New Cement Process Would Produce Zero Emissions

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Cement is the world’s top construction material. However, some people don’t realize it’s a major source of emissions.

Researchers at MIT have developed a new way of manufacturing cement that eliminates emissions. This new electrochemical process drastically reduces or removes the two primary sources of carbon dioxide emissions during production.

Image credit: Rodolfo Quirós via Pexels (Free Pexels licence)Image credit: Rodolfo Quirós via Pexels (Free Pexels licence)

Image credit: Rodolfo Quirós via Pexels (Free Pexels licence)

Portland cement, the most widely used variety, gets created by exposing ground limestone, sand and clay to the heat produced by burning coal. Both coal and limestone release toxic gases when hot. The two materials contribute roughly the same amount of emissions

According to scientists, this new method could make cement without emissions-generating components.

What’s Different About This Process?

What makes this cement production method produce fewer emissions is its dependence on renewable energy, rather than coal, for the heating process.

The team’s new process requires an electrolyzer to replace the current fossil fuel-based techniques. The process requires submerging a battery connected to two electrodes in a glass of water. One wire produces oxygen bubbles and acid, while the other makes hydrogen bubbles and a base. The electricity splits the water molecules into their constituent atoms.

With the new process in effect, the team dissolves the ground-up limestone into the acid. This process emits a high-purity kind of carbon dioxide in a concentrated stream. The other electrode makes a solid form of lime, also known as calcium hydroxide. The next step involves processing the calcium hydroxide to make the cement. The resulting product is primarily calcium silicate.

No part of this process releases carbon dioxide into the environment, making it drastically different than conventional methods of cement creation. Because the carbon dioxide produced here is pure, researchers believe there’s potential for using it in other ways, such as in carbonated beverages or during oil recovery processes. Conventional cement plants emit highly contaminated carbon dioxide filled with carbon monoxide and nitrogen oxides.

Another Way to Get the Same Cement

Companies that specialize in making concrete know the cement paste and the aggregate to water ratio largely determines the quality. For example, a mixture of 15 to 20% water is typically necessary for concrete to remain strong and durable over time.

Researchers have tried to determine different techniques for making cement not associated with carbon dioxide emissions.

The MIT group, however, felt taking such a path would pose too many roadblocks. They knew people are accustomed to using cement they trust. Builders, in particular, may decide it’s too risky to consider a new type. Making the same kind of cement in a new way boosts the chances of widespread adoption, a decision that makes economic sense.

The Future of This Research

The MIT team knows they have more work to do before this new process becomes commercially viable. However, while working towards their goal, scientists may investigate ways to recombine the hydrogen and oxygen from the electrolyzing process.

Early calculations suggest possibilities of recombining them into a fuel cell or burning them for energy. If those worked, this new process would only produce cement and water vapor.

The group claims they’ve studied the feasibility of operating a manufacturing process for this cement with renewable energy. They believe this approach would only require small amounts of supplemental, non-renewable energy.

Other nations are looking at zero-emissions cement manufacturing options, too.

Norway seeks to revamp a facility to use carbon capture and storage (CCS) during cement-making. The move will initially use CCS to deal with half of the plant’s CO2 emissions, a percentage that will gradually expand.

Creating a Path to More Planet-Friendly Methods

Cement is a necessity in today’s world. However, the knowledge that it produces emissions pushed researchers to look for different production methods.

Future developments will demonstrate how societies don’t need to reduce their reliance on cement for sustainability reasons. Instead, they should investigate new methods of production that don’t involve emissions.

Written by Kayla Matthews, Productivity Bytes.


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