Renewable biofuels: animal, vegetable and mineral

The internal combustion engine, like its owner, is omnivorous. Its diet isn't limited to mineral fuels -- it's able to eat from animal and vegetable sources as well.

The flash point and combustion behaviour of ethyl alcohol -- ethanol -- are close enough to those of petroleum for petrol engines to run on ethanol without a complete redesign.

And because compressing any oil hard enough sets it alight, diesel engines can be modified to run on all manner of animal and vegetable fats. That's what's known as biodiesel.

The presence of biofuel is denoted in the name of the fuel at the pump. That green 'E10' label in service stations across the country means a 10 per cent ethanol blend. At the diesel pump, 'B20' means 20 per cent biodiesel.

EU policy is aiming to take biofuel consumption to 10 per cent of total by 2020. China is looking at 15 per cent in the same period.

Despite all the recent enthusiasm, Australia's production of renewable fuels has changed little in 30 years.

Ethanol
Ethanol has plenty going for it. For a start, it can be derived from organic rubbish, making it potentially easy and relatively cheap to produce.

Performance buffs have long loved it for its high octane count. It burns nice and clean and, coming from crop sources that consume excess CO2, it has plenty of carbon offset potential.

Advocates claim that in 'ideal conditions' -- namely, a world full of greenhouse-friendly production methods and cars running on E85 -- ethanol has the potential to cut transport carbon emissions by up to 80 per cent. It's also not that hard for auto makers to modify their engines to create so-called 'flexible fuel vehicles' (FFVs), able to move happily between blends from pure petrol up to E85.

E10 is now common across Australia -- in Sydney it's hard to find a big-brand servo that doesn't sell it. But in the greater scheme of ethanol fuel consumption, our contribution is miniscule. Brazil and the USA are far ahead of the rest of the world in this respect, accounting for about 80 per cent of the 45-50,000 million litres consumed by transport worldwide in 2007 (that's only about 2 per cent of the total transport fuel consumption, by the way). Consumption is growing at around 10-20 per cent a year in those two countries.

Flexible fuel vehicles
Over the last five years, FFVs have become increasingly popular in Europe and the US, with increasing numbers of service stations selling E85. In Sweden, 25 per cent sell it.

All major auto makers offer FFVs. Saab's 9-5 BioPower is the only one on sale in Australia, but that's set to change with Saab's GM sibling, Holden, announcing it has scheduled a flexible-fuel Commodore for release in 2010.

But ethanol is not without its downside...
Several downsides, in fact. Ethanol contains less energy by volume than petrol, and less again than diesel. This means engines consume up to 50 per cent more of it than petrol to travel the same distance. Plus any carbon offset benefits are in turn offset by the none-too-efficient use of fossil fuels, water use in crop production and refinement processes.

And while it's convenient to make it from waste materials, a good deal of it comes from foodstuffs like grains and corn. The warm inner glow cools down pretty fast knowing your eco-friendly Ford pickup is gobbling material that might otherwise be put to use feeding children in Somalia.

Biodiesel
The diesel engine can burn all manner of vegetable and animal fats as well as petro-diesel. This gives it a huge range of potential fuel sources, from canola fields to the grease-traps out the back of KFCs.

Dr Rudolf Diesel was running prototypes on peanut oil as far back as 1900. It just didn't seem very sensible to do it back then, when nasty tasting, potato-hostile mineral oil was in such plentiful supply.

Now it's running out, however, the doctor's trick will come in handy. Through a process called transesterification, fuel manufacturers can turn pretty much any old vegetable oil or animal fat, new or used, into a mono-alkyl ester -- read: diesel fuel. According to Biofuels Association of Australia figures, the commonest source oils here, in order of volumes used, are tallow, used cooking oil and oilseeds like canola.

Among potential new sources, algae has proved an exciting discovery for its potential yield rates of 100,000 litres of oil per hectare -- and that's from low-quality land with undrinkable water. The next most efficient source is the palm plantation, which yields around 5000 litres per hectare.

Biodiesel burns clean
Testing biodiesel sourced from used cooking oil, the CSIRO put its total life-cycle greenhouse gas emission rates around 90 per cent below 'clean' (extra low-sulphur) petro-diesel. And advocates say it's not just good for the planet -- its superior lubricating qualities make it good for engines. It can also be used as a two-stroke petrol additive.

So who's using it? Well, not Australians in any big way. Europe leads the world by some margin in the use of biodiesel, accounting for more than 80 per cent of global consumption. The Biofuels Association claims US consumption is growing at double-digit rates year on year.

Bear in mind, however, that all these figures are anchored to very low bases. Australian road transport consumption came to about 60m litres, or 0.4 per cent of total, in 2007. But the Biofuels Association says interest is rising, with a number of organisations trialling B5 and B20 blends across their fleets. And it's likely to become more viable -- local biodiesel manufacturers already have the capacity to produce nearly 10 times that 60m litres.

At this point, biodiesel is used in its pure form very rarely, and only for specialist applications.