Queenstown's historic steamship the TSS Earnslaw could soon be powered by something other than coal. 

A feasibility study is under way to investigate whether the ship, which is 109 years old today, can become carbon neutral or carbon zero. 

Options include wood pellets and bio-diesel fuel, both carbon neutral, or carbon zero power sources such as renewable hydrogen fuel, battery-electric or fully electric.

The TSS Earnslaw, the oldest passenger-carrying coal-powered steamship in the Southern Hemisphere, is owned and operated by Real Journeys, a subsidiary of RealNZ (recently rebranded from Wayfare). 

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But its environmental impact was highlighted in June, when Otago Regional Council's first Greenhouse Gas Emission Inventory estimated it was responsible for 1% of Queenstown Lakes District's transport-related greenhouse gas emissions. 

The inventory estimated the much-loved Queenstown icon smoked out 4076 tonnes of 'carbon dioxide-equivalent' between July 2018 and June 2019.

Carbon dioxide equivalent (CO2e) is a standard unit for counting greenhouse gas emissions, regardless of whether they're from carbon dioxide or another gas, such as methane.

Gross emissions for the Queenstown Lakes District were estimated at 600,895 tonnes of CO2e, with transport accounting for 45% of that. 

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RealNZ CEO Stephen England-Hall says the ship is a significant part of New Zealand's history. 

"But as responsible kaitiaki, we have to weigh up every inch of her heritage value with our ambition to protect and preserve the places where we operate." 

The ship's original boilers will soon be more than 110 years old and will need replacing, requiring the vessel to be out of the water for an extended period of time. 

"That would be the obvious time to implement a carbon neutral or carbon zero solution," says England-Hall.  

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"We will essentially look for a new source of heat to generate steam that replaces the coal. The aim is to keep the engine room fully operational and intact."

On her 109th anniversary, RealNZ CEO Stephen England-Hall will be announcing that as part of RealNZ’s commitment to conserving the national icon for future decades, it was exploring alternative ways to generate steam to fuel the steamship.

RealNZ has established a TSS decarbonization team, made up of RealNZ Head of Asset Management Chris Fleck, TSS Earnslaw Chief Engineer Peter Dorrington and Project Engineer Sander Kristensen. 

It has already looked across both the process heat and marine industries at alternative ways to fuel the steamship.

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 England-Hall says the technology required is advancing all the time and preserving the steamship's authenticity makes it a complex project.  

"Conservation for us, is about conserving our history as well as our natural heritage. 

"The grand old ‘Lady of the Lake’ has been respectfully maintained and operated by RealNZ for the last 50 years, so as always, we will be proceeding with care.  

"But we’re looking forward to finding ways the TSS Earnslaw can operate sustainably – for the next 100 years."