How would you like it if, perhaps in the future, an energy company delivered fuel to your door? You could refuel in your garage, or at the office. If we can home-deliver everything from groceries to roses – why not fuel? Think of the real estate it would free up via suddenly redundant servos; the time it would save. It’s not as if the service station experience is sentimental … being asked, ad nauseum, if you have a shopper docket, or Fly Buys, or if the notion of two-for-one Kit Kats appeals.

As a sweetener, how about if the home-delivery option meant – kilojoule for kilojoule – you’d get the equivalent of a tankfull of petrol for less than half today’s going petrol price? Most people would go for it.

Stop dreaming, because such a fuel is probably delivered to your street now. Australia has vast reserves – at least a century’s worth on current consumption, which (although there’s a major greenhouse issue) could at least help solve our Persian Gulf dependency problem. The fuel is of course natural gas (NG). Delivery infrastructure is in place. A licensed gasfitter could install the fittings in your garage this afternoon. A purpose-built compressor and sundry plumbing (and, of course, the right tank in the car) is all it would take to get the job done.

If you’ll pardon the pun it’s not a pipe dream: NG home refuelling stations can be bought in North America and Europe now. They’re especially popular in New York and California. Check one out at www.myphill.com.

Fiat, Volkswagen, General Motors and Peugeot sell dual-fuel (NG and petrol) cars now. Plenty more, including Honda, have experimental NG-only cars on trial. All petrol cars could run NG, which enjoys a higher octane rating than petrol. Engines running on it alone can exploit higher compression ratios and develop greater efficiency. There are currently an estimated 5.7 million NG vehicles worldwide (about 0.6 per cent of the vehicles on earth). These include trucks – diesel engines, with appropriate modifications, also run happily on NG.

NG is clear and odourless (a chemical called Ethyl Mercaptan is added so you can smell any leak). It’s lighter than air, unlike LPG, so it won’t form combustible ‘pools’ in depressions if it does leak. It spontaneously ignites at just under 600 degrees C, and only burns if it’s mixed with air in the range of five to 15 per cent. It’s non-toxic, but doesn’t support life (so it won’t poison you, although you can suffocate in it).

NG is mainly methane. It’s the simplest hydrocarbon, one atom of carbon joined with four hydrogens. Methane is the first in a family of hydrocarbons called ‘alkanes’, in which methane is followed by ethane, propane (LPG), butane (lighter fluid), pentane, hexane, heptane and octane (petrol), etc. Each in this list has one more carbon atom than its predecessor, respectively, and there are plenty more after octane.

Methane to butane exist as gasses. From pentane up to the one with 17 carbons, they’re liquids (like petrol and diesel), and from 18 carbons up they’re solids (like paraffin and bitumen).

Liquid fuels are practical because they pack a lot of energy into a small volume (high energy density), and they can easily be pumped into an engine. Gasses less practical because, uncompressed, you don’t get much energy in a given volume.

This is a problem with methane. You’d need 56 cubic metres of it, uncompressed (a box four metres by seven metres by two metres) to hold the same energy as a 60-odd litre petrol tank – impractical. There are two options: compression or liquefaction. Compression leads to compressed natural gas (CNG), which stores the gas in a pressure vessel at up to 250 atmospheres, which is about a third of the pressure in the best compressed hydrogen fuel systems. That shrinks its volume to less than one per cent of the uncompressed size – which is quite manageable. CNG has about a quarter the energy density of petrol, so the range for any particular tank volume is about a quarter that of petrol.

Liquefied natural gas (LNG) isn’t practical for cars. (Hydrogen has similar problems.) It needs expensive, aerospace-spec super-insulating pressure vessels and must be maintained at around minus-150 degrees C. Too hard, except for bulk (supertanker) transport.

In 2003, ExxonMobil made the largest discovery of natural gas in Australia’s history – bigger, even, than the acclaimed Northwest Shelf – when it located the Jansz gas field 200km off the WA coast. It totals the equivalent of 20 years’ worth of our NG production, and added one-fifth to the country’s known reserves. It’s located entirely within Australia’s economic zone, and appears to be unaffected by native title claims.

The CSIRO recently dropped the bombshell, in its thought-provoking Fuel for Thought report, that natural gas will be one of only two alternative fuels with any real clout over the next decade (the other is LPG). Why is it, then, that the darling of the alternative fuel set appears to be the problematic alcohol, ethanol, while natural gas seems swept under the rug?

‘Dear local member, I just bought 58 litres of petrol for $87. Then I got my gas account. Why is it that AGL can sell me the same amount of energy as natural gas for $33? Please explain…’