Could Super-Green Hydrogen Be a Reality?
June 13, 2013
A group of scientists claim to have hit upon an inexpensive, workable way to get carbon dioxide out of the atmosphere, store it, and convert it into something that will “offset ocean acidification” -- and produce hydrogen fuel in the bargain.
Think of it as giving the ocean a big Alka-Seltzer.
According to a recent press release from Lawrence Livermore National Laboratory (LLNL), scientists have “demonstrated a new technique to remove and store atmospheric carbon dioxide while generating carbon-negative hydrogen and producing alkalinity, which can be used to offset ocean acidification.”
It’s an interesting project for the Livermore, Calif.-based laboratory, which states its mission as “strengthening the United States’ security through development and application of world-class science and technology,” specifically to “Enhance the nation’s defense, reduce the global threat from terrorism and weapons of mass destruction, and respond with vision, quality, integrity, and technical excellence to scientific issues of national importance.”
We’ll try to describe what exactly they reported in as non-technical language as possible:
When you put water through electrolysis, what that does is break H2O down into its H and O components. So by using the process, you can collect hydrogen and other compounds, depending on whether there’s salt or other stuff in the water when it’s being electrolyzed.
Hold that thought.Oceans Collect Lots of CO2. Lots.
Now when carbon dioxide is released into the atmosphere, a lot of it is absorbed by the oceans. That forms carbonic acid in the ocean, making the ocean more acidic -- the more carbon dioxide in the air, the more carbon dioxide in the ocean, the more acidic the ocean. Higher acidity in the ocean is bad for marine life, particularly coral and shellfish.
Some people believe that the earth will warm by at least 2 degrees Celsius over the next few decades. If so, that means the oceans “will experience a more than 60 percent increase in acidity relative to pre-industrial levels,” according to the LLNL press release. But now the Livermore scientists have found a way to get, in addition to hydrogen, an electrolyte solution “significantly elevated in hydroxide concentration,” that is “strongly absorptive and retentive of atmospheric CO2.”Just Like Alka-Seltzer.
Which is to say it attracts and keeps carbon dioxide out of the air, reducing atmospheric CO2 levels. As a result, “the alkaline solution generated by the new process could be added to the ocean” to help neutralize all the extra acid that’s been building up, “similar to how an Alka Seltzer neutralizes excess acid in the stomach.”
In other words, they’re claiming to have foudn a way to reduce the CO2 in the atmosphere as well as acidity in the ocean, and end up with lots of hydrogen usable for fuel.
Here’s the money paragraph from the abstract from the study itself:
Greg Rau, an LLNL visiting scientist, senior scientist at the University of California at Santa Cruz and lead author of the paper which appeared the week of May 27 in the Proceedings of the National Academy of Sciences (see link above), admitted that further research is needed.
“Using nongrid or nonpeak renewable electricity, optimized systems at large scale might allow relatively high-capacity, energy-efficient (<300 kJ/mol of CO2 captured), and inexpensive (<$100 per tonne of CO2 mitigated) removal of excess air CO2 with production of carbon-negative H2. Furthermore, when added to the ocean, the produced hydroxide and/or (bi)carbonate could be useful in reducing sea-to-air CO2 emissions and in neutralizing or offsetting the effects of ongoing ocean acidification.”
If it all works as advertised, though, it could be a stone to kill a lot of nasty birds.
"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," Rau said in the LLNL press release. "But the process also would produce a carbon-negative 'super-green' fuel or chemical feedstock in the form of hydrogen."What he’s saying is that given a renewable way to power this system at suitable scale -- both pretty big ifs at this point -- then not only can we efficiently and relatively cheaply remove “excess” carbon dioxide from the air, we can get “super-green fuel” in the bargain, or at least a lot of “chemical feedstock.”
So why isn’t this being done now, you wonder? Sounds like a pretty simple process, relatively speaking. As the LLNL release notes, it’s expensive as heck: “Most previously described chemical methods of atmospheric carbon dioxide capture and storage are costly, using thermal/mechanical procedures to concentrate molecular CO2 from the air while recycling reagents, a process that is cumbersome, inefficient, and expensive.”
A Better Way to Electrolyze.
The LLNL process is an improvement, Rau says, because it doesn’t need CO2 concentrated from air and stored in a molecular form, which means the LLNL system is “more cost-effective, environmentally beneficial, and safer air CO2 management with added benefits of renewable hydrogen fuel production and ocean alkalinity addition.”
If it does pan out it would be a truly momentous advancement. As Graham Templeton writes in ExtremeTech, LLNL is saying that “the water left over after we’ve squeezed out the hydrogen fuel is said to be an electrolyte solution with a very high affinity for atmospheric CO2 -- a claim that, if true, would be remarkable.”
Templeton notes that “there are currently no numbers available to quantify the efficiency of this system,” but allows that “even a moderate ability to take up atmospheric CO2 through the simple interface of air and water would be an incredible step forward.”
Maybe Just A Pipe Dream.
Templeton writes that “while it might seem like a bit of a pipe dream to just dump a bunch of bicarbonate into the sea and hope that everything evens out,” there’s a reason to suppose it might work: “The precise reaction the researchers are referring to is actually one of the most common acid-base reactions in all of nature... the carbonic acid-bicarbonate buffer is the primary acid-base buffer found in life itself.”
Obviously significant questions remain: How much energy do we need to power this process? How much carbon can we capture? Where’s the renewable energy going to come from to power all this? And as Templeton says, “what sort of water are we left with as a waste product after all this has been done?”
Keep your fingers crossed.