Grantee Research Project Results
Final Report: Low Embodied Carbon Wallboard Made with Biochar
EPA Contract Number: 68HERC22C0028Title: Low Embodied Carbon Wallboard Made with Biochar
Investigators: Draper, Kathleen
Small Business: Cinterest LLC
EPA Contact: Richards, April
Phase: I
Project Period: December 1, 2021 through May 31, 2022
Project Amount: $100,000
RFA: Small Business Innovation Research (SBIR) Phase I (2022) RFA Text | Recipients Lists
Research Category: Small Business Innovation Research (SBIR)
Description:
The carbon impact of residential and commercial building materials is substantial. Wallboard is used in enormous quantities and comes with a considerable carbon footprint. Adding biochar to wallboard (BWB) could convert walls from high embodied carbon facades to large-scale, above-ground carbon sinks while also potentially offering enhanced features over contemporary wallboard options. The purpose of the research was to formulate and test various types of biochars combined with different binders and identify composites that meet or exceed performance of commercially available wallboard.
For BWB materials to compete effectively against conventional gypsum drywall and newer alternatives, Cinterest LLC addressed two compelling research questions in our Phase I SBIR project:
- Is the mechanical and physical performance of BWB comparable with commercially available drywall and newer alternatives with lower embodied carbon?
- What are the key variables related to material formulation and processing parameters that would allow the optimization of properties for our proposed panels in a cost-effective manner?
To derive answers to these questions, a technical and commercial research plan was formulated and executed with our partners at Rochester Institute of Technology (RIT).
A total of 23 different composites were formulated, comprised of various combinations of biochar and gypsum, and some also incorporated innovative organic binders and inorganic fillers that have the potential to further reduce the embodied carbon of the final BWB material. All in-house BWB samples as well as three commercially available wallboard materials were tested following ASTM standards for mechanical performance (edge hardness, nail pull resistance and flexural strength), core water uptake, and thermal conductivity. The three most promising composites based on performance, manufacturability and carbon sequestration potential were scaled-up.
Summary/Accomplishments (Outputs/Outcomes):
1. Reviewed current wallboard material specifications for different types of commercial products and developed a functional specification for BWB proof-of-concept. A review of both information related to commercially produced wallboard and peer-reviewed literature on this topic was conducted to identify the key specifications to be measured and relevant performance ranges. Also, a specification was developed that will be used as a target for the properties of BWB and to serve as a benchmark for ongoing BWB development.
2. Identified key biochar properties that influence wallboard performance. We evaluated a number of formulations and process parameters for the proposed concepts and included an extensive characterization protocol following several relevant ASTM standards. This approach enabled the project to leverage Cinterest's extensive experience with creating, optimizing and analyzing different types of biochar used in a wide variety of end uses, including its use in roof tiles, bricks, water filtration, concrete, plaster, paper, printer inks and other industrial uses. Our partners at Rochester Institute of Technology (RIT) contributed their extensive laboratory facilities and expertise in formulating and testing composite materials. The partnership with RIT provided advanced testing equipment and methods, as well as mixing and molding for sample preparation.
3. Identified and tested organic binders and inorganic fillers that enhance wallboard performance. A parametric approach was used to screen the formulations and select three high potential options for further assessment of environmental impacts that was determined primarily through qualitative estimation of embodied carbon. We followed an approach similar to that outlined in recent literature that ranks building material options by high, medium or low greenhouse gas (GHG) or global warming potential (GWP) impact, based on relative life cycle contributions at product, construction, use and end-of-life stages.
4. Developed bench prototypes that met or exceeded current performance of commercial products. Larger format bench prototypes were fabricated with the most promising formulations and process conditions and characterized for wallboard specifications similar to commercially available gypsum board.
Based on our extensive characterization protocol, we determined that biochar blended with selected binder materials at mass loadings up to 20% yielded very low embodied carbon with minimal effects on mechanical, moisture or thermal properties. Both wood and rice husk biochar produced BWB samples that met our specification, whereas sugarcane bagasse biochar did not. Adding recycled glass in either pellet or powder form did not offer significant improvements in physical properties of BWB. We also identified an alternative fully renewable binder that can completely eliminate gypsum and achieve even lower embodied carbon. Our top three formulations were used to produce prototypes compared to three commercial wallboard products: Type X, EcoSmart and Forever Board. All three in-house materials provided properties comparable to these commercial benchmarks, but with significant reduction in embodied carbon.
Conclusions:
Based on the comprehensive technical and commercial research outcomes of this Phase I SBIR project, we believe biochar wallboard (BWB) is a viable concept with significant potential to displace conventional gypsum-based wallboard at commercial scale. Wallboard is used in enormous quantities, estimated at 26 billion square feet produced and sold in the United States in 2020, consuming 40.9 million metric tons of gypsum. Therefore, even with relatively small market penetration the industry would benefit from substantial reductions in embodied carbon by locking carbon in biochar for 50 year or greater building lifetimes.
To assure our technical efforts were focused on bringing viable, cost-competitive BWB to market, the following commercial objectives were included as part of our Phase I SBIR project:
1. Developed a list of questions for customer discovery process, to initiate dialogue with potential customers and assess interest in BWB technology, identify performance parameters of greatest concern, and opportunities for low-carbon materials in future buildings.
2. Compared performance characteristics of the down-selected prototypes to standard and enhanced feature wallboard products currently used in residential and commercial construction to assess market viability.
3. Compared initial cost of goods sold (COGS) estimates for BWB to comparable products currently used in residential and commercial construction to assess market viability.
4. Solicited feedback regarding the down-selected prototypes from project partners, including local architecture firms, Architecture faculty at RIT, construction companies and engineering firms to assess market viability.
Our research showed that certain types of BWB can meet or exceed performance criteria for traditional wallboard while significantly reducing the carbon footprint. Composites that completely eliminate gypsum would be able to not only sequester carbon but could be beneficially returned to soil at the end-of-life (or unused portions could go immediately into surrounding soils instead of being landfilled). Certain composites showed thermal conductivity comparable to or lower than expanded polystyrene, which introduces the possibility of also using it as an insulation material.
The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.