Coal and natural gas are still a major staple in the world’s energy supply. These elements release CO2 into the atmosphere. It is an ongoing battle to find a way to reverse this effect through carbon capture methods. Recently, researchers have found a way to use microcapsule technology that may make post-combustion carbon capture cheaper, safer, and more efficient. This is wonderful news because even with pollution controls, burning fossil fuels for energy releases a tremendous amount of carbon dioxide into the atmosphere which needs to be dealt with.
Even though renewable energy is on the rise, it’s still not the only energy supply and it won’t be for a few more decades to come. For now, we have to deal with the effects of coal and natural gas while we wean them out. These are the statistics quantifying the issue: In the U.S. alone, coal and natural gas contributed 1,713 million metric tons of CO2 or 98 percent of all CO2 emissions from the electric power sector in 2017.
Great efforts are being put towards mitigating these effects. Researchers are constantly looking for more affordable and efficient ways to capture the carbon dioxide from power plant exhaust. This hunt has resulted in very interesting solutions.
One study, in particular, is research led by the University of Pittsburgh and Lawrence Livermore National Laboratory (LLNL) where they’ve used microcapsule technology. Katherine Hornbostel, assistant professor of mechanical engineering at Pitt’s Swanson School of Engineering said:
“Our approach is very different from the traditional method of capturing carbon dioxide at a power plant. Instead of flowing a chemical solvent down a tower (like water down a waterfall), we are putting the solvent into tiny microcapsules.”
Microencapsulation is a process in which liquids are surrounded by a solid coating. To visually illustrate this, the technique is similar to how they contain liquid medicine in a pill. Hornbostel explains the process:
“In our proposed design of a carbon capture reactor, we pack a bunch of microcapsules into a container and flow the power plant exhaust gas through that. The heat required for conventional reactors is high, which translates to higher plant operating costs. Our design will be a smaller structure and require less electricity to operate, thereby lowering costs.”
Furthermore, the microcapsule design created by Hornbostel and her collaborators at LLNL uses a solution that is made from a common household item, unlike conventional designs that use a harsh amine solvent which is expensive and can be dangerous to the environment. Hornbostel says:
“We’re using baking soda dissolved in water as our solvent. It’s cheaper, better for the environment, and more abundant than conventional solvents. Cost and abundance are critical factors when you’re talking about 20 or more meter-wide reactors installed at hundreds of power plants.”
The small size of the microcapsule gives the solvent a large surface area for a given volume. This high surface area makes the solvent absorb carbon dioxide faster, which means that slower absorbing solvents can be used. “This is good news because it gives cheaper solvents like baking soda solution a fighting chance to compete with more expensive and corrosive solvents,” says Hornbostel.
Hornbostel explains why this idea is so exciting and why it is such a promising solution:
“Our proposed microcapsule technology and design are promising for post-combustion carbon capture because they help make slow-reacting solvents more efficient. We believe that the decreased solvent cost combined with a smaller structure and lower operating cost may help coal and natural gas power plants maintain profits long-term without harming the environment.”