Awareness has risen that inland navigation is not as “green” as thought. Regarding emission of CO2, NOx and fine particulates, inland waterway ships are clearly underperforming. Readily available alternatives only offer partial solutions: biofuels, fuel-optimized engines with end-of-pipe treatment, Euro VI engines and hybrid propulsion (diesel-electrical).
"Zero emission" solutions are hydrogen and battery-electric
In PortLiner's view hydrogen still needs a good number years before it becomes technically and financially feasible for inland navigation. Also from safety viewpoint a lot of progress needs to be made (high pressure, up to 700 bar).
Battery-electric is the zero emission option that is available now, at competitive conditions, provided the appropriate battery technology is chosen!
In mobile applications (automotive) lithium-ion is usually chosen, with high power density and decreasing kW cost. But there are huge downsides - e.g. overheating, limited economic life and recycling issues, not to mention investment cost.
Go with the flow
PortLiner has identified flow batteries as a perfectly viable alternative for inland shipping, without the downsides of lithium-ion but with the upside of operational efficiency and competitive operational and investment cost.
In flow batteries, the electrical energy is stored in a liquid electrolyte (no pressure, ambient temperature) and converted in flow cells ("stacks") into electricity to feed into electro engines for propulsion. The "spent" electrolyte is subsequently recharged with electricity. The electrolyte can be used for almost indefinite time - there is hardly any degradation.
PortLiner, with partners, has developed a vessel design with flow battery technology, and a battery recharging infrastructure that meets operational requirements and is scalable, to serve multiple vessels.
In Q1 2021, PortLiner will launch its first "zero emission" vessel, a 135m container ship.