Green with rage!

Yesterday's events where motorists complained that their cars had malfunctioned when they had filled up with petrol at Tesco or Morrisons is unfortunate for a number of reasons.

Greenergy who supplied their fuel is one of a new breed of biofuel manufacturers. Morrisons and Tesco have been blending bioethanol with their petrol for some time now as part of their commitment to greener fuels and carbon reductions. Indeed - the blending of biofuels into the mix is an EC commitment set to increase over the next few years.

It is highly unlikely that these fuels would cause engine damage, but it seems that the vehicles affected are ones fitted with Lambda sensors which measure the oxygen content of the exhaust. Ethanol molecules do contain a certain amount of oxygen and so the fuel/air ratio when using ethanol from any source will be slightly different.

What is more likely in my view is that the ethanol in the fuel has dissolved some pre-existing contamination from the fuel system which the petrol on its own would not remove. For example gum deposits which can build up over a period of time - they won't dissolve in petrol, but are loosened by the ethanol and then cause a blockage somewhere else in the fuel system.

The worrying aspect of all this is the number of motorists who take their vehicles to independent garages who will see the opportunity to make a quick buck by changing a perfectly good Lambda sensor and then encourag the hapless motorist to make a claim. Their claims are unlikely to be successful and the risk is that the episode will get biofuels a bad name that they do not deserve.