[dZired]

Tata Motors has showcased the country's first Liquefied Natural Gas powered bus in Kerala. This bus is part of the automaker's plans to be prepared to see a potential increase in the demand of LNG vehicles in the future.

Named the Tata LPO1613, the LNG powered bus is lighter in weight as compared to conventional diesel buses, and boasts of relatively higher payloads. The use of LNG in commercial vehicles will not only help in keeping the emission levels in check, but will also increase the fuel efficiency, thanks to higher energy density of Liquefied Natural Gas. The company further claims that LNG powered buses boast of slightly better NVH levels, especially in comparison to their diesel powered counterparts.

Being liquid in nature, LNG is easier to store, with a packaging similar to that of diesel. LNG powered engines are claimed to need lesser maintenance due to it being a clean fuel, thus reducing operating costs. Moreover, since it is lighter than air, LNG evaporates readily when exposed to atmospheric temperature and pressure, making it a safe fuel.

Link to Team-BHP News

[norhog]

LNG at -160 deg C, how is it easy to store.?
It cannot be stored for a long time as no insulation is perfect and some boil off needs to be released. Also tank construction needs to be looked into for safety.
Unlike LPG which can be liquified under pressure LNG having a critical temperature of around -80 deg C cannot be liquified by pressure at ambient temp.
Also how is the bus lighter.? I think it is running a Diesel engine with gas injection then weight would be similar. But if a aluminum alloy block used only then it will be lighter.
Coming to pollution, what is the methane slip of this engine.?
A very good effort no doubt but gurus please share more technical details.

[rajeev k]

The country's first liquefied natural gas (LNG)-fuelled bus was launched here on Tuesday by Minister of petroleum and Natural Gas Sri Dharmendra Pradhan in the presence of Kerala Chief Minister Sri Pinarayi Vijayan on the sidelines of the "Fourth Conference of State Transport Ministers"

source : manoramaonline


it is a pilot project and the LNG-driven bus will run on trial-basis before being certified for commercial operation.

[binaiks]

Originally Posted by dZired

The company further claims that LNG powered buses boast of slightly better NVH levels, especially in comparison to their diesel powered counterparts.

AFAIK, both CNG and LNG engines are similar. CNG engines are actually much more noisier than Diesel engines. I am really not sure how this claim about the NVH levels work.

Originally Posted by dZired

Being liquid in nature, LNG is easier to store, with a packaging similar to that of diesel. LNG powered engines are claimed to need lesser maintenance due to it being a clean fuel, thus reducing operating costs. Moreover, since it is lighter than air, LNG evaporates readily when exposed to atmospheric temperature and pressure, making it a safe fuel.

Oh My! LNG easier to store?

Originally Posted by norhog

Also how is the bus lighter.? I think it is running a Diesel engine with gas injection then weight would be similar. But if a aluminum alloy block used only then it will be lighter.

CNG Engines are similar to Petrol engines, from what little I know. May be thats why they are lighter.

[Turbo Head]

Originally Posted by binaiks

AFAIK, both CNG and LNG engines are similar. CNG engines are actually much more noisier than Diesel engines. I am really not sure how this claim about the NVH levels work.

CNG engines are basically gasoline engines and all these years whichever CNG cars I have driven are as silent (or even more) as their petrol counterparts. Don't know how you got this perception that CNG is noisier than Diesel engines.

Originally Posted by binaiks

Oh My! LNG easier to store?

That's the question, I'll be spending hours to find an answer.

Originally Posted by binaiks

CNG Engines are similar to Petrol engines, from what little I know. May be thats why they are lighter.

You didn't take into consideration the increase in weight due to heavy tanks used for storing CNG.

[binaiks]

Originally Posted by Turbo Head

CNG engines are basically gasoline engines and all these years whichever CNG cars I have driven are as silent (or even more) as their petrol counterparts. Don't know how you got this perception that CNG is noisier than Diesel engines.

Please do get into a CNG powered bus any time and do update me again about the engine noise.

[norhog]

Further to this discussion, most methane powered engines have something called as methane slip. It is the methane that goes out the exhaust without burning. This contributes to the green house effect, methane being a green house gas. So would be interesting to learn about this point. This is applicable to CNG engines as well.

[rajeev k]

I read an article which discusses about the requirement of Cryogenic storage for LNG. This could make LNG systems expensive than CNG; is it so?

These buses in Kerala would be sourcing LNG from Petronet LNG, a consortium of Central Public Sector oil Companies which has a Terminal at Kochi.

LNG was preferred as a cheaper fuel option for thermal power generation by a Combined Cycle Process compared to HSD or Coal. But infrastructure development for LNG import and storage moved at a slow pace and the Petronet LNG's Terminal at Kochi is yet to be fully operational.

Initially this was scheduled to be commissioned by 2005

[Ashley2]

Originally Posted by norhog

...
Also how is the bus lighter.? I think it is running a Diesel engine with gas injection then weight would be similar. But if a aluminum alloy block used only then it will be lighter.
Coming to pollution, what is the methane slip of this engine.?
A very good effort no doubt but gurus please share more technical details.

Bus is lighter in comparison to CNG. CNG as stored in gas state, the tanks are very heavy and makes the ULW of weight much higher (though composite tanks are developed, they are slightly expensive) . Many CNG buses are running with as much as 25% to 30% overload condition due to the fact that they are heavier. This is what Tata is trying to address with LNG.

But LNG as an alternate fuel, is still a long way to go. Not sure about the vehicle performance and its consequential effects in a long run, especially when its from Tata.

Originally Posted by Turbo Head

CNG engines are basically gasoline engines and all these years whichever CNG cars I have driven are as silent (or even more) as their petrol counterparts. Don't know how you got this perception that CNG is noisier than Diesel engines.

You didn't take into consideration the increase in weight due to heavy tanks used for storing CNG.

You are right!
CNG engines being a derivative of petrol engines have much reduced NVH levels in comparison to diesel counterparts. But they emit much more heat and require more cooling.