The floating filling station: bunkering zero-emission fuel at sea

Much like a filling station by the roadside, a new concept may allow ships to bunker on the go, with clean, green fuel created using the power of nature.

ZEEDS, or Zero Emission Energy Distribution at Sea, is a novel concept using wind and solar power to produce hydrogen, ammonia or liquid biogas at sea, with production and bunkering initially located along The Northern European Shipping Highway. The partners are Equinor, Kværner, Aker Solutions, Grieg Star, DFDS and Wärtsilä.

  • ZEEDS concept sketch
  • ZEEDS concept sketch

Central to the concept is a system of offshore hubs that will produce, store and distribute clean fuel to vessels. The hubs are designed as gravity-based structures in shallow regions and potentially semi-submersible floaters in deeper water. Clean energy for topside fuel production will be supplied by around 75 large wind turbines per hub. One 12MW turbine can produce enough energy to fuel one ship, meaning that each hub could potentially produce enough fuel to supply 65 vessels per day.

“Our goal is a faster route to zero-emission shipping, but the goal has to be met with 100 percent renewable energy,” says ZEEDS project spokesperson Cato Esperø. The idea is to close the gap between the present situation and future needs, based on the 17 UN sustainable development goals.

“Imagine a network of clean energy hubs placed near the world’s busiest shipping lanes, capable of supplying and distributing clean fuels to the global fleet,” Esperø says. “It sounds ambitious, but if we are truly serious about managing climate change, we need big ideas and bold action.”

Cato Esperø
Cato Esperø

Combining competence

Such a multi-faceted project requires what Esperø calls “composite competence”. “We knew we needed energy, engineering and construction players, coupled with power suppliers, and global and Nordic shipping. What all the different project partners have in common is a sustainable perspective.”

He points out that the partners are not necessarily competitors, but that they may be in certain contexts. “This is one of those situations where we can compete and cooperate as needed. We have a common challenge, and we need to agree on a common goal. Once that is done, all parties have to share what they can to achieve the goal.”

The project defines most of the workflows, but partners will also work on their own initiatives. “And along the way we will of course redefine and recalibrate assignments,” Esperø confirms.

ZEEDS: why and how?

“Public opinion and regulations have built up the argument for alternative solutions,” Esperø says, but he believes that the current concept of clean shipping lacks a suitable fuel in order to be realized. “We believe that by addressing the supply, storage and distribution chain, we can accelerate the switch to cleaner shipping fuels.”

The idea of placing hub installations adjacent to shipping lanes is not without its challenges, Esperø acknowledges. “We identified hubs in strategic locations, presented the concept, and asked the question: Is this feasible?” The result is a concept that should be scalable and flexible for global application, he says. The project is looking to utilize existing technology, but assembled in new ways, incorporating further development goals for selected technologies.

The right fuel in the right place

“The industry has not yet decided which is the right fuel,” Esperø points out, “so we had to land on one. We started with hydrogen, but ammonia is a hydrogen product, and arguably easier to work with, with a higher energy density than hydrogen.”

Though ZEEDS’ current focus is on green ammonia as a feasible zero-emission fuel, given that it can be used on existing LNG-powered vessels without major modifications, the concept is classified as “fuel agnostic”, with the possibility of including fuels such as hydrogen or liquid biogas.

Ammonia would either be stored on the installations or in seabed tanks using water pressure to keep the fuel liquid. Distribution would use ship-to-ship (STS) bunkering at sea, minimizing operational downtime and avoiding port congestion. Bunkering would be performed by autonomous units dubbed Energy Providing Vessels (EPVs), fueled by their own cargo and with a range of 50 nautical miles around the mother hubs.

Fueling a breakthrough

“The ZEEDS concept would require a new type of infrastructure and a new supply model, and this kind of renewal requires a realistic incentives program. Then the question becomes, should we use the carrot or the stick? Should society or business act as the driver? In any case, we need incentives to get started.”

He underscores that collaboration is the key. “Together, we can awaken the public to the new possibilities. The spirit of the project must be generous, open, and trusting, but we must also have sufficient drive and progress. We have to be both high-energy and high-level in order to make it work.”


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