Stored LNG similar to boiling water, only cooler

Cliff Goudey’s op-ed, “LNG and Maine’s underbelly” (BDN, Dec. 16), was an interesting read.

Washington County needs economic development that will create jobs. The county is rated one of the poorest areas in the nation and it is self-evident that the tourist trade and fisheries will not support the area.

Notice the crumbling canneries, foundations where canneries used to be, and rotten, broken weirs, along with the population decrease. It is suggested that MIT revisit the economy of Washington County.

As for the raging tides, ships now go up the St. Croix River to load and unload cargo at Bayside, New Brunswick, shipping into Eastport, where there has been discussion of having cruise ships visit.

The kicker was during World War II when German submarines came into the bay and St. Croix River to refuel from a farmhouse that German moles had bought and set up as a fuel depot. They came through these raging tides, running at night, not on the surface, and without navigational aids. It is suggested that MIT revisit the raging tides.

In a northerly direction, 21/2 miles from our farmhouse there is a compressor station for the Maritimes & Northeast Pipeline that is bringing natural gas from Sable Island off Nova Scotia. They have added additional compressors. The LNG terminal project site in Robbinston is 22 miles from this pipeline.

Once natural gas is in a pipeline it is in a lucrative gas market.

This company is considering building a $9 billion pipeline from the Alaska slopes to the United States. A pipeline is the safest, most efficient, most economical way to transport natural gas on land. Tanker ships are merely the bridge or extension of a pipeline.

To build a terminal complex will create hundreds of well-paying jobs. There will be many trades involved. Building a pipeline to connect with the Maritimes & Northeast Pipeline will create more.

Forty people to run a terminal on a day-to-day operation is too small. You have to recognize the human element for mistakes. One is always checking each other.

Since there is no way to create a storage cavern such as in a salt dome, the storage tanks could also serve the same purpose. The storage tanks themselves are interesting units.

How is it kept cold? The insulation, as efficient as it is, will not keep the temperature of LNG cold by itself, LNG is stored as boiling cryogen, that is, it is a very cold liquid at its boiling point, for the pressure it is being stored at.

Stored LNG is similar to boiling water, only 470 degrees cooler. The temperature of boiling water, 212 degrees, does not change even with increased heat, as it is cooled by evaporation, steam generation.

In much the same way, LNG will stay at near constant temperature if it is kept at constant pressure. This phenomenon is called auto refrigeration. As long as the steam – LNG boil-off – is allowed to leave, the tea kettle, tank and the temperature will remain constant.

If the vapor is not drawn off, then pressure and temperature inside the vessel will rise. However, even at 100 PSI, LNG will still be only about minus 200 degrees.

When you cool natural gas to a temperature of minus 260 degrees at atmospheric pressure, it condenses to a liquid called liquefied natural gas – LNG. In its liquid form the gas takes up one sixth-hundredth the space occupied by an equivalent amount of vapor, like reducing a car to the size of your fist.

LNG is returned to a gaseous state in a regasification facility where it is warmed in a controlled environment. The natural gas is regulated for pressure and fed into the pipeline as needed.

George F. Hill is a resident of Baileyville.