Page 36: of Maritime Reporter Magazine (April 2026)

THE PATH TO ZERO HYDROGEN READY CATAMARAN| ating electricity for electric propulsion. That mechanical ap- • Crew training and emergency protocols proach reduces weight and maximizes ef? ciency — critical Horizon X highlights a critical point for port operators in a high-speed catamaran. and energy suppliers: ships can be built ahead of infra-

Total shaft power reaches 36.4 MW, with overall ef? cien- structure, but only up to a point. If hydrogen-ready vessels cy approaching 50%. For comparison, earlier generations of enter service without parallel port investment, the transi- gas turbine ferries in the 1990s operated closer to 30–35% tion stalls. Moberg acknowledges this reality. The ship will ef? ciency — insuf? cient for modern economics. operate conventionally until hydrogen bunkering becomes

For Moberg, combined cycle was non-negotiable. With- viable. That means LNG and diesel capability remain essen- out it, fuel ef? ciency would not have supported the busi- tial in the near term. However, by committing to hydrogen ness case. Michael Welch of Siemens Energy emphasizes readiness now, Gotland effectively signals to ports and en- the maturity of the SGT-400 platform. Originally launched in ergy providers that demand is coming. In fuel supply chains, 1997 for oil and gas and co-generation markets, the turbine’s credible demand often drives investment.

twin-shaft con? guration allows variable output speeds — well suited for waterjets. Its high exhaust temperature makes ENGINEERING CHALLENGES AND APPROVALS it particularly effective in combined-cycle con? gurations. Adapting a land-based turbine for marine use required

The result is a propulsion system optimized not only for extensive collaboration with DNV for type approval of the peak output, but for part-load ef? ciency — a critical factor in turbine core, package and control systems. Combined-cycle real-world ferry operations where power demand ? uctuates. integration presents additional complexity. Weight and vol- ume are critical in a high-speed catamaran. The OTSG was

HYDROGEN-READY: WHAT THAT MEANS selected speci? cally for low weight and compact footprint.

“Hydrogen-ready” is often used loosely in shipping. In Ho- Fuel handling presents further engineering hurdles. LNG rizon X’s case, it is tied to a de? ned development pathway. operations bring boil-off management issues, and high-pres-

Siemens has been working on hydrogen combustion in the sure fuel requirements add design complexity. Hydrogen in-

SGT-400 for more than a decade. According to project docu- troduces even greater challenges, particularly in combustion mentation, the platform achieved 100% hydrogen operation dynamics and ? ashback prevention.

in 2023 under the EU-funded HYFLEXPOWER project, These are not incremental adjustments. They are system- with further testing ongoing. level integration exercises.

The turbine features a Dry Low Emissions (DLE) system and is designed to meet IMO Tier III NOx limits without SCR. THE COST OF FLEXIBILITY

A new combustor con? guration allows operation on 100% hy- Moberg estimates a capital cost premium of roughly 25% drogen, 100% natural gas/LNG, or blends between, with ret- compared to a more conventional vessel of similar capacity.

ro? t potential and minimal changes to the turbine core. Under pure head-to-head economics, that premium would

But Moberg is clear: the engine is only part of the equation. be dif? cult to justify. But Horizon X is part of a broader ? eet “If you’re talking hydrogen, you need a complete arrange- strategy with strong seasonal demand peaks. High capacity ment in order to get it on board,” he says. and high speed unlock value in summer operations while

Hydrogen’s small molecular size, storage challenges and future-proo? ng the asset for a 25-year lifecycle.

safety requirements mean that fuel handling systems de? ne “If we would have gone on a fuel cell version we would practical fuel ? exibility. Designing a ship capable of storing have been more locked in,” Moberg says. “The ? exibility and managing hydrogen — whether liquid or pressurized — here is key.” Fuel cells might offer ef? ciency bene? ts, but requires careful integration with classi? cation societies, port they risk technological lock-in. A multi-fuel turbine platform authorities and regulators. provides optionality — critical in an era of regulatory uncer-

The vessel’s ability to transition fuels does not eliminate tainty and volatile fuel pricing. the need for shore-side readiness. It ampli? es it.

PART-LOAD EFFICIENCY: A PRACTICAL INSIGHT

PORTS AS THE NEXT BOTTLENECK One of Moberg’s most signi? cant observations concerns

Today, ordering diesel is simple. Ordering hydrogen is not. part-load performance. Traditional gas turbines lose ef? cien-

The transition from LNG to hydrogen introduces a new cy sharply away from full power. Combined-cycle con? gu- layer of complexity for ports: ration ? attens that curve. “Ef? ciency actually is almost ? at • Dedicated storage infrastructure from 100% down to 50% or lower,” he notes.

• Safe transfer systems For ferry operators, that changes the calculus. Ships rarely op- • Regulatory frameworks erate at full power continuously. Designing for real-world oper- • Supply chain reliability ating pro? les — not theoretical peak conditions — is essential.

36 Maritime Reporter & Engineering News • April 2026

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