CNG anyone?

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mercfan
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CNG (compressed natural gas) is quietly being used by a lot of councils for their vehicles, but not really pushed as a consumer product.

A lot cheaper than LPG, easy fill from home gas supply, seems a no brainer.

Anyone had it done or has a CNG vehicle?

What is it like?

gav.helme
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Re: CNG anyone?

Involved with many of those councils running many Econic CNG bin wagons

Great pieces of kit, a few Sprinters too and all good reports...

Not heard too much outside of that....

As for a comparison between LPG / CNG then literally are the chalk and cheese

LPG is in the main a tedious and poor substitute in my view, especially on vehicles 15 years or never...

CNG seems to be seamless but a different animal...

LPG + PETROL ENGINE = HEAT

CNG + DIESEL ENGINE = ECONOMY

CNG + PETROL ENGINE = ??? I HAVE HAD NO CONTACT

Just my findings...

mercfan
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Re: CNG anyone?

Thanks Gav,

Useful to know.

Seems the sprinter ones are dual fuel petrol ones and the new name is now NGT, but still the same thing.

http://www.mercedes-benz.com.au/content/australia/mpc/mpc_australia__website/en/home_mpc/van/home/new_vans/models/sprinter_906/sprinter_ngt.html

 

prwales
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Re: CNG anyone?
mercfan
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Nice find ! 

Great article.

prwales
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CNG essentially methane CH4 has a much lower calorific and hence octane rating than LPG and is problematic for cars. Methane, Ethane, Propane, Butane, where LPG is a blend of the last two gases in the sequence, and the octane rating is similar or higher than for petrol. In short you will need more CNG to achieve the same result so you need to store more gas at a higher pressure to achieve similar results. You also need the filling stations to supply the gas. So stronger bigger and heavier tanks required and a network of supply, potentially a useful alternative to petrol but more work needed.

mercfan
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Re: CNG anyone?

Just found this bit of research by CARB(California Air Resources Board):

CNG is essentially methane (CH4), which has a calorific value of 900 kJ/mol. This burns with oxygen to produce 1 mole of CO2 and 2 moles of H2O. By comparison, petrol can be regarded as essentially benzene (C6H6) with a calorific value of about 3,300 kJ/mol, which burns to produce 6 moles of CO2 and 3 moles of H2O. From this, it can be seen that per mole of CO2 produced, CNG releases more than 1.6 times as much energy as that released from petrol (said another way: for the same amount of energy, CNG produces nearly 40 percent less CO2). The corresponding figures are 78 and 25.8 grams, respectively, for nitrogen oxides.

Carbon monoxide emissions are reduced even further. Due to lower carbon dioxide and nitrogen oxides emissions, switching to CNG can help mitigategreenhouse gas emissions.[11] The ability of CNG to reduce greenhouse gas emissions over the entire fuel lifecycle will depend on the source of the natural gas and the fuel it is replacing.

The lifecycle greenhouse gas emissions for CNG compressed from California's pipeline natural gas is given a value of 67.70 grams of CO2-equivalentper megajoule (gCO2e/MJ) by CARB (the California Air Resources Board), approximately 28 percent lower than the average gasoline fuel in that market (95.86 gCO2e/MJ).

CNG produced from landfill biogas was found by CARB to have the lowest greenhouse gas emissions of any fuel analyzed, with a value of 11.26 gCO2e/MJ (more than 88 percent lower than conventional gasoline) in the low-carbon fuel standard that went into effect on January 12, 2010.

Lots of info on the net generally.

14.8 million CNG vehicles on the road worlwide as of 2011. Very common in Asia and South America. In Europe it seems that Italy is leading the way with at least 1173 CNG filling stations.

