The coastal buoy tender Henry Blake traveled 3,500 nautical miles on alternative fuel earlier this summer. Here, the ship transits the Puget Sound in August 2011. (U.S. Coast Guard)
The U.S. Coast Guard has completed a trip of 3,500 nautical miles on alternative fuel in an effort to help the Navy expand its understanding of potential renewable fuel sources.
The 175-foot coastal buoy tender Henry Blake and its crew of 28 sailed a round trip from Puget Sound to Juneau, Alaska, on a 50-50 blend of petroleum F-76 and hydroprocessed renewable diesel fuel derived from algal oil. The Navy supplied the fuel for the operational evaluation, which lasted from June 21 to Aug. 1.
The Coast Guard is examining alternative fuels in preparation for an eventual changeover in the military pipeline, said Sam Alvord, energy fuel section chief for the Coast Guard’s office of energy management.
“What we don’t want was to have that fuel out there and us not knowing what it would mean in terms of our assets,” he said.
The Blake evaluation could be especially important, since the vessel’s mission encompasses so many variables. For example, the cutter moves at full throttle through open water, but also maneuvers at slow speeds for buoy tending duties. That creates a different load profile and a different operational tempo, Alvord said.
In the same vein, operators put all of the ship’s systems to the test by carrying out the entire mission on alternative fuel, as opposed to past exercises that had run on both conventional and alternative fuels.
“In this case, it was a full load of alternative fuel, so all systems got exposed: The engines, the fuel handling equipment, the purification equipment, the piping,” Alvord said. With a successful demonstration across all systems, “it means you can burn the alternative fuel without changing any of your systems or processes.”
The Coast Guard is especially keen to understand the effects of alternative fuels due to negative experiences in the past.
In 2009, a supply chain error caused a medium-endurance cutter to be fueled with a 20 percent blend of fatty acid methyl esters, which turned to gel as a result of environmental factors, clogging the fuel filters and choking off fuel flow to the engines.
“In that case, they were surprised by it, and we don’t want to be surprised again,” Alvord said.
This recent evaluation looked for “distinguishing differences across the boards” between the biofuel mix and conventional fuel, Alvord said. Variables included engine temperature and pressure, fuel injector performance and uneven wear of engine parts.
These measurements will be compared against previous Navy findings in similar evaluations.
“All the other tests that have been done by the Navy have seen no discernible difference, and we fully expect this to be the same thing,” Alvord said. “There were no leaks, no uneven wear, nothing that would raise any eyebrows. It was very short and sweet.”