Scientists convert carbon-dioxide emissions to useful building materials, using genetically altered yeast

Sep 22, 2010 by Anne Trafton, MIT News
Carbon dioxide is bubbled into a solution of mineral ions. Photo: Patrick Gillooly

Every year, about 30 billion metric tons of carbon dioxide are pumped into the Earth’s atmosphere from power plants, cars and other industrial sources that rely on fossil fuels. Scientists who want to mitigate carbon dioxide’s effects on global climate have started experimenting with storing the gas underground, a process known as carbon sequestration. However, there are still many unknowns surrounding the safety and effectiveness of that strategy.

MIT engineer Angela Belcher is now taking a new approach that would not only remove from the environment, but also turn it into something useful: solid carbonates that could be used for building construction.

“We want to capture carbon dioxide and not put it underground, but turn it into something that will be stable for hundreds of thousands of years,” says Belcher, the W.M. Keck Professor of Energy.

By genetically engineering ordinary baker’s yeast, Belcher and two of her graduate students, Roberto Barbero and Elizabeth Wood, have created a process that can convert carbon dioxide into carbonates that could be used as building materials. Their process, which has been tested in the lab, can produce about two pounds of carbonate for every pound of carbon dioxide captured. Next, they hope to scale up the process so it could be used in a power plant or industrial factory.

Carbon dioxide combines with the mineral ions to form solid carbonates. Photo: Patrick Gillooly

Biological inspiration

To create the yeast-powered process, Belcher drew inspiration from marine animals that build their own rock-solid shells from carbon dioxide and mineral ions dissolved in seawater. (Her 1997 PhD thesis focused on the abalone, a sea snail that produces exceptionally strong shells made of .)

Funded by the Italian energy company Eni, the new MIT process for turning carbon dioxide into carbonates requires two steps. The first step is capturing carbon dioxide in water. Second, the dissolved carbon dioxide is combined with mineral ions to form solid carbonates.

don’t normally do any of those reactions on their own, so Belcher and her students had to engineer them to express genes found in organisms such as the abalone. Those genes code for enzymes and other proteins that help move carbon dioxide through the mineralization process. The researchers also used computer modeling and other methods to identify novel proteins that can aid in the mineralization process.

“We’re trying to mimic natural biological processes,” says Belcher. But, “we don’t necessarily want to make the exact same structure that an abalone does.”

Some companies have commercialized a process that captures carbon dioxide and converts it to solid material, but those efforts rely on a chemical process to capture carbon dioxide. The MIT team’s biological system captures carbon dioxide at a higher rate, says Barbero. Another advantage of the biological system is that it requires no heating or cooling, and no toxic chemicals.

Next, the team plans to try scaling up the process to handle the huge volumes of carbon dioxide produced at fossil-fuel-burning power plants. If the process is successfully industrialized, a potential source for the mineral ions needed for the reaction could be the briny water produced as a byproduct of desalination, says Barbero.


This story is republished courtesy of MIT News (web.mit.edu/newsoffice/), a popular site that covers news about MIT research, innovation and teaching.

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danman5000
not rated yet Sep 22, 2010
This seems like a lot of work to do exactly the same thing as bubbling CO2 through lime water. Seriously, even the yield is the same - one pound of CO2 bubbled through an excess of lime water produces 2.27 pounds of calcium carbonate. So why exactly is this research significant?
Eikka
not rated yet Sep 22, 2010
What they didn't adress is, where do they get the calcium? As far as I know, most of it is trapped in carbonate minerals.

So they'd have to release carbon dioxide to capture it back again?
Alburton
not rated yet Sep 22, 2010
well,yeast must be less expensive than limewater as it grows nearly on its own.(unless companies put the genes responsible for reproduction out to assure sellings)
But ,seriously,what are the risks of inputting our own genetical modifications and as such species (arent they?) in the ecosystem?Because it is obvious that this information contained in the genes will not only be useful for industries but also slowly spread throughout the world.
Just as everything else does.
Is this risky? Even if it "just" means losing the psicological relief of treating with "real" nature?
I am really asking.I dont know anything about how genes,or proteins,or whatever ammount of strange stuff a bloody biological body has, works.
Thanks in advance for answering.
TJ_alberta
not rated yet Sep 22, 2010
I wonder what mineral ions can be converted to carbonates by the yeast, if they are chlorides and sulfates then I can see some useful applications. Then of course it would be good to know what happens to the anion. I do not believe that the manufacture of calcium carbonate is the objective, converting an industrial by-product, for example gypsum, to a carbonate might be useful in some areas, particularly if the sulfur is recoverable in a usable form. Putting CO2 through salt brine and letting the yeast convert it into soda ash may be economically sound. Otherwise ... I think we already have plenty of limestone, chalk, etc.
kaypee
not rated yet Sep 23, 2010
Gotta use hard water to make this work.
GSwift7
5 / 5 (3) Sep 23, 2010
"Another advantage of the biological system is that it requires no heating or cooling, and no toxic chemicals"

They are saying this like it's a bonus, but it's really not. I work in the commercial baking business. My plant provides a significant portion of the bread in the South East US. I know yeast. Yeast doesn't handle heat well at all. Using this to treat power plant exhaust would mean that you would need to cool the exhaust. Also, the toxic chemicals such as sulfur in the exhaust would kill the yeast.

"well,yeast must be less expensive than limewater as it grows nearly on its own"

Actually that's wrong. Baker's yeast is expensive on commercial scales. It's hard to keep it alive. You need big fermentation tanks with delicate temperature controls, like at a brewery. It's a science and an art. Yeast is the most expensive ingredient in our bread; more expensive than butter or enzymes. Yeast batches also don't last much more than a day

This probably won't work
GSwift7
5 / 5 (3) Sep 23, 2010
They are also not mentioning the fact that you have to feed yeast. This article doesn't say what they are going to use to feed the yeast. Wheat gluten, sugar, starch. That's all expensive stuff. Yeast is almost half of the cost of making a loaf of bread. We make well over a million pounds of bread each week, and we have to empty out our yeast system and clean it out twice a week. I assume that you can't shut down a power plant twice a week so that you can clean the yeast system, so you would need at least two complete systems. It's a mechanically complex system that requires keeping the yeast within a very narrow temperature range while you store it and pump it around. Like +/- 5 degrees at most.
Alburton
not rated yet Sep 24, 2010
Thank you GSwift7 for such insightful comments
Planetbob99
not rated yet Sep 27, 2010
"Using this to treat power plant exhaust would mean that you would need to cool the exhaust. Also, the toxic chemicals such as sulfur in the exhaust would kill the yeast."


A CO2 producer wouldn't do this on-site. They'd buy 'sequestration' contracts that countered their production.

Eikka
not rated yet Sep 27, 2010
Baker's yeast is expensive on commercial scales. It's hard to keep it alive.


Ever thought that it might be that way by design? If it's too difficult for the bakeries to keep alive, they'll keep buying it.

There are yeast strains that are hard to kill. I know my grand-grandmother used some that had survived generations by leaving some of the dough behind and using it to start the next batch.