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.

Natural gas is considered by many to be a 21st century energy resource that will enable multiple sectors, including shipping, to transition away from petroleum fuels. But questions remain about whether the economic and energy potential benefits include co-benefits for the environment.

In a study published this week in the international journal Energy Policy, University of Delaware professor James Corbett, James Winebrake, a professor at Rochester Institute of Technology, and recent UD doctoral graduate Heather Thomson, evaluated whether a transition to liquefied natural gas (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 liquefied natural gas are a slam-dunk over traditional marine fuels, and the long run price of LNG looks to be advantageous,” said Corbett. “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.”

The findings have important energy policy implications as the shipping industry, for the first time, comes under regulations that will change its real behavior with regard to pollution.

New maritime regulations require ships operating within 200 miles of the U.S. coast to reduce sulfur emissions. In 2016, additional regulations will require exhaust treatment to reduce nitrogen oxide emissions in new vessels.

At the same time, the availability of large domestic reserves of gas from U.S. shale fields has dropped the price of LNG below diesel and extended the market for gas into diesel-engine domains such as marine vessels and railroads. If prices stay stable, switching to liquefied natural gas could be an investment that saves shipping company’s money over the lifetime of their fleet.

“Our purpose it to help policymakers assess the potential impacts of energy and environmental policies aimed at improving air quality, reducing greenhouse gas emissions, and moving toward non-petroleum based fuels like natural gas,” 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 study finds that natural gas in marine engines may reduce greenhouse gases under certain conditions and timeframes. However, these conditions depend upon low-greenhouse gas LNG infrastructure and advanced combustion technologies to reduce methane leakage.

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.