Environmental and economic analysis of cold ironing using renewable hybrid systems

This paper investigates shore-based photovoltaic (PV)/proton exchange membrane fuel cell (PEMFC) and PV/battery renewable energy (RE) plants for cold ironing (CI) configurations. The hydrogen for PEMFCs is produced in ammonia (NH3) electrolyser by the PV panel-sourced electricity using green, blue or grey NH3 as the feedstock. The system models based on PV technology are developed using minimum, average, and maximum monthly irradiation levels. The environmental and economic analyses benchmark CI based on grid/RE electricity with onboard electricity generation using diesel and dual-fuel systems with light fuel oil (LFO) and liquefied natural gas (LNG). Results show that LNG usage in the ship electrification plant reduces equivalent carbon dioxide (CO2e) by 14.27%, sulphur oxides by 90.79%, and nearly eliminates other emissions. Using grid electricity as the CI source cuts CO2e by 58.92%, while the PV/battery system reduces it by 80.73% to 85.82%, depending on irradiation. The PV/PEMFC system with green NH3 achieves the highest CO2e reduction (99.92%-100%), while blue NH3 provides the second largest decrease (97.46%-97.54%). The grid electricity CI has the shortest payback period (PBP) at 2.06 years and a levelised cost of energy (LCOE) of $186.92/MWh. The PV/battery system has an LCOE of $174.67 to $196.52/MWh and a PBP of 6.98 to 8.78 years. The PV/PEMFC system using grey NH3 shows a PBP of 7.78 years, rising to 9.01 years with blue NH3 and 23.69 years with green NH3. LCOE of the PV/PEMFC ranges from $129-$184.18/MWh with grey NH3, $151.94-$233.36/MWh with blue, and $177.09-$359.89/MWh with green NH3.