Any additional, newly-built ferry to serve Estonia's two main islands, Saaremaa and Hiiumaa, will need to use tech and fuel which fits in with environmental requirements, the state says.
The state-owned TS Laevad serves the island routes, and has a fleet of five ferries, some of which are hybrid diesel-electric vessels.
The new vessels' procurement will be overseen by the Transport Board (Transpordiamet).
Valentin Bratkov, the board's project manager for ferries, told ERR that: "The plan is to implement waste heat recovery or electrical energy conversion technologies, while a vessel's hull suitable for our conditions will also be developed."
"Modern tech will be used that will enable a vessel which will in the future be used, while creating as little environmental impact as possible," said Bratkov.
Bratkov told ERR that Finnish company Deltamarin Ltd, which is developing the new ferry concept, will need to take into account all viable, and reasonably suitable and environmentally friendly technologies, including emissions-neutral fuels, more energy-efficient power sources, those which emit less, or zero, noise and vibration, and those using renewable energy power sources.
Heltermaa harbor, the port which connects Hiiumaa to the mainland, should not need any major work, barring that already planned, in order to accommodate the planned new ship, Bratkov added, unlike with previous procurements.
Kaida Kauler, board member of Saarte Liinide, which manages the islands' ports, also said that depending on the type of fuel to be used the port's infrastructure must be adapted.
"During the competitive process for the design, it will become clear what the vessel's type will be and what kind of fuel it will run on - of we have, for example, electric-powered ships, we would to adapt our infrastructure to them," he said.
"At the moment, we are not building anything yet. Technology is developing, ships are developing, infrastructure is developing with them," he added.
Further feasibility studies will be needed, which will be followed by completion of the concept and then the tender process for designing and constructing the ferry.
At the other end of the scale, TS Laevad also operates the 51-year-old Regula.
The remaining four vessels are all only a few years old, while one of them, the Tõll, was converted into a hybrid vessel in 2019.
Last summer, a minor incident in which the Tõll struck a pier at Heltermaa attracted plenty of media attention, partly because one of the passengers was then-President Kersti Kaljulaid, and also as a result of push-back over the Tõll's replacement being the ageing, smaller-capacity Regula, while the Tiiu, which normally serves Hiiumaa, was put on the Saaremaa route instead.
TS Laevad is a subsidiary of the Port of Tallinn (Tallinna Sadam).