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Is natural gas really “green”?

March 8, 2010

So in light of news that Royal Dutch Shell and PetroChina are putting in a US$2.96 billion bid for Arrow Energy (Australian LNG firm) (story here), I thought I’d explore whether natural gas is really “green”.

I’ve always been curious if Liquified Natural Gas (LNG) or CNG is really clean, green and efficient as its proponents often say it is. There are a few articles I found that also question this and here they are:

Is Natural Gas enough to help with climate change?

Natural gas, it’s green, but in what sense?

And of course, as some of you may know, Singapore also has been promoting CNG use in cars, buses and other forms of vehicular transport. I checked out the local CNG provider via and they do provide quite a load of information about CNG vs. the use of petrol based fuel. The website suggest these benefits from using CNG:


  • Enhances Air Quality
  • Refill without Inhaling Toxic Fuel Vapor
  • Helps to save the World from Global Warming
  • Reduces Smog Potential
  • Keeps your engine cleaner as it burns almost residue-free
  • Ecologically sensitive energy generation and usage is therefore an environmental challange to all of us.

CNG does not contain any toxins and endangers neither soil nor water. Moreover, it is lighter than air, so no potential for ground or water contamination in case of fuel release or leak occurs. CNG does not only cause fewer harmful emissions than kerosine, but the whole exploitation process chain is more eco-friendly.Ecologically sensitive energy generation and usage is therefore an environmental challange to all of us.

Less emission with CNG compared with Petrol
Less emissions with CNG compared with Diesel
It also suggests financial benefits.
  • CNG: 1.24 – 1.43 SGD/kg
  • Diesel: 1.293 SGD/litre
  • Petrol: 1.817 SGD/litre

The website also offers a payback calculator to see an illustration of savings you may achieve by driving on CNG.

So while I think it’s commendable that Singapore has embarked on a journey towards providing “clean” energy for us, there are several concerns raised in the articles provided above.

These are:

  • Production of LNG releases methane, a greenhouse gas 25X more potent than carbon dioxide
  • LNG drilling can compromise groundwater and cause pollution. The carcinogens released include benzene, which is linked to leukemia.
  • LNG is flammable and explosions have occured due to improper and unsafe methods of drilling.

Also, we must remain critical about the label “green” or “clean” that is attached to LNG or CNG. It isn’t really a green form of fuel if you think about it. It still releases carbon dioxide and it’s methods of drilling are still destructive and deplete resources. LNG does not help to reduce our dependency on fossil fuels since it’s a by-product of oil production. It serves as a supplement of fossil fuels and also, compressing/cooling it into liquid form requires a lot of energy!

I think further studies should be done to accurately determine it’s efficiency in terms of it’s production methods and the entire process from its source. It may just add up to be as energy thirsty as in the production of petrol for vehicular consumption and the total emissions may be the same! So have a thought the next time you see a LNG or CNG powered car/bus, but that is not to say that there are no benefits of course! There are, but people tend to get carried away by cost-savings and the notion of being “green”! I suppose it’s just as well that some people are conscious enough to add a CNG tank to their cars for a price and I do commend that effort but I wonder if they did proper research into it before converting? I’d love to hear from you if you converted your car to be powered by CNG!



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