It was in use before a written language was invented. Today it is being studied as a possible means of staving off ailments ranging from bowel cancer to gallstones. It has been used to provide heating and lighting for centuries. Even the trendiest of today's celebrity chefs does not disdain to slosh it around.

Now olive oil, the golden liquid on which commercial empires, to say nothing of the Mediterranean diet, have been built is about to get yet another use.

Endesa, one of Spain's biggest utilities, yesterday announced plans to build two olive oil fired power stations at a cost of almost £25m.

Well the fuel was not quite olive oil. Actually the solid residue - known in the trade as orujillo - left after every drop of oil has been pressed from the fruit.

At a time when the other stuff that comes out of places like the North Sea, the Middle East and some of the less hospitable parts of Russia is heading for $30 (£19) a barrel Endesa's initiative has obvious commercial potential.

But it is environmentally friendly too. The fibrous mass that is orujillo - though it has a high thermal value when burnt - is otherwise pretty tricky for the olive growers to get rid off.

Spain is handily placed as a provider of orujillo. It has getting on for 200m olive trees making it the world's largest producer of olive oil and consequently of fuel for the new plants. They will be built in Jaen and Cuidad Real at the heart of Spain's olive growing region and when they come into operation in the second half of next year will produce a total of 32 megawatts, or enough to supply 100,000 people. They will be the first in the world to use olive residues to generate electricity.

If the technology turns out to be a commercial success Spain's neighbours - olive oil producers all - could well be tempted to follow Endesa's lead.

That could give Opec a whole new meaning. Instead of the Organisation of Oil Exporting Countries it might find itself reinvented to become the Olive Producers Electricity Cooperative.

Now that would give them something to thing about - be it in Aberdeen or Azerbaijan.