Unique, Efficient & Low-cost Carbon Capture Method
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.
How it Works: Process Flow
Synthetic Limestone Coating
The carbonated solutions formed from the captured CO2 are used to form a carbonate mineral coating over a nucleus or substrate. The carbonate minerals form a synthetic limestone coating. This permanently sequesters the captured CO2 as CO3= in the carbonate minerals comprising the limestone coating. The aggregate can be produced in different sizes, ranging from sand-sized to gravel-sized.
To reform our capture solution, it is exposed to a “Geomass” which is our 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.
Blue Planet Process is Similar to Ooid Formation in Nature
A rock particle is coated with our synthetic limestone, forming a carbon-sequestering coating that is 44% by mass CO2.The coating can contain residual fine particles from the capture solution regeneration.
44% (by mass) of CaCO3 Coating is CO2
Blue Planet carbon sequestration plants produce coarse and fine aggregate made from sequestered CO2 utilizing the carbon mineralization process. The use of Blue Planet aggregate is the most effective way to achieve carbon neutral – or even carbon negative – concrete. Standard concrete by comparison, typically comprises the largest CO2 footprint in a building or infrastructure project. In strength, performance and cost, Blue Planet CO2-Sequesterd Aggregate is equivalent to that of standard quarried aggregates.
The coating consists of synthetic limestone [CaCO3] crystallized on the surface of recycled aggregate, giving it a smoothened surface finish. Each ton of CO2-sequestered limestone traps 440 kilograms of carbon dioxide, preventing it from accumulating in the atmosphere.
Upcycled Aggregate is a by-product of demolished and returned concrete that has been through a calcium extraction process for Blue Planet’s carbon dioxide sequestered limestone. This aggregate is useful in most concrete mixes, and is well indurated and harder than virgin aggregates due to the uniform process of Blue Planet’s reformation step. While our Upcycled Aggregate does not directly sequester CO2, it offers significant benefit compared to virgin aggregate by adding recycled content value, and the avoidance of CO2 related to mining and transportation.
San Francisco International Airport
Blue Planet’s limestone-coated light weight aggregate was specified in Interim Boarding Area B at San Francisco International Airport where it was included in the concrete poured in 2016 by Central Concrete. Concrete testing showed that Blue Planet’s concrete met all necessary specifications. Photographs show the placement of Blue Planet’s concrete at SFO.
A typical cubic yard of concrete has a carbon footprint of approximately 600 lbs. of embodied CO2 mainly from manufacturing the portland cement component of the cubic yard. The current approach to lowing this carbon footprint is reducing the amount of portland cement in the mix, usually with an SCM (supplementary cementitious material like fly ash). But this approach is limited to only reducing the carbon footprint, and only by about 50% or 300 lbs per cubic yard (CarbonStar ratings of 600 and 300 respectively).
Using Blue Planet products the carbon footprint of a cubic yard of concrete can be not just reduced, but the cubic yard of concrete can become carbon-negative by two specific methods: First, by replacing conventional fine and coarse aggregate (sand & gravel) with Blue Planet synthetic limestone aggregate, which is 44% by mass CO2 now converted to a permanent crystalline solid state in CaCO3, the entire carbon footprint of the portland cement can be completely off-set and can further be more than offset, taking the carbon footprint into the negative carbon range. For instance a typical cubic yard of concrete may have 3000 lb.s of aggregate; if it is all Blue Planet synthetic limestone, then 44% of it is sequestered CO2 (from a power plant or other industrial plant), or 1320 lbs of CO2 is offset.
Second, If the portland cement in the mix originates from a cement kiln where Blue Planet has captured the CO2, then the typical 600 lb. carbon footprint of the portland cement in the mix doesn’t come into the calculation. Thus the total offset is 1320 lb.s industrial or atmospheric CO2 sequestered in aggregate + 600 lb.s captured from the production of portland cement, totaling 1320 + 600 = 1920 lb.s CO2 offset, or nearly one ton CO2 (2000 lb.s) captured and incorporated per cubic yard of concrete.
