Every year, about two gigatons (2,000,000,000,000 Kg) of CO2 are released into the environment due to the production and use of cement. According to a report by the United States Environmental Protection Agency (EPA), cement ranks third among the top ten sources of industrial pollution. An ecological cement made from algae seems to be the solution to such problems.
Surprisingly, a team of researchers claim that we can end these carbon emissions from cement overnight by replacing traditional cement with their new eco-algae cement (a substance made using living organisms).
A team of researchers from the University of Colorado at Boulder, USA, in association with their colleagues from the National Renewable Energy Laboratory (NREL) and the University of North Carolina Wilmington (UNCW), have developed a unique point-neutral method of view of carbon, by which Portland cement can be produced from biologically grown limestone.
This new material can drastically reduce environmental pollution caused by construction activities around the globe, he writes Interesting Engineering.
Traditional cement versus ecological cement from algae
Concrete which is mainly made using Portland cement, water and gravel is considered the most consumed material from the globe, next to water. Whether it is North America, Europe or Asia, construction activities cannot be imagined without concrete and especially without Portland cement.
“We make more concrete than any other material on the planet, and that means it impacts everyone’s lives,” said Wil Srubar, principal investigator and professor at CU Boulder, emphasizing the importance of concrete.
However, it is very unfortunate that the commercial production of Portland cement involves the incineration of large quantities of limestone, leading to massive CO2 emissions. Moreover, the air quality in the area where the cement is produced is also severely compromised as the burning of limestone releases various pollutants and toxic gases into the air.
How did the idea of ecological cement from algae come about?
The solution to this problem occurred to Professor Wil Srubar in 2017 during a trip to Thailand.
Professor Srubar noticed during his trip calcium carbonate structures built naturally around coral reefs. He knew that limestone is also made of calcium carbonate. Looking at the CaCO3 deposits, it occurred to him that maybe the limestone could also be grown naturally instead of being quarried. “If nature can grow limestone, why can’t we?” he asked himself.
When he returned to the US, he and his research team decided to cultivate microalgae called coccolithophores. Members of this species of algae are able to give rise to biogenic limestone by creating calcium carbonate deposits during photosynthesis.
Faster and cheaper production
The researchers noted that unlike natural limestone, which takes millions of years to form underground, the biogenic version created by coccolithophores could be produced in real time.
In addition, the coccolithophores produced calcium carbonate in less time compared to the coral reefs Professor Srubar observed in Thailand. The raw material required for the formation of biogenic limestone in seawater included only dissolved carbon dioxide and sunlight. Also, because microalgae can survive in both salt and fresh water bodies, they can be used to grow limestone almost anywhere in the world.
Algae cultured limestone is the future
The researchers claim that the production of limestone with coccolithophores is so feasible that if you want to meet the total demand for cement in the United States, all you have to do is allow the coccolithophores to multiply in a body of water that covers an area of about 8,000 square kilometers. This would occupy only 0.5% of all available land in the country.
Surprisingly, the production of ecological cement from algae is not only carbon neutral, but even negative, because microalgae remove carbon dioxide from the environment and store it in the form of calcium carbonate. Therefore, concrete made from this cement could usher in a new era of sustainable construction around the world.
“For the industry, now is the time to solve this very serious problem. We believe we have one of the best solutions, if not the best solution, for the cement and concrete industry to address the carbon issue,” said Professor Srubar.