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Tina Casey headshot

5 Unusual Ways to Decarbonize the Shipping Industry Right Now

By Tina Casey
A ship with Oceanbird's rigid sails.

In this rendering, the smokestack-like objects atop this ship are actually aerodynamic sails that can make a significant cut in fuel consumption. (Image courtesy of Oceanbird) 

Carbon emissions from the global shipping industry are “headed in the wrong direction,” despite efforts to replace the heavy fuel oil currently used by most ships with cleaner fuels, according to a 2023 assessment from the United Nations

Still, the fuel transition is just one pathway to decarbonize the shipping industry. New technologies are also emerging to help get shipping emissions back on track until heavy oil is banished forever.

Emissions from the shipping industry are headed in the wrong direction

“The shipping industry accounts for over 80 percent of the world's trade volume and nearly 3 percent of global greenhouse gas emissions, with emissions escalating by 20 percent in just a decade,” according to the United Nations Commission on Trade and Development (UNCTD).

The UNCTD also notes that almost 99 percent of the global shipping fleet still relies on conventional fuels. With an estimated 60,000 cargo ships currently in operation, alternative fuels have barely made a dent.

The future looks somewhat brighter in the years to come, with 21 percent of new ships on order designed for alternative fuels. However, that still leaves plenty of room for conventional fuel. With a cargo vessel’s typical lifespan of 20 to 30 years, the gears of decarbonization will grind slowly.

The persistence of conventional fuels notwithstanding, new technologies can help make a significant reduction in shipping industry emissions within the near future. Here are five retrofits that can make a difference.

1. The return of wind power

New high-tech, rigid sails are appearing on cargo ships. While not entirely replacing conventional fuel, they can make a significant cut in fuel use, drawing aerodynamic lessons learned from racing yachts, motorsports and aircraft.

Some don’t resemble sails at all. The Swedish firm Oceanbird and the United-Kingdom-based startup Green Energy Technologies, for example, are developing rigid sails for shipping vessels that resemble long, tall smokestacks.

Another kind of approach is represented by the Finnish company Norsepower. Its hard sail is based on the Magnus effect, which refers to a sideways force on a spinning object, such as a curveball. Norsepower harnesses the Magnus effect in a long tube called a Flettner rotor. 

Norsepower has installed its Rotor Sail technology on cargo vessels for 10 years. The company recently announced that it is preparing for mass production.

In a recent voyage to validate the technology, a tanker owned by the Japanese firm Sumimoto made the Atlantic crossing between Amsterdam and New York City with a fuel savings of 16 percent attributed to the Rotor Sails alone. Another 12 percent in fuel savings came from Norsepower’s route optimization system, for a total of 28 percent.

2. Producing calcium carbonate at sea

Another emerging trend that could be brought to bear on ship emissions is the carbon capture-and-recycling trend, in which airborne carbon is repurposed to make fashion accessories, plastics, yarns, fabrics, synthetic fuels, and other products normally made with virgin petrochemicals.

In a seagoing twist, the U.K. startup Seabound created a system aimed at capturing 95 percent of the carbon emissions from a cargo ship’s exhaust. The exhaust is exposed to calcium oxide pebbles in a controlled environment, which traps carbon in the form of calcium carbonate.

In addition to its use in medicine, calcium carbonate can be rendered back to calcium oxide, a common industrial chemical used in making cement, paint, chalk, paper and plastic, among other products.

Seabound recently completed a two-month pilot test of the system on a 787-foot long cargo ship capable of holding more than 3,200 standard containers. The real-life pilot project achieved promising results with a carbon capture efficiency of 78 percent.

Near-term prospects for commercial development also look promising. In addition to funding from the U.K. government, Seabound is working with investors and leading stakeholders in the global shipping industry toward a goal of launching the technology into the market in 2025. 

3. New energy-efficient materials and designs

A transition to lighter, more fuel-efficient materials is taking shape. The superstructure of a cargo ship, which refers to the parts of the boat above the main deck, is one key focus of attention. The U.S.-based shipbuilder General Dynamics NASSCO, for example, began the complex process of transitioning its ship works from heavy gauge steel plates to lightweight, ultra-thin plates for use in superstructures beginning in 2017. 

The European Union also launched a fuel-efficient materials initiative, one result of which is the introduction of lightweight plastic composite “sandwich” panels for deck structures. 

New treatments for the hull of a ship can also make a significant difference in fuel consumption by reducing friction as the ship moves through water. For example, in December the global shipping firm Stolt Tankers announced the world's first application of a new graphene coating on the hull of its Stolt Lotus ship that resulted in an estimated fuel savings of between 5 percent and 7 percent.

“[The] graphene technology, developed by Graphite Innovation and Technologies Coatings, has the potential to reduce fuel consumption and resulting greenhouse gas emissions,” according to Stolt. 

4. The solar-powered ship of the future

Solar panels are another way to introduce alternative energy into the shipping industry, though a lack of adequate deck space presents an obstacle. The newly launched U.S. startup Voltic Shipping is addressing that hurdle. It’s developing a barge that provides more space for solar panels. The company’s ultimate aim is to apply its system to seagoing cargo ships, enabling them to run on 100 percent solar energy.

That may take years of development and testing, but the near-term goal of a solar-enabled barge appears well within reach. The leading U.S. firm Crowley already introduced an electric tugboat that could be powered by solar panels on a solar-equipped barge. Shipbuilders in China and Turkey also introduced electric tugboats.

To maximize deck space, Voltic’s solar array is arranged on a retractable, expandable rack elevated above the deck, allowing for cargo underneath. While the barge is moving in open water, the rack can expand well beyond the footprint of the deck, significantly increasing the area available for solar panels. The rack folds up accordion-style for cargo loading and unloading and maneuvering in tight spaces.

“Our barges will be able to transport cargo in a wide variety of settings, including low sunlight and night-time thanks to onboard batteries,” according to the company.

5. The seagoing energy storage systems of the future

The high cost of batteries is an obstacle to ship electrification. Voltic’s solar solution could help cut costs by enabling batteries to recharge while at sea. A broader downward trend in the cost of energy storage could also help propel the ship electrification movement.

Last May, participants in a U.S. Department of Energy workshop on energy storage were presented with a 2022 study that found electrification to be a more efficient way to cut shipping emissions compared to another emerging electricity-based option, carbon-neutral electrofuels.

The advantage of direct electrification is a steep drop in the cost of battery-type energy storage systems alongside improvements in battery performance, according to the study.

“Past studies on ship electrification have relied on outdated assumptions on battery cost, energy density values and available on-board space,” the researchers with Lawrence Berkeley National Laboratory and the University of California, Berkeley, observed. 

“We describe a pathway for the battery electrification of containerships within this decade that electrifies over 40 percent of global containership traffic, reduces [carbon dioxide] emissions by 14 percent for U.S.-based vessels, and mitigates the health impacts of air pollution on coastal communities,” they concluded.

The signs of progress are clear, though it will take years before new technologies and alternative fuels make a significant impact on global shipping emissions. In the meantime, a complete rethinking of the way that goods and materials are used in the global economy would go a long way toward reducing unnecessary emissions by eliminating unnecessary trips.  

Tina Casey headshot

Tina writes frequently for TriplePundit and other websites, with a focus on military, government and corporate sustainability, clean tech research and emerging energy technologies. She is a former Deputy Director of Public Affairs of the New York City Department of Environmental Protection, and author of books and articles on recycling and other conservation themes.

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