Large engines for sustainable shipping solutions

Nicole Wermuth,
HyMethShip Project Leader,
Area Manager at Large Engines Competence Center (LEC GmbH),
Graz, Austria

Since the IMO adopted a resolution in 2018 to decrease the emissions of greenhouse gases from marine transportation by 50 % by 2050, the focus of ship emission reductions shifted from sulfur oxides and particulate matter to carbon dioxide emission reduction. The Large Engines Competence Center (LEC GmbH) in Graz, Austria, works towards this goal and develops sustainable shipping solutions for medium- and high-speed engines. Together with a consortium of 12 major players from the shipping sector, the European research project HyMethShip is currently being completed.

The carbon dioxide emission reduction goals are far beyond what efficiency increases alone can deliver. Innovative concepts and changes in fuel or energy supply are required. Large engines are well proven, reliable and efficient prime movers in maritime shipping and—in principle—can be operated with almost any kind of e-fuel. While the use of hydrogen as a carbon-free fuel in land-based applications seems straightforward, logistics, safety requirements and most of all space constraints on board of vessels strongly favor the use of liquid fuels with high energy density. E-fuels such as methanol and ammonia are strong candidates but currently there is no clear favorite solution in sight. Thus, various viable solutions need to be examined in depth and approved.  This technology qualification process requires participation of numerous stakeholders, including shipbuilders and classification societies.

Over the last two decades the LEC developed advanced combustion systems for a wide range of different fuels, applications and emission legislations using a combination of simulation-based and experimental methods and applying specialized measurement technologies to investigate in detail processes in the combustion chamber. Today the LEC is taking aim at large engine applications using renewable fuels – methanol, ammonia and hydrogen in particular.

The LEC introduced the novel HyMethShip concept for sustainable ship propulsion that features a methanol-based closed-loop carbon cycle combining the benefits of liquid fuel bunkering and storage with carbon dioxide-emission free hydrogen combustion in a large bore internal combustion engine. The concept uses on-land methanol synthesis using hydrogen plus recycled carbon dioxide and onboard methanol decomposition to hydrogen used for propulsion and carbon dioxide. The advantages of this concept are its use of established reciprocating engine technology, bunkering of a liquid fuel that does not require high pressure or cryogenic storage, and the recovery of engine waste heat for the precombustion carbon capture process.

The onboard setup consists of two interconnected subsystems: the fuel producing and carbon capture subsystem and the fuel consuming subsystem that provides the propulsion power. The first subsystem consumes methanol and water and produces hydrogen via methanol steam reformation in the catalyst portion of the membrane reactor. After hydrogen and carbon dioxide are separated in the membrane section of the membrane reformer, the carbon dioxide is liquefied and transferred to the tank system, while hydrogen is released to the fuel consuming subsystem. The two subsystems exchange the hydrogen fuel and the engine exhaust gas enthalpy; the latter energizes fuel production, which consists of methanol reforming (an endothermic process that requires heat to be sustained) and absorption cooling used for carbon dioxide liquefaction. Only little electric energy is required on top,

The LEC developed a flexible hydrogen combustion system on a single-cylinder research engine and transferred it to a full-scale engine demonstrator in the 1–2 MW power range. In cooperation with its project partners, the LEC also built the fuel production subsystem and integrated it together with a full-scale engine into a technology demonstrator. The project also included the design of a case study for a full-scale ship to demonstrate the integration of the complete system into the vessel. Based on this design, a classification society conducted a comprehensive risk and safety assessment of the design and operation strategies.

The technology demonstrator was built at the LEC facilities and commissioned in September 2021. It constitutes the development platform for the evaluation of subsystems, the implementation of identified improvement measures and the development of additional technology components for fuel pre-treatment and carbon dioxide capture. The main research questions that remain to be solved beyond the project’s duration are the quality of the carbon dioxide separation, the optimal cascading use of the waste heat from the engine, and the best possible maintenance-friendly design of the entire plant. There are still a few hurdles that need to be removed before the system can go into series production on a ship in probably a few years.

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