The future of DAC is knocking

Photo: Drmakete

by Peter Minor, PhD, director of science and innovation

In discussions of promising carbon removal technologies, direct air capture (DAC) can often steal the limelight. That tracks with the industry narrative: a futuristic technology that will cheaply “solve” climate change by literally sucking CO₂ out of the air, without the verification and land use challenges of many other solutions. But in reality, the progression of current DAC technologies has been tempered by steep challenges with cost, efficiency, and energy requirements.

To have a meaningful impact on the climate, DAC needs to achieve gigaton scale at <$100/ton by 2050. That’s a far cry from our current position: Over the last 10 years, approximately 10,000 tons of CO₂ have been removed by DAC at a cost of $500–$1000/ton. Fortunately for the planet, we’re at the frontier of a new evolution of DAC — or DAC 2.0, as we like to call it.

A few start-ups have embraced new innovations that will greatly accelerate the path to gigaton-scale removal. C180’s been keeping an eye out, and we’ve identified three core developments that could supercharge the DAC industry — and the policy support needed to implement them.

The features defining DAC 2.0

Passive Air Contacting

The atmosphere’s current CO₂ concentration of ~400 ppm is alarming for the health of our planet, but it’s too low a concentration to easily separate CO₂ from ambient air at a reasonable rate. To overcome that, most plants use large fans to funnel more air into their systems, a process known as active air contacting. While this boosts the rate of CO₂ removal, it comes with additional costs and complexity. At current electricity rates, active air contacting requires ~200 kWh and $10 to remove each ton of CO₂ — when the price of carbon eventually reaches $100/ton, the electricity required to power these fans will constitute a hefty 10% of the purchase price.

That’s led some DAC leaders to adopt a new alternative: passive air contacting, or DAC without the fans. Increased surface area compensates for a lack of forced airflow, and design optimizations (like vertical stacks) position this to be a lower-cost approach in the long term.

Modular, Simple, and Off-the-Shelf

The cost and complexity of a gigaton carbon removal industry will be tremendous — equivalent in mass to global wheat production. One way to hasten this effort and minimize cost is to revamp DAC systems with simple, modular builds. This helps in two ways:

  1. Simple designs are often easier to mass-produce and deploy. If components are produced at a high volume for off-the-shelf purchase, DAC companies can mostly rely on external supply chains rather than building from scratch each time. We see frequent examples of this in other industries: A 100MW gas turbine, with its site-specific customization, requires 30 months to develop and construct. Compare that to the 18 months it takes to stand up a 150MW solar PV plant using highly modular and standardized components.
  2. When a huge volume of standardized parts are assembled, the industry accelerates its learning rate — a measure of how quickly a technology can drop down the cost curve while increasing the number of manufactured units. Solar PVs are a great example of this economic phenomenon, which have continued to drop in price as more panels are produced.

Beyond Chemical Sorbents

Current DAC technology is highly reliant on chemical sorbents to separate CO₂ from ambient air. These technologies are proven, with roots in submarine and space programs from the 1940s and 1950s.

However, alternate forms of sorbents are emerging with exciting potential:

  1. Low-cost alkaline materials that reversibly bond with CO2 to form carbonates, effectively acting as a mineralization-DAC hybrid that allows CO₂ to be captured in a mineral form (before being geologically stored as liquid CO₂).
  2. Metal-organic frameworks (MOFs) that are highly porous, with an internal structure that can be designed to selectively adsorb CO₂, positioning them to enable high-efficiency DAC.
  3. A variety of biologically-enhanced capture mechanisms, including biocatalytic carbon capture and conversion, carbonate formation using synthetic biology, and enzymatic acceleration of enhanced weathering.

While most of the above are still in early development, they bring opportunities for lower energy requirements, faster cycle times, and the potential for built-in, permanent CO₂ storage.

The emergence of DAC 2.0

Fortunately, DAC 2.0 isn’t some distant dream — we’re starting to see these features trickle into new DAC designs today. Heirloom, which launched out of the Carbon180 EIR Fellowship, is a bellwether of the potential ahead. In April 2021, the startup announced a new approach to direct air capture that fulfills all three criteria of DAC 2.0, by…

✅ Optimizing for passive air contact

✅ Using a highly modular design that relies on off-the-shelf components

✅ Utilizing naturally available carbonate materials to absorb CO₂, which costs <1% of the chemical sorbents in most current DAC technology.

As a result, the company has a credible plan to remove billions of tons of carbon at <$100/ton by the mid-2030s — an incredible leap forward from our current DAC capacity, unlocked by embracing the full suite of features that define DAC 2.0.

How we ramp up DAC 2.0 — on the Hill

For DAC to reach its full potential and achieve gigaton scale, we need smart policy design that creates an environment conducive to new approaches — and ramped-up demand for massive carbon removal purchases. That largely hinges on two levers: expanded corporate purchases and direct federal procurement.

It’s clear that DAC innovation has surpassed the original vision of the technology. As it stands, minimum capture thresholds prevent new DAC companies from immediately leveraging current incentives like 45Q — stifling new innovations and players from competing in the field. Future federal projects, like the proposed regional DAC hubs, must be designed to accommodate a diversity of technical approaches. Only by recognizing DAC in all its potential forms and intermediaries can we maximize the opportunity for direct air capture to be a viable tool in the fight against climate change.

Meanwhile, direct federal purchases of carbon can expand removal capacity, bring the technology down the cost curve, and maximize the impact of DAC. The government wields the power to set industry standards that both aid innovation and center environmental and labor protections crucial for community buy-in. Policymakers have the unique opportunity to empower entrepreneurs to build the technology needed to fight climate change, while also creating an industry focused on tangible impacts and benefiting communities.

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A new breed of climate NGO on a mission to reverse two centuries of carbon emissions. Newsletters 👉 http://bit.ly/3gjXhgR

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