Liquefy Natural Gas (LNG) Super-Tanker

LNG, Technology — By on April 5, 2013 at 5:05 PM
LNG-SOKOTO

The LNG “SOKOTO”

Richard Hammond (*) reveals the ingenious engineering required to transport one of the most potentially hazardous cargoes in the world in some of the biggest vessels afloat. The huge ships, bigger than the Titanic, carry enough fuel to heat a city the size of London for a week – the energy equivalent of 55 Hiroshima atom bombs. Shipping this potentially volatile cargo required engineering solutions inspired by cutlery, mid-air refuelling and fire engines.

Though the cargo is safe as a liquid at -162C, any trace of gas could be dangerously flammable, so potentially hazardous areas around the cargo are kept safely inert. Thanks to mid-air refuelling – first introduced in 1938 to permit mail planes to cross the Atlantic – which uses inert nitrogen, the tankers never fear any gas explosion. At ‘cryogenic’ temperatures, ordinarily strong materials start to fail. The same material that makes reliable scaffold poles shatters when chilled -190C. The solution lies in the stainless steel used in cutlery.

Liquid cargoes can slosh around and capsize a vessel. In 1987 the so-called ‘free surface effect’ sank the ferry Herald of Free Enterprise after it took on water. Richard demonstrates the problem in a specially adapted van, fitted with a large tank of water which causes the vehicle to topple over. LNG tankers stop sloshing with specially shaped tanks.

These high-tech vessels rely on an ancient technology for power – steam. Richard demonstrates its power with a purpose-built ‘steam bomb’ that destroys a wooden shed. LNG tankers also use steam to produce fresh water for drinking, relying on one of naturalist Charles Darwin’s lesser known discoveries; how reduced atmospheric pressure lowers the boiling point of water.

Natural gas presents an exciting alternative to petroleum because of its abundance and relatively inexpensive price. While it’s not a renewable fuel like solar or wind power, it could present a bridge toward a more renewable-based energy future.

Natural gas is gas pumped from the Earth’s crust that has been converted into a liquid. When the gas is cooled to minus 260 degrees Fahrenheit (126.7 degrees Celsius), it becomes a liquid that is easier to store. From there, it can be transported in a supertanker, much like oil. Currently, that’s the easiest way to move natural gas over long distances. The gas is odorless and colorless, and when burned, it creates far less emissions than petroleum.

Once it is transported in its liquefied form, natural gas is used for a wide variety of purposes like heat and power generation. According to the U.S. Energy Information Administration, 65 million people use natural gas to heat their homes. Natural gas provides 76 percent of the energy for the residential and commercial sectors, and provides 40 percent of the industrial sector’s energy needs.

Did you know that natural gas is used to power automobiles, as well? Liquefied natural gas is often converted into compressed natural gas after it has been transported, which makes it more usable to consumers. Cars and trucks that run on compressed natural gas are especially popular in vehicle fleets used by municipalities and businesses. Of course, consumers can buy them too. Honda makes a natural-gas powered Civic sedan that achieves 36 miles per gallon (15.3 kilometers per liter) on the highway, but never uses any actual gasoline.

As of fall 2011, natural gas fuel for cars is far cheaper than gasoline. In California, it costs around $2.10 or so per gallon — one reason why Honda has seen the sales of its natural gas Civic GX nearly triple this year.

(*) Richard Hammond is an English broadcaster, writer, and journalist most noted for co-hosting the car programme Top Gear with Jeremy Clarkson and James May, as well as presenting series 1–4 of Brainiac: Science Abuse on Sky1. Hammond co-hosted Total Wipeoutwith Amanda Byramon BBC Onefrom 2009 until its cancellation in 2012. Hammond presented Planet Earth Live alongside Julia Bradbury.

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