About This Project

Direct air capture (DAC) of CO2 is a technology for low-cost and scalable carbon dioxide removal (CDR). These systems will collect and concentrate CO2 from around 400ppm to approximately 20% CO2 by volume. The use of ocean based mineralization and enhanced weathering processes present a huge opportunity for gigaton sequestration of CO2. This project will explore low-cost sensors to quantify the mineralization and reaction rate of CO2 in a simulated ocean environment.

Ask the Scientists

What is the context of this research?

It is known that atmospheric CO2 can be durably sequestered by reacting with mineral species in water. This process relies on CO2 gas from the atmosphere dissolving in water and then disassociating to form bicarbonate species. These bicarbonates can react with dissolved minerals in the water, such as brucite to precipitate as magnesium carbonate species. While the chemistry for this is well understood, the sensors and methods for monitoring, reporting, and verification (MRV) of reactions is more difficult due to the complex nature of ocean chemistry, related to the equilibrium conditions of dissolved species in water. This project looks to develop a test system that is able to mineralize 100 g of CO2 per test and explore options to characterize the reaction rate with a range of sensors.

What is the significance of this project?

High-quality monitoring, reporting, and verification (MRV) is critical to deploying carbon dioxide removal projects at scale. Currently, projects that rely on brines, oceans, or aqueous mixtures as a means of CO2 sequestration often take liberties with estimating the real-world impact of their solutions, which may be extrapolated from ideal laboratory conditions. Many existing sensor technologies are prohibitively expensive, or difficult to automate, such as titration based sensors for measuring dissolved inorganic carbon (DIC), total alkalinity (TA), or other critical parameters for characterizing ocean based measurements. The accuracy of expensive, laboratory grade sensors is not required for industrial applications and low cost sensors will enable scalability of this critical approach.

What are the goals of the project?

A test system that is able to sequester approximately 100 gCO2 by reacting with dissolved minerals in a simulated ocean environment will be constructed. The system will allow for the incorporation of sensors to measure aqueous and gaseous parameters, such as pCO2, pH, flow rates, and more. Data will be used to correlate these sensor values to understand the real-time reaction rate that is occurring within our test system. The end goal is to determine the minimum viable sensor suite required to characterize real-time water based chemistry reactions to adequate accuracy for high quality monitoring, reporting, and verification (MRV). This will help to develop and scale systems that can confidently and durably sequester large volumes of CO2.