MIT Creates Steamless CO2 Scrubbers
Global climate change is not only a planet-wide problem, but its effects have been shown to lead to life threatening weather conditions such as droughts and floods, and potentially even super storms like Hurricane Sandy. So it's not surprising that researchers from numerous fields have been looking for ways that they can do their part to mitigate the risk.
Carbon dioxide is widely considered to be the gas most responsible for global climate change, and a major source of CO2 emissions comes directly from fossil-fuel power plants. Researchers have not been blind to this, and many plants already use CO2 “scrubbers” to remove the harmful gas from the emissions. However, the systems needed to do this rely on a steam connection that requires complex plumbing, and as a result are not the best choice for retrofitting existing plants.
However, researchers at MIT have discovered a way to eliminate carbon dioxide from the emissions without this steam connection. Not only that, but it can operate at lower temperatures and it can adapt easily to any existing power plant.
In the original system, chemical compounds, also known as amines, would bind to the carbon dioxide in the emission stream. When heated in a separate chamber, the harmful gas was then released. But for this to happen almost half of the power plant’s low-pressure steam would need to be diverted and this would require an incredible amount of alterations to the power plants.
The new system is an electricity-free variation that has an electrochemical process instead of a steam-based one. The system still uses amines that bind with the carbon dioxide but once they are bound together they are processed electrochemically. This means that a metal electrode releases the carbon dioxide instead of steam. Once this has taken place, the amine molecules are regenerated and can be used again.
Not only is this new system easily adaptable to preexisting power plants, but it can also remove a staggering 90 percent of the carbon dioxide from the emissions. If this wasn’t enough to persuade a plant to switch over, the new system only consumes about 25 percent of a plant’s power output, whereas the old system used about 40 percent.
Another benefit that the new system offers is that it can be turned down when there are other demands. Michael Stern, a doctoral student who helped write the paper on the new electrochemical system, stated, “Our system is something you just plug in, so you can quickly turn it down when you have a high cost or high need for electricity.” The steam-based systems have to operate continuously so the same benefit is not available.
So far, only mathematical modeling and small-scale lab tests of the system have been done. The research team, which also includes Fritz Simeon, a former MIT research scientist, and Howard Herzog, a senior research engineer at the MIT Energy Initiative, hopes to do these tests on a much larger scale to see how the system can perform at those levels.
The research team believes that it could be another 5-10 years before it is fully developed and commercialized.