Investigation of liquid organic hydrogen carriers for marine 
applications

Poulios, Panagiotis Apostolos; Πούλιος, Παναγιώτης Απόστολος

dc.contributor.author	Poulios, Panagiotis Apostolos	en
dc.contributor.author	Πούλιος, Παναγιώτης Απόστολος	el
dc.date.accessioned	2025-09-15T08:45:12Z
dc.date.available	2025-09-15T08:45:12Z
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/62439
dc.identifier.uri	http://dx.doi.org/10.26240/heal.ntua.30135
dc.rights	Αναφορά Δημιουργού-Όχι Παράγωγα Έργα 3.0 Ελλάδα	*
dc.rights.uri	http://creativecommons.org/licenses/by-nd/3.0/gr/	*
dc.subject	Υδρογόνο	el
dc.subject	Τεχνο-Οικονομική Ανάλυση	el
dc.subject	Μηχανές Εσωτερικής Καύσης	el
dc.subject	Ναυτικοί Κινητήρες Diesel	el
dc.subject	Hydrogen	en
dc.subject	Liquid Organic Hydrogen Carriers	en
dc.subject	Hydrogen Engines	en
dc.subject	LOHCs	en
dc.subject	Techno-economic Assessment	en
dc.title	Investigation of liquid organic hydrogen carriers for marine applications	en
heal.type	bachelorThesis
heal.classification	Techno-economic Assessment	en
heal.language	en
heal.access	free
heal.recordProvider	ntua	el
heal.publicationDate	2025-02-27
heal.abstract	The maritime industry, responsible for approximately 3% of global anthropogenic greenhouse gas (GHG) emissions, faces urgent challenges in reducing these emissions to meet International Maritime Organization (IMO) targets. This thesis investigates Liquid Organic Hydrogen Carriers (LOHCs) as a sustainable solution for hydrogen storage and utilization in marine applications, coupled with hydrogen-fueled internal combustion engines (ICEs). The study evaluates hydrogen’s viability as a marine fuel, focusing on production methods (grey, blue, green), storage technologies and the technical-economic feasibility of LOHC systems. LOHCs, particularly dibenzyltoluene (DBT) and benzyltoluene (BT), emerge as optimal carriers due to their high hydrogen storage capacity, thermal stability, and compatibility with existing infrastructure. A techno-economic comparison reveals LOHCs as cost-competitive for long distance transport, with levelized hydrogen costs projected to decline as catalyst and reactor technologies advance. Hydrogen-fueled ICEs are analyzed for maritime use, addressing modifications for fuel delivery, combustion stability and emissions. While carbon-based emissions are eliminated, nitrogen oxides (NOx) remain a challenge, mitigated through lean combustion, exhaust gas recirculation (EGR) and selective catalytic reduction (SCR). The research advances with a detailed methodology for retrofitting dual-fuel engines to operate on hydrogen, preserving structural parameters while optimizing heat recovery and combustion dynamics. Performance analyses across partial and full load profiles demonstrate hydrogen’s adaptability, achieving efficiencies ranging from 45.9% to 48.3% at full engine load conditions. System configurations integrating exhaust gas heat recovery (secondary preheater, thermal oil unit and combined system) are also analyzed and selected, in order to optimally enhance the dehydrogenation process efficiency. Application case of a Ro-Pax vessel reveals daily hydrogen consumption of 2.4 tons, requiring 55.3 tons/day of LOHC (benzyltoluene), after replacing 2 of 3 Diesel Generators with Hydrogen ones. Considering a 5-day bunkering interval, LOHC storage demands exceed those of fossil fuel-burning engines. Strategic tank design (segregated tank) is considered essential to mitigate spatial challenges. Emissions analysis shows a 76.5% reduction in CO2-eq emissions (4.32 vs. 18.32 tons/day), yielding $ 1190/day in carbon credit savings under EU ETS. However, economic barriers persist, with hydrogen fuel costs ($ 9596/day) triple those of diesel ($ 2825/day) and capital expenditures of the hydrogen system being 447% higher than those of the original system, underscoring the need for scalable green hydrogen production and policy incentives. The thesis concludes that integrating LOHC and ICE technologies presents a pragmatic approach to maritime decarbonization, aligning with the IMO's 2050 net-zero targets. Subsequent research directions ought to emphasize improving catalyst economics and longevity, expanding the scale of dehydrogenation reactors and hydrogen engines and corroborating sustained operational performance in maritime applications	en
heal.advisorName	Δημόπουλος, Γεώργιος	el
heal.committeeMemberName	Παπαδόπουλος, Χρήστος	el
heal.committeeMemberName	Τσούβαλης, Νικόλαος	el
heal.academicPublisher	Εθνικό Μετσόβιο Πολυτεχνείο. Σχολή Ναυπηγών Μηχανολόγων Μηχανικών. Τομέας Ναυτικής Μηχανολογίας	el
heal.academicPublisherID	ntua
heal.numberOfPages	148 σ.	el
heal.fullTextAvailability	false