Tag : Seawater

Massachusetts (US): Researchers from all around the world have been working for years to find effective techniques to remove carbon dioxide from the atmosphere as it continues to accumulate in the planet's atmosphere. The ocean, on the other hand, serves as the planet's top "sink" for atmospheric carbon dioxide, absorbing between 30 and 40 per cent of all the gas generated by human activity. Another interesting option for reducing CO2 emissions that could eventually result in net negative emissions is the prospect of drawing carbon dioxide directly out of ocean water. This possibility has recently come to light. Although there are a few businesses trying to break into this market, the notion has not yet resulted in any broad adoption, similar to air capture systems. Now, a team of researchers at MIT says they may have found the key to a truly efficient and inexpensive removal mechanism. The findings were reported this week in the journal Energy and Environmental Science, in a paper by MIT professors T. Alan Hatton and Kripa Varanasi, postdoc Seoni Kim, and graduate students Michael Nitzsche, Simon Rufer, and Jack Lake. The existing methods for removing carbon dioxide from seawater apply a voltage across a stack of membranes to acidify a feed stream by water splitting. This converts bicarbonates in the water to molecules of CO2, which can then be removed under a vacuum. Hatton, who is the Ralph Landau Professor of Chemical Engineering, notes that the membranes are expensive, and chemicals are required to drive the overall electrode reactions at either end of the stack, adding further to the expense and complexity of the processes. "We wanted to avoid the need for introducing chemicals to the anode and cathode half cells and to avoid ...