The beneficial effects of the Mediterranean diet on our hearts are well known and the demand for one of its main ingredients, olive oil, continues to grow around the globe. Last year olive oil sales increased by some 20 per cent, mainly in western Europe and the United States, and more than two billion litres were consumed worldwide.
But the benefits of this healthy diet have brought their own problems: what to do with the more than nine million tons of pulp, known in Spanish as "orujillo", that remain after the oil has been pressed out of the olives. In many other cases organic waste matter can be reused for animal feed or as a fertiliser; but olives are different as they don't contain enough trace elements to make them useful for fertilisers, and because of its fibrous nature farmers have found orujillo unsuitable for cattle food. It is even dangerous for the environment as it contaminates the water, starving fish of oxygen if orujillo is flushed into rivers.
The only use for orujillo is as a fuel, and in many areas small quantities were used in the past to heat houses or to fuel the small brick and tile factories scattered around rural Spain. But under primitive conditions, and it was inefficient and dirty. Nowadays people prefer more modern fuels such as electricity or gas to heat their homes and the factories have switched to gas fired kilns.
However Spain's largest power company, Endesa, has come up with a solution which is clean, efficient and puts the waste matter to good use. It recently announced plans to invest some £26 million (€33 million) in the construction of two power plants to turn orujillo into electricity. The plants will be built in the heart of Spain's major olive growing regions: Jaen in Andalusia and Ciudad Real in central Spain.
The plants, which are the first of their kind in the world, will use a revolutionary process although a similar small-scale pioneering plant was built by an Endesa subsidiary near Cordoba a couple of years ago using a less efficient form of orujillo. The results of the Cordoba plant, which has a capacity of 12.5 megwatts, were so good that Endesa researched further before deciding to invest in the two new plants.
They are scheduled to begin producing electricity in about a year's time and will each turn 105,000 tons of orujillo a year into 16 megawatts of electricity, sufficient to supply the household needs of 100,000 people. "It's an ideal use of the residue because it produces a clean fuel," says Mr Jesus Garcia Toledo, director of Endesa's renewable energy office based in Seville.
Spain has around 190 million olive trees and is the world's largest producer of olive oil - much of the so-called "Italian" olive oil on our supermarket shelves was exported from Spain to Italy before being bottled, labelled and re-exported. The cost of orujillo is negligible, currently around £11 per ton including transportation costs, and it is estimated that the country has enough orujillo for 30 power plants which could produce around 500 megawatts of electricity or 50 per cent of the capacity of a nuclear power plant.
But electricity is not the only use for olive oil. Bionet, a Spanish consortium of four private and public companies, announced last weekend the construction of a plant to convert used cooking oil into 50,000 tons of "biodiesel". The factory, due to start operating next March, is being built in Reus, south of Barcelona. Ms Isabel Monreal, director of IDAE, one of the partners whose company policy is the search for renewal energy sources, estimates that Spain should be in a position to produce 550,000 tons of biodiesel fuel, less than similar fuels being made in France, Germany and Italy.
Ms Monreal said that it was immaterial whether the cooking oil used in the process was used olive, sunflower or soy oil: any of them can be used to produce Bionet biodiesel, the fuel which can replace petrol or diesel oil. Above all, it is clean. Used cooking oils from private homes or industrial kitchens will no longer be flushed down the drains after frying food. In addition the oil could help the greenhouse effect on the oxone layer. The 50,000 tons of biodiesel which will be produced in Reus will prevent the emission of 138,000 tons of Co2 into the atmosphere. Unlike conventional fossil fuels, biodiesel gives off minimal emissions of sulphur, carbon monoxide, chlorine and sulphates.
Some international scientists are sceptical of Spain's incursions into these alternative energy experiments - other enterprises in the country are making fuels from artichokes and animal dung as well as sawdust, sunshine and wind power. But if the prices of crude oil continue to rise, maybe the experts will be forced to rethink their views and Spain's experiments will not be as quixotic as they at first appear.
