Electric calcination is a key solution to decarbonizing industries and negative emissions

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Geoengineering News

May 24, 2023, 6:29:46 AM5/24/23
to CarbonDiox...@googlegroups.com

Published on 21 May 2023 

The importance of achieving carbon neutrality is now a universal understanding. Among several pioneering initiatives striving to attain this goal, the transformation of conventional ovens into electric-powered solutions is a significant endeavor. In the midst of this decarbonization revolution, stand several ambitious developers and projects, from Calix's LEILAC to SaltX Technology, intent on reshaping industry practices for the betterment of our planet.

The Calix's LEILAC (Low Emissions Intensity Lime And Cement) project stands as a beacon of technological innovation in the industrial world. The project is dedicated to developing an oven for Direct Air Capture (DAC) processes, a technology poised to be a game changer in reducing carbon dioxide emissions. Heirloom Carbon, a leading carbon sequestration company, has expressed intentions of utilizing this technology to capture CO2 directly from the atmosphere, adding a valuable tool to their arsenal in the fight against climate change.

Read more about Leilac and Heirloom Carbon...

While the cement industry is notoriously carbon-intensive, Origen Carbon Solutions is ambitiously tackling this challenge. In partnership with Singleton Birch, they aim to electrify the cement industry and capture carbon dioxide from the production process. This transformative initiative not only aligns with global decarbonization efforts but also promises to establish new standards for sustainable practices in the cement industry.

Read more about Origen Carbon Solutions and Singleton Birch...

SaltX Technology and SMA Mineral are also in pursuit of innovative solutions, albeit in a different sphere. They seek to electrify the production of burnt lime, aiming for a zero-emission production process. Green steel production stands to benefit from this endeavor, as it relies heavily on lime. The promise of sustainably produced lime not only bolsters the greening of steel production but also contributes to the broader decarbonization efforts.

Read more about SaltX Technology and SMA Mineral

Research organizations and universities worldwide are developing electric calcination processes to cut emissions and promote sustainable industry. For example, VTT Technical Research Centre of Finland collaborates with industry partners and the global research community to develop electric rotary kilns and electrify fluidized bed technologies. The increasing electrification of industries aligns with the growing availability of renewable energy. Choosing electric calcination offers a competitive edge and meets the demands of environmentally conscious customers. It also creates new business opportunities by capturing CO2 for industrial use. Additionally, the changing electricity market presents prospects for industry players through Demand Side Response and Frequency Containment Reserves. Collaborations between research institutions and industry partners are vital for this sustainable transition.

Read more about VTT's electric calcinators


Calcination, a crucial process in the production of cement and lime, offers immense potential for capturing and reusing CO2. As industries electrify, millions of tonnes of CO2 could be reclaimed annually through calcination within the next decade. This transformation would contribute also to a circular economy where waste is reduced, and resources are optimally utilized.


As this electric calcination technology progresses, the production volume of calcination and burnt lime is expected to multiply, with an exciting application in sight: boosting ocean alkalinity. Increasing the alkalinity of the oceans can help mitigate ocean acidification, a significant concern given the rising levels of CO2. By 2050, billions of tonnes of lime could be required annually for this purpose, illustrating the massive potential of this technology.


In an increasingly electrified world, the production of lime can be used to offer carbon dioxide wherever needed, thanks to the decarbonization initiatives. In a world striving for negative emissions, electric fuels can be produced with the aid of captured carbon dioxide.


In conclusion, the electrification of industrial lime kilns and subsequent CO2 capturing promise a sustainable future for various industries. As more companies embrace these technologies, the prospect of achieving a carbon-neutral world becomes brighter. Through the combined efforts of projects like LEILAC, companies like SaltX Technology, Origen Carbon Solutions, and Heirloom Carbon, we are witnessing an exciting phase in industrial decarbonization and direct air capture.


Origen Carbon Solutions & Singleton Birch

Calix & Heirloom Carbon

SaltX Technology & SMA Mineral - ZEQL - Zero-Emission QuickLime

VTT Technical Research center of Finland


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Roger Arnold

May 24, 2023, 12:59:22 PM5/24/23
to Carbon Dioxide Removal
I'm skeptical of the economic feasibility of electric calcination for use in DAC or OAE. It's too energy intensive.

