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Ocean shipping, the backbone of international trade, is already significantly more energy-efficient than air or land transport. However, making it more efficient is another matter. Credit: Getty Images
When people think of greenhouse gas emissions from transportation, what often comes to mind are airplanes and land vehicles like cars or trucks. But as efforts to slow climate change are ramping up, the spotlight is on another form of transport: ships.
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The United Nations’ International Maritime Organization (IMO) has set targets to reduce shipping greenhouse gas emissions by at least 40% by 2030, and 70% by 2040, aiming for net zero by 2050. Shipping currently accounts for about 3% of global annual greenhouse gas emissions. The pressure is on shipping companies to meet these ambitious goals.
Across Georgia Tech, researchers are working toward a sustainable future for ocean shipping. This includes Valerie Thomas, the Anderson-Interface chair of natural systems and professor in the H. Milton Stewart School of Industrial and Systems Engineering, as well as in the School of Public Policy. She’s a scholar of energy systems, sustainability, assessment, and low-carbon transportation fuels, and her work touches many aspects of the maritime industry.
Finding sustainable solutions
“Today, we ship a lot of goods by ocean freight, and there’s certainly an environmental impact with shipping,” Thomas says. “But the emissions from shipping a product from East Asia to the U.S. on a bulk carrier vessel are significantly lower than trucking a product across the U.S. When ships are filled to the brim with cargo and are moving slowly across oceans, this is energy-efficient, fuel-efficient, and even cost-efficient per ton of ‘stuff’ transported.”
While ocean shipping is significantly more energy efficient than air or land transport, and contributes far fewer emissions, Thomas says cutting down on ocean freight emissions will require a great deal more effort. One way is to find more eco-friendly fuels.
“I look at big systems, and one of those areas is investigating alternative fuels,” Thomas says. “I’m often trying to figure out how much greenhouse gas various fuels emit, what other types of emissions or matter are coming out, and how to compare different fuel options.”
‘It’s not just about the fuels we use; it’s about optimizing supply chains, reducing empty freight, and leveraging multimodal transportation options.’—Valerie Thomas
Thomas is a leading expert in life-cycle assessment. It’s a method used to evaluate a fuel’s or technology’s environmental impact throughout its entire cycle—from raw materials extraction, processing, manufacturing, distribution, and, ultimately, use. Right now, basically all ships use petroleum fuels, which emit carbon dioxide and particulate matter into the air.
Finding fuel alternatives isn’t a simple task. Just because a fuel might initially seem like a promising low-carbon option, that’s not always the case in the end. Thomas’ expertise in life-cycle assessments helps her figure out whether these possible fuels are truly environmentally friendly.
“One such example is hydrogen: It doesn’t emit carbon dioxide when burned,” Thomas says. “But the manufacturing of hydrogen can emit carbon dioxide, and therefore hydrogen isn’t always a low-carbon fuel on a life-cycle basis.”
Helping the shipping industry cut carbon
Patricia Stathatou, a researcher at Georgia Tech’s Renewable Bioproducts Institute, specializes in sustainability assessment of chemical engineering processes and products, which includes life-cycle assessments and techno-economic assessments. She evaluates both the environmental effects and economic viability of products and processes. Stathatou, who will join the School of Chemical and Biomolecular Engineering as an assistant professor in January 2025, also conducts experiments to support these assessments and guide the development of new technologies.
“My contribution to the life-cycle assessment field is that I support assessments with in-field emission monitoring, taking samples and performing chemical analyses,” she says. “This helps identify specific pollutants that might be emitted into the air or be present in water, wastewater, or solid-waste streams.”
But as maritime shipping companies rise to the challenge of cutting emissions, they often don’t know where to start. This is where Stathatou’s experience comes in.
During her postdoctoral research at MIT, a major shipping company reached out to Stathatou and her colleagues asking for help in cutting emissions. They wanted to increase the energy efficiency of their fleet and investigate different strategies and technologies to eventually reach the IMO’s emissions goals.
Because of Stathatou’s expertise in alternative fuels, biofuels, and sustainable energy sources, she investigated potential solutions for the company, which included a six-day research trip monitoring emissions aboard one of the company’s bulk carrier vessels in East Asia. Her work involves designing experiments, measuring emissions, and evaluating the environmental effect of different fuels onboard bulk carrier vessels.
“Ten years ago, there weren’t rigorous goals or guidelines for reducing emissions in the shipping industry—and not much scientific collaboration in the process,” Stathatou says. “If we’re to make a difference in the industry in regard to climate, we need partnerships with shipping companies to help guide their efforts.”
Stathatou plans to continue her collaborations with shipping companies and expects to carry out more on-ship evaluations soon.
Patricia Stathatou prepares to measure particulate matter emissions in the vessel’s funnel—a very windy area of the ship. (Credit: Patricia Stathatou)
The big picture
According to Thomas, a holistic approach is needed to make shipping more sustainable. “It’s not just about the fuels we use; it’s about optimizing supply chains, reducing empty freight, and leveraging multimodal transportation options,” she says. “By embracing net-zero freight initiatives and maximizing efficiency in logistics, we can achieve meaningful reductions in emissions while meeting the demands of global trade.”
Encouraging shifts to ocean freight is another means of reducing emissions. For example, if a company wants to transport goods from Miami to Baltimore, they don’t need to go by road or rail. “You can ship your freight on the ocean along the coast, and that could be more environmentally efficient,” Thomas says.
The work Thomas and Stathatou do is part of a broad portfolio of shipping sustainability research at Georgia Tech, which also includes the Georgia Tech Supply Chain and Logistics Institute, the Panama Logistics and Innovation Research Center, and the Net Zero Freight Systems Program, which Thomas co-leads. These partnerships aim to enhance the efficiency and sustainability of global supply chains, leveraging innovative research and practical applications.
“The work of evaluating different fuels, technologies, and strategies isn’t trivial, and figuring out these new methods doesn’t happen quickly,” Thomas says. “These are difficult technologies, and it takes a long time to put them in place. That’s why we need to do this work now.”
Stathatou envisions that, with more shipping companies now looking to curb their emissions, there will be significant adoption of new fuels and technologies within the next decade.
“Ocean shipping is a transportation sector that we cannot go without, and so decarbonizing it is very important,” Stathatou says. “I believe the ability to perform these assessments and guide the development of future solutions will have a tremendous impact on humanity.”
Published June 11, 2024, by Georgia Tech.
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