Sandia National Laboratories partnered with the Scripps Institution of Oceanography, the naval architect firm Glosten and the class society DNV GL to assess the technical, regulatory and economic feasibility of a hydrogen fuel-cell coastal research vessel.
A report released this month shows it is technically and economically feasible to build such a vessel in a manner consistent with marine regulations. The project team nicknamed the vessel the “Zero-V,” short for zero-emissions research vessel.
The report found feasible a 10-knot vessel with 2400 nautical mile range, able to perform 14 Scripps science missions, that could be refueled with liquid hydrogen at 4 different ports of call along the US west coast.
An integrated fuel-cell electric plant supplemented with small lithium-ion bridging batteries provides both propulsion and ship service electrical. The fuel cells are Hydrogenics HyPM HD 30 fuel-cell power modules arranged into power racks with each rack holding six fuel-cell modules, with total power output of 180 kW.
With ten racks total, the vessel has 1,800 kW of installed power. The 10 hydrogen fuel-cell racks are evenly distributed between Starboard and Port fuel cell rooms, allowing the vessel to continue operation at reduced power if one space must be taken out of service for maintenance. The fuel cells provide DC power, which must be conditioned, converted and inverted to provide bus DC and AC power, respectively. . . .
The Zero-V uses one propulsion motor to power each of its two propellers. Based on the resistance and powering calculations, the team determined that 500 kW motors provide sufficient power for the various mission requirements and also have enough reserve power for safe operation in heavy seas and for dynamic positioning.
High-torque alternating current (AC) permanent magnet type motors were selected as the propulsion motors. These motors can be directly coupled to the propeller shaft to provide efficient and quiet operation.
To reduce weight, the vessel has to be constructed of aluminum. The beam and length requirements were driven by the requirement that the vessel be able to dock at all primary ports of call for the vessel.
CO2(eq.) and criteria pollutant (smog) emissions were estimated for the Zero-V based on a complete “well-to-waves” (WTW) analysis. The annual WTW CO2(eq.) emissions from the Zero-V fueled with LH2 from fossil natural gas (NG) would be 2.16 Gigagrams (Gg) of CO2 (eq.) per year, produced entirely by the production and delivery of the LH2 fuel.
This is slightly worse than the equivalent vessel running on fossil diesel, with WTW CO2(eq.) emissions of 1.91 Gg CO2 (eq.)/year, despite the fact that the fuel-cell-powered Zero-V is 22% more energy efficient than the equivalent diesel vessel
. This WTW CO2(eq.) emission increase is due to the facts that making hydrogen from NG is energy-intensive in the first place, the carbon in NG is released into the atmosphere as CO2 during the hydrogen manufacturing process, and hydrogen liquefaction involves significant energy and associated emissions.
- The situation is dramatically improved using renewable hydrogen, such as that made from biogas, or by water electrolysis using wind or low-carbon nuclear power. Our analysis shows the annual WTW CO2(eq.) emissions from the Zero-V using renewable LH2 becomes 0.164 Gg CO2 (eq.)/year. This is 91.4% less than the WTW CO2(eq.) emissions from the equivalent diesel vessel running on conventional diesel fuel.
In our discussions with the gas suppliers Linde and Air Products, renewable LH2 can be made available to the Zero-V today in the quantities required. The gas suppliers are currently working to make renewable hydrogen more broadly available.
Summarizing the CO2(eq.) results, hydrogen PEM fuel-cell technology can dramatically reduce the CO2(eq.) emissions from operation of the Zero-V. However, nearly 100% renewable hydrogen must be used to achieve the desired deep cuts in CO2(eq.) emissions that are commensurate with the challenge presented by increased levels of infra-red radiation trapping gases in the atmosphere.
The fuel-cell technology can significantly reduce WTW NOx and hydrocarbon (HC) emissions below the most advanced Tier 4 criteria pollutant emissions requirements, regardless of whether the hydrogen is made by NG reforming or using more renewable means.
No “show-stopping” issues were identified by either DNV GL or the United States Coast Guard. The feasibility of the Zero-V, as well as the ability to refuel it with ~ 11,000 kg of hydrogen, has implications for large hydrogen fueled vessels such as cargo vessels and cruise ships. The work was funded by the Maritime Administration (MARAD) within the US Department of Transportation.
One of the biggest additional benefits of using hydrogen to power a boat is the absence of ecologically damaging fuel spills. According to Sandia chemist and project lead Lennie Klebanoff, it is impossible to have a polluting hydrogen spill on the water. More buoyant than helium, hydrogen rises on its own and eventually escapes into outer space. . . .
Fuel cells generate water so pure that the ship’s crew can drink it (with conditioning), or use it for scientific experiments, reducing the need to desalinate seawater (which currently consumes large amounts of energy). . . .
The Zero-V project evolved from earlier Sandia work on the SF-BREEZE, a hydrogen-powered passenger ferry designed to operate in the San Francisco Bay.
Whereas the SF-BREEZE requires refueling after 100 miles, the Zero-V can go at least 2,400 miles or 15 days before requiring a refuel; enough to get from San Diego to Hawaii. Given the great distances it needs to travel, a refueling terminal in one central location isn’t what is needed. The Sandia team found an innovative approach that allows liquid hydrogen suppliers to drive fuel trucks directly to the ship at ports of call. Thus, the Zero-V would require little investment in fueling infrastructure.
In addition to the aforementioned requirements, Glosten’s Sean Caughlan said finding a way to store the heavy hydrogen tanks while accommodating at least 18 scientists, 11 crew members and three laboratories was a challenge.
Part of the solution was selecting a trimaran boat design—a design with three parallel hulls, usually used for high-speed boats. The design offers a great deal of space above deck for the tanks, and adequate below-deck space for other science instrumentation and machinery.
The team designed the Zero-V using proven, commercially available hydrogen technology so they could be sure it would work. Once completed, the vessel design was reviewed by DNV GL and the U.S. Coast Guard. Both regulatory bodies independently came to the same conclusion: there are no “show-stopping” technical issues with the Zero-V design.
DNV GL hydrogen expert Gerd Petra Haugom says the Zero-V design shows an essential understanding of the safety-related properties of hydrogen, and how it can be used safely and securely on a vessel. . . .
The next step for the Zero-V is finding the funding to build it. Compared to diesel-powered research vessels, the Zero-V has a similar capital cost, but would cost roughly 7% more to operate and maintain. Given its benefits—much quieter, zero emissions and no risk of polluting fuel spills—Bruce Appelgate, who oversees the Scripps fleet, is hoping that like-minded donors will step up to support the project.