For production of portland cement, it's fine. I'd even say inevitable. Production of cement is a high value process, and calcination of limestone is an essential part of that process. For that application, electric calcination furnaces provide a double win. First, they eliminate the burning of coal to supply the heat energy for calcination of limestone. Second, the CO2 that calcination releases comes as a relatively pure stream that's easily captured and sequestered. The cement that's produced using lime from the calcination furnace will, over time, absorb CO2 from the atmosphere. It's fair to advertise it as a high value carbon negative product. But if the lime is only going to be used as an agent to capture CO2, there are alternatives that are much more energy efficient. 

Greg Rau

May 24, 2023, 3:47:07 PM5/24/23
to Carbon Dioxide Removal, Roger Arnold
Curious why solar thermal calcination hasn't gotten attention. Why convert solar to electrons to heat when you can do it directly?

Also, in the DAC vs OAE appllication, the former (in theory) recyles CaCO3 to make conc CO2 for storage whereas OAE is a once throught process that consumes limestone and ocean/air CO2 to make (approx mols/mol CaCO3) 1Ca++ + 1.48HCO3- and 0.17CO3-- stored in in the ocean. Subtracting the the 1 mol CO2 generated in solar calcination of 1 mol CaCO3 leads to a net CDR of about 0.29 t CDR per t calcined CaCO3. Without CCS, the net CDR per t calcined CaCO3 in DAC is zero.  Plus OAE gets further brownie points (in some circles) for countering oceean acidification. No?

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Ronal Larson

May 24, 2023, 4:46:53 PM5/24/23
to RAU greg, Carbon Dioxide Removal, Roger Arnold
Greg et al.

Agreed on solar thermal.  And there are combined PV and solar thermal panels these days in Europe (not yet in US).  Probably improved economics that way.

But I’m  guessing even better economic with the thermal energy always available with any biochar operation.  Brings CDR funding not possible with any solar approach.


Michael Hayes

May 24, 2023, 5:39:44 PM5/24/23
to Greg Rau, Carbon Dioxide Removal, Roger Arnold
A Technical View of the Solar Concentrators/mCDR Link.

To add to the uses of solar concentrators mentioned above: 

1) Dewatering and pyrolysis of cultivated marine biomass for Biochar can use solar concentrators. 

2) Electrolysis of seawater likely can use old school steam engines for generating electricity.

3) Thermal cracking of CO2/CH4/H20 is within the potential heat range of a solar condenser. 

If our highly stable and calm oceanic deserts had large instalations of concentrators, a number of critically needed CDR processes can likely use the heat to scale up to significant size and output with rather straightforward, even old school, technology.

Jim Baird

May 24, 2023, 10:42:20 PM5/24/23
to Greg Rau, Carbon Dioxide Removal, Roger Arnold

Why convert solar to electrons to heat when you can do it directly?


CSP systems have an efficiency of between 7 and 25%.


Utility-scale solar power plant may require between 5 and 10 acres per megawatt (MW) of generating capacity. Taking the lower figure this would be ~ 20,000 square meters.


The average installation cost for concentrated solar power (CSP) worldwide from 2010 to 2021 (in U.S. dollars per kilowatt) is $7613.75/kw. For a GW this would be $ $7,613,750,000.


Thermodynamic Geoengineering has an efficiency of 7.6%. A one gigawatt plant would have a footprint of about 43,000 square meters and would cost $2,900,000,000.


Because it is cheaper, mainly because it requires a smaller footprint, and is more efficient because the 92.4% of the heat sent into deep water resurfaces in 226 years and can be recycled.


Electric calcination for use in DAC or OAE is the least of the benefits of a providing a 226 global warming respite.


A 62% cost reduction also could make calcination a more viable proposition.

