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Splitting Water For Fuel While Removing CO2 From the Air (arstechnica.com)
An anonymous reader quotes a report from Ars Technica: A new study led by the University of California, Santa Cruz's Greg Rau highlights another tool for our CO2 removal toolbox: splitting seawater to produce hydrogen gas for fuel while capturing CO2 with ocean chemistry. In electrolysis, a device powered by electricity is used to split H2O, producing hydrogen gas. Several chemical modifications to this process have been proposed that can also grab CO2 from the atmosphere. Like the idea of using biofuels, this represents a "win-win" by producing an energy resource while capturing CO2, bringing the cost down. [T]he gist is that atmospheric CO2 goes into the ocean as bicarbonate -- which won't acidify the water or harm ecosystems. So if you power the electrolysis process with renewable energy, you can turn solar/wind/hydroelectric energy into hydrogen fuel while also removing CO2 from the air.
The new study focuses on a basic estimate of the cost and maximum potential of this technique. First, the researchers worked out its efficiency of CO2 capture -- about 0.3 tons captured per gigajoule of electricity input, including the losses from quarrying and crushing rock. That's around 10 times greater than biofuel schemes, but it depends on the assumption that there is demand for all the hydrogen fuel you make. The hydrogen can be used by vehicles, and there's the possibility of using hydrogen as a type of storage for the electric grid -- using excess power to make hydrogen that can run a power plant when needed. So it's not too farfetched that demand could rise to meet supply. The researchers' back-of-the-envelope estimate puts the cost of this system at between $3 and $161 per ton of captured CO2, depending on which type of renewable energy powers it. The study has been published in the journal Nature Climate Change.
The new study focuses on a basic estimate of the cost and maximum potential of this technique. First, the researchers worked out its efficiency of CO2 capture -- about 0.3 tons captured per gigajoule of electricity input, including the losses from quarrying and crushing rock. That's around 10 times greater than biofuel schemes, but it depends on the assumption that there is demand for all the hydrogen fuel you make. The hydrogen can be used by vehicles, and there's the possibility of using hydrogen as a type of storage for the electric grid -- using excess power to make hydrogen that can run a power plant when needed. So it's not too farfetched that demand could rise to meet supply. The researchers' back-of-the-envelope estimate puts the cost of this system at between $3 and $161 per ton of captured CO2, depending on which type of renewable energy powers it. The study has been published in the journal Nature Climate Change.
The gist that atmospheric CO2 goes into the ocean as bicarbonate and won't acidify the water is not correct.
From the sub-heading of TFA:
"Technique could be practical enough to scale."
The real "Libtards" are the Libertarians!
If you're generating electricity, it's much more efficient to use that to charge electric cars, and reduce the amount of CO2 that goes into the atmosphere, rather than using inefficient methods to get it out.
Also, hydrogen fuel is a dumb idea. There is no infrastructure, conversion/storage is inefficient and it makes metals brittle. It's much better to focus on electric battery cars.
To possibly produce jet fuel from sea water on aircraft carriers while underway. In addition to obtaining hydrogen and oxygen from electrolysis of sea water you also liberate some of the carbon dioxide that's dissolved in solution as part of that sea water. The combination of hydrogen, oxygen and carbon dioxide can, with sufficient energy input, most likely from the nuclear reactors that power the ship, be converted to a mixture of carbon monoxide, hydrogen and some carbon dioxide in a mixture known as SynGas or "synthesis gas". From there it can be converted via the Fischer Tropsch Process into heavier hydrocarbons and eventually into a mixture of longer chain hydrocarbons approximating JP-5 jet fuel.
Why aren't we already doing this on land you might ask? Well, in a word, because it's expensive in both industrial plant and equipment and also from an energy input perspective. Much more expensive than simply pumping crude oil out of the ground and refining it. However, that matters less on a ship underway at sea, away from land supplies, and with nuclear energy to spare where cost is less of a factor than ease of supply, which is militarily advantageous.
So assuming the low-end cost of $3 per ton of CO2, we're talking a mere $3,030,000,000,000 to mitigate anthropogenic CO2 emissions Sounds like just the type of pragmatic negative emissions technology we so desperately need!
Until you can quantify the costs of *not* mitigating anthropogenic CO2 emissions or identify the value of this method relative to that of other mitigation techniques it is impossible to gage the absolute value of this particular method.
I wish I'd known this was publishable. I wrote up a report on this years ago while working for the Navy... they actually funded someone to try this out, I think.
Short version: it's expensive. Slightly longer version: chlorine is a problem. If you think you're electrochemically evolving hydrogen gas strait from sea water, you're probably just going to kill a lot of people instead. Catalysts are the answer. Bonus detail: the ocean (for a few reasons) concentrates carbon. There's a lot of carbon in there, and the core of this idea is very good.
Palm oil production uses a lot of land though. This typically means deforestation. As most of the world's arable land is already used up, I'd prefer it if electricity and fuel production could be compact facilities that don't use up land that's needed for farming and indigenous animals' habitat.
$3 trillion is a drop in the bucket and sounds way too good to be true, so I think you've got your numbers wrong. Climate change is projected to cost the world economy $33 trillion a year by 2050, and already costs the USA alone $300B a year (couldn't find a figure for current worldwide annual cost, but you can assume that it must in the trillions).
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Because then you might learn why the range is so large (spoiler: cheap input energy = cheap captured CO2; expensive energy = expensive captured CO2).