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LNG Not Clear Greenhouse Gas Winner

LNG bunkering
file photo

By The Maritime Executive 09-22-2015 11:12:06

As the maritime shipping industry transitions toward cleaner fuels in response to new environmental regulations and emissions standards, abundant supplies of natural gas in the United States, and worldwide, appear to offer a promising solution in transportation industries.

But, questions remain about whether the economic and energy potential benefits include co-benefits for the environment. 

A study conducted by the University of Delaware in cooperation with the non-profit organization Rare looked at how mascots can influence people around environmental issues.

The University of Delaware’s James Corbett, a professor of marine science and policy, has spent the past 15 years working to improve environmental policy on global shipping.

In a study published this week in the international journal Energy Policy, Corbett, in partnership with James Winebrake, a professor at Rochester Institute of Technology, and recent UD doctoral graduate Heather Thomson, evaluated whether a transition to using LNG to power marine vessels can reduce both local pollution and greenhouse gas in the marine environment, and whether fueling ships at major ports can help develop the natural gas infrastructure. 

Study findings indicate that while using natural gas will reduce emissions in the marine sector, the implications for greenhouse gases depends on how the natural gas is extracted, processed, distributed and used.

“Local and regional air pollution benefits of LNG are a slam-dunk over traditional marine fuels, and the long run price of LNG looks to be advantageous. But LNG was not a clear winner for climate change with regard to greenhouse gas implications, especially if the fuel supply infrastructure is not designed to minimize natural gas losses,” Corbett said. 

According to Corbett, a successful transition to LNG will require a carefully constructed infrastructure development policy that requires state-of-the-art infrastructure that minimizes leakage at the earliest stages of the fuel cycle.

The researchers used an advanced method known as a “technology warming potential” (TWP) approach to analyze the life cycle of LNG production and delivery over three case studies. 

“Assessing the technology warming potential of a fuel transition addresses inherent problems with the more traditional global warming potential comparison,” said Winebrake. “Our approach uses TWP in a more realistic analysis whereby diesel powered vessels are replaced by natural gas vessels that create emissions over their useful lifetime.”  

The researchers are among the first to compare technology warming potential with traditional methods used to measure how good or bad a fuel is based on greenhouse gas comparisons.

The case studies represented typical marine vessel trips in the following categories: local, regional and long haul cargo transportation. For each case study, the scientists compared LNG to commercial marine diesel fuels traditionally used in the industry. 

The approach accounted for emissions of nitrogen oxides, sulfur oxides and particulate matter in each case, while also quantifying and comparing greenhouse gas emissions including carbon dioxide, methane and nitrogen oxides. The scientists also considered regional drivers that might influence the adoption of natural gas as a marine fuel.

This study considers the entire lifecycle, from the extraction of natural gas from the ground to the production of LNG to its ultimate use, providing a more complete accounting of the co-benefits or trade-offs of energy policy decisions related to ship fuel choices and natural gas development. 

The study finds that natural gas in marine engines may reduce greenhouse gases (lower technology warming potential) under certain conditions and timeframes. However, these conditions depend upon low-greenhouse gas LNG infrastructure and advanced combustion technologies to reduce methane leakage.  

Other important considerations include the conditions that may favor converting marine transportation systems to natural gas.

This work is supported in part through ongoing funding from the U.S. Department of Transportation Maritime Administration (MARAD). MARAD has also been studying the necessary infrastructure to enable vessel fueling and operations that may provide LNG to ships in U.S. ports.

“This study is an important example of how the U.S. Maritime Administration supports research to address maritime environmental issues and overall feasibility of using natural gas as a marine propulsion fuel,” commented Dan Yuska from MARAD’s Maritime Environmental Technical Assistance (META) Program. 

While a global conversion to LNG in maritime transport is unlikely in the near term, the pace of development depends on regional motivation to develop supply and delivery systems. 

“Our work shows the need for investments in a low leakage infrastructure, and further innovations by engine manufacturers to capture and prevent the release of methane during engine operation, in order to ensure greenhouse benefits to switching to LNG accompany the air pollution and economic benefits,” Corbett said.