Overview #
I built Project Karbonite as a small scale, eco friendly CO2 capture device aimed at indoor environments. I focused on the literature linking elevated indoor CO2 to reduced cognitive function, and I designed a robotics based system that removes CO2 and stores it as calcium carbonate.
If you have seen my RBC simulation work, that was about fluid dynamics under lunar gravity. Karbonite is the chemistry, sensing, and hardware side of my interests.
This work was published as: “A Robotic Solution to the CO2 Induced Thinking Epidemic” (Journal of Harbin Engineering University, Vol 44 No. 11, Nov 2023).
Role / Team / Timeline #
Role: I led the independent research and device development. Timeline: 2021-2023
Problem Context (from the paper) #
In the paper I summarize studies showing that outdoor CO2 can reach around 500 ppm in urban areas, while indoor levels can rise into the thousands of ppm. I note that up to 1000 ppm shows no significant cognitive effects but is still abnormal vs outdoor air, around 2500 ppm reduces cognitive function, and around 5000 ppm worsens the impact, with higher levels becoming harmful.
System Architecture #
My system is built around two subsystems:
1. CO2 Detection System (CDS) #
- Arduino Gravity Infrared CO2 Sensor V1.1 (0 to 5000 ppm range).
- Alternative sensors noted: MQ-135 and SKU-SEN0159.
- The sensor triggers an Arduino UNO, which runs an inlet pump to pull air until CO2 drops to a safe threshold.
2. Air Extraction System (AES) #
I use a two step alkaline scrubbing loop to convert CO2 into calcium carbonate:
- Wet scrubbing: NaOH absorbs CO2 to form aqueous Na2CO3.
- Causticization: Na2CO3 reacts with Ca(OH)2 to regenerate NaOH and precipitate CaCO3.
- NaOH is reused across cycles; CaCO3 is moved to a storage chamber (with water used for transport and later evaporated).
The design is based on the “air extraction via alkaline liquid sorbent” approach described by Zeman and Lackner, adapted for small scale use and with the final calcination step removed to avoid re releasing CO2.
Heat Management and Power #
The reactions are exothermic, so I use thermoelectric generators (TEGs) to recover a portion of the heat as electricity. The paper notes typical TEG efficiencies of 4 to 10 percent and assumes 7 percent for analysis, which is sufficient to provide a hybrid power source for the 2V Arduino setup (alongside a battery or external power).
Results / Status #
- In the paper I emphasize feasibility and outline plans for prototype builds and in home testing.
- I propose community based deployment (neighborhood cooperatives) for handling or selling CaCO3 produced by the system.
- I cite the underlying industrial process with a cost estimate of $25 to $75 per tonne of CO2 (from Zeman and Lackner).
Earlier prototype notes from my own tracking include:
- About 83 percent lower cost vs typical CO2 capture solutions.
- Multi month operation with a new 2W charge roughly every 3 months.
Tools / Stack #
- Arduino UNO
- Infrared CO2 sensor (Gravity V1.1) and alternatives
- Pumps and fluid handling
- Alkaline scrubbing chemistry (NaOH, Ca(OH)2)
- Thermoelectric generator modules