CNG vs LNG

Billy345

Hi Everyone-

 Can someone please enlighten me on the difference between CNG and LNG in terms or practicle application?  I've seen CNG cars but I don't think I've seen LNG - 

 Any info would be great - thanks in advance!

Billy



jstack6
jstack6's picture
Re: CNG vs LNG

Another fact is the US hit peak natural gas in 2004 and we now import a lot from Canada. As was noted in earlier post LNG is much more costly because of the energy to cool it and keep it cool. Either way it's still a fossil fuel, which is limited.

 An interesting item is that Canada is running low on NG but is forced to sell it to the US via NAFATA regulations. They are preparing for thier peak by building 3 large LNG termials to take in sea going tankers with LNG at high cost. It will be imported at greater cost for their use. We in the US will see prices continue to climb very fast.

 The Pickens plan wants to use NG in cars. This will put limited NG into Internal Combustion Engines that waste 84% of that energy because they have so much heat and friction. This doesn't see very smart when you could use the NG in combines cycle power plants at 60% or greater efficiency to make electric power.

 You could also use NG in hybrids at double the ICE efficiency. Honda makes hybrids and CNG cars but not together. When I asked they said it was too expensive. 

  Using NG produces 1/2 the air pollution wich is better than Oil derived gasoline. It can be a step to help us but I would like to see it used in the best most efficient way and not wasted. 

  We need lots of solutions and technology and reduced travel by vehicles. The recession is helping reduce our use and demand for energy. Renewable energy will create jobs and reduce pollution and it's cost. Now is the best time to keep going green. It saves in the short and long range life cycles. 

the solar stacks

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solar stacks



Billy345
Re: CNG vs LNG

Makes sense - do you agree with the Piken's plan to have the US start to convert from Oil over to Natural Gas?



ctyankee
Re: CNG vs LNG

Yes, I agree, as long as everyone understands the way the switch needs to happen. Commercial fleets need to be the leaders. Starting with the large vehicles, trucks! Then buses & other municipal fleet vehicles. This minimizes the number of CNG stations that need to be build immediately.

As the amount of renewable electricity increases there will be a gradual surplus of NG, causing the price to decline. The tendency will be for the generators to re-evaluate the use of NG for electric power... This will be the critical time-frame!

But the fleets will be on NG, and the manufacturers will then be ready to push NG for the domestic fleet...

The key is getting the renewable electricity to come on line fast enough to prevent a relapse toward NG for generation. Even if that means some temporary government restrictions a few years down the road...



ctyankee
Re: CNG vs LNG

CNG is "Compressed Natural Gas" it exists at room temperature in strong steel tanks at pressures as high as 350 bar (5,000 PSI).

LNG is "Liquified Natural Gas" it exists as a cryogenic fluid at about -250F in superinsulated tanks at or about atmospheric pressure.

CNG can be stored indefinitely with the twist of a valve. 

LNG requires refrigeration or the bleeding of pressure.

LNG tanks are much more economical than CNG tanks as tank size increases i.e. large ocean-going ships.



Billy345
Re: CNG vs LNG

Hi ctyankee,

 

This is great info!  Do you know why one is selected over the other- is one more effeicnetn in one vehicle vs another?  Again - thanks for such a fast reply and for the solid info.

Best,

Billy



ctyankee
Re: CNG vs LNG

Why does business choose? In a word, *COST*

A vehicle sized LNG needs too nuch support equipment and / or would leak too much gas in a given time of inactivity.

A vessel sized CNG would be too heavy, and represent an enormous mechanical explosion hazard if anything happened to cause the tank to burst.