Roger Arnold

May 24, 2023, 10:57:10 PM5/24/23
to Greg Rau, Carbon Dioxide Removal
Greg makes a good point about the energy efficiency of calcination for DAC vs. OAE. Closed cycle calcination and slaking to capture CO2 from the atmosphere captures exactly one molecule of CO2 from the atmosphere per molecule of CaCO3 that's calcined, whereas adding one molecule of calcined CaCO3 (aka CaO) to the ocean results (eventually) in the uptake of almost two molecules of atmospheric CO2 by the ocean. So the energy cost per CO2 removed is almost half for OAE than it is for DAC.

Regarding electricity vs. concentrated solar thermal energy for calcination, I think the main reasons for preferring electricity are issues of scaling and economic cost. One might think that concentrated solar would enjoy a 5:1 advantage over electricity, as solar PV is only 20% efficient in converting sunlight to electrical energy. Concentrated solar delivers thermal energy directly, with no need for conversion. It ought to be possible to deliver nearly 100% of the solar energy incident on collector surfaces for calinination.

In practice, it should indeed be possible to deliver around 90% of incident solar energy for driving the endothermic calcination reaction. However, there's a catch. Achieving that level of performance requires a parabolic solar mirror with dual axis tracking. The calcining oven must be a well-insulated quasi black body cavity, with only a small aperture admitting concentrated sunlight. The oven must move with the mirror to keep the image of the sun focused on the aperture of the oven cavity as the sun moves across the sky.

That type of system is expensive, even at small sizes. There are strong diseconomies of scale that preclude sizing it for industrial applications. The solar oven that was used by the researchers in the first article that Greg referenced is a step down from a tracking parabolic mirror, but still way too expensive for industrial use. 

Greg Rau

May 25, 2023, 1:41:57 AM5/25/23
to Roger Arnold, Carbon Dioxide Removal
Thanks for the realities, Roger. I misspoke in my previous email. Each cycle of 1 mol of Ca-based DAC does capture in net 1mol of air CO2, with the exception of the initial solar calcination that releases fossil CO2 from the original limestone CaCO3. In contrast, Ca-based OAE releases 1 mol fossil CO2 for each mol of limestone CaCO3 solar calcined and CaO used, but because 1.65 mols of air CO2 can be captured and stored with that 1 mol of CO2 release, 0.65 mols of net CDR is effect without using CCS to capture and store that 1 mol of CO2 emissions. DAC on the otherhand must store that 1 mol of CO2 from each cyle of its calcination. 

But how about a hybrid? DAC does the air CO2 capture and then the conc CO2 is reacted with limestone and seawater to sponatenously make ocean alkalinity, no need for underground storage, and the ocean acidity gets reduced. Have 45Q qualify the ocean as a saline aquifer (the largest on the planet) and we're in business(?) Or have plants to the CO2 capture and then burn the biomass to make ocean alkalinity from the CO2 + limestone and seawater.   Turf and surf?

Andrew Lockley

May 25, 2023, 2:01:21 AM5/25/23
to Carbon Dioxide Removal
Ronning discussed limestone weathering on Reviewer 2, concluding it doesn't work reliably iirc https://open.spotify.com/episode/5oZnfXVREfnk8G3imTCqbT?si=KT97hPxqSDyVZqeVqSS5cQ

OAE also suffers from biological compensation, where shell forming organisms are energetically favoured. I assume increasing calcium availability would worsen that.


Michael Hayes

May 25, 2023, 2:45:34 AM5/25/23
to Andrew Lockley, Carbon Dioxide Removal
Andrew, et al.,

Operations out in the marine deserts will likely not effect wildlife as there is very little wildlife in the deserts. Lack of life, not water, is why they are called deserts. In brief, there's not a lot of shell forming going on out there.

Also, any planning of massive operations needs to factor in the wide diversity of the regulatory environments found in coastal areas, and how such regulatory environments can possibly change rather quickly with each election. (Think about Trumpian fun and games). The deserts have a far more stable long-term political factor than any coastal region and the use of oceanic deserts greatly simplifies biological considerations.

Transportation cost to and from the sites is the only added expense for using the deserts relative to using coastal waters, yet that likely is not a deal breaker. Marine transport is the cheapest form of bulk transport, and some mCDR methods can possibly supply the C neutral if not C negative fuel. And, electrolysis-based mCDR tech would seem to have the smallest transport factor.

