Monday, September 18, 2006

More information on why CNG is better than LPG

I have been doing further research into the benefits of using CNG for fuel and how it compares to LPG. It turns out that about 80% of Australia's LPG is produced from refining natural gas, while the remaining 20% is produced during refining crude oil.

However, the approximate composition of natural gas is as follows:

Component %
Methane (CH4) 80-95
Ethane (C2H6) 5-15
Propane (C3H8) and Butane (C4H10) < 5

Nitrogen, helium, carbon dioxide and trace amounts of hydrogen sulfide, water and odorants can also be present. Mercury is also present in small amounts in natural gas
extracted from some fields. The exact composition of natural gas varies between gas fields.

CNG is compressed methane.

LPG is a compressed blend of propane and butane.

Even though LPG is partly derived from natural gas supplies, it is much less abundant than methane. This makes CNG a much better long term option for fuel, even though it is still not created from a renewable source. Essentially, using CNG buys us more time to develop genuinely sustainable energy sources and technology for transport.

It is estimated that Australia has about 30 years supply of natural gas in existing fields, while crude oil supplies will run out in about 5 years.

Some other advantages that CNG has over LPG are:

  • Methane burns cleaner (no nitrous oxides) and is much less polluting than LPG
  • Methane is very close to hydrogen - so the infrastructure (tanks and compressors) for it could transition to hydrogen (this is not the case for LPG infrastructure)
It therefore makes much more sense to use methane as a fuel source than propane/butane.

Australia exports methane (as LNG) for about 3 cents per litre to China, and this contract is locked in for 20 years without any indexing to oil prices - which highlights the gross stupidity and economic incompetence of the Howard Government.

Write to your local politician and Mr Howard, and urge them to develop a strategy to transition to CNG for transport fuel, rather than LPG, petrol or diesel.

You could remind them of the lyrics of James Taylor's song "Traffic Jam" from his 1977 album "JT":

"Now I used to think that I was cool running around on fossil fuel,
Until I saw what I was doing was driving down the road to ruin."

For more information see:

Natural gas

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