NREL: National Lab Collaboration Shows Biofuels Are Competitive Alternatives to Petroleum Across the Board

In the race to reduce global greenhouse gas emissions, renewable fuels still carry a high burden of proof: They need to be high performing, efficient, and cost-effective. Now, analysis performed by a collaboration of national laboratory researchers has uncovered a slate of biofuels produced from organic materials, including plants and agricultural waste, that have the potential to replace petroleum-derived fuel.

In two new studies, researchers from the U.S. Department of Energy’s (DOE’s) National Renewable Energy Laboratory (NREL), Argonne National Laboratory, Pacific Northwest National Laboratory (PNNL), and Idaho National Laboratory showed that, together with advanced engine design, biofuels could reduce greenhouse gas emissions by more than 60% compared to petroleum gasoline. On top of that, the biofuels studied could improve fuel performance in cars and trucks, reduce tailpipe emissions, and compete with nonrenewable energy in terms of cost.

Andrew Bartling, an NREL process engineer, Pahola Thathiana Benavides, an energy system analyst from Argonne, and Steven Phillips, a PNNL engineer and analyst, served as lead analysts for two research articles published in ACS Sustainable Chemistry & Engineering. The first studied optimal fuel sources and combustion for diesel engines mainly used in freight transportation, while the second paper focused on bioblendstocks optimized for the engines of light-duty vehicles, like cars.

Together, the research studies found multiple paths to cost-effectively slash carbon emissions in both cars and trucks.

“Rather than just focusing on each bioblendstock independently, by studying them simultaneously, we were able to get a bird’s-eye view of the entire field of these fuels,” said Bartling, who helped to lead the techno-economic analysis for both studies. “We were able to identify multiple biofuel candidates that could be cost-competitive with petroleum-derived fuels and could also create significant reductions in greenhouse gas emissions or fossil energy consumption over their life cycles. It’s a win-win from both sides.”

The research was supported by the now-completed Co-Optimization of Fuels & Engines (Co-Optima) initiative, a consortium of nine national laboratories led jointly by DOE’s Office of Energy Efficiency and Renewable Energy, Bioenergy Technologies Office, and Vehicle Technologies Office.

Co-Optima’s work hinged on developing new high-performance fuels that can boost engine efficiency and reduce emissions when combined with advanced combustion approaches. In the biofuels field, this combination approach is critical: While biofuel has significant advantages over petroleum gasoline, engines themselves are also essential to energy efficiency. Designing low-carbon fuels and engines to work together can maximize energy use and vehicle performance.

“We are at the intersection of new innovations in both engines and biofuel,” said Troy Hawkins, Argonne’s group manager for fuels and products and an author on both studies. “Our goal was to develop new biofuels blended with conventional fuels to improve engine performance.”

Finding Viable Biofuel Pathways
In collaboration with Co-Optima’s fuel experts, researchers from all four national laboratories used a screening process to develop a list of biofuels for further study.

“We used specific criteria to narrow many biofuel candidates down to a short list for our research based on the required properties and the engine’s combustion mode,” Benavides explained.

Then, because converting biomass to biofuel is such a complex process—involving countless variables in feedstock, conversion technologies, and fuel types—researchers from NREL and PNNL conducted a techno-economic assessment of different possible biofuel production pathways, analyzing each pathway for both cost and performance. This kind of analysis, Bartling said, plays to one of NREL’s strengths, as the laboratory is considered by many to be world-class in its techno-economic research.

“For each chosen biofuel, we developed an industrial-scale process simulation using thermodynamically rigorous simulation software. Once developed, we were able to figure out what the current cost of fuel production would be, or even what the future cost of production may be as research progresses on things like better catalysts and improved fermentation performance,” Bartling said.

Together, the two studies assessed 27 pathways for producing biofuel optimized for different engines. Both studies were consistent: They showed that many of the biofuels were cost-competitive with current gas prices, and most of the technologies performed well. In particular, results from one study’s life cycle analysis showed that 10 biofuels have the potential to reduce greenhouse gas emissions by more than 60% compared to petroleum gasoline.

Creating a Biofuel Playbook
One of the most promising aspects of the research, Bartling said, is that it shows the breadth and flexibility of biofuel solutions.

“We found that not only can many of these biofuels be produced cost-competitively but also that there is choice and flexibility in how you design your process, what conversion approach you’re going to take, and in the feedstock that you can choose,” Bartling said. “Because there is such a variety of fuels, each brings its own performance advantage to the table. And so, not only can we displace a large amount of the fuels produced in the United States with these renewable types of biofuels, but we can also do so sustainably with significant greenhouse gas emission reductions and with the potential to be economically competitive in the market.”

These flexible solutions offer a guide for stakeholders to select biofuel pathways that best meet their needs, from efficiency to total ownership cost.

“We provide researchers and industry guidance on assessing biofuels based on a number of complex variables,” Benavides said. “The life cycle and techno-economic analysis is important in guiding stakeholders as early as possible. We can’t tell stakeholders what choices to make. But these tools can point them in the right direction from the beginning.”