The Race for Limestone as climate change’s Big Solution: Sulzer, Blue Planet sign key partnership

July 22, 2021 | Jim Lane

As we continue with Gas Week at The Digest, today we move past green hydrogen (where we will return on Monday) and the nitrogen technology we looked at with Pivot Bio yesterday, and onto Blue Planet’s carbon-negative building material technology. Recently, we highlighted the future we see for carbon capture at scale has to take us towards building materials and away from CO2 injection into petroleum well and salt caves.

And now, Sulzer and Blue Planet have signed a significant partnership for converting CO2 into limestone.

The partnership

Sulzer is enabling the further development and optimization of Blue Planet’s innovative carbon mineralization process for carbon capture, utilization and storage (CCUS) solutions. The process will leverage Sulzer’s carbon reduction technologies to help reduce greenhouse gas emissions from industrial activities, for example by supporting the cement industry to produce carbon neutral or carbon negative concrete.

Sulzer Chemtech is developing an efficient and effective carbon capture unit that will be a key enabler in Blue Planet’s process. This will be installed in Blue Planet’s pilot plant, which is being constructed in Pittsburg, California, USA, and will capture emissions from an adjacent natural gas-fired power plant. The facility will leverage Sulzer Chemtech’s technologies providing high CO2 absorption performance while maintaining low energy consumption.

The technology

Blue Planet is developing a profitable and sustainable CCUS system that captures CO2 from a variety of emission sources. These include power, steel, cement, refining, direct air capture and other CO2 emitting industries.

Blue Planet’s technology uses CO2 as a raw material for making carbonate rocks. The carbonate rocks produced are used in place of natural limestone rock mined from quarries, which is the principal component of concrete. CO2 from flue gas is converted to carbonate (or CO3=) by contacting CO2 containing gas with a water-based capture solutions. This differentiates Blue Planet from most CO2 capture methods because the captured CO2 does not require a purification step, which is an energy and capital intensive process. As a result Blue Planet’s capture method is extremely efficient, and results in a lower cost than traditional methods of CO2 capture.

To reform the capture solution, it is exposed to a “Geomass” which is Blue Planet’s term for common rock waste and/or industrial waste materials that contain available alkalinity, which recharges the capture solution, and metal ions such as calcium, magnesium, and iron. When the “spent” capture solution reacts with the Geomass, reforming it, these metal ions are released and combined with the carbonate solution to form the carbonate mineral coating.

Aggregate is the main component of concrete (70 – 90%) and the most used building material worldwide. Aggregates in concrete are bound together by cement, a significant contributor to global CO2 emissions (7% as per the International Energy Agency). With this process the CO2 footprint of cement in the concrete is more than off-set.

The limestone backstory

We have highlighted limestone as a famed and proven building material, which happens to be 44 percent CO2 by weight (the remaining 56 percent is calcium oxide). There are limits to how much CO2 gas been affordably injected anywhere, but there are virtually no human-scale limitations to the amount of carrying capacity that Planet Earth has for limestone, and there are no meaningful limitations on the availability of calcium and oxygen to make limestone (which is calcium carbonate), in comparison to the amount of excess CO2 that our civilization needs to sequester.

It comes down to acres, for one. You can place limestone 200 meters deep in a desert at 5.4 millions tons of limestone per hectare — that’s 2.3 megatons of CO2, per hectare, and there are 28.5 million hectares in the Great Sandy Desert, just to make the point that the carrying capacity is limitless — not that the Great Sandy Desert is a better place to put limestone than the Sahara, the bottom of the ocean or as a building material for freeways or lower Manhattan.

Reaction from the stakeholders

Brent R. Constantz, Ph.D., CEO at Blue Planet, comments: “Sulzer Chemtech is an ideal partner to help us meet our goal of delivering cost and energy efficient plants to permanently store CO2 in concrete by producing sustainable cement and concrete using Blue Planet’s technology. Together, we will be able to offer market leading solutions to help businesses reduce their carbon footprint.”

Torsten Wintergerste, Division President Chemtech, concludes: “We are delighted to contribute our expertise of circular applications to such a cutting-edge project. It will help reduce carbon emissions from industrial applications and the cement sector – a main concern of our customers.”