Ever since medical research trumpeted the beneficial effects of olive oil on the heart, our appetite for the Mediterranean staple has been insatiable. Last year some 2 billion liters were consumed worldwide, and demand is increasing by around 20% a year in high-growth markets like the U.S. and Western Europe. But this oil boom has presented a pressing problem: what to do with 9 million-plus tons of olive pulp that remain after the oil has been extracted. Unusually for organic waste, this biomass, called orujillo in Spanish, is unsuitable for use as a mix for animal feed due to its fibrous nature. It's even downright dangerous for the environment: when flushed into rivers after rains, it starves fish of oxygen.
Spain's biggest power company, Endesa, has come up with a solution that makes light of the predicament — literally. It plans to build two power-generating plants at a cost of $39 million to turn orujillo into electricity. Owing to its high fat content, orujillo burns easily, with minimal air contamination. "It's an ideal use of the residue," says Endesa director Jesus Garcia Toledo. The plants will be built at the heart of Spain's olive-growing region, in Jaen and Ciudad Real. When they come into operation in a year's time, they will each turn 105,000 tons of orujillo per year into 16 megawatts of electricity — enough to supply the household needs of 100,000 people.
As the world's biggest producer of olive oil, with 190 million trees, Spain has enough orujillo for 30 power plants which could produce around 500 megawatts of electricity, or half the capacity of a nuclear power station. If the cost of orujillo remains negligible — it's currently around $17 per ton — olive-pulp power stations might become as famous a feature on the landscape of La Mancha as its windmills.
Transforming organic waste into electricity has become a burning issue for alternative energy enthusiasts. Everything from sugar beets to sawdust, genetically modified artichokes to animal manure, has been the subject of extensive research. Dr. Glynn Skerratt, director of the Centre for Environmental Technology at Staffordshire University in England, is circumspect about the viability of many of these projects. "In principle, it's great if you can take a material that there's a surplus of and generate energy from it. But in practice, it's often more trouble than it's worth and just not cost-effective."
So do initiatives like Endesa's really make economic sense? Optimizing any particular mