Integrating climate and physical constraints into assessments of net capture from direct air capture facilities
This week, we give a closer look at the paper recently published in PNAS (Proceedings of the National Academy of Sciences). The study was conducted by Patrick Shorey and Ahmed Abdulla from the Department of Mechanical and Aerospace Engineering of Carleton University in Ottawa, Canada.
To meet Paris Agreement climate targets, deep decarbonization and large-scale carbon dioxide removal (CDR) are essential. Direct air capture (DAC) is a key technology being explored to address emissions from hard-to-decarbonize sectors and legacy emissions. However, global assessments have overlooked factors affecting DAC’s net capture and cost, such as ambient conditions and energy system emissions. This study integrates climate data, process models, and emission factors to assess DAC’s global deployment potential, providing critical insights into capture rates, energy use, and emissions intensity, helping inform policy and investment decisions.
The authors first discuss why it is essential to consider physical factors (e.g., local temperature, humidity) and the emissions of the electricity grid in assessing the efficiency and cost-effectiveness of DAC systems, arguing that current models often overlook these factors, leading to unrealistic or overly optimistic projections for DAC’s performance and its ability to meet climate goals. The integrated assessment framework used to evaluate the global deployment potential of this technology is then presented: employing a chemical process model, climate data, grid emission factors, and fugitive methane emission factors, this framework can predict critical performance metrics, including carbon dioxide capture rates, and water-, energy-, and emissions-intensity of capture.
Results show how climate conditions (e.g., temperature and humidity) and energy system characteristics (e.g., grid emission factors, renewable energy mix) influence DAC’s energy, water, and emissions intensity. As shown in Figure 1, different locations with varying climates and grid emissions profiles will impact the overall performance and efficiency of DAC facilities. Results also reveal how performance metrics (including carbon capture rates, water usage, energy intensity, and emissions associated with DAC facilities) may vary depending on climate and energy system factors, providing insights into where DAC might be most effective or cost-efficient.
Understanding regional differences in DAC performance will be key for effectively deploying DAC facilities, developing credible policy instruments, and ensuring that investments are directed toward the most effective sites for large-scale deployment.
Figure 1 Figure 2
Here is a list of the key take-aways from this paper:
- Direct air capture (DAC) is crucial for achieving climate targets, but its performance and cost-effectiveness depend on local climate conditions and energy system emissions.
- Current global assessments of DAC often ignore critical factors like temperature, humidity, and grid emissions, leading to inaccurate predictions of its net capture potential.
- This paper introduces a new framework combining chemical process models, climate data and energy system factors to accurately assess DAC performance across regions.
- Regional variations in temperature, humidity and energy system emissions affect DAC’s energy use, water consumption, and emissions intensity, influencing its scalability.
- Results can inform policymakers and investors on regions where DAC is most effective, to support the development of region-specific policies for large-scale deployment.
Read the full paper here: Integrating climate and physical constraints into assessments of net capture from direct air capture facilities