Engineers develop new method for ultra-clean biofuel combustion

In new research published in the journal Fuel, Baylor University researchers with the Cornerstone Atomization and Combustion Lab (CAC) have unveiled a pioneering method for the efficient combustion of biofuels, using a revolutionary Swirl Burst (SB) injector to burn glycerol/methanol blends with near-zero emissions. This new technology enables ultra-clean combustion of fuels that are typically difficult to burn due to their high viscosity.

The research is poised to make significant contributions to both academic research and industrial applications, setting a new standard for sustainable energy solutions.

“The current research demonstrates how viscous bio-waste can be transformed to clean energy by the Baylor combustion technology,” said lead author Lulin Jiang, Ph.D., principal investigator of the CAC Lab and assistant professor of mechanical engineering at Baylor’s School of Engineering and Computer Science.

Significance for biofuel industry, environmental impact

Conventional injectors struggle to burn glycerol—an abundant byproduct of biodiesel production—due to its high viscosity, though it has moderate energy density.

In contrast, the SB injector’s ability to handle glycerol without requiring costly fuel preheating or processing could transform biofuel economics. The process allows the SB injector to achieve a complete and clean burn by producing fine droplets, significantly reducing emissions of harmful pollutants like carbon monoxide (CO) and nitrogen oxides (NO_x).

Jiang said this novel technology also enables biodiesel producers to convert glycerol waste into a viable fuel source, promoting a circular economy and reducing the carbon footprint for generating power. The SB injector’s flexibility allows the combustion of various glycerol/methanol ratios without hardware modifications, making it ideal for power plants aiming to meet stringent emissions regulations.

By pioneering innovative solutions to pressing global challenges, Jiang and her team exemplify Baylor’s commitment to advancing knowledge for the betterment of society.

“Being able to transform waste, such as waste glycerol, into cost-effective renewable energy promotes energy resilience and energy equity for economically disadvantaged groups in a changing climate,” Jiang said.

Testing fuel blends

The research team tested three different fuel blends—50/50, 60/40 and 70/30 glycerol to methanol ratios by theoretical heat release rate—at multiple atomizing air-to-liquid mass ratios (ALR). All blends achieved over 90% combustion efficiency, including complete combustion by the 50/50 blend, with near-zero CO and NO_x emissions, even in non-preheated, uninsulated combustion setups. This is a significant improvement over conventional air-blast or pressure-swirl injectors, which often generate high emissions with high-viscosity fuels.

“The demonstrated high viscosity tolerance and fuel flexibility of the technology signifies that not only waste glycerol, but also the viscous source oils of biodiesel, and other waste-based bio-oils can be directly utilized for energy generation without further processing, significantly reducing biofuel cost and thus potentially stimulating its broad application,” Jiang said.

The breakthrough could help reduce the biodiesel industry’s environmental impact and improve cost-effectiveness.

Jiang and her research team are members of the National Science Foundation’s National Innovation Corps—or I-Corps—program. Through the National I-Corps program, scientists and engineers are prepared to extend their focus beyond the university laboratory—accelerating the economic and societal benefits of basic research projects that are ready to move toward commercialization.

In a related NSF project, Baylor and the City of Waco are partnering on the NSF Civic Innovation Challenge Project to develop climate-smart, waste energy, fuel combustion at the Waco Landfill to help reduce methane and other air pollutants and transform waste into clean energy.