---

Beginning in September 2014, the Scripps Institute of Oceanography at the University of California ran the research vessel Robert Gordon Sproul on biofuel for more than a year.

During the test, funded as a result of a grant from the U.S. Department of Transport to test long term use of biofuel, the vessel was the greenest ship in the institute's academic research fleet.

The University of California has a stated aim to become carbon neutral by 2015, and so the San Diego-based oceanographic unit was keen to test biofuel on its own research vessels. Renewable biofuel is nearly carbon neutral and produces cleaner emissions, thus decreasing greenhouse gas emissions and improving air quality relative to fuels derived from petroleum.

"Part of the Scripps mission is to protect the environment, and one of the most significant changes that we could make in our ship operations involved moving toward the use of cleaner, renewable fuels," said Bruce Applegate, Associate Director, Ship Operations and Marine Technical Support at Scripps, "As scientists, we know we need to develop sustainable means of powering our ships to address pollution concerns as well as to mitigate future increases in fossil fuel costs."

Managed by Applegate and Lynn M Russell, Professor of Atmospheric Chemistry, the biofuel project was tasked with investigating the viability of long-term use of hydotreated renewable diesel fuel (HRD).

Originally, Scripps planned to test renewable biodiesel produced from algae, but when they failed to source the required quantities they turned to Neste Oil Corporation to access a reliable supply of a newly established biodiesel, a hydrogenation-derived renewable diesel (HDRD) called NEXBTL Renewable Diesel.

An added bonus was that no modifications of the R/V Robert Gordon Sproul engines were required to run on HDRD. HDRD biofuel is hydrotreated, meaning all oxygen has been removed, so it's left with a chemical composition nearly identical to the kind of marine diesel fuel typically used in California.

Over the course of the biofuel experiment, which concluded in December 2015, R/V Robert Gordon Sproul conducted 39 regular oceanographic research and education missions, spanning 89 operational days at sea and covering more than 14,400 nautical miles. During this time the vessel used a total of 52,500 gallons of 100-percent renewable diesel.

Throughout the project, Professor Russell and her team used instruments installed on board to continuously measure pollutants such as carbon monoxide (CO) and nitrogen oxides (NOx), organic and black carbon aerosols, and engine performance.

During the 15-month project the institute conducted two separate five-day research cruises focused on the air quality-related emissions, comparing biofuel with emissions from ultra-low-sulphur diesel. The Robert Gordon Sproul held biofuel and diesel in two separate tanks and the researchers could switch back and forth at will to collect different emission samples.

Experiments showed that when running on biofuel, emissions of NOx were about 13 percent lower that when running on diesel, particularly if the ship was running at lower speeds, (700 and 1,000 revolutions per minute). However, the particle emissions were 35 percent higher for biofuel when the engine was running at higher speeds (1,600 revolutions per minute). Black carbon or soot counts were also slightly higher for biofuel.

Onboard scientists also looked at the organic chemistry of the particles emitted by the two different fuels, particularly what happened after the emissions had aged in the atmosphere. Results showed that emissions from both biofuel and diesel plumes were similar and mostly composed of hydrocarbon compounds. They found evidence of sunlight breaking apart the molecules in both the fuel types.

The R/V Robert Gordon Sproul is now back to running on diesel, as its biofuel supply ran out in December 2015. The project showed that biofuel is a workable renewable fuel source for long-term use; however, it costs about 10 percent more than fossil fuels, which is a key consideration for academic research vessels.

"We were able to show that our existing ship ran as well if not better on biofuel," said Russell about the long term project and its results. "The hope is that the price of biofuel will come down as the manufacturing process gets better understood, and as people test it and start adopting it. Now that there’s proof of concept, it should be easy to keep doing it."

About Scripps

Scripps Institution of Oceanography, at the University of California in San Diego is one of the oldest, largest, and most important centres for ocean, earth and atmospheric science research and education.

Research at Scripps encompasses physical, chemical, biological, geological, and geophysical studies of the oceans, Earth, and planets. The institute operates one of the most capable research fleets in the world, which includes three research vessels and one floating research platform. These seagoing vessels venture worldwide as the scientists and students on board conduct research. Scripps undergraduate and graduate programs provide educational and research opportunities in ocean, earth, and atmospheric sciences, as well as degrees in climate science and policy and marine biodiversity and conservation.

Bruce Applegate

Bruce Appelgate, is a research scientist and leader in ocean technology and seafloor mapping. He is Associate Director for Ship Operations and Marine Technical Support at Scripps Institution of Oceanography at UC San Diego.

Appelgate joined Scripps from the University of Hawaii's Institute of Geophysics and Planetology. He has also served as an associate research specialist and director of the Ocean Technology Group - part of the university's School of Ocean and Earth Science and Technology.

Lynn M Russell

Lynn Russel is Professor of Atmospheric Chemistry at Scripps Institution of Oceanography, where she has led the Climate Sciences Curricular Group since 2009. Her research is in the area of aerosol particle chemistry, including the behaviour of particles from both biogenic and combustion processes.

She leads The Russell group within the university, which develops models and analyses observations to understand the microphysical and chemical evolution of aerosol particles in the atmosphere.