Environmental and economic assessment of electric ferries with different lithium-ion battery technologies

Electrification of passenger ferries is an important strategy for reducing the emission of greenhouse gases and air pollutants from domestic shipping. Although several battery electric ferries are currently operational, there is still a lack of information on how different lithium-ion battery chemistries and sizing will affect environmental impact and overall cost competitiveness. This study compares the environmental impact and economic performance of using varying charging strategies for two different battery types (defined by the active material of the positive electrode – lithium nickel manganese cobalt oxide or lithium iron phosphate) for electric ferries using life cycle assessment and life cycle costing. The results demonstrate that, compared to conventional marine gas oil-powered ferries, fully electric ferries offer more than 90 % reduction in contributions to climate change, while biodiesel offers around 65 % reduction. This is despite the fact that the production of batteries and other electric powertrain components causes an increase in greenhouse gas emissions from ferry manufacturing, compared to the marine gas oil ferry option. Battery electric ferries also significantly reduce other impacts like acidification (−75 %), marine eutrophication (−65 %), particulate matter formation (−70 %), and ozone depletion (−90 %) over the life cycle; however, there is an increase in environmental impact related to resource utilization (1.2 to 1.5 times) and ecotoxicity (8–9 times). Comparing the two battery alternatives assessed, lithium iron phosphate batteries are preferable both in terms of life cycle environmental impact and cost competitiveness. Extended opportunity charging intervals can reduce environmental impacts further, as they reduce the installed battery capacity, and this also indirectly saves energy due to the reduced ship weight. Carbon abatement cost is around 100€/tCO2eq. A lower interest rate on capital investment in a battery electric ferry brings the carbon abatement cost below zero. This finding indicates that battery electric ferries can be cost-competitive with fossil fuel alternatives with policy support.