Tech Deep Dive
Direct Air Capture 4: Techno-economics and Final Thoughts
CDR News
MIT paper that highlights DAC Factories
Europe getting ahead of scaling removals
Climeworks and 44.01 working on a DAC facility in Oman
Crucial paper on ocean CDR via kelp sequestration
Nerd rating: 5 (1 to 10 scale on the technical density of the post)
Revisions:
As Tom McDonald, removal technology inventor and entrepreneur, pointed out, I mixed up Carbon Capture, and Carbon Collect on their technologies in this post. That correction has been made.
Regarding regeneration temperature-pressure swings, Tom noted, “high temperature vs. low-temperature regen is really more tied to the sorbent chemistry than if it's a solid and liquid. Both Heirloom and CE are going to need 900C heat for regen, because they both make carbonates even though one is solid and one is liquid.” He also rightly pointed out that I just made high temp and low temp distinctions when there are technologies that use MOFs and similar chemistries that use temperature ranges around 225-250 C. This mid-range deserves its category since it is not “high heat” if that bar is set at 900 C.
Thank you, Tom, for these notes, and I encourage everyone to reach out with corrections, increased context, and insight to make this substack more valuable.
Techno-economics
I am not an economist, researcher, or engineer, so my credentials for doing any techno-economics are pretty thin. Instead of failing my way through pages of analysis, I’ve decided to rely on an old idiom: a picture is worth a thousand words.
Techno-economics associated with direct air capture are sparse and rely on many assumptions, which is entirely understandable given the novelty of the technology and the immaturity of the markets. Below are some of the most compelling figures researchers and think tanks put together. Check the source below each figure for the full report, and enjoy the reading from the best and brightest in the arena.
This figure represents “Total net removal cost estimates (50th, 90th, and 10th percentiles) for solid sorbent (red bars) and liquid solvent (blue bars) technologies under (A) PAU scenario and (B) 2DC scenario. The results are reported for 2020 (dark colors) and 2050 (light colors) for each expert. The orange and gray boxes indicate the range of values reported in the National Academy of Sciences (National Academies of Sciences Engineering and Medicine, 2019) reports for solid sorbent and liquid solvent technologies respectively. Experts 2, 5, 6, and 16 did not provide answers to the cost estimate questions.”
Final Thoughts
Direct Air Capture will remain one of the most exciting and essential technologies for climate mitigation and adaptation. The capture and regeneration mechanisms are garnering serious attention from public funding and private capital. The costs associated with these and the modular nature of some designs will drive down the total capital and operational costs.
What’s limiting DAC? As the figure below notes, policy and regulations were the number one answer amongst “experts” in the space. I agree with them, but two things keep me up at night regarding deployment.
The lack of a carbon price
Geological storage
These two are interrelated as the primary revenue from DAC facilities will be an implicit or explicit price on carbon. The ETS exists in Europe, but America only has sub-national pricing programs. As many have noted, DAC and removals are essential in the waste removal industry. But there's no market analog where they differ from physical refuse. No one is paying for trash pick-up on carbon removals. And so, we must monetize the removed carbon for removal sake, not for usage sake. We can start with government procurement, tax credits, private purchases in the voluntary market, and other policies tools. Eventually, we will need a clear market signal; a carbon price is that signal.
In concert with the waste removal analogy, we need to ensure we have enough trash cans. Subsurface saline aquifers will be the place to store carbon dioxide at scale. The regulations and permitting for public and private subsurface pore space are not ready to handle the volume of removals necessary for meaningful climate mitigation. This has to happen now. I am very nervous about a future where we can pull it out of the sky, but we bottleneck in storage. This is not a technical issue. We have established MRV and aquifers that are technically viable as storage space. We need markets, regulations, and regulators to catch up.
Moving on from DAC and heading into some biochar, the best hope for near-term reductions!
Next week: Biochar
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