Optimising Green Ammonia Production via SOEC Heat Integration to Support Decarbonisation of The Maritime Sector: A Techno-Economic Study
Translated title
Optimising Green Ammonia Production via SOEC Heat Integration to Support Decarbonisation of The Maritime Sector
Author
Hansen, Rie Emilie
Term
4. term
Education
Publication year
2025
Submitted on
2025-08-29
Pages
75
Abstract
At mindske skibsfartens CO2‑udledning er svært, fordi skibe er vanskelige at elektrificere direkte. Denne afhandling undersøger grøn ammoniak som et muligt brændstof, produceret med vedvarende strøm. Konkret vurderes et 500 MW elektrolysebaseret ammoniakanlæg, der laver brint ved damp‑elektrolyse, trækker kvælstof ud af luft ved kryogen luftseparation og samler de to i en Haber‑Bosch‑reaktor. To elektrolyseteknologier sammenlignes: højtemperatur faste oxid elektrolyseceller (SOEC) og lavtemperatur protonledende SOEC (P‑SOEC). Et nøglespørgsmål er, om varme fra ammoniakreaktoren kan genbruges i damp‑elektrolysen (varmeintegration) for at øge effektiviteten og reducere omkostningerne. Ved hjælp af proces‑ og elektrokemiske simuleringer sammenlignes fire konfigurationer (hver teknologi med og uden varmeintegration). Resultaterne viser, at varmeintegration klart forbedrer anlæggets ydeevne. Den varmeintegrerede højtemperatur‑SOEC opnår den højeste elektriske effektivitet på 82,3 % og den laveste niveauiserede omkostning for ammoniak (LCOA) på 310–535 USD pr. ton NH3, hvilket gør den konkurrencedygtig med andre grønne ammoniakveje. P‑SOEC har størst gavn af spildvarmegenvinding, men er stadig begrænset af lavere Faraday‑effektivitet (mindre af strømmen går til den ønskede reaktion) og højere anlægsomkostninger. Samlet peger arbejdet på, at varmeintegreret damp‑elektrolyse er en lovende og omkostningseffektiv vej til at levere grøn ammoniak til skibsfartens vej mod klimaneutralitet.
Cutting emissions from shipping is difficult because ships are hard to electrify directly. This thesis investigates green ammonia as a potential fuel made with renewable electricity. It evaluates a 500 MW electrolysis‑based ammonia plant that produces hydrogen via steam electrolysis, extracts nitrogen from air using cryogenic separation, and synthesizes ammonia in a Haber–Bosch reactor. Two electrolyser technologies are compared: high‑temperature solid oxide electrolysis cells (SOECs) and lower‑temperature proton‑conducting SOECs (P‑SOECs). A key question is whether reusing heat from the ammonia reactor in the steam electrolysers (heat integration) can raise efficiency and lower costs. Using process and electrochemical simulations, four configurations are assessed (each technology with and without heat integration). Results show that heat integration clearly improves performance. The heat‑integrated high‑temperature SOEC achieves the highest electrical efficiency of 82.3% and the lowest levelised cost of ammonia (LCOA) of 310–535 USD per ton NH3, making it competitive with other green ammonia pathways. The P‑SOEC benefits most from waste‑heat recovery but is still constrained by lower Faradaic efficiency (less of the current drives the intended reaction) and higher capital costs. Overall, heat‑integrated steam electrolysis emerges as a promising, cost‑effective route to supply green ammonia for the maritime sector’s transition to carbon neutrality.
[This summary has been rewritten with the help of AI based on the project's original abstract]
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