How many uses are there for rotten fish? Powering cruise ships might not immediately spring to mind, but that’s exactly what Hurtigruten, the world’s largest expedition cruise line, has planned.

By 2021, the Norwegian cruise operator will run at least six of its growing fleet of ships on a mixture of biogas, liquified natural gas (LNG) and large battery packs.

Liquified biogas (LBG) is a fossil-free, renewable gas produced from dead fish and other organic waste – and the most eco-friendly fuel available.

Hurtigruten's CEO Daniel Skjeldam Credit: RUNE KONGSRO/Hurtigruten

Hurtigruten CEO Daniel Skjeldam said: “What other[s] see as a problem, we see as a resource and a solution. By introducing biogas as fuel for cruise ships, Hurtigruten will be the first cruise company to power ships with [fossil]-free fuel.

“While competitors are running on cheap, polluting heavy fuel oil, our ships will literally be powered by nature. Biogas is the greenest fuel in shipping, and will be a huge advantage for the environment. We would love other cruise companies to follow.”

But the WWF says that while it hopes Hurtigruten can lead the way and encourage other companies to get on board with renewables, the industry "has a huge job to hit its target of cutting emissions by at least 50 per cent over the next three decades."

“International shipping is responsible for twice the greenhouse gas emissions of the UK," said Gareth Redmond-King, WWF’s Head of Climate Change. "That’s fuelling climate change, as well as polluting and damaging the very nature and wildlife they’re taking tourists to see."

Hurtigruten offers cruises to some of the world's most remote and unspoiled areas, from the Norwegian coast to South America.

Hurtigruten expects to invest more than $850million (£660m) in building the world’s greenest cruise line. Skjeldam says the ultimate goal is to operate its ships completely emission free.

It will retrofit at least six of its existing vessels, replacing diesel propulsion with large battery packs and an LNG engine. In addition to LNG, it will use LBG.

In 2018, the cruise line announced a ban on single-use plastic across its fleet of 17 ships.

MS Nordnorge in the Norwegian fjords Credit: Lars Lund/Hurtigruten

And next year will see the launch of MS Roald Amundsen, the world’s first battery-hybrid powered cruise ship. With near-silent engines, it will also avoid disturbing wildlife.

Two other battery-hybrid powered ships are under construction in Norway’s Kleven shipyard – MS Fridtjof Nansen, due to launch in 2020 and a third, unnamed sister ship due to launch in 2021.

These three hybrid sister ships will not be powered by biogas or LNG as they will be operating in areas where these fuels are not widely available. Instead they will combine the cleanest engines with large battery packs.

LBG is already used is small parts of the transport sector, especially in buses, but Hurtigruten will be the first to use it as a fuel for cruise ships.

The large fishery and forestry sectors of Northern Europe (including Norway) produce a steady volume of organic waste. Hurtigruten suggests this presents a unique opportunity for Northern Europe to become a world leader in biogas production.