Harpswell Information

Cheryl Golek.

This is a section taking from the book Brittle Power: Energy Strategy for National Security by Amory and Hunter Lovins: Part 2 Chapter 8 Disasters Waiting to Happen

Liquefied Natural Gas Natural gas can be sent by pipeline over long distances. For a price, it can be piped from North Sea platforms to the British mainland, from Algeria to Italy, or from Siberia to Western Europe. But pipelines are not a feasible way to send gas across major oceans—for example, from the Mideast or Indonesia to the United States. A high-technology way to transport natural gas overseas has, however, been developed in the past few decades, using the techniques of cryogenics—the science of extremely low temperatures.

In this method, a sort of giant refrigerator, costing more than a billion dollars, chills a vast amount of gas until it condenses into a colorless, odorless liquid at a temperature of two hundred sixty degrees Fahrenheit below zero. This liquefied natural gas (LNG) has a volume six hundred twenty times smaller than the original gas. The intensely cold LNG is then transported at approximately atmospheric pressure in special, heavily insulated cryogenic tankers—the costliest non-military seagoing vessels in the world—to a marine terminal, where it is stored in insulated tanks. When needed, it can then be piped to an adjacent gasification plant—nearly as complex and costly as the liquefaction plant—where it is boiled back into gas and distributed to customers by pipeline just like wellhead gas.

Approximately sixty smaller plants in North America also liquefy and store domestic natural gas as a convenient way of increasing their storage capacity for winter peak demands which could otherwise exceed the capacity of trunk pipeline supplying the area. This type of local storage to augment peak supplies is called "peak-shaving." Such plants can be sited anywhere gas is available in bulk; they need have nothing to do with marine LNG tankers.

LNG is less than half as dense as water, so a cubic meter of LNG (the usual unit of measure) weighs just over half a ton. LNG contains about thirty per cent less energy per cubic meter than oil, but is potentially far more hazardous. Burning oil cannot spread very far on land or water, but a cubic meter of spilled LNG rapidly boils into about six hundred twenty cubic meters of pure natural gas, which in turn mixes with surrounding air. Mixtures of between about five and fourteen percent natural gas in air are flammable. Thus a single cubic meter of spilled LNG can make up to twelve thousand four hundred cubic meters of flammable gas-air mixture. A single modern LNG tanker typically holds one hundred twenty-five thousand cubic meters of LNG, equivalent to twenty-seven hundred million cubic feet of natural gas. That gas can form between about twenty and fifty billion cubic feet of flammable gas-air mixture—several hundred times the volume of the Great Pyramid of Cheops.

About nine percent of such a tankerload of LNG will probably, if spilled onto water, boil to gas in about five minutes. (It does not matter how cold the water is; it will be at least two hundred twenty-eight Fahrenheit degrees hotter than the LNG, which it will therefore cause to boil violently.) The resulting gas, however, will be so cold that it will still be denser than air. It will therefore flow in a cloud or plume along the surface until it reaches an ignition source. Such a plume might extend at least three miles downwind from a large tanker spill within ten to twenty minutes. It might ultimately reach much farther—perhaps six to twelve miles.

If not ignited, the gas is asphyxiating. If ignited, it will burn to completion with a turbulent diffusion flame reminiscent of the 1937 Hindenberg disaster but about a hundred times as big. Such a fireball would burn everything within it, and by its radiant heat would cause third-degree burns and start fires a mile or two away. An LNG fireball can blow through a city, creating "a very large number of ignitions and explosions across a wide area. No present or foreseeable equipment can put out a very large [LNG]...fire." The energy content of a single standard LNG tanker (one hundred twenty-five thousand cubic meters) is equivalent to seven-tenths of a megaton of TNT, or about fifty-five Hiroshima bombs.

A further hazard of LNG is that its extreme cold causes most metals to become brittle and contract violently. If LNG spills onto ordinary metals (that is, those not specially alloyed for such low temperatures), such as the deck plating of a ship, it often causes instant brittle fractures. Thus failure of the special cryogenic-alloy membranes which contain the LNG in tanks or tankers could bring it into contact with ordinary steel — the hull of a ship or the outer tank of a marine vessel — and cause it to unzip like a banana, a risk most analyses ignore.

LNG can also seep into earth or into insulation — the cause of the Staten Island terminal fire that killed forty workers in 1973. ...

 This is just a small piece of this book. At the link below you can down load the whole thing: http://reactor-core.org/brittle-power/

Cheryl A. Golek Resident