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article imageScientists create C02 sequestration method that produces H2 fuel

By JohnThomas Didymus     May 29, 2013 in Science
Scientists at the Lawrence Livermore National Laboratory have demonstrated a new process that can be used to remove excess carbon-dioxide from the atmosphere while generating "carbon-negative" hydrogen fuel.
The potential breakthrough in the search for alternate fuel sources also involves production of an alkaline solution that can be added to oceans to offset acidity, a serious environmental problem.
A process is describes as carbon negative when it produces a permanent removal of the greenhouse gas carbon dioxide from atmosphere.
Scientists are interested in carbon negative processes because they are potentially more effective means than reduction in emissions for reversing the accumulation of greenhouse gas carbon dioxide in the atmosphere.
In their paper titled, "Direct electrolytic dissolution of silicate minerals for air CO2 mitigation and carbon-negative H2 production," published in the Proceedings of the National Academy of Sciences, the Lawrence Livermore team demonstrated a "laboratory scale" process that harnesses acidity produced in saline water electrolysis to speed up silicate mineral dissolution.
Note that both silicate minerals and saline are abundant in nature, pointing to the potential industrial scale application of this process.
Saline water electrolysis involves the decomposition of water (H20) into its component oxygen and hydrogen gases by passing a current into the water using two electrodes made from an inert metal, such as platinum or stainless steel.
Acidity, in the form of hydrogen ions, appears at the cathode (the negatively charged electrode), while oxygen appears at the anode (the positively charged electrode).
The electrolyte solution obtained from the process involving saline and mineral solution was found to have high levels of hydroxide that exhibited strong atmospheric C02 absorption and retention capacity. The researchers suggested that the alkaline carbonate and bicarbonate products of the process could also be used to offset the environmental problem of ocean acidification in the same manner that doctors prescribe Alka Seltzer, an alkaline solution, to offset excess acid in the stomach.
Greg Rau, a senior scientist at UC Santa Cruz, and lead author of the study due for publication on May 27 in the Proceedings of the National Academy of Sciences, said: "We not only found a way to remove and store carbon dioxide from the atmosphere while producing valuable H2, we also suggest that we can help save marine ecosystems with this new technique."
According to the researchers in a news release, ocean acidification is a fallout of carbon dioxide emission which occurs when a fraction of the gas released into the atmosphere is absorbed by ocean waters to from carbonic acid which drives ocean acidification.
Researchers have shown that acidification threatens the marine ecosystem, especially corals and shellfish. It is projected that by the middle of this century the planet will likely have warmed by at least 2 degrees Celsius, leading to a more than 60 percent increase in acidity compared to pre-industrial levels.
The good news from the Lawrence Livermore team is that their new process could be used to generate an alkaline solution that can be added to the ocean to neutralize excess acidity and possibly save the marine ecosystem.
The scientists emphasize, however, that more research and development is required to develop their "laboratory scale" demonstration for industrial application. According to Rau, more research is needed to optimize cost-effectiveness, plant design and procedures.
He said: "When powered by renewable electricity and consuming globally abundant minerals and saline solutions, such systems at scale might provide a relatively efficient, high-capacity means to consume and store excess atmospheric CO2 as environmentally beneficial seawater bicarbonate or carbonate. But the process also would produce a carbon-negative 'super green' fuel or chemical feedstock in the form of hydrogen."
The prospects are exciting when it is considered that previously demonstrated chemical methods for capturing and storing atmospheric carbon dioxide are very expensive. Most employ thermal or mechanical techniques to concentrate molecular C02 from the air with the reagents recycled in a typically complex and inefficient process.
Comparing their process to previous methods, Rau said: "Our process avoids most of these issues by not requiring CO2 to be concentrated from air and stored in a molecular form, pointing the way to more cost-effective, environmentally beneficial, and safer air CO2 management with added benefits of renewable hydrogen fuel production and ocean alkalinity addition."
More about Co2, hydrogen fuel, Ocean acidification, Lawrence Livermore National Laboratory, carbon negative hydrogen fuel
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