How flexible marine fuels can help cut emissions from shipping

How flexible marine fuels can help cut emissions from shipping

By David Elliott

Index

Outside of its striking size, the cargo ship Daisy Leader might not appear remarkable to the casual observer.

A giant floating metal box capable of carrying about 7,000 vehicles, Daisy Leader is an example of a 'Pure Car and Truck Carrier' (PCTC). Towering monolithically above the waves, it delivers rolling cargo to destinations all over the globe.

A glance toward Daisy Leader's stern and its 'LNG powered' label reveals that this particular marine workhorse runs on up-to-the-minute emissions-reducing technology.

The ship is fitted with a LNG Fuel Gas Supply System (FGSS), a liquefied natural gas (LNG) system for dual-fuel marine engines made by Mitsubishi Shipbuilding, a Mitsubishi Heavy Industries (MHI) Group company.

Dual-fuel engines allow ships to run on either conventional marine fuels or alternative fuels such as LNG.

An FGSS enables fuels to be easily switched, and this flexibility allows operators to choose the best option at any given time - offering a pathway to decarbonization for a sector under increasing pressure to cut emissions.

The LNG-fueled vehicle carrier, Daisy Leader

A step to lower-carbon shipping

Cleaner shipping is vitally important, as the sector transports around 90% of the world's traded goods.

However, the industry is responsible for almost 3% of global greenhouse gas emissions, and these emissions have grown by 20% in just a decade. Shipping firms are therefore grappling with how to balance operational efficiency and compliance with necessary regulations and targets, including from the International Maritime Organization (IMO) and the industry's customers.

It's a tricky issue because industrial shipping is difficult to decarbonize, with challenges around the current capabilities of electrification technology and powering cargo vessels that require tens of thousands of gallons of marine fuel a day. There are, today, no batteries big enough to take large ships across the ocean, and other technologies still need to be developed to commercial scale. As such, almost 99% of the global shipping fleet still relies on conventional fuels, according to UN Trade & Development.

By allowing the use of either traditional fuel or alternative fuels - such as the lower-carbon-content LNG or carbon-free ammonia - dual-fuel engines offer the opportunity for shipping firms to make a vital step toward carbon-reduced shipping without disrupting their critical role in global economies.

Ammonia-powered ships are under development at several shipyards

Alternative fuels making waves

Against this backdrop, the market for dual-fuel engines is experiencing significant growth. By some estimates, by 2030, 85% of all ship engines ordered will be dual-powered. More than 75% of new car carrier orders last year, for example, were for dual-fuel LNG engines.

LNG is currently the most common choice for dual-fuel ships in the global fleet, and demand will remain "robust", according to S&P Global. This is due to factors including competitive pricing, abundant supply, and a well-developed infrastructure, with almost 200 LNG bunkering locations worldwide.

LNG can offer shipping a reduction in carbon emissions of up to 25%, reduced nitrogen oxide emissions, as well as vastly decreased particulate matter and sulfur oxide emissions, due to the absence of sulfur. It can also bring cost and efficiency benefits.

Methanol, meanwhile, is attracting increasing attention from the industry, particularly for container ships and roll on, roll off (RORO) vessels. Mitsubishi Shipbuilding has recently received an order for Japan's first methanol-fueled RORO cargo ship, which will be powered by a high-performance dual-fuel engine that reduces CO₂ emissions by more than 10% compared to heavy oil vessels. In the future, green methanol could be used in such engines to further reduce emissions.

And ammonia, which emits no CO₂ emissions when combusted, is also beginning to make an impact as a shipping fuel, with some of the first ships fitted with ammonia dual-fuel engines starting to appear. Mitsubishi Shipbuilding is also collaborating with industry partners to develop large-size ammonia carrier ships, themselves powered by ammonia.

FGSS modules, such as that fitted on the cargo ship Daisy Leader

A reliable system built on experience

Reliably delivering alternative fuels to the ship's engine is a crucial aspect of dual-fuel marine engine technology. Mitsubishi Shipbuilding's FGSS has been designed drawing on the company's extensive experience in building LNG carriers.

The system comprises an FGSS module, fuel tanks for onboard LNG storage, and facilities that allow the ship to receive LNG from shore facilities or bunkering vessels. It is designed to save space, be easy to maintain, and features a control system that can be customized to the ship's exact demands, contributing to operability and safety.

The company has received orders for more than 26 FGSS units and has also recently received an order for its Ammonia Fuel Supply System (AFSS) from Japan Engine Corporation, further contributing to the development of decarbonized maritime infrastructure by promoting the use of ammonia as a fuel of the future for shipping.

As the industry continues to slot the pieces of its decarbonization puzzle into place, such systems can help firms bridge their net zero transition with dual-fuel engines.

Learn more about Mitsubishi Shipbuilding's LNG Fuel Gas Supply System

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David Elliott

David Elliott has two decades' experience working as a journalist, communications professional and content creator, including for some of the world's biggest technology brands.