After stumbling on biofuel, algae steps up to save the concrete and cement industries from themselves (photo courtesy of Prometheus Materials).

The Algae Phoenix Rises: Biofuel Down, Concrete Up

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To the surprise of no-one, ExxonMobil finally canceled its long-running algae biofuel research program earlier this year. That’s not the end of the road for algae, though. It is popping up again in the field of bio-based, zero-emission concrete, and it could be coming soon to a building near you.

New Life For The Algae Economy Of The Future

The University of Colorado at Boulder has emerged as a hotspot for zero emission concrete research based on algae. The topic crossed the CleanTechnica radar back in 2021, when the Rocky Mountain Institute interviewed associate professor Dr. Wil Srubar III, who leads the school’s Living Materials Laboratory.

Srubar is the Chief Technology and co-founder of the green concrete startup Prometheus Materials, which spun out of the CU-Boulder research in 2021. He is credited with co-inventing the company’s core technology.

The Prometheus website is holding the details close to the vest, but Surbar told Rocky Mountain Institute that his team was researching an organism called the coccolithophore.

“They’re tiny little microalgae that form calcium carbonate shells. And they grow really rapidly. They grow in seawater. What’s really exciting is that growing calcium carbonate is a form of carbon capture and storage,” Surbar explained.

“My lab is particularly interested in taking the coccolith’s shells and using that as an input for making portland cement, rather than mining or quarrying limestone and burning off the CO2 that has been stored for millennia,” he added. “We kind of had this epiphany a few years ago — why not grow the limestone in real time and make a carbon-neutral portland cement?”

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What’s The Big Deal About Algae Concrete?

Last summer Prometheus attracted $8 million in Series A financing from an A-list group of investors that included the European life sciences and sustainability venture capital firm Sofinnova Partners as leader, along with the Microsoft Climate Innovation Fund, the architecture and engineering collective Skidmore, Owings & Merrill (SOM), the US roofing materials company GAF, and The Autodesk Foundation.

US taxpayers can also give themselves a group hug for lending a hand. In 2020 Surbar received a $500,000 grant from the CAREER program of the National Science Foundation to help push the research forward. The NSF provides a handy summary of what it all means.

“Concrete is the second-most consumed material on earth after water,” NSF observes. “The production of cement alone accounts for 2.2 billion tons — or 6% — of global carbon dioxide emissions.”

“Given that global demand for mineral aggregates for concrete materials exceeds 50 billion tons per year, a grand opportunity exists to leverage biological processes to produce carbon-storing minerals for use in cement paste, mortar, and concrete,” NSF adds.

“In contrast to traditional portland cement, Prometheus Materials’ microalgae-based bio-cement emits little-to-no CO2 and recycles 95% of the water used during its production. Following production, the bio-concrete has the ability to sequester embodied carbon throughout its lifespan,” Prometheus also notes.

As described by the NSF, the Living Laboratory at CU-Boulder has had a lot on its plate. The assigned task was not as simple as conjuring up one new concrete product. The grant covered engineered bacteria as well as algae and other photosynthetic microorganisms, with the aim of comparing the mechanical properties of various new cement paste, mortar, and concrete bio-materials with the properties of conventional materials, in addition to measuring the potential for carbon storage.

NSF To Haters: Buzz Off

The NSF grant also established the Living Materials Laboratory as the centerpiece of a recruitment and education program aimed at mentoring “a new, diverse generation of materials scientists in a Living Materials Laboratory experience that will foster the creation of a new discipline at the intersection of synthetic biology and civil engineering.”

Specifically, NSF tasked the lab with creating “graduate school pathways for lesbian, gay, bisexual, or transgender engineering students by engaging and mentoring them in interdisciplinary materials science research.”

“This project will lay the scientific foundation for the PI [Principle Investigator Wil Srubar] to achieve his long-term career goals of transforming the built environment from a carbon emitter into a carbon sink, while broadening the diversity, inclusion, education, and training of next-generation materials scientists and civil engineers,” NSF explains.

As context, when Srubar received his NSF grant, he described himself as “both a first-generation college graduate, member of the LGBTQ community and former NSF Graduate Research Fellow.”

“I am wholeheartedly committed to providing research mentorship opportunities to underrepresented students in science and engineering,” he added.

Everything Is Coming Up Algae, At Last

The latest news from Prometheus hit the wires on February 7, when the company announced that its bio-cement has passed muster with the standardization organization ASTM International, an critical step along the way to commercial production.

For those of you keeping score at home, the certifications were ASTM C129 for non-loadbearing CMUs [Concrete Masonry Units made of cement, aggregates and water] and ASTM C90 for loadbearing CMUs.

If all goes according to plan, this could be a big comeback for algae, which has been getting some bad press of late. Aside from the massive Sargassum algae bloom threatening Florida, in February ExxonMobil finally shut the door on its on-again, off-again algae biofuel research project, apparently in favor of squeezing more life from its natural gas resources.

Well, too bad for them. They will be missing out on other emerging algae markets. The Georgia Institute of Technology, for example, is developing a bio-based rocket fuel from algae, with a trip to Mars in mind. Deploying algae biofuel as a carbon capture system for industrial waste gas is another angle.

The US Department of Defense experimented with new biofuels of various kinds during the Obama administration, including used cooking oils as well as algae. Those efforts all but sank out of view during the Trump administration, but suddenly algae biofuel is back with a roar.

In addition to the Air Force, Air Company has support from JetBlue, Virgin Atlantic, and the startup Boom Supersonic.

United Airlines has also jumped into the field. Earlier this month, the company announced a $5 million investment in the algae biofuel company Viridos (formerly Synthetic Genomics), which has introduced new technology for accelerating the production of oil from microalgae.

What now, ExxonMobil?

UPDATE: An earlier version of this article included the firm Air Company as an example of algae-derived fuel. That was an error. Air Company makes sustainable aviation fuel using carbon CO2 captured from fermentation and industrial alcohol plants prior to it being emitted into the atmosphere. More information is available here.

Photo (cropped): Bio-based concrete from algae courtesy of Prometheus Materials via businesswire.com.


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Tina Casey

Tina specializes in advanced energy technology, military sustainability, emerging materials, biofuels, ESG and related policy and political matters. Views expressed are her own. Follow her on LinkedIn, Threads, or Bluesky.

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