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This Lab-Made Mineral Just Became a Key Candidate For Reducing CO2 in The Atmosphere
Scientists just worked out a way of rapidly producing a mineral capable of storing carbon dioxide (CO2) - giving us a potentially exciting option for dealing with our increasingly overcooked planet. Magnesite, which is a type of magnesium carbonate, forms when magnesium combines with carbonic acid - CO2 dissolved in water. If we can produce this mineral at a massive scale, it could safely store large amounts of carbon dioxide we simply don't need in our planet's atmosphere.
[...] Being able to make the mineral in the lab could be a major step forward in terms of how effective carbon sequestration might eventually be. "Using microspheres means that we were able to speed up magnesite formation by orders of magnitude," says [Ian] Power. "This process takes place at room temperature, meaning that magnesite production is extremely energy efficient."
[...] With a tonne of naturally-occurring magnesite able to capture around half a tonne of CO2, we're going to need a lot of magnesite, and somewhere to put it all as well. As with other carbon capture processes, it's not yet clear whether this will successfully scale up as much as it needs to. That said, these new discoveries mean lab-made magnesite could one day be helpful – it puts the mineral on the table as an option for further investigation.
Related: Negative Emission Strategy: Active Carbon Capture
Carbon Capture From Air Closer to Commercial Viability
(Score: 3, Interesting) by VLM on Tuesday August 21 2018, @01:53AM (6 children)
From a strictly historical perspective the Romans saw their infrastructure as a mix of a welfare/jobs program and a propaganda outlet. Like if the USA delivered postal mail with Saturn-5 rockets we wouldn't be doing it to be environmentalist or economically efficient.
We could build a 10000 year concrete bridge or whatever, but it would be a heck of a lot cheaper to build a 100 year bridge 100 times.
And some very powerful people would be very pissed off.
Some epic stories from China in the last decade or so about crumbling concrete.
Just making the point that merely being able to make 1000 year concrete doesn't mean anyone will or will want to. No actual disagreement.
(Score: 2) by Runaway1956 on Tuesday August 21 2018, @02:09AM (5 children)
You say that like it might be a bad thing?
More seriously - I suspect that a lot of environmentalists don't have clue one about the production of concrete, or the alternatives to Portland. If they did, there would probably be more high profile protests at construction sites around the nation, or even around the world.
Adobe, for instance, is far more environmentally friendly than concrete, and it can be very durable. People have been using adobe since prehistory. But, we don't see major corporations dealing in adobe. It would be anathema to produce cheap, eco-friendly, durable building materials to the masses. It's much more profitable to provide concrete foundations, and cut down pine plantations to make homes with.
(Score: 2) by VLM on Tuesday August 21 2018, @08:22PM (4 children)
The masses are kinda limited to Nevada, in that it doesn't work below grade, where it rains, there there's intense freeze/thaw cycles, where there's earthquakes; still millions of people could use adobe in theory.
I suspect mass adobe use would suffer even worse from corruption and poor installation than cement. Lots of building collapses.
Cement is some pretty nasty stuff WRT environmental cost; makes it all the worse when its wasted via bad short lived design. If you're gonna "destroy the planet" by making the cement for concrete for a road, at least design the road to last longer than 20 years, etc.
(Score: 0) by Anonymous Coward on Tuesday August 21 2018, @10:38PM (3 children)
How many road surfaces in the world are actually made with portland cement, though? Does it represent a significant amount of portland cement use globally?
Most road surfaces are made with asphalt concrete, which uses bitumen (essentially the shit left over when you've finished extracting all the other useful compounds out of crude oil) as a binder. Incidentally it is also one of the most recyclable materials in use today: basically all of the bitumen can be recovered from an old road surface by heating it.
(Score: 2) by Runaway1956 on Wednesday August 22 2018, @01:25AM (2 children)
Can't speak for any other countries, but a lot of the US highways and interstate highways are concrete. Some lesser roadways, such as city streets, as well. Oftentimes, you don't see the concrete - roadways with a lot of wear on them are often resurfaced with asphalt.
https://pubs.usgs.gov/fs/2006/3127/2006-3127.pdf [usgs.gov]
(Score: 0) by Anonymous Coward on Wednesday August 22 2018, @01:53PM (1 child)
So what you're saying that for roads in the US, even if they were originally surfaced with portland cement concrete, when surface repairs are needed those repairs are often done using asphalt concrete. In other words, portland cement is typically not used for resurfacing work.
So there is 48 million tonnes of cement currently in place in US interstates, in total. That's about 1% of global production of cement which is about 4 billion tonnes per year. And it sounds like that cement is mostly from the original construction if repairs are done with asphalt... roads aren't looking like a major consumer of cement in the world.
(Score: 2) by Runaway1956 on Wednesday August 22 2018, @02:29PM
Need some clarity, I guess.
Typically, an Interstate Highway was built of concrete. After a few years use, the surface would be "profiled", that is, a big old machine would come along, and grind up the top 1/2 inch or so. A few more years use, and they put a layer of asphalt on top of the already profiled surface. Relatively quickly, the asphalt wears down - two or three years, and it's ready to be replaced. The DOT might pull that old asphalt up, or they might surface over top of it again with more asphalt. Of course, all these years, they are watching the edges of the concrete, watching for erosion, and scanning the roadway with X-rays. Nowadays, they use GPS-like satellite data, so they can see more clearly which slabs might be moving, horizontally or vertically. At SOME POINT, the DOT makes up their mind that the roadbed is no longer serviceable.
They come out, pull up all the asphalt to be recycled, then start breaking up the concrete, and hauling that off to be recycled. Strip the roadbed, reinstall drainage, rebuild the roadbed on top of that, then pour another "superslab".
I leave it to you to find out how long the "typical" slab of concrete lasts. I grew up in Pennsylvania. There was an awful lot of news during my junior and senior high days about fraud. Highways that were expected to last for 20 years and more were being torn up and replaced when I was a teen. (A bit of context - Interstate 80 was being laid down when I was born.)
Now, SOME of those problems were technical. Sharon Pa. was kinda infamous for being near impossible to build across. Apparently, they worked for months to build their stabilized roadbed across the swamp. The bed finally passed inspection, and the crews went home for the night, expecting to start forming the next morning. Problem was - next morning, the roadbed and all the equipment sitting on it had sunk out of sight, into the swamp!
But, there was a helluva lot of fraud involved, as well. Areas further up in the mountains, built on bedrock, were falling apart as well, because the contractors used low-grade mixes, and the inspectors let them get away with it. Profit, profit, profit!!
If the roads are built to the highest standards, you might expect the concrete to last 30 or 40 years. If the standards slip, 20 years is unlikely.
Generally, if you're driving on a major highway in the US, you are probably riding on or above a concrete slab. If you're seeing macadam or some other surface, that surface is just dressing on top of the concrete.
Tertiary roads may or may not have concrete under them. State highway 41, in front of my house, has none. Stabilized earth, pretty good drainage, and about three or four inches of blacktop. When the road needs resurfacing, it gets a chip&tar treatment. Towns and cities pretty much do whatever they want to do, or what their budget allows.