True-zero (not net-zero) cement making for a post-carbon world

Our process makes the same concrete without the emissions

Today’s portland cement is made by cooking limestone, sand, and clay in massive fossil-fueled 1450°C kilns. This results in a tremendous amount of CO₂: on average 0.9 tonnes per tonne of OPC in the USA. About half of this CO₂ is released from limestone, which is ~50% by weight CO₂, as it decomposes in the kiln to form reactive lime. The other half of the CO₂ emissions is from the fossil fuel (often bituminous coal) needed to reach 1450°C, the temperature required to form the crystal structure characteristic of OPC. This temperature is currently impossible to electrify efficiently.  

We skip both emissions sources, instead using the elegance of electrochemistry to extract reactive calcium (Sublime Lime™) and silicates from abundant raw materials that are then blended into a final Sublime Cement™. Our cement’s crystal structure is different than the OPC produced in a fiery kiln, but its performance and hardened phase in concrete are the same.

Sublime Cement™ meets ASTM C1157, the standard performance specification for hydraulic cement, enabling architects and engineers to specify it into building construction.  
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We call our process true-zero

Our process decarbonizes cement production by avoiding CO₂ emissions in the first place. We skip the carbon addition and subtraction typical of net-zero solutions — and the associated expense and complexity of carbon capture, sequestration, credits, and clean up.

A refinery for rocks

Our process transforms electrical energy into chemical energy to break feedstocks down into their constituent elements. We then reassemble these pure, reactive ingredients into the ideal cement composition. We use every part of the rock, leading to near-zero waste, unlike the limestone mined for OPC, 50% of which ends up as greenhouse gas emissions or otherwise wasted.

Learn about our process in depth

Sublime CementTM

>90% CO₂ Reduction Possible

Ideal
 

Cost

Ideal
 

Meets Ready-Mix Specs

Ideal
 

Fossil Fuel Use

Ideal
 

Embodied Energy

Ideal
 

Cement today (OPC)

>90% CO₂ Reduction Possible

Insufficient
 

Cost

Ideal
 

Meets Ready-Mix Specs

Ideal
 

Fossil Fuel Use

Insufficient
 

Embodied Energy

Ideal
 

OPC + Carbon Capture

>90% CO₂ Reduction Possible

Ideal
 

Cost

Ideal
 

Meets Ready-Mix Specs

Suboptimal
 

Fossil Fuel Use

Insufficient
 

Embodied Energy

Insufficient
 

Supplementary Cementitious Materials

>90% CO₂ Reduction Possible

Suboptimal
 

Cost

Ideal
 

Meets Ready-Mix Specs

Suboptimal
 

Fossil Fuel Use

Insufficient
 

Embodied Energy

Ideal
 

Carbonated / CO₂-Cured

>90% CO₂ Reduction Possible

Suboptimal
 

Cost

Suboptimal
 

Meets Ready-Mix Specs

Insufficient
 

Fossil Fuel Use

Insufficient
 

Embodied Energy

Ideal
 

Starting
Feedstocks

We replace carbon-intensive limestone with calcium silicate minerals or industrial wastes.

Electrochemical
Transformation

We use electricity, not heat, to break down feedstocks into their constituent minerals.

High-Value
Co-Products

This intrinsically purifying process extracts all the individual minerals from the rock, including iron oxide and magnesium hydroxide —providing a cleaner, cheaper source of these materials that are critical for many industrial applications today.

Cementitious
Ingredients

Calcium and silicates are produced from this process as the essential, reactive ingredients for cement.

Final Sublime
Cement™

The final result is an ASTM C1157 Sublime Cement™ to displace OPC.

High-Value
Co-Products

This intrinsically purifying process extracts all the individual minerals from the rock, including iron oxide and magnesium hydroxide —providing a cleaner, cheaper source of these materials that are critical for many industrial applications today.

The greatest CO₂ reduction impact from a green electron

Sublime was invented because the proliferation of renewable energy meant that the fossil-fueled processes of the Industrial Revolution could finally be electrified. While many decarbonization technologies are working to access this clean grid electricity, Sublime’s manufacturing has the highest impact. Each kWh displaces limestone emissions (the majority emissions from traditional cement-making) and the energy emissions from coal-fired kilns.

Why carbon avoidance technologies matter

Not just a low-carbon
solution, but a circular one

The mass of man-made things now exceeds the mass of living things on earth — and half of that mass is concrete. To preserve the health of ecosystems and biodiversity, we must avoid both carbon emissions and waste. Our Sublime™ electrochemical process can be adapted to produce Sublime Lime™, silicates, and cementitious ingredients from a range of both naturally occurring minerals and many industrial wastes that are currently landfilled. This spans slag byproducts from steelmaking, kiln ashes and dusts, and even returned and demolished concrete.

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Get Sublime Cement™
for your low-carbon construction project

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