The Carbon Engineering Design
CE’s patented technology integrates two processes: an air contactor, and a regeneration cycle, for continuous capture of atmospheric carbon dioxide and production of pure CO2.
These two processes work together to enable continuous capture of CO2 from atmospheric air, with energy (and small amounts of make-up chemicals) as an input, and pure CO2 as an output. The stream of pure CO2 can be sold and used in industrial applications and/or permanently sequestered (geologically stored) deep underground.
Our capture technology brings atmospheric air containing CO2 into contact with a chemical solution that naturally absorbs CO2, in a device called a contactor. This solution, now containing the captured CO2, is sent to a regeneration cycle that simultaneously extracts the CO2 while regenerating the original chemical solution, for re-use in the contactor. The extracted CO2 is combined with all the CO2 from the systems energy use and both are delivered as a high-pressure pipeline-quality product.
CE’s air contactor design captures carbon dioxide with a strongly alkaline hydroxide solution. This solution has been optimized to quickly absorb CO2 by careful selection of concentrations and additives.
We have developed, patented, and prototyped a unique contactor design that maximizes CO2 absorption by utilizing a large solution surface area, optimized air turbulence and mixing, and solution-refresh rates. Our contactor design enables us to capture industrial-scale quantities of CO2 using a cost-effective device with low solution pumping and fan energy inputs, and with minimal land use requirements. Our prototype air contactor was 12’ tall and 40’ long, during summer/fall 2011 we commissioned and during summer/fall 2012 it captured 2 tonnes of CO2 from the air without a single breakdown.
Both the potassium hydroxide [KOH] reactant used in our air contactor and the produced potassium carbonate [K2CO3] are non-toxic, and are in fact used at low concentrations in the preparation of certain foods.
In CE’s regeneration cycle, the CO2-rich chemical solution from the air contactor is processed to release pure, compressed CO2, and also to re-generate the original capture solution for further use.
This cycle is an innovation based on a 100 year old industrial process made up of well understood and existing technology. Our collaborators who are industry leaders in the field have reviewed our innovations and are excited about the potential of what we have achieved.
- After CO2 is captured in the air contactor, it forms a chemical known as potassium carbonate [K2CO3], which is carried to the regeneration cycle dissolved in solution. This solution is fed into a device called a pellet reactor which simultaneously reacts it with calcium hydroxide [Ca(OH)2] to regenerate the potassium hydroxide [K2CO3] for reuse in the air contactor and precipitates the CO2 out of solution as solid calcium carbonate [CaCO3].
- Once the solid calcium carbonate [CaCO3] has been separated from the solution, it is sent to a device called a fluid-bed calciner. The calciner operates at about 900°C which causes the calcium carbonate [CaCO3] to decompose into calcium oxide (CaO), during which pure CO2 is released as a gas. The calciner burns fuel, such as natural gas, in an oxygen environment to supply the heat needed to perform this reaction. The calciner also generates heat that is used to supply electricity for the rest of the air capture plant. The CO2 produced by burning the fuel mixes with the captured atmospheric CO2 and all the CO2 is sent to a final “compression and clean-up” stage to produce pure, pipeline-quality CO2.
- After the solids have released their CO2, they are then sent to a mixing tank where they react with water to re-form fresh calcium hydroxide [Ca(OH)2]. This calcium hydroxide is recycled to the pellet reactor for reuse.
Upcoming End-to-End Pilot
CE has completed a 3-year R&D phase that produced the design, engineering, and cost assessment for our proprietary direct air capture system. During this time, we have also built relationships with our key equipment vendors who will supply components for our full-scale plant.
CE has recently concluded a second round of investment funding, in order to fabricate and test a fully-integrated end-to-end pilot plant of our technology. We have worked with our key vendors to design this pilot to meet their data gathering needs so they can supply our full-plant at low risk. We will be working through this pilot phase from 2013-2015, and this is the last step before before we plan to build a first-of-a-kind commercial air capture plant in ~2017.
Integration with Carbon-Free Energy
In CE’s lowest-technical risk ‘baseline’ design, all the input energy required onsite is supplied by natural gas. The carbon dioxide from gas combustion is also captured along with the CO2 extracted from the atmosphere, so that no new CO2 is emitted to the atmosphere by our technology.
In the longer term, we expect that carbon-free power will drive air capture. CE is building collaborations to conduct full-scale studies on using solar thermal or nuclear energy as the source of energy for its air capture system.