Dartmouth leads multidisciplinary team to assess lower-emission biofuel

According to the U.S. Environmental Protection Agency, greenhouse gas (GHG) emissions in the transportation sector account for nearly 30% of the nation’s total GHG emissions. In a study by a team from Dartmouth College, Hanover, New Hampshire, the U.S. Department of Energy’s (DOE) Argonne National Laboratory and other institutions, researchers discovered a cost-effective way to convert ethanol into a hydrocarbon fuel that can reduce emissions by as much as 96% . The multidisciplinary team’s discovery marks a major advance in interchangeable biofuels and can promote research on their use in aviation, long-haul trucking and shipping.

Recent advances enabled the team to consolidate a three-step method converting ethanol to hydrocarbons into one step to create a process called consolidated alcohol dehydration and oligomerization, or CADO. CADO promises lower costs and a smaller environmental footprint. The team evaluated the environmental impacts of CADO using Argonne’s GREET (Greenhouse Gases, Regulated Emissions, and Energy use in Transportation) model. A powerful analytical tool, GREET is one of only a few tools to provide a complete picture of the energy and environmental impacts of an entire vehicle and fuel system.

Study participants included the Boeing Company; the Brazilian Bioethanol Science and Technology Laboratory; the Brazilian Center for Research in Energy and Materials; the Federal Aviation Administration; Imperial College London; the National Renewable Energy Laboratory; Oak Ridge National Laboratory; Pennsylvania State University; the University of California, Riverside; and Vertimass LLC.

Dartmouth team tracks salts through Antarctic sea ice — with Argonne help

Sea ice — the frozen water at Earth’s polar regions — helps regulate the exchange of heat and chemicals between oceans and the atmosphere and has a significant effect on climate. Sea ice contains the salts found in seawater, and these are concentrated in brine channels that run through the ice. Scientists want to understand how bromide and other salts get from the ocean to the lower atmosphere, where they play a role in many atmospheric chemical interactions important to climate change, such as ozone depletion.

To investigate these findings, a team led by Dartmouth College professor Rachel Obbard traveled to the Antarctic to collect samples of sea ice. They used a technique called synchrotron X-ray microfluorescence spectroscopy at Argonne’s Advanced Photon Source (APS) to help them identify the salts’ precise location in sea ice.

The extremely bright X-rays of the APS, a DOE Office of Science user facility, can be focused on a very small spot and then maneuvered over the sample, which enabled the team to map the location of bromide and other salts at a very fine spatial resolution in their samples. Knowing more about the location of these salts helps scientists make assumptions about chemical interactions between sea ice and the atmosphere that play a role in climate change.