DIRECT AIR CAPTURE
Direct Air Capture is the process of capturing carbon dioxide directly from the atmosphere.
MC3's DAC Team aims to test novel methods to reduce the operating expenses of modular DAC designs, with a focus on using aqueous absorbents to facilitate CO2 capture.
1. DIRECT AIR CAPTURE SUMMARY
Direct Air Capture (DAC) is the process of capturing carbon dioxide directly from the atmosphere. The difficulty in this endeavor stems from both the low concentration of CO2 in air, and the high energy penalty associated with the capture and release of CO2. For DAC to be a viable carbon dioxide removal solution at scale, the energy demand for these processes must be reduced significantly.
MC3's DAC Team aims to test novel methods to reduce the operating expenses of modular DAC designs, with a focus on using aqueous absorbents to facilitate CO2 capture.
3. EXPERIMENTAL & TESTING WORK
Currently, our testing is performed mostly at the benchtop scale, with the priority being to develop CO2 absorption and desorption profiles against the variables of time and temperature, respectively. To achieve this, the absorbent solution is cycled through the contactor, where its CO2 absorption capacity is monitored over time using a high-precision CO2 gas sensor. Samples of the saturated solution are then heated at different temperatures, where the thermal desorption performance is measured through displacement under a controlled set of operating conditions. Currently, we are using this method to test the performance of three different absorbents; potassium hydroxide, potassium glycinate and monoethanolamine.
2. RIG DESIGN AND ASSEMBLY
Currently, we are in the process of assembling a bench top scale DAC rig from off-the-shelf components. This rig contains three main unit operations - the evaporative air cooler contactor, to facilitate CO2 capture by the absorbent solution; a thermal desorption system, to release and purify the captured CO2; and a gas syringe, to quantify the volume of CO2 captured.
The absorbent we are currently testing is potassium glycinate, due to it’s potential for low temperature regeneration, as well as its non-volatile, non-corrosive and environmentally friendly properties.
FUTURE PLANS
In the short term, the goal of the team is optimise the benchtop rig, such that it enables continuous, closed loop carbon dioxide capture. In particular, the design of a small-scale regeneration process, where the post-desorption potassium glycinate solution is purified and recycled back to the contactor, is a primary area of focus.
In addition, we are also investigating methods to improve the purity of the captured CO2 gas stream. In order to achieve this, we intend to integrate analytical techniques, such as gas and liquid chromatography, into our experimental testing. This will enable us to more precisely ascertain the composition of our absorbent mixture at different stages in the DAC loop, enabling us to make more informed decisions related to the design of rig components.