New Material Can Selectively Capture CO2

Socguy brings us a story from CBC News about a recently developed crystal that can soak up carbon dioxide gas "like a sponge." Chemists from UCLA believe that the crystals will become a cheap, stable method to absorb emissions at power plants. We discussed a prototype for another CO2 extraction device last year. Quoting: "'The technical challenge of selectively removing carbon dioxide has been overcome,' said UCLA chemistry professor Omar Yaghi in a statement. The porous structures can be heated to high temperatures without decomposing and can be boiled in water or solvents for a week and remain stable, making them suitable for use in hot, energy-producing environments like power plants. The highly porous crystals also had what the researchers called 'extraordinary capacity for storing CO2': one litre of the crystals could store about 83 litres of CO2."

Measuring a gas in litres?

[Anonymous Coward]

Ok I'm the first to admit I haven't RTFA, but does it strike anyone else as pointless to talk about "83 litres" of CO2? It depends how much you compress it, and if it's absorbed in a 1l crystal, it clearly is no more than 1l. It would be a lot more meaningful to talk about the MASS ratio.

Re:Measuring a gas in litres?

[Anakron]

That's 83 liters at STP.
Carbon dioxide weighs in at 1.98 grams/L at STP.
1.98*83 = 164.34 grams

They're absorbing 164.34 grams in 1 liter of the crystals. Definitely underwhelming.

They would fill one room of your house every year

[giafly]

• The average US household produces 7.5 tons [whatsmyco2.com] of CO2 equivalents per year.
• The density of C02 is 1.799 kg/m3 [answers.com]
• So the average US household produces about 7.5*1000/1.799 m3 of CO2 = 4,169 m3 = 4,169,000 litres
• One litre of the crystals could store about 83 litres of CO2.
• So per family requires 4,169,000/83 = 50,228 litres of crystals per year
• I guestimate the average house (of say 10 rooms) has a floorspace of about 1500 ft2 = 150 m2, with each room being 10 ft or 3 m high,
• So the average house is 450 m3 = 450,000 litres, split between 10 rooms.

These crystals would about fill one room of every house every year, floor-to-ceiling.

As about half the other commentators have already said, this does not allow for the financial and environmental costs of producing these crystals.
They might even cost more CO2 to produce than they store.

Re:Measuring a gas in litres?

[Sinbios]

Well given that 1 mol of gas in STP is 22.4L, 83L of CO2 comes to about 3.7 mol. The molar mass of CO2 is about 44 g/mol (12 + 16 + 16), so 83L comes to about 162.8g. Now I don't know what the density of this crystal is, but it's hard to believe that it's less than 0.1628g/cm^3, at which point the absorption mass ratio is 1:1. So I think it's safe to say that the absorption ratio will be more than 1:1 (that is, more crystal mass is required to capture a significantly smaller mass of gas).

I'm guessing they decided to go by the volume ratio of 1:83 to hype it up a bit (Wow! That must be a lot!), but anyone who's had basic chemistry education would know that gas densities are so low that a high volume compared to a solid means nothing.

More detailed link Re: . affect ... environment?

[Precipitous]

I doubt that long term studies have been completed. It doesn't seem like ZIFs are extremely new, this process for creating them and this particular variation are new. That said, several other sources provide better information than the CBC link and speak directly to your question. The CBC article states in first paragraph: "the crystals are non-toxic and would require little extra energy from a power plant."

http://www.sciencedaily.com/releases/2008/02/080214144344.htm/ [sciencedaily.com] Suggests that this looks much cleaner than existing state of the art:

Currently, the process of capturing carbon dioxide emissions from power plants involves the use of toxic materials and requires 20 to 30 percent of the plant's energy output, Yaghi said. By contrast, ZIFs can pluck carbon dioxide from other gases that are emitted and can store five times more carbon dioxide than the porous carbon materials that represent the current state-of-art.

Yaghi's initial idea of what to do with the material afterwards appears to involve geologic storage.

It's also always useful to hunt down the primary source. I think this PDF [ucla.edu] is it (I only skimmed).

Re:Very Good...

[dubl-u]

Well, you get up to 21 pounds of CO2 from a pound of crude oil - a 21:1 increase in "stuff". This sponge apparently can do a 1:83 reverse, so the whole system appears to be a 21:83 savings in space underground. Why not pump it right back into the ground?

That is so wrong that I am forced to suspend your Slashdot license.

First, that page page doesn't say "pound of crude oil"; it says "gallon". That's like 7.5 pounds of oil. So that's a 3x increase in stuff. (Which some would call "mass".) Then these crystals do 1:83 in volume, but more like 10:11 in mass. So to get rid of your pound of crude oil, you'd need about 30 pounds of these crystals.

Please go study Dimensional Analysis [tamu.edu] (aka the unit-factor method or the factor-label method). Once you have mastered that, you will be permitted to post on science-y topics again.

Re:I already have a CO2 storage device

[MightyYar]

I once worked at a materials lab that studied how things hold up in a marine environment, and I grew up on the ocean. Nothing lasts very long. Not stainless steel, not titanium, and certainly not any kind of mechanism. Constant maintenance and replacement is required in a marine environment, and this is one of the reasons that tidal power has been so slow in coming.

