The amazing story of liquefied natural gas (LNG)

  • The amazing story of shape-shifting liquid natural gas
  • Why it’s increasingly important in the UK’s energy mix
  • How many football pitches long is an LNG tanker?

 

When is a gas not a gas? When it’s a liquid – or LNG (liquefied natural gas), to be exact.

Lauren Bravo investigates the fascinating story behind LNG, and finds out why around 17% of the UK’s gas supply arrives at our shores in liquid form.

 

Meet liquefied natural gas, or LNG. Cooled to a chilly -162°C, it shrinks to 600 times its original size – making it the Alice in Wonderland of the energy world.

 

Give me the condensed version?

“It’s exactly the same gas that you get when you turn your cooker on… it’s just gone through a different process to make it transportable,” explains Jonathan Westby, Co-Managing Director of Energy Marketing & Trading at Centrica, British Gas’ parent company. “Shrinking it makes it economically viable to put on a ship and sail around the world.”

 

If only we could do the same with an overstuffed suitcase...

Well, LNG is a serious globetrotter – it’s the most useful way to get it from remote sources to areas of high demand. The UK’s primary source is Qatar, currently the world’s biggest producer of liquefied natural gas, though Australia is set to overtake soon.

 

So apart from the temperature, what else makes LNG special?

Liquefied natural gas is odourless, colourless, non-toxic and non-corrosive. It weighs less than half the weight of water and is also a master shapeshifter. “Once it’s been extracted, the gas gets liquefied at the liquefaction plant, put on a vessel to sail off,” says Jonathan. “When the vessel arrives at its destination it goes through a regasification facility before being injected into the National Grid transmission system to reach people’s homes.”

 

Um, regasification?

Just warming it back up again. In the UK, Centrica brings its LNG into The Isle of Grain on the Medway in Kent – home to the largest LNG terminal in Europe, it can ‘warm up’ around 58 million cubic metres of LNG per day.

 

So we’re gonna need a bigger boat?

Oh yes. A single LNG tanker can measure in at nearly three football pitches long (the 345m Q-Max tanker), containing up to 265,000 cubic metres of liquid natural gas. “That’s a range of 45 to 60 million therms of energy per vessel,” says Jonathan. “One carrier would have enough gas on it to meet the needs of at least a million homes.”

 

And surely those tankers are guzzling gas themselves?

No, in fact. Despite their hulking size, the ships have smart ways to keep things streamlined. “There’s a phenomenon called ‘boil-off gas’ – at any time, a small proportion of the liquid gas is constantly evaporating,” Jonathan reveals. “But the tankers capture that gas, run it through the engine and use it as propulsion for the vessel, meaning nothing is wasted.” How clever.

 

So are we adding more liquid to the UK’s energy recipe?

Currently LNG makes up just 17% of the UK’s energy mix, but as supplies in the North Sea decline, more and more of our gas will need to be imported from further afield– around 75% by 2030, experts predict. “Liquefied natural gas is going to become a bigger and bigger part of our energy mix – from the Americas in particular,” Jonathan says.

LNG is also helpful for ensuring the security of our energy supply. “If there was a disruption on any of the gas pipeline infrastructure, LNG would be one alternative to bridge the gap,” says Jonathan. “And people will often turn to gas-fired generation – which is cleaner than coal – to help smooth out the intermittency of energy generated from renewable sources.”

 

Looks like we’re sailing into the future on LNG…

Light, safe, efficient, portable – and literally supercool.

 

Published March 2017. All facts and figures correct at the time of publishing.

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