Powering Carbon-free Autonomous Shipping: Ammonia/Hydrogen dual-fuelled Linear Engine-Generator

The project aims to develop a new power generation technology for full electrical propulsion (FEP) ships, based on an ammonia/hydrogen dual-fuelled Linear Engine-Generator (df-LEG), proposed in this application. The external ammonia reactor of the df-LEG uses a small amount of hydrogen, electrolysed from ammonia as the pilot fuel, to sustain continuous and stable ammonia combustion. Ammonia is identified as one of the most promising hydrogen carriers to enable a 'Hydrogen Economy' in the marine sector. It can be produced with renewable sources and stored in a safe and volumetrically-efficient way (-34C and ambient pressure) on board ships for long-distance maritime journeys. The 'carbon-free' emissions from complete ammonia oxidisation are mostly water and nitrogen, which could make a substantial contribution to reducing maritime transport carbon emissions (which currently stand at approximately 1000 million tonnes of CO2 annually). The research will potentially contribute to important debates at national and international level regarding the nature of the future hydrogen economy, mainly: how will shipping be powered in the 'Hydrogen Era' and can this technology contribute to future 'carbon-free' autonomous shipping.

The proposed df-LEG utilises a novel configuration, which is the first-of-its-kind to fully integrate a linear alternator into a linear engine. Conventional internal combustion free-piston engine prototypes (10-20kWe), such as those built by Toyota (42% electric efficiency) and Newcastle University (34-45%) have already proved to be as efficient as proton-exchange membrane fuel cells. While the df-LEG prototype will demonstrate a comparable efficiency to the existing technologies, it has the potential to further advance the efficiency to more than 40% due to friction reduction, transmission loss minimisation, and thermodynamic cycle improvement. The pressure ratio can be increased to 30:1 due to the closed-cycle structure to further boost the overall efficiency.

The prototype design approaches will involve a mixture of computational design and experimental testing, and builds upon ongoing research projects at Newcastle University (Innovate UK TS/P010431/1, EPSRC Impact Acceleration Awards). The research will be the first to demonstrate the feasibility of this integrated design and seek to answer questions regarding the fundamental relationships between ammonia chemical reaction, thermodynamic process, moving part (piston and magnets) dynamics, and electric energy generation. The experimental study on the prototype will fill the gap on our understanding of thermodynamics and dynamics of the linear engine-generator operating with a non-air working fluid. The research will also identify the best ratio of ammonia, air and hydrogen to optimise heat output and NOx emissions, eventually aiming to make the df-LEG the first direct 'ammonia-to-electricity' energy convertor.

The fellowship will be set in the vibrant academic environment of Newcastle University's disruptive linear engine and linear alternator technologies team. The project will include collaborations with national and international stakeholders: Meyer Werft (shipyard), Siemens (system designer), BNC (linear engine engineering), Wessington Cryogenics (cryogenic and pressurised tank manufacturer) and Arnold Magnets (linear alternator magnets manufacturer). The proposed new marine power technology will be considered in a scenario design for a cruise ship under construction at Meyer Werft, during the secondment of the PI.

The highly-disruptive Ammonia/ Hydrogen dual-fuelled Linear Engine-Generator (df-LEG) has the potential to benefit a large cross section of society through zero carbon emissions, safe hydrogen energy storage using cryogenic liquified ammonia and highly efficient, compact power generation. The proposed df-LEG is pioneering in the global shipping sector where developing innovative carbon-free technologies is imperative. It has an enormous potential to eliminate global shipping related carbon emissions (currently approx. 1000 million tonnes of CO2 p.a.). Aiming for a zero-carbon economy and wider hydrogen application, the marine sector has been contemplating the challenging problem of how to store hydrogen in a safe and economically-viable manner on board vessels. The invention of df-LEG utilises cryogenic liquified ammonia as both a fuel and a hydrogen carrier, which can be safely and efficiently stored on board ships, thereby addressing this issue. The df-LEG also has the potential to promote the use of ammonia and hydrogen produced by renewable electricity, in turn, supporting the penetration of renewable energy.

The df-LEG pioneers the merging of linear engine and linear generator into one device, and offers direct 'ammonia-to-electricity' energy conversion, yielding the following advantages: a) a compact fuel-to-electricity marine power solution without the need for complicated transmission and speed reduction systems between engine and generator; b) a modularised power generation to facilitate a wire-only electrical interconnection among multiple df-LEG units, enabling decentralised power generation deployment, in turn, increasing ship design flexibility, space usability, profitability and safety; c) enhanced operational flexibility, as all components on df-LEG units are electrically, not mechanically, controlled. This distinguishes the system from traditional technologies and offers the potential for remote control of the df-LEG units thereby supporting an autonomous shipping future. Consequently df-LEG technology introduces novel design philosophy to shipyards and supply chains, providing an opportunity to innovate vessel design and improve the economics of the sector.

The proposed project is innovative and novel. Through its interdisciplinary nature and significant stakeholder engagement, the project will lead linear engine-generator development. The scientific results will be communicated and published via leading engine/generator international conferences (ICAE, ASME, IET) and publications in high quality journals (Applied Energy, Fuel, etc.). The fellowship research activities will build upon the international renown of marine research at Newcastle University, and the UK's position as a leading innovator in linear engine/generator and hydrogen/ammonia marine applications. Further impact will be achieved through exploitation of Newcastle University's IP in df-LEG technology and associated technologies. Evidence of the significantly increased benefit of df-LEG, compared to the current and projected state-of-the-art marine power technologies, will open-up significant opportunities for further research, commercialisation and impact. Further collaborations through KTP and Innovate UK funding will be sought.

As well as the public, academia and related industries, other beneficiaries include the government and policy makers. These beneficiaries need viable solutions for cost-effective mitigation of carbon dioxide emissions whilst safeguarding energy security, industrial output and UK jobs. In the shipping sector, the government continues to work with industry to develop low carbon, high fuel efficiency technologies, including new propulsion systems, hull design and aerodynamic structures. The proposed technology allows government to develop policies which could safeguard energy security, industrial output and jobs through UK-designed, developed and manufactured technologies.