And this is without getting into big storms, which can wipe out a whole island - let alone some man-made fixture.

Re:I already have a CO2 storage device

[wumingzi]

Dude, you really need to cut back on the hydro, in more ways than one.

A pyramid is a static structure. All it has to do is sit year after year.

A power-generating station is full of moving parts. Things with moving parts break down over time. You may want to look at this handy informational link [usbr.gov] which shows maintenance over time on our local power plant. (since it's run by falling water, it provides some of the world's cheapest power, regardless)

When you start talking about tidal power, you are talking about putting devices which sit in salt water day after day. Go find someone who owns a boat. ANY boat, large, small, freighter or dinghy and talk about this idea of "set it and forget it". Watch as peals of laughter come rolling from their mouth. Boat owners in this part of the world (US Pacific Northwest) will pay a substantial rental premium to moor their boats in fresh water because it saves so much money on maintenance.

Finally, remember that electricity is like no other commodity on earth. You can not store it for a rainy day. You use it when it's generated, or not at all. Even fish (our other highly perishable commodity) can be canned or packed in salt. Good luck doing that with electricity.

Yes, oil gets some subsidies. Yes, euphemistically named "energy companies" almost certainly throw their weight around to discourage development of alternative energy sources. These are fairly small market-distorting effects which reinforce (but do not change) an underlying fact: historically, petroleum has been the cheapest and most flexible means of generating energy. While we get spoiled in this part of the world by abundant hydropower, there are some fairly serious environmental consequences (check out our vanishing salmon runs!) and hydro is a one-off. Once you've dammed the river, you're done. You can't scale this solution forever.

While more needs to be done with alternative energy sources, there seems to be this meme running around that there is cheap power floating around which is being withheld from the people by "The Man". Standing in the way of that cheap power in reality is not some gigantic conspiracy, but some really tough unsolved engineering problems (i.e. how do you store enough energy to power a city for when the sun don't shine or the wind don't blow? A big pile of batteries doesn't really work).

Re:Solution without a Problem

[Waffle Iron]

It never actually gets around to explaining why these scientists don't think the ice core data throws the link into question.

If you understood the article, it should be pretty obvious that CO2 likely didn't trigger the end of the last few ice ages given that there probably weren't any large releases of CO2 like we're making now. (And before anybody gets any big ideas: Volcanoes aren't the culprit. They release a tiny fraction as much CO2 as humans.) As the article points out, the changes likely were triggered by other factors like changes in the earth's orbit.

If the CO2 didn't trigger the changes, but does participate in a positive feedback loop, then of course it would lag the temperature. But that has nothing to do at all with the question of whether an increase in CO2 levels could also trigger a warming cycle.

Re:Solution without a Problem

[Waffle Iron]

The answer "because humans are emitting lots of CO2" doesn't cut it. Why aren't the natural causes of the past the causes today?

They still are. But you, like so many others, seem to be completely ignorant of the concept of rate of change. Humans are changing the CO2 levels orders of magnitude faster than natural factors have in the past, so those effects get lost in the noise.

So "humans are emitting lots of CO2" does cut it.

Re:Or just liquify it.

[budgenator]

Where the new zeolite will come in handy is getting the CO2 concentrated enough for the compressors; the real use of zeolites is to first absorb, then later release. The 64 thousand dollars question isn't how easy it is to get the CO2 into the zeolite, but how easy is it to get the CO2 back out of the zeolite to recharge it for reuse.

Re:I already have a CO2 storage device

[Anonymous Coward]

Pumped hydro is insane. I can't imagine what your power loss is on taking water that you've run downhill and running it uphill again. Almost certainly in excess of 100%. If not, you have a perpetual motion machine on your hands. Go forth!

To pull out one cite [electricitystorage.org] from a quick Google search [google.com], pumped hydro is around 75-85% efficient. In other words, you get back about 75-85% of the energy you used to pump the water uphill when you let it run back down again. That's pretty decent when you realise that the wear and tear is significantly less than chemical-based storage methods (like batteries). Flywheels can get up to around 90% according to Pikiwedia [wikipedia.org].

So that takes care of the "lose too much in storage" argument. As for the loss in transfer, you build the storage close to where the energy will eventually be used. Losses in transmission will occur regardless, so it's not a major concern comparatively. It comes down, in other words, to the cost of building these things in an environment where we already have large scale coal and fission plants to provide "baseload" power - in other words, the incentive to build energy storage just isn't there at the moment. Which is a damn shame, IMO.

Re:I already have a CO2 storage device

[dryeo]

Pumped hydro is insane. I can't imagine what your power loss is on taking water that you've run downhill and running it uphill again. Almost certainly in excess of 100%. If not, you have a perpetual motion machine on your hands. Go forth!

You don't use hydro to pump the water. In this thread the talk is about tidal power. Tidal power runs all night so you store the power for peak times by pumping water uphill. Wind is sorta the same, doesn't happen when you want it always so when it does get windy you store the power behind a dam for peak need.