Recently, engineers at the University of Delaware in the United States successfully demonstrated a method that can not only effectively capture 99% of carbon dioxide from the air using a new electrochemical system powered by hydrogen, but also successfully improve the performance of hydroxide exchange membrane (HEM) fuel cells.
This is a major advance in carbon capture technology that could bring more environmentally friendly fuel cells closer to the market. The research team, led by Yushan Yan, a professor at the University of Delaware, recently reported their approach in Nature Energy. Fuel cells work by converting the chemical energy of the fuel directly into electrical energy. They can be used in vehicles such as hybrid or zero-emission vehicles.
HEM fuel cells are an economical and environmentally friendly alternative to traditional acid-based fuel cells currently in use. But such fuel cells have a drawback that makes them impossible to apply in the real world, that is, they are extremely sensitive to carbon dioxide in the air. This defect quickly reduces the performance and efficiency of fuel cells. So for 15 years, Yan has been working on solving this problem.
A few years ago, researchers realized that this drawback could actually be a solution — removing carbon dioxide. "Once we delve deeper into this mechanism, we find that fuel cells are capturing every bit of carbon dioxide that goes into them, and they're really good at separating it to the other side," the researchers said. ”
While this is bad for the fuel cell, the team knows that if they can take advantage of this built-in "self-decontamination" process in a separate device upstream of the fuel cell stack, they can turn it into a carbon dioxide separator. "Our approach has proven to be very effective," they said. If we have the right design and configuration, we can capture 99% of the carbon dioxide in the air at once. ”
Specifically, they found a way to embed electrochemically power supplied into the separation membrane. It looks like a normal filter membrane for separating gases, but it can continuously collect trace amounts of carbon dioxide from the air like a more complex electrochemical system.
The researchers explain that embedding the device's wires inside the membrane creates a shortcut that makes it easier for carbon dioxide particles to move from one side to the other. It also enables the research team to build a compact spiral-shaped module with a large surface area in a smaller volume. In other words, they now have a smaller package capable of filtering more air at once, making it both efficient and cost-effective in fuel cell applications. At the same time, fewer components mean fewer costs and, more importantly, provides a way to easily scale up the market.
The team's results showed that an electrochemical battery measuring 2×2 inches can continuously remove about 99 percent of the carbon dioxide from the air. The researchers say an early prototype screw device about the size of a 12-ounce soda can filter 10 liters of air per minute and remove 98 percent of carbon dioxide.
They also say that if the device is enlarged to a car, it is about the size of a gallon of milk, and the device can also be used to remove carbon dioxide from other places. For example, patented technology from the University of Delaware could enable lighter, more efficient carbon dioxide removal devices in spacecraft or submarines, where continuous filtration is essential.
In addition, since this electrochemical system is driven by hydrogen, this electrochemical device can also be used in aircraft and buildings as the hydrogen economy develops, where air recirculation is considered an energy-saving measure.