Researching How To Turn Buildings Into ‘Carbon Storage Structures’

Written by Susannah Shoemaker on August 5, 2022. Posted in Current News

The National Renewable Energy Laboratory (NREL) has been selected to receive over $5.4 million from the U.S. Department of Energy Advanced Research Projects Agency-Energy (ARPA-E) for the development of technologies that can transform buildings into carbon storage structures.

The funding is part of ARPA-E’s Harnessing Emissions into Structures Taking Inputs from the Atmosphere (HESTIA) program, which aims to address barriers to designing and constructing ‘carbon-storing buildings’.

The building construction sector is responsible for a significant fraction of total annual ‘greenhouse gas’ emissions in the United States, making it an important target for decarbonization—as well as one of the most difficult sectors to decarbonize.

Within the HESTIA program, NREL researchers will develop ways to increase the total amount of carbon stored in buildings to create carbon sinks, which absorb more carbon from the atmosphere than the amount released due to manufacturing of building materials and the construction process.

Of the 18 projects funded, NREL received two prime awards and is a sub-awardee on a third.

Insulation You Can Grow

A team led by Robbin Garber-Slaght at NREL and co-principal investigator Philippe Amstislavski at the University of Alaska Anchorage received nearly $2.5 million in HESTIA funding to develop cost-effective, bio-based insulation materials. The project, “Celium: Cellulose-Mycelium Composites for Carbon Negative Buildings/Construction,” will create carbon-negative insulation by combining foamed cellulose with mycelium—the root network of fungi.

“The idea behind the project is that we’re taking cellulose and binding it together with mycelium,” said Garber-Slaght, a sustainable buildings engineer at NREL’s Cold Climate Housing Research Center. “What’s more carbon-negative than insulation you can grow?”

The NREL team has been working with the University of Alaska Anchorage for nearly six years to refine the technology. The group is focusing on cellulose specific to Alaska—a market in which insulation can represent 30–50 percent of the cost of home building supplies.

“For this technology, I’m the end user,” said Garber-Slaght, who lives and works in Fairbanks, Alaska. “Buildings in Alaska are incredibly inefficient, and trying to bring them up to any level of efficiency is very difficult. Our goal is to develop modular, portable fabrication units, so that we can harvest local trees or cellulose and develop insulation on site. Coming up with something that doesn’t have to be shipped represents a huge savings, both costwise and energywise.”

In addition to the cost and energy savings, the new method for creating insulation also has a thermal performance that makes it comparable to plastic foam—bringing the team closer to a direct (and cleaner) replacement for plastic insulation.

“We’re finally to a point where the technology is close to something we can commercialize,” Garber-Slaght said. “Three years from now, we intend to have a marketable insulation product. Five years from now, I’d like to see modular fabrication out in rural communities. And 10 years from now, I hope that we’re able to retrofit every building in Alaska.”

In addition to the University of Alaska Anchorage, the NREL team has been working with the VTT Technical Research Center of Finland and the U.S. Department of Agriculture’s Forest Products Laboratory as collaborators. Although Garber-Slaght is based in Alaska, the team has a robust collaboration with NREL’s Golden, Colorado, office. Key NREL contributors include Peter Ciesielski, Mike Himmel, Gokulram Paranjothi, and Ryan Tinsley.

Carbon-Negative Concrete

NREL Researcher Wale Odukomaiya and his team received approximately $1.8 million in funding for their project, “High-Performing Carbon-Negative Concrete Using Low Value Byproducts from Biofuels Production,” which focuses on decarbonizing the concrete used for building construction.

The project aims to create new, bio-based supplementary cementitious materials (SCMs) that can replace a significant amount of cement that is used in concrete. The new, bio-based SCMs will enable the carbon dioxide (CO₂) sequestered from the atmosphere by the native biomass to be locked away in concrete. The team chose to focus on cement—the “glue” that holds the other constituents of concrete together—because of its significant carbon impact.

“The use of cement in concrete is responsible for about eight percent of global ‘greenhouse gas’ emissions caused by humans. That’s equivalent to 40 percent of the United States’ emissions, and twice Japan’s emissions,” said Odukomaiya, a researcher in NREL’s Building Energy Science group. “Concrete is the second-most consumed material globally after water. And most of its emissions—between 80 and 85 percent—come from the cement that is used in concrete.”

The team is leveraging the low-value byproducts from another NREL project—Sustainable Aviation Fuel From [i] Renewable Ethanol (SAFFiRE)—to create LignoCrete, their new, lower-carbon concrete.

“If the SAFFiRE process scales the way we think it will, then we’ll have enough byproducts for LignoCrete to replace between 20 and 60 percent of the concrete used in the United States annually,” Odukomaiya said. “There are a few existing SCM options for cement substitution, but most of them don’t have the potential to scale to such quantities, and their supply is tied to other ‘polluting’ industries, such as coal and steel.”

In addition to developing concrete with a lower ‘carbon footprint’, the team also hopes to demonstrate improved strength and increased thermal insulation.

“We’re excited for the potential to use a more insulative concrete in buildings to improve their thermal performance,” Odukomaiya said. Most residential buildings have foundations and basement walls made from concrete, so there’s a lot of opportunity there.”

As with NREL’s other ARPA-E projects, collaboration and industry partnerships are key. The team is partnering with Carbon Upcycling Technologies (CUT) and the University of Colorado Boulder to develop and characterize their new concrete. CUT’s technology will allow the team to enhance the properties of their bio-SCMs while enabling additional CO₂ sequestration.

“In addition to our industry and university partners, we have a really interdisciplinary team across several centers at NREL,” Odukomaiya said. “This is really a team effort.”

From Microalgae to Cement

NREL is also contributing to a University of Colorado Boulder-led project on biogenic-limestone-based cement, titled “A Photosynthetic Route to Carbon-Negative Portland Limestone Cement Production.” Of the $3.2 million awarded for this project, the NREL team—led by Michael Guarnieri—is set to receive $1.2 million.

The project, led by the University of Colorado Boulder’s Wil Srubar, aims to manufacture and commercialize a carbon-storing portland limestone cement using biogenic limestone—a type of limestone that uses biogenic cement clinker derived from coccolithophores, microalgae that sequester carbon dioxide via photosynthesis and calcification, to store carbon.

“At present, most cement-related CO₂ emissions are caused by calcining quarried limestone to CaO, which releases CO₂. So it’s a pretty heavy ‘greenhouse-gas’-emitting process,” Guarnieri said. “The potential to generate a green alternative is really exciting.”

The project will leverage NREL’s existing capabilities in algae engineering and cultivation. For the past decade, NREL’s algae research has been working toward commercialization of algal biofuels. But now this work is finding new applications.

“The foundation we have built on NREL’s algae platform will enable a lot of this work in this new space. We’ve spent years developing broad host-range genetic tools that will improve strains used to make this cement,” Guarnieri said. “It really shows the broad potential impact of work we do at national labs.”

The team already has a pathway to commercialization in place via their industry partner, Minus Materials. The University of North Carolina Wilmington is also collaborating on the project, providing expertise in coccolithophore cultivation. The team’s goal over the funding period is to demonstrate that the integration of components is economically viable.

“Much of this proposed work lies in the integration of established, disparate technologies, but the overarching process is novel,” Guarnieri said. “And the sustainability and potential life-cycle impact of this work is massive.”

See more here: nrel.gov

Header image: NREL

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