Precise values are determined applying LifeCycle Carbon Analyses (LCA), that incorporate the auxiliary load carbon footprint of Blue Planet’s processes and transportation at specific plant locations and CO2 emission industry-specific types. Additionally, specific comparative mix designs can be simply and quantitatively compared using the CarbonStar rating which plainly shows the consequences of different proportions of aggregate and cement of the mix designs of interest. For example, the CarbonStar rating of the carbon-negative mix design discussed above is -1920, or about one ton carbon negative per cubic yard. In practice, this means that every cubic yard of this concrete which is places contains the 1920 lb.s of CO2 that would have otherwise entered Earth’s atmosphere
Magnitude of CO2 Sequestered Aggregate Impact
Approximately 50 billion tons (50 Gigatons) of rock is mined every year worldwide for use in concrete, asphalt, and road base. This market is growing at a rate around 8% per year. 70% of the aggregate used in concrete is already limestone. Limestone (CaCO3) is 44% by mass CO2. Every ton of limestone contains 440 Kg of CO2, now transformed in CO3 (carbonate) in a crystalline state. 50 billion tons for limestone contains 22 billion tons of CO2.
Balance of Aggregate Demand and Anthropogenic CO2
We believe human (anthropogenic) contributions to Earth’s atmospheric CO2 levels is about 35 billion (35 Gigatones) per annum, and growing. More than half of this CO2 (22 billon tons) could be consumed from the production of limestone aggregate used in place of the currently mined aggregate. This approach would also save enormous transportation costs and carbon footprint.
Government Procurement Power
Most aggregate on a worldwide basis is purchased by governments, or for government-funded projects. Governments have the procurement power to specify carbon-sequestered rock in construction projects, providing what may be the strongest lever we have world-wide to prevent CO2 from entering Earth’s atmosphere. This approach is a truly global one in that both rich and poor countries alike purchase rock by funding infrastructure projects every year.
With the exception of water, aggregate is the most transported material on Earth. Creating aggregate from CO2 is one of the few highly impactful, globally sustainable means to significantly address climate change, since a new infrastructure is not required. The transportation and product delivery infrastructure for delivering Blue Planet’s carbon sequestered aggregate is already in place in every country and at every site in the world that is producing concrete, asphalt and road base.
Circular Economy and Concrete Upcycling
On a mass basis, concrete is the most recycled material on Earth. Typically if it is not landfilled, it is broken up and recycled for a low value use – such as a road base. Blue Planet uses this recycled concrete in its remediation process as a means of obtaining calcium and alkalinity. The remaining by-product is the original sand and gravel used in the concrete, which would normally be limited to low value applications. But because Blue Planet denudes it of its weakened crushed components, it is now upcycled to the equivalent regular aggregate.
Comparative CO2 Capture Process
Blue Planet converts CO2 to CO3 after capture, but at no point do we purify the CO2. That’s because purification of CO2 requires vast amounts of energy, taking away from our objective of a net reduction in CO2. This sets Blue Planet apart from other CO2 capture companies, where the goal is to concentrate the CO2 in to a pure form so it can be pressurized and liquefied for use in geological sequestration.
CarbonStar Embodied Energy Rating System
Blue Planet’s Government Affairs and Built Environment teams are working with global leaders in the green building industry to develop a simple way to communicate the carbon footprint associated with concrete. The CarbonStar rating is a metric-based on the embodied mass of CO2 in a unit of concrete. Of the three components in concrete – water, cement and aggregate – cement is the most significant contributor to CO2 emissions. If a cubic yard of concrete uses 600 lbs of cement, its CarbonStar rating is 600. The goal is to get the CarbonStar rating as low (or negative) as possible. One approach to lowering the CarbonStar rating for a cubic yard of concrete is to replace traditional aggregate with Blue Planet aggregate. The difference being that Blue Planet aggregate contains sequestered CO2, which when used in place of traditional aggregate, reduces CO2 in concrete.
©2015 Blue Planet, Ltd.