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.

To provide the required position-keeping for on-station science work, the vessel is fitted with a retractable azimuthing bow thruster as well as stern thrusters in each outer hull. High-lift flap rudders are provided to maximize steering forces produced from the main propellers during station keeping.

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.

—Sandia report

The fuel-cell technology can significantly reduce WTW NO_x 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.

Rendering of the Zero-V hydrogen-powered research vessel. (Photo courtesy of Glosten)

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.

If you’re working in a sensitive ecological area and you spill liquid hydrogen there, the fuel not only removes itself from this environment, it removes itself from the planet.

—Lennie Klebanoff

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). Also, fuel cells are electrical devices, and as such, they offer a faster power response than internal combustion engines.

Sandia’s expertise in this area stems from a portfolio of hydrogen projects that aim to develop efficient transportation solutions with clean domestic fuels. Sandia’s role was to lead the project, choose the kind of fuel cell to use, the method of storing the hydrogen and provide information on the safety-related properties of hydrogen to the US Coast Guard and the regulatory partner, DNV GL.

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. (Earlier post.)

Small hydrogen-powered pleasure crafts made for very short distances already existed. But prior to the SF-BREEZE, there hadn’t been a project that looked at the technical as well as economic feasibility of powering large, fast commercial boats with hydrogen, according to Joe Pratt, who led the SF-BREEZE project for Sandia.

Based on the SF-BREEZE and other related work, Pratt came to believe so strongly in hydrogen’s commercial potential that he took entrepreneurial leave from Sandia to start Golden Gate Zero Emission Marine. The company builds hydrogen fuel cell powertrains for the maritime market.

The SF-BREEZE design accommodates 150 passengers on four 50-mile round trips in the San Francisco Bay per day while traveling at a top speed of 35 knots (roughly 39 miles per hour). Ensuring the ferry could achieve that speed meant adopting a 100-foot, slightly longer than usual catamaran design.

All the plan elements, including ship design, weight distribution and refueling options had to be re-evaluated for the Zero-V.

Instead of going fast for short periods and carrying a lot of people, the research vessel goes slower for much longer distances, carries fewer people and must allow the operation of sensitive scientific instrumentation. The research vessel is a different animal from a passenger ferry.

—Lennie Klebanoff

While working on the SF-BREEZE, Pratt and Klebanoff approached the Scripps Institution of Oceanography to see whether researchers there were interested in a hydrogen-powered vessel. They were, if the Zero-V could complete tasks that are routine for ocean-going research missions, such as marine ecosystem studies, physical oceanography, tsunami risk and ocean chemistry research.

Mapping or installing equipment on the ocean floor requires a vessel to be stable over a single point for long periods, even if there is wind or waves. Glosten determined that the aid of propulsion devices installed in each side hull would enable the Zero-V to maintain its position with more than 25 knots of wind and waves from any direction.

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.

This project has been a good test of our own rules and the alternative design approach for using hydrogen and fuel cells. The results from the Zero-V will be part of a benchmark to guide our assessment of similar vessels in the future.

—Gerd Petra Haugom

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.