We require essential manpower, specialized equipment and consumables for our experiments, including, 1) a 50% part-time research technician to set up and run the bench-top testing chamber in the first three months of the project; 2) various small items for the bench-top set-up (chamber enclosure, pumps, flow meters, gas pipelines, testing facilities, etc) and consumables for day-to-day experiments (gas cylinders, chemicals, PPE, etc).

The CFD modelling we proposed is computationally intensive. We have some in-house computational capabilities already, but we would utilize this budget to expand our access to more computing. We will also need a 25% part-time research assistant to conduct the CFD modelling for the entire project period.

Additional Information

To assist the Review and Evaluation process, I respond directly to the evaluation criteria here:

• Innovation and Creativity

The proposal is developed from a novel and unique idea proposed by R. de Richter and T. Ming et al. in 2017. They suggested to utilise solar chimney power plants (SCPPs) as gigantic air-moving devices and integrate them with photocatalysis to remove methane. Since then, I have been collaborating with them and building up my independent research to develop this solution.

Instead of photocatalysis, we start to search for cheaper and more effective reactions and learn from what the nature does to remove methane in the troposphere. The answer is hydroxyl radical (•OH, known as “natural detergent”), which is the main sink of atmospheric methane.

In this project, we propose to integrate solar pond and UV at the entrance of SCPP to enhanced hydroxyl radical generation.

The integration also enables a promising synergy. The air entering the system will contain increased humidity, the water vapor will condense after entering the chimney at a certain height, release significant latent heat to the airflow, enhance the temperature difference between the top and bottom of the chimney, and boost the system's pumping force and airflow. The boosted airflow in the system can process more air (and more CH4), accelerate the chemical reactions and generate more power, resulting in higher CO2eq removal.

The idea integrates insights from multiple disciplines, e.g., engineering, thermodynamics, atmospheric chemistry, and will integrate more disciplines, including techno-economic and life cycle analysis, governance, engagement, perspectives, and justice to address the problem comprehensively in future phases.

• Feasibility and Technical Soundness

The proposed idea is based on sound foundations. The two single components, 1) solar updraft is established on demonstrated technology in the 1980s, 2) hydroxyl radical chemistry naturally exists in the troposphere and can be summarised using these two equations: O3 + UV-light + H2O → O2 + •OH, and CH4 + •OH → CO2 + H2O.

The methodology of this project includes three parts. 1) Based on our extensive experience of testing various gas reactions in an enclosed chamber, we will build a bench-top set-up to acquire reaction kinetics of •OH generation and subsequent CH4 oxidation considering the influence from different factors (i.e., humidity, UV intensity, O3 concentration). 2) We also have existing computational fluid dynamics (CFD) models to calculate the fluid dynamics. The new and important variable is humidity. The potential latent heat will induce significant difference comparing to the previous models. 3) The CFD methods we developed allow the input of reaction kinetics (i.e., we can import reaction kinetics data into ANSYS FLUENT for numerical solutions by a user-defined function), so that we can model the SCPPs with combined fluid dynamics and chemical reactions. This is the ultimate step for this project to generate the much-needed new data (e.g. the AMR rate and amount of a giant 200 MW device, and their influencing factors) to inform further development.

The resources required to carry out the proposed research include manpower (a part-time research assistant, and a part-time research technician), computational resources, and a bench-top experimental set-up. These are all identified, budgeted and attainable in my institution. Gas analyser capable of analysing low concentrations of methane and other reaction species is already available in my lab.

• Potential for Technology to Scale

The scalability is challenged by the low concentration of methane in the air: ~2 ppm today, which means that large volumes of air must be processed to remove a meaningful amount of methane. The idea of this project - using solar energy to move and clean large volumes of air - is best placed to solve exactly this challenge.

As elaborated earlier, a single 200 MW SCPP can drive airflow of 6200 km3/yr. It can process about 190,000 tons CO2eq/yr considering GWP of CH4 over 100 years (up to 0.6 Million tons Co2eq considering GWP over 20 years). 525 such SCPPs can remove about 0.1 Gt CO2eq/yr from AMR and avoid the emissions of more than 0.1 Gt CO2 by the renewable energy produced.

The process proposed will remove not only CH4, but also provide many co-benefits such as the removal of VOCs and CO, and consume surface ozone (O3) which is also a GHG.

Research on this proposed idea is just beginning. This project aims to generate experimental data to inform the next stage of development (i.e., process design, techno-economic and life cycle analysis), and to identify and address potential technical or market barriers.

Beyond this project, we aim to 1) design and demonstrate a prototype, 2) assess techno-economic, life cycle, and environmental impact, 3) model regional and global climatic impacts, and 4) develop a business model for commercialisation.

• Impact on Greenhouse Gas Removal Acceleration to Scale

Over the project period, we aim to generate the following essential experimental data, 1) the reaction kinetics of •OH generation and subsequent CH4 oxidation, 2) the rate and scale of air movement and CH4 removal efficiency of a giant hybrid SCPP.

The new data will inform the next stage of development and significantly accelerate efforts to scale this technology.

Beyond this project, we have a clear path to further advance this technology as described earlier.

• Strength of Team and Plan

Team expertise and project plan are presented in the sections of Project Timeline and Meet the Team.

Risk management is an essential part of any research project. I have extensive experience to put contingency plans in place. For example, part-time researchers for short period are difficult to recruit, I have already identified suitable candidates in my institution to take up the positions. To ensure smooth construction of bench-top testing systems and minimise any possible delays, we have multiple design options as back-ups.