,000+ years (varies by production method). Can be durable for millenia, but stability depends on soil conditions and management
Readiness for Deployment	Early-stage, limited commercial sites, not yet widely deployable	Readily deployable at local and regional (small to medium) levels with relatively low investment
Carbon Removal Potential	Theoretically can remove gigatonnes of CO₂ annually, independent of location (5–10 GtCO₂/year)	Moderate: 1–2 GtCO₂/year – limited by biomass availability and land use for production
Scalability	Can be scaled globally but requires substantial infrastructure and energy	Scalable at a regional level, particularly in areas with excess biomass.
Energy Use	Energy intensive; access to renewable energy needed	Low to moderate. Pyrolysis uses moderate energy; by-products can offset some energy needs
Co-benefits	CO₂ can be reused industrially e.g. to make Sustainable Aviation Fuel	Many agricultural benefits – soil health, crop yields and reduced emissions
Land Use	Has a small physical footprint	Needs fairly large land and biomass feedstock, which could compete with food production
Infrastructure Needs	Storage, pipelines, and a renewable energy source	Low – localised production possible
Technology Maturity	Early commercial	Established and low-tech

Conclusion

DAC has immense potential for large-scale carbon removal, especially if costs can be reduced and energy demands met with renewable sources. Biochar offers a more immediate, lower-cost solution for carbon sequestration, especially with its co-benefits for agriculture. In the end, both technologies have their merits, and combining them could complement broader climate mitigation efforts, each playing to its strengths.

For more:

Interested in NEG8 Carbon’s CO₂ capture technology?

Contact the NEG8 Carbon Team