Crest of the Royal National Institution of Naval Architects - Click to return to the homepage




Air Products June 2022


International Registries June 2022

Marintec_New_July_December 2022

Demystifying zero-emission ships

The Naval Architect: July/Aug 2019Zero-emissions

For some time, the idea of using hydrogen and fuel cells to power ship fleets was viewed as a fanciful trend. As other green technologies picked up momentum, hydrogen was cast aside. But in the past couple of years, the abundant element has become a mainstream enterprise.


Why? Because it stands as one of the most promising zero-emission solutions. More and more hydrogen powered vessels are hitting the drawing boards as the consensus that hydrogen could be one of the best future fuels grows.


One young organisation that is trying to push hydrogen and zero-emission ships to the forefront is Zero Emissions Maritime Technology (ZEM-Tech). Established in November 2018 by Madadh MacLaine, who previously worked in the hydrogen sector at ITM Power, ZEM-Tech is working with partners to design zero-emission ships because, as MacLaine says, “to do anything else would be irresponsible”.


The IMO’s climate strategy aims to reduce the total greenhouse gas emissions by at least 50% by 2050 compared to 2008. In order to reach the IMO’s goal, however, zero-emission vessels need to enter service by 2030, if not sooner.


Many are both unconvinced that the shipping industry can be overhauled in such a short amount of time and sceptical of newer zero-emission technologies. “There are a lot of unknowns and a lot of mysteries that need to be unbaffled, people think of zero-emissions as science fiction but it’s not,” says MacLaine, who also founded the Zero Emissions Ship Technology Association, which works to facilitate the uptake of hydrogen and other zero-emission technologies.


Overcoming doubts
Although hydrogen could meet 18% of the world’s final energy demands by 2050, according to the Hydrogen Council, it’s progress as a zero-emissions solution has suffered due to a lack of information and misconceptions.


“The biggest issues with hydrogen are a lack of available fuel, the cost and the volume that it takes up onboard a ship,” says MacLaine. Additionally, how to produce sufficient amounts of the gas remains a major concern. Production through natural gas reforming is currently the most popular and cheapest option, however, it has a substantial carbon footprint. But ZEM-Tech is designing a solution to get around these hurdles: a zero-fuel ship. “What we mean by zero-fuel is that it’s a ship that doesn’t necessarily need to bunker. And the way it does that is that it produces its own fuel while underway through energy recuperation.”


To achieve this, the company plans on using onboard electrolysis. The vessel will use wind as a means of propulsion and as a direct renewable. The excess energy produced will be captured and stored in batteries and then as hydrogen using proton exchange membrane (PEM) electrolysis, which will later generate electrical power for propulsion or hotel load. “When you start pulling together all these different zero-emission technology options, you start seeing the possibilities and how all these things can work together.”


The technology to do this, MacLaine says, already exists. “We have a marinized electrolyser, it’s just not to scale, and we have electrolysers to scale but they’re just not marinized.” ZEM-Tech is collaborating with various clients to design a full spectrum of zero-fuel ships and MacLaine believes “that we will have the technology to design a zero-fuel VLCC from 2023.


What’s the biggest holdup in evolving this concept? MacLaine believes it’s regulation and investment into research and development. “Regulation will trigger investment, which will bring in the money required to bring things up to an economy of scale. If you just sprinkle a little bit of funding on that those innovations will grow until they’re the sized required.”