Cited advantages: 

  • CNG does not contain any lead, thereby eliminating fouling of spark plugs(unleaded fuel is lead free, but still can cause plugs to foul).
  • CNG-powered vehicles have lower maintenance costs than other hydrocarbon-fuel-powered vehicles.
  • CNG fuel systems are sealed, preventing fuel losses from spills or evaporation.
  • Increased life of lubricating oils, as CNG does not contaminate and dilute the crankcase oil.
  • Being a gaseous fuel, CNG mixes easily and evenly in air.
  • CNG is less likely to ignite on hot surfaces, since it has a high auto-ignition temperature (540 °C), and a narrow range (5–15 percent) of flammability.[11] 

And this here from AAG Ltd:

Of all the current fuels available in the UK mains Natural Gas is by far the most affordable and accessible. Its in nearly every urban household. Natural Gas can be compressed and stored at 200 bar making it possible to store a considerable amount of fuel in a tank which makes it a fantastic alternative to petrol or diesel in cars and light vans. Compressed Natural gas can be used in virtually every petrol combustion engine turning out excellent performance whilst substantially reducing environmentally unfriendly emissions and costs. If using CNG Compressing dispenser it can be termed as Carbon neutral as the fuel is produced from things that have grown in the atmoshere.

EFM offer several CNG solution for either spark ignition petrol engines or compression ignition diesel engines. These are efficient, high-performance system with prices starting from £1996, depending on vehicle model. See our photo gallery for examples of CNG conversions to different vehicles. 

 

Personally, I am not a greenie - far from it. But I am not comfortable with being held to ransom by what happens in the middle east and the fact that what happens there dictating what happens to my meagre income when I visit the petrol station.

Apart from the pure convenience of being able to fill up from the gas standpipe at home, if the sh*t hits the fan in the wider world out there, we can start digging our own cesspits and apart from fuelling our homes, also fuel our cars, like the South Americans and others do. I'll never forget a few years ago when we had that big fuel strike, the freedom of going into Tescos and filling two big trolleys with rapeseed oil and filling up my G's tank in the car park without a worry in the world. No queues, no traffic, virtually had the roads to myself in North London. Four wide open lanes to choose from at rush hour, mmm which one to pick...it was pure bliss.

You'd say our governments would be pushing this (CNG) all out, full on. Freedom from the middle east = no more wars there, right?

The only possible explanation why they're not doing so, is that it is rather difficult collecting fuel duty from it.

From casually starting a thread out of curiosity, I now know exactly what I'll be doing to as many of my cars as possible.

I must thank all those of you who commented. Without your input, I wouldn't have dug deeper into this.

 

 

mercfan
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To think the oil companies are burning this stuff off as "waste"

bigblock
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Re: CNG anyone?

mercfan wrote:

 

A lot cheaper than LPG, easy fill from home gas supply, seems a no brainer.

 

 

I don't think that you would be able to travel very far if you tried to fill your tank from your domestic gas supply.

To convert natural gas into CNG it is compressed to 3000psi which allows it to be stored in your fuel  tank in sufficient volume to get beyond the end of your driveway.

Natural gas has a domestic pressure entering the home of around 1psi and so without the aid of a compressor you are not going to get very much stored in your tank. It would take roughly 140 cubic feet of gas at atmospheric pressure to equate to 1 gallon of diesel.  

mercfan
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Quite right, regulated down to actually 0.3psi at the meter, even in the mains, max is around 1450psi.

There are some developments around/in progress to store the gas more efficiently in sponge like materials at around 500psi.

Until they become available, there are specific units freely available to do the filling from a normal domestic/home supply.

Lots around in the states and elsewhere, but essentially something like this: http://www.gasfill.com

Looks like the excavator has some work coming - dig a hole, fill, seal, pipe...

bigblock
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The problem with the HomeFill type units is that it still takes around 10 hours to fill the car for around a 200 mile range.  

You would need a bulk storage tank and a big compressor to be able to refuel in a similar time to a petrol station with CNG.

prwales
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And despite the protestations of safety a gas that has the ability to expand 2 or 3,000 times has enormous explosive potential. The gas pipe line from Milford to England is liquefied at 96 atmospheres which a 14 per sq inch for one is 1344 psi. Scary stuff and as most CNG is from gas fields or as a oil product it is not in the least bit environmentally friendly

mercfan
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Well, I've spent many many hours now researching this, even bought some case studies/research reports and the evidence is overwhelming in favour of CNG at the present moment in time. Cheaper, greatly enhanced engine life, safer than petrol or LPG, tax reductions, zero congestion charge (due to low emissions), relatively easy and safe to self-produce in an anaerobic digester and several other points. Break-even on investment in my case works out at 8 months, calculated at filling station pump price, half price if sourced from domestic supply. There is obviously a good reason after all why so many councils use it. And why it is so wide spread in poorer parts of this world. Necessity driving innovation perhaps in the latter case. Time to get working...