Mountain Tunnel DAC Using Natural Convection and Solid Sorbents
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Solution Overview
Problem
Existing direct air capture (DAC) technologies face challenges in efficiently capturing large amounts of CO2 from atmospheric air due to the dilute concentration, requiring large volumes of sorbent and high energy consumption, and suffer from inefficiencies when scaled up, with CO2-depleted air reentering downwind units.
Innovation Solution
A process utilizing a tunnel with a solid sorbent for CO2 capture, leveraging natural altitude differences and temperature gradients to induce airflow, combined with microwave-assisted desorption, allowing continuous operation and reduced energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If large volumes of sorbent are used for direct air capture, then CO2 capture capacity is improved, but device complexity and land use increase
Solution Approach 1:
The invention transitions from horizontal expansion (large volumes of sorbent in conventional DAC) to vertical utilization by embedding sorbent tubes within mountain terrain. The airflow is directed through the mountain slope, utilizing the three-dimensional space of the terrain to achieve high CO2 capture capacity without proportionally increasing land footprint or device complexity.
Solution Approach 2:
The sorbent material is distributed throughout the mountain terrain in segmented tubes rather than concentrated in a single large volume. This segmentation allows the CO2-depleted air to be dispersed and returned to the atmosphere at multiple points along the mountain slope, preventing re-entry into capture zones while maintaining high total capture capacity.
2Quantity of substance
If large quantities of gas are treated through sorbent beds, then CO2 capture amount is improved, but energy consumption increases
Solution Approach 1:
The mountain terrain itself provides the driving force for airflow through natural convection and gravity-driven flow. The CO2-depleted air flows down the mountain slope without requiring additional energy input for compression or movement, as the terrain geometry and temperature gradients naturally propel the airflow through the sorbent tubes.
Solution Approach 2:
The invention utilizes temperature gradients between the mountain terrain and ambient air to drive natural convection currents. By changing the thermal parameters of the system (using warmer mountain rock or cooler ambient air), the airflow is sustained without mechanical energy input, reducing overall system energy consumption while maintaining high CO2 capture rates.
3Quantity of substance
If multiple DAC units are scaled up nearby, then CO2 capture capacity is improved, but CO2-depleted air reenters downwind units reducing efficiency
Solution Approach 1:
The invention uses the vertical dimension of mountain terrain to separate capture zones. Airflow moves through different elevation levels and the terrain physically blocks the path of CO2-depleted air from re-entering capture zones. The three-dimensional mountain landscape creates natural barriers that prevent downwind re-entry, allowing multiple units to operate efficiently in close proximity.
Solution Approach 2:
The mountain terrain is designed to preliminarily direct and contain the CO2-depleted air flow along specific pathways before it can reach other capture units. The terrain geometry pre-organizes the airflow patterns to prevent inefficient re-entry, ensuring that exhaust from one zone does not interfere with intake of adjacent zones.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Scales up DAC technology to large volumes with reduced land use and energy costs, prevents CO2-depleted air reentry, and achieves efficient CO2 capture and concentration suitable for storage or industrial use.
Implementation Method 1
passing a flow of atmospheric air through at least one tunnel provided with at least one solid sorbent with affinity for CO2. The airflow travelling from the inlet to the outlet of the tunnel passes through said at least one sorbent and CO2 contained in said flow of air is transferred to the sorbent
Implementation Method 2
The different altitude may provide a natural circulation of air within the tunnel, due to the different air temperature between inlet and outlet
Implementation Method 3
combined with microwave-assisted desorption, allowing continuous operation and reduced energy consumption
Data Source
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AI summary
A process to capture CO2 contained in the atmospheric air, the method comprising passing a flow of atmospheric air through at least one tunnel, such as a tunnel in a mountain, in the presence of a natural induced air convection where the inlet and the outlet of the tunnel are in different locations and have a different altitude; providing at least one solid sorbent with affinity for CO2 in the tunnel to remove CO2 from the air flow, wherein the CO2-depleted air leaves the tunnel and returns to atmosphere, and CO2 transferred to the sorbent is cyclically removed from the sorbent to obtain a CO2-containing stream.