No, seriously, LNG does not burn

lng_shipment_cheniere
The Celestine River LNG vessel is moved into Cheniere Energy’s Sabine Pass LNG terminal on Friday, April 11, 2008. (Mark M. Hancock / The Beaumont Enterprise).

That’s not to say liquefied natural gas isn’t dangerous, but some readers of our story in Saturday’s paper about the arrival of an LNG tanker to the new Cheniere terminal across from Sabine Pass, Texas seemed to think it was like the arrival of the Death Star.
LNG itself doesn’t burn because it doesn’t contain oxygen. It also can’t explode because it isn’t stored or transported under pressure (and, again, doesn’t contain oxygen). LNG vapor — essentially the super-chilled liquid heating up and turning back into natural gas — is flammable.
But even then, it can only be ignited in a somewhat narrow range of mixture with air, between 5 percent and 15 percent. Below 5 percent and there’s not enough gas to burn, above 15 percent and there’s not enough oxygen to burn.
So, in order to create a huge flaming cloud of gas from an LNG tanker spill you need the wafting white cloud of LNG to stay in that 5 to 15 percent concentration range and then ignite it. Once a cloud of LNG vapors does ignite, however, it’s not easy to extinguish. The Cheniere LNG terminal has huge dikes built around its storage tanks designed to hold any leaked LNG and let it burn off, should there be such an incident.
This document is a bit dated, from 2003, but it has a pretty good explanation of LNG.
If you really want to freak yourself out, go to this web site, created by an attorney with a home near some proposed California terminals. In a nutshell it tends to paint everything in terms of worst-case scenarios. This site tries to debunk the claims made above, however.
BTW, another LNG shipment is expected on the Gulf Coast shortly. Freeport LNG will take its first cargo on Tuesday.

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