The United States Environmental Protection Agency reported that the highest greenhouse gas emissions in 2017 were in the transportation sector, making up almost 30% of total greenhouse gas (GHG) emissions across all sectors in the US. It goes without saying, then, that improvements in the transportation sector should be of utmost priority nationally. But what are the best methods for reducing GHG emissions in transportation? Research recently published in Proceedings of the National Academy of Sciences highlights a potential new development that uses an existing technology with a more cost-efficient twist.
The research comes from a team of scientists collaborating from the U.S. Department of Energy's (DOE) Argonne National Laboratory, as well as DOE's National Renewable Energy Laboratory and Oak Ridge National Laboratory. It focuses on converting ethanol – a low-cost fuel that is supposed to burn cleaner than gasoline - by way of catalysis and process development in the most efficient process yet. The process the researchers developed is called Consolidated Alcohol Dehydration and Oligomerization, or CADO.
CADO was a result of using the GREET model (Greenhouse Gases, Regulated Emissions, and Energy use in Transportation), a sophisticated model that is capable of calculating energy use and emission levels across multiple vehicles and fuel systems. "GREET is one of the only tools out there that can provide a complete picture of the energy and environmental impacts of an entire vehicle and fuel system," said co-author Michael Wang.
From GREET, the researchers were able to compare the life cycle GHG emissions produced by hydrocarbon fuels originating from different raw materials and conversion methods, thus leading them to CADO.
The research team concluded that hydrocarbon blends made through the CADO conversion process cut greenhouse gas emissions between 40-96%, variable on the feedstock and the conversion pathway. They reported that with corn grain, GHG emissions fell by 40%; with sugarcane juice, they fell 70%; with cellulosic biomass such as sugarcane straw and corn stover, they fell between 70-96%.
"In order to move towards more sustainable development, we will need fuels that can generate fewer emissions and that are economically feasible," Benavides said. "This work is an exciting indicator that building such a future is possible."