LNG-Fueled Marine Engines

21 July 15

Turn on your kitchen stove, hot water faucet or the furnace that heats your house. For most people in North America the fuel that cooks your food, warms your home, and (in some places) creates the electricity that lights your night is the same natural gas that helped power the ancient Oracle of Delphi and drives some of the most modern marine engines on the oceans today.

Holy Gas!

2,600 years ago, a Greek goat herder tending his flock on Mount Parnassus came across what looked like a “burning spring,” a flame dancing out of a crack in the rock. The amazed people of the surrounding area built a temple over the flame and for the next 1,900 years the natural gas emitting from the rock powered the Oracle of Delphi.

Although natural gas (NG) is mostly composed of methane, a more potent greenhouse gas than carbon dioxide, it is the cleanest fossil fuel. It produces about 29% less carbon dioxide per joule than oil and 44% less than coal with potentially fewer pollutants than other hydrocarbon fuels.

From the Earth to the Oceans to the World

How does this “greener” fuel get from the ground to your house? Most of this gas in the world travels from the well through pipelines to local distributors to you, the end user. Now, due to an ever-increasing demand for cleaner fuels, ever-increasing volumes are being shipped across oceans where pipelines are impractical.

As a gas at normal pressure, NG takes up about 640 times the volume of its liquid phase. In order to transport it efficiently it’s condensed by cooling it to -162ºC (-260ºF) and transported as “liquefied natural gas” (LNG) in specialized ships that carry huge super-refrigerated tanks.

When the first LNG carrier the “Methane Pioneer” left the Louisiana Gulf coast in January of 1959 carrying about 2,000 tons of LNG to the UK, it began a trade that has grown worldwide. Today the global LNG carrier fleet has grown to more than 359 ships with an average capacity of 150,000 cubic meters of LNG per ship. The latest design—the “Q-Max”—are the largest LNG vessels in the world (“Q” stands for Qatar and “Max” for the maximum size of ship able to dock at the LNG terminals in Qatar). These cryogenic giants are able to transport 266,000 cubic meters (9,400,000 cubic feet) of LNG.

Oddly, diesel engines burning the much dirtier Heavy Fuel Oil (HFO) power most of the ships transporting the cleaner burning LNG. New stricter regulations for clean air aimed at reducing sulfur emissions in sensitive coastal regions (“emission control areas”) are forcing LNG shippers to look at cleaner ways to move their product.

The Qatari shipping company Nakilat, the world’s largest owner of LNG carriers, along with Qatari LNG producers Qatargas, RasGas, and engine manufacturer MAN Diesel and Turbo, recently announced plans to convert the engines of a Q-Max vessel to a dual fuel system that can run on either the cleaner LNG or the dirty old HFO.

And LNG fueled marine engines are not limited to the transport of LNG. The U.S.-based shipping giant TOTE, Inc., announced plans in 2012 to build the first container ships to use LNG as a primary fuel source. These “flex fuel” engines will be able to run up to 4,000 nautical miles on LNG, but will still be able to switch to HFO and cruise another 10,000 miles.

Liquid Gas Moves People!

LNG marine engines are being developed for passenger operations in the U.S. and around the world. There are 20 LNG-fueled car and passenger ferries operating in Norway. LNG-driven passenger vessels are currently under construction or in design for service in Argentina, Uruguay, Finland, and Sweden.

In North America, Washington State Ferries, running the world’s largest ferry fleet, has been studying the possibility of using LNG as a source of fuel for its fleet. Both British Columbia Ferries and Staten Island Ferries are looking at options to convert their vessels from diesel to LNG fuel. Recently the Quebec Ferries Company has contracted for the construction of three new LNG driven ferries.

The day is coming when the gas that powered the flame at the Oracle of Delphi will also bring you products from around the world and fuel your ferry to the Statue of Liberty.

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