From the molecules up, a revolutionary engineering approach is designing our sustainable future.
Imagine designing a complex machine, not by building a prototype, but by starting with the very metal crystals that form its gears. This is the essence of Multiscale Process Systems Engineering (PSE), a revolutionary field that is transforming how we create everything from life-saving medicines to technologies that combat climate change. It is the art and science of understanding and optimizing chemical processes, all at once, from the nanoscopic world of molecules to the massive scale of industrial plants.
In a world grappling with the urgent need for sustainable energy and environmental protection, this holistic approach is not just innovative—it is essential. By bridging vast scales of time and space, multiscale PSE allows engineers to build more efficient, less wasteful, and more powerful systems, turning laboratory breakthroughs into real-world solutions.
At its core, Multiscale PSE is about integration. Traditional engineering often struggles to connect what happens at one scale—for instance, a chemical reaction at a molecule's surface—with the overall performance of an entire factory-sized process. Multiscale PSE tears down these silos.
It creates a digital framework where information flows seamlessly between different levels of detail, allowing for a complete picture that was previously impossible 1 .
A powerful way to understand this approach is through a four-scale framework, often used in cutting-edge research like electrochemically mediated CO₂ capture 1 :
Ångstroms to nanometers
This is the foundation. Here, scientists design the very building blocks of a process, such as designing novel molecules for more efficient CO₂ capture or simulating the atomic structure of a catalyst to make it more selective 1 .
Nanometers to millimeters
This scale focuses on the interface and morphology. Think of it as the "architecture" of materials—designing the porous structure of an electrode to ensure gases and liquids can flow through it optimally, maximizing contact and reaction efficiency 1 .
Millimeters to meters
This is the scale of individual equipment pieces, such as a specific reactor or a separation column. Engineers use computational fluid dynamics to model how reactants mix and flow within a device, intensifying the process to get the most out of the carefully designed molecules and materials 1 .
Meters to kilometers
Finally, at the macro-scale, all the individual units are integrated into a full plant. The focus shifts to overall energy consumption, economic costs, and environmental impact, ensuring that the brilliant molecular design leads to a viable and sustainable large-scale operation 1 .
The power of multiscale PSE is supercharged by modern technology. Machine learning algorithms can sift through vast datasets to identify new materials or predict process behavior, while advanced computing allows for the coupling of different models that describe each scale, from quantum mechanics to plant-wide thermodynamics 1 .
To see multiscale PSE in action, let's examine one of the most promising applications: Electrochemically Mediated Carbon Capture (EMCC). This technology aims to pull CO₂ directly from the air or factory smokestacks using electrical energy, a vital tool for mitigating climate change 1 .
A crucial experiment in this field, explored through multiscale modeling, involves developing and testing a continuous EMCC system 1 .
Researchers first use computational chemistry to design and screen redox-active carrier molecules. These molecules change their affinity for CO₂ when an electrical voltage is applied 1 .
A porous electrode is engineered with a high surface area to host these carrier molecules. Its structure is designed to maximize the contact between the gas, the electrolyte, and the active sites.
The designed electrode is integrated into an electrochemical cell, often a flow system. A dilute stream of CO₂ (simulating flue gas or air) is passed through this cell.
The cell is coupled with a regeneration unit. Applying a voltage "switches" the carrier molecules, releasing the captured CO₂ as a concentrated stream for storage or use and regenerating the capture solution for another cycle 1 .
The success of such an experiment is measured by key performance indicators that span the different scales. The table below outlines some typical outcomes and their scientific importance.
| Performance Metric | Experimental Outcome | Scientific & Practical Importance |
|---|---|---|
| CO₂ Capture Capacity | High capacity at low CO₂ concentrations (e.g., 400 ppm) | Proves effectiveness in capturing CO₂ from dilute sources like air, a major challenge. |
| Energy Consumption | Significantly lower than traditional thermal capture methods | Highlights the key advantage of EMCC: potential for massive energy savings and integration with renewables. |
| Cyclical Stability | Stable performance over thousands of charge/discharge cycles | Demonstrates the durability and long-term economic viability of the material and process. |
| Capture Kinetics | Rapid adsorption and desorption of CO₂ | Ensures the process is fast enough for practical, continuous operation in an industrial setting. |
The analysis shows that by carefully designing the molecule and the electrode architecture (molecular and meso-scale), researchers can directly influence the energy efficiency and cost of the entire carbon capture process (process-scale) 1 . This integrated approach avoids the traditional trial-and-error method, dramatically accelerating development.
Building these complex systems requires a sophisticated toolkit that blends physical experiments with digital simulations. The following table details some of the essential "research reagents" and methods used in a multiscale PSE framework.
| Tool/Material | Category | Primary Function |
|---|---|---|
| Redox-Active Molecules | Material | The workhorses that capture and release CO₂ or other target molecules upon application of an electric potential 1 . |
| Porous Electrodes | Material/Device | Provide a high-surface-area scaffold to hold active molecules; their design dictates mass and charge transfer efficiency 1 . |
| Multi-scale Models | Computational | Digital frameworks that couple equations describing different scales (e.g., atomistic + continuum) to predict overall system behavior 2 . |
| Machine Learning (ML) | Computational | Analyzes vast datasets to identify new candidate materials, optimize process parameters, and build accurate surrogate models 1 . |
| Process Intensification | Methodology | A design principle aimed at making manufacturing dramatically smaller, cleaner, and more efficient by combining multiple operations . |
Quantum chemistry and molecular dynamics simulations predict molecular behavior and interactions at the atomic level.
Techniques like SEM, TEM, and XPS analyze material structure and composition across multiple scales.
Neural networks and other ML algorithms accelerate discovery and optimization across scales.
The journey of Multiscale PSE is just beginning. As noted by Professor Ricardez-Sandoval, a Canada Research Chair in the field, the development of new computational tools is crucial for designing novel products and systems for emerging applications in energy and advanced manufacturing . The future will see the widespread adoption of "digital twins"—virtual, real-time replicas of physical processes that can predict outcomes and self-optimize 5 .
Where crystallization processes are tightly controlled at the molecular level for precise pharmaceutical production.
Designing energy storage systems with optimized materials and architectures for improved performance and safety.
Fully integrated facilities with real-time optimization across all scales for maximum efficiency and sustainability.
Closed-loop processes designed from molecular principles to minimize waste and maximize resource utilization.
By engineering in harmony across all scales, from the infinitesimal to the industrial, we are building a more efficient, sustainable, and technologically advanced future—one molecule at a time.