Best wishes

Andrew Lockley

May 25, 2023, 1:55:21 PM5/25/23
to Michael Hayes, Carbon Dioxide Removal

I usually don't engage with your voluminous posts, but as this is addressed directly to me I will reply.

There's no reason to assume that OAE would be restricted to ocean deserts. Transport costs and legal restrictions would suggest it would be done mainly in the EEZ or littoral zone. Caserini, for example, considers the Mediterranean. 
OAE is normally done into the surface ocean, above the thermocline. This reduces fluxes into the deep ocean. 
OAE would sensibly be done in waters that remain in contact with the atmosphere for an extended period of time. This means it would travel (at approx 5mph) over a considerable extent of ocean - influencing shell formation in all environments. 
Both macro and micro organisms form shells, so they're not restricted to one habitat.

There is therefore no clear evidence of which I'm aware that OAE will be helpfully modified by being conducted in ocean deserts. On the contrary, this will raise logistics costs and legal complexity. 

Andrew Lockley 

Michael Hayes

May 25, 2023, 2:51:04 PM5/25/23
to Andrew Lockley, Carbon Dioxide Removal

I addressed you in a polite way, your petty nastiness is now noted by me and the entire group. 

BTW, your posts far exceed mine. I've never actually initiated a post, just responded to what was posted. If you are personally offended by me responding, try not to flood this group with your Geoengineering labeled posts. 

Best regards 

Andrew Lockley

May 25, 2023, 6:17:02 PM5/25/23
to Michael Hayes, Carbon Dioxide Removal

I simply noted that your posts were voluminous, and explained why I was replying to this one. If you feel that's a criticism, you have the opportunity to post less frequently. 

"My" posts are not as implied. They are almost always:
A) done by Ayesha
B) partly funded by list members - https://www.patreon.com/Geoengineering, for those who may care to contribute
C) cut-and-paste 3rd party content, rather than our own work or views

I'm not going to respond further, as flame wars are not an appropriate use of the list. 


Michael Hayes

May 25, 2023, 8:01:49 PM5/25/23
to Andrew Lockley, Carbon Dioxide Removal

[...] flame wars are not an appropriate use of the list. [...]

I agree, now please abide by that.

Thank you for your warm response.

Josh Perfetto

May 25, 2023, 8:03:24 PM5/25/23
to Greg Rau, Roger Arnold, Carbon Dioxide Removal
Hi Greg,

How viable do you think that hybrid idea is? I mean in your scenarios we have already done either the capital + energy cost of DAC, or collected all the biomass for burning. So now we need to decide between underground sequestration or ocean alkalinity. For alkalinity we need to mine and transport 1.5 mol limestone just to sequester 1 mol CO2. It seems to me in these scenarios that the hard part (DAC/biomass collection) has already been done, and now we're choosing a harder way to store it. Do you see scenarios where this makes sense?

I guess in addition to the acidity-reducing benefit you point out, the method in your paper has the benefit of being a lower-tech approach which would be easier to deploy, and obviously it could be done in regions where geological sequestration wasn't an option. It just seems like a whole lot of mining for storage.


Greg Rau

May 25, 2023, 11:17:11 PM5/25/23
to Andrew Lockley, Michael Hayes, Carbon Dioxide Removal
Guy, please take this disagreement off line. I'm the moderator and if you have an issue with posts bring it to my attention privately and I will evaluate. There are now 948 CDR members so please be respectful of their inboxes, and only post stuff that is civil and CDR-relevant to this large audience. Otherwise, please take it private.
Thank you,

Anton Alferness

May 26, 2023, 12:37:28 AM5/26/23
to Josh Perfetto, Greg Rau, Roger Arnold, Carbon Dioxide Removal
Josh - 

I don't think "additional" mining is required in Rau's proposition. Rather, the mining is there already and much of the reactive minerals are abundant in many places (basalts, limestone, etc). So I think given that mining companies leave piles of basalt rock in their pursuit of other minerals, I don't think there would be an extra (substantial) effort or cost to achieve volume. Please correct me if I'm wrong. 


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