31 Aug 06
Many European-made diesel engines of the 1980s and 1990s - including most Volkswagen Group engines - were able to run on biodiesel, and even those not factory-ready could use it if fitted with appropriate synthetic rubbers for seals, fuel hoses and gaskets. However, manufacturers are now claiming that modern high-tech fuel injection technology - such as pumpe-duse, high-pressure direct injection or piezo-electric injection - is not compatible with 'neat' biodiesel, as the complex engines are specifically tuned for conventional fuels, and will only warrant their engines to run on a blend of up to 5percent or, in some cases, 30percent. Pro-biodiesel groups dispute this in many cases, arguing that the car makers are simply trying to cover their backs against warranty claims. Either way, we recommend that you contact the relevant customer services department, quoting your engine number, for further details before using a biodiesel blend of more than 5percent.
Absolutely (if it's biodiesel-compatible in the first place, of course) and you can mix and match, as biodiesel and derv are entirely miscible. DME (the one that's not strictly a biodiesel) can also be blended with conventional diesel, offering improved fuel quality and reduced emissions.
Given the raised awareness of the fuel and increased demand, there is now an incentive for more companies - including the large oil firms - to join the game, so availability should increase. We will also see the launch of more conventional diesel fuels with increasingly high percentages of biodiesel mixed in, sold from mainstream forecourts. Used and recycled industrial frying oils alone will not meet demand, though, so expect more biodiesel from specially-grown crops. But before we get too excited about the prospects for biodiesel, let's just bear in mind that the agricultural resources of the UK only hold out the prospect of a maximum contribution of 5-10% of current diesel fuel consumption. So unless the UK, together with the whole of Europe, starts growing crops for biodiesel on every piece of spare land available (especially that currently under set-aside subsidy) we're going to stay dependent on crude oil for some time to come - or import more biodiesel from abroad. This comes with some more serious ethical implications, such as the use of land in the developing world for the growth of fuel crops for export instead of crops to feed the local population. There is already evidence that in certain regions, large oil companies have bought land and evicted the indigenous tenant-farmers. Biodiesel may not come enirely guilt-free: we recommend buying locally-sourced fuels wherever possible.
