Computer Simulations Create Carbon Capture Materials
Complex computer simulations are being used to screen hypothetical new materials for direct air capture of carbon dioxide.
The world of engineering depends largely on computer simulations or sims. Gone are the days of building things by seat-of-the-pants with the hope that everything would work out okay in the end.
Image used courtesy of NIST
Today, designs are made with the help of sketching software transferred into computer-aided design (CAD) programs, refined and optimized with high-level analyses simulations, and shared with production, marketing, and sales teams to build a product that meets all its performance targets while being easy to manufacture with minimal waste, and at a cost that can ensure a profit.
There are almost as many computer simulations as engineering problems that need to be solved. Stress analyses or structures, the strength of materials, aerodynamics, fluid flow through piping and valve systems, and energy usage are just some of the popular simulations used daily in the engineering community. The key is to create a series of algorithms that can help describe the physical situation and determine an answer to a specific series of problems.
Screening New Materials
One area of computer simulation getting a great deal of recent attention is screening new materials for various applications. In the past, working in a physical laboratory to create compounds using beakers, test tubes, and reagents was necessary. This was not only time-consuming but, by its nature, could be prone to error.
An example of this kind of computer simulation has been developed by the National Institute of Standards and Technology (NIST), part of the U.S. Department of Commerce. It is used to help search for materials that can capture carbon dioxide (CO2) from the atmosphere using direct air capture (DAC).
Our efforts at decarbonization won’t be enough to prevent widespread climate catastrophes, according to the Intergovernmental Panel on Climate Change (IPCC), and DAC will be necessary to reduce the level of CO2 in the atmosphere. The global search is for materials or combinations of materials that can successfully and economically remove CO2 and reduce the effects of climate change.
How Carbon Capture Works
Carbon dioxide can be captured by passing air through a liquid hydroxide chemical solution that removes CO2 by forming a precipitate or through a solid process by passing air through a chemically treated filter.
The computer simulation developed by NIST scientists can calculate the direction CO2 molecules will travel when exposed to solid capture materials. The gaseous molecules will either be drawn into voids in the capture material—a success—or be pushed out into the surrounding air. Traditionally, the way to test new capture materials was to create them in a laboratory and test them. With the NIST computer simulation, a range of hypothetical materials that have never existed can be evaluated and, if they look promising, created for real-world testing.
Porous Crystalline Materials
The key to the computer simulations used in this type of study is the statistical methods used to predict the motion of the CO2 molecules. NIST has determined that porous crystalline materials have an affinity for carbon dioxide molecules and, when arranged into three-dimensional structures, can leave voids that provide space for the CO2 molecules. Because electrons have an uneven distribution in the crystalline structure, electric fields are formed that can either be attractive or repulsive. If everything is lined up correctly, the CO2 molecules are attracted into the voids by electrostatic attraction and an effective capture material results.
A rendering of a potential porous crystalline material with voids represented as yellow spheres. Image used courtesy of NIST
This type of porous crystalline structure can be created from the atoms of various elements, which can further synthesize into different geometric shapes. This is where the computer simulation comes into play, as the different combinations are nearly endless, and the computer allows NIST scientists to examine a wide range of possibilities. The NIST program can also examine the material behavior over a wide range of temperatures and pressures.
Although the NIST scientists claim they haven’t yet found the optimum material to use as a DAC filter, their computer simulation program is available to researchers worldwide who can now examine novel combinations more quickly.