Monday :: Jun 29, 2009

Open Thread

by Mary

One of the largest sources of CO2 emissions today is all the concrete that we use. But today, I heard a program on sustainability that provided an interesting report on that very problem: what if we could create cement that not only didn't emit CO2, but could be used to suck CO2 out of the atmosphere? Colera cement is created by a process that is designed to suck CO2 out of the atmosphere, essentially capturing the CO2 pollution off a plant and it can used anywhere Portland cement which emits CO2 can be used.

I've posted the relevant section of the transcript from the sustainability program below the fold.

See also this analysis which provides some of the pluses and minuses for the process.


There are some obvious, big-time emitters of greenhouse gas that you can probably name off the top of your head, but here’s one you probably DIDN’T know of. It’s estimated that concrete accounts for close to 5% of the world’s CO2 emissions. Michael Prather from the Intergovernmental Panel on Climate Change explains why.

PRATHER: Concrete manufacturer basically involves taking calcium carbonate rock and driving the CO2 off it.

In the cement manufacturing process, about a ton of carbon dioxide gets put off into the atmosphere for every ton of cement that’s made. But now engineers are looking at ways to change that. Liv Haselbach (Leev HOSS el bock) is an Environmental Engineering professor at Washington State University. She’s an expert on concrete. You can tell she is, because she likes telling jokes like this

HASELBACH: Concrete isn’t really concrete in that sense, it’s a funny thing to say.

Well, no it’s not. But anyways, Liv was given about 35-thousand dollars by the National Science Foundation to find ways of making the concrete manufacturing process more carbon-neutral. She’s seized on an idea that’s basic to the chemistry of concrete.

HASELBACH: Concrete itself can reabsorb the CO2 fairly rapidly.

And not only can it absorb it, but when carbon dioxide gets inside concrete,

HASELBACH: It actually turns back into limestone.

Liv Haselbach’s grant, among other things, is designed to look into ways of using that natural process to reduce global warming.

HASELBACH: There is potential for us to build sidewalks where -- yes -- these sidewalks will suck CO2 out of the air.

And while that’s exciting enough – and who ever thought they’d hear the words “Concrete” and “Exciting” in the same sentence – that’s only part of it.

CONSTANTZ: Well what we are going to do is -- we are putting on our hard hats right now and a we are going to head out and hop in the Land Rover.

Brent Constantz is one of those people you read about in business magazines. He makes things that make life better and that make him very, very rich. Brent invented a type of concrete for orthopedic surgeons. Doctors loved it. Brent cashed in and sold the company. Then he got involved with the Woods Institute Of The Environment at Stanford, where, he came to the conclusion that

CONSTANTZ: The only way to address climate change is to do carbon capture and sequestration.

That means grabbing CO2 out of the air and putting it someplace where it can’t do any harm. Brent started a new company called Calera (suh LAIR uh), that does just that. They’ve invented a process whose impact is stunning. Potentially a total game-changer when it come to global warming. Basically, what they do is set up a cement plant next to an emitter of CO2.

CONSTANTZ: The main ones are power plants -- principally coal-fired power plants, gas-fired power plants, oil plants etc.

They grab the CO2 out of the plant, before it gets into the atmosphere and then

CONSTANTZ: Our green cements actually takes the carbon dioxide from the emissions from the power plant and converts that carbon dioxide into carbonate mineral. Maybe a simpler way to say it is: it turns the carbon dioxide into a solid, by converting the carbon dioxide to carbonate, which then becomes essentially limestone.

The carbon dioxide never reaches the atmosphere. They turn it back into rock before it ever hits the air. Right now Calera has one plant, which they set up next to a major greenhouse gas polluter.

CONSTANTZ: The power plant here at Moss Landing produces about 3.42 million tons of carbon dioxide a year. And that is equivalent to about 700,000 cars.

The work Liv Haselbach is doing would take the concrete industry and move it from being a greenhouse gas polluter to being, basically neutral. The Calera process takes it that one step farther.

CONSTANTZ: This gives the material itself a negative carbon footprint. So it is not just less bad, it is actually taking us into the negative zone.

America used 2.35 billion tons of cement in 2007. China made 1.4 billion tons. Remember; a ton of carbon dioxide gets put into the air for every ton of cement. If the Calera process was in wide use, that’s 4 billion tons of CO2 that would never reach the air. Think what that could do for global warming.

Mary :: 12:00 AM :: Comments (28) :: Digg It!