ILIOFOS Co.

Phil Sharp, CTO of Genevos and inventor of the Hydrogen Power Module marine fuel cell, discusses how the technology can decarbonize service vessels.

 

 

 

 

 

What is the Hydrogen Power Module (HPM) and what would be a typical application?

 

The HPM is a fully integrated and modular marine fuel cell pack that provides a drop-in zero-emissions solution to decarbonize vessels. The modules are available in sizes of 15kW and 40kW, which can be stacked into systems, typically up to 500kW. These higher power systems can be containerized for deck installation or installed directly in the engine room, and combined to provide higher power outputs depending on the custom needs of the vessel. The HPM range has achieved AiP marine certification from Lloyd’s Register and is in the Type Approval process. Typical applications include small to large vessels such as yachts, ferries, service vessels, inland transport and shipping. This zero-emission technology can be applied across the sector to decarbonize vessels through primary, hybrid or auxiliary integration.

 

Why was the HPM developed?

Green hydrogen is forecast to undercut other renewable fuels and diesel by 2030, and with rapid development in regulation, fuel cells provide a scalable, low-weight, practical solution for next-gen zero-emission vessels. To enable this technology to be accessible to boats of many sizes, powers and purposes, Genevos developed the concept of a marine-certified, modular unit that houses the fuel cell stack, balance of plant and power conversion –to make it as simple as possible to install on a vessel in place of an engine or genset, with a flexible output compatible with a variety of electric propulsion systems.

Why are hydrogen fuel cells well suited to service vessels?

They have a large variability in power requirements during a day’s work, so hybrid-electric drives can offer significant efficiency gains over a conventional diesel direct drive. These vessels often spend much of their time at idle, but also need to transit at high speed. An electric powertrain fed by HPMs can deliver around twice the efficiency of a diesel-electric system, due to the higher efficiency of fuel cells, which operate at 50-55% – instead of 20-30% for a diesel engine.

 

 

How does the weight of a hydrogen system compare with diesel and battery technology?

The weight of a full hydrogen-electric power system can be very close to that of a traditional diesel system, and in some cases, can be even lighter than a diesel-electric hybrid system that uses generators. Genevos’ HPMs are optimized for low weight and are three times lighter than the equivalent diesel generator. However, compressed hydrogen storage, at 250-350 bar pressure, comes with a twofold weight penalty over diesel fuel and so, depending on a boat’s energy-to-power ratio, it can normally be quite close in terms of the overall vessel weight.

Service vessels are typically associated with long working days, with large amounts of energy storage required. This is where full-battery systems become impractically heavy and expensive, with a total energy system weight that will likely be between three and five times greater than that of hydrogen and fuel cells. An all-battery system adds significantly to the capex of the vessel, and increases energy consumption when accounting for the additional weight – which may be 20% heavier overall.

What types of service vessel is the HPM adapted to?

There is enormous potential for crew transfer vessels to convert to hydrogen power due to their considerable energy use, where the carbon savings and environmental benefit can be significant. A vessel powered by green hydrogen will be at a footprint of less than 10% per annum of that of a diesel equivalent, and so the carbon credits start to make a big difference in reducing operating costs, which will only get more substantial with time. For wind farms in particular, it is counterintuitive to be burning more diesel as more turbines are installed offshore.

Is there a benefit to using fuel cells in diesel-electric hybrid vessels?

Using fuel cells to power a vessel at low speed or idle can be a very effective transition option to reducing the overall carbon emissions of a vessel. For a diesel-battery hybrid vessel, there is always a weight penalty over direct drive. Often, for high-speed vessels, the additional energy expelled in lugging around the extra weight of batteries can offset the increased efficiency, making such a vessel’s environmental benefit negligible. Substituting diesel with a clean fuel solution including HPMs and hydrogen storage enables a much higher efficiency system at low speeds, and so the emissions saving is significant. For a wind farm service vessel, the emissions saving can be typically 30-35%. Bearing in mind that quantities of green hydrogen are currently limited, the initial hybridization of service vessels using Genevos’ power modules presents a practical short-term solution for many craft, either for retrofits or new vessels.

How do you size the fuel cells for the operation of a vessel?

An optimization tool determines the power requirements, battery size and hydrogen storage required. This is driven largely by TCO, which inherently means a compromise between equipment cost, efficiency and weight.

Based on the statistics in Figure 3 (above), an example of a hydrogen-powered CTV is shown in Diagram 1 (below). This shows the power requirement of the vessel (in green) over the course of a full day of servicing on a wind farm, and how this is delivered through fuel cell (blue) and battery power (yellow).

Near full-load is used for one hour both at the start and end of the day to go to and from the wind farm, by which the battery is heavily depleted to complement the fuel cell power and energy Diagram 2 (below ).Throughout the day of servicing at low speeds, the battery acts more as a buffer to provide dynamic loads for maneuvering while enabling the fuel cell to operate at a more constant load for maximizing fuel cell stack efficiency and lifetime.

In this example, three systems of 500kW are used to meet the total fuel cell power requirements. Here, 350kg of daily hydrogen fuel consumption provides the total propulsion and auxiliary requirements of the vessel, stored in 48 x 350L Type IV cylinders at 350 bar. These can be refuelled directly or supplied in a 20ft container which can be swapped on and off the vessel.

All this technology is now available off-the-shelf and regulation is advancing solidly to enable hydrogen-electric energy systems to become the reference for service vessels in the near future.

*An interview that mr Phil Sharp, CTO of Genevos gave at TRISTAN SMITH of Electric & Hybrid Marine Technology International Magazine and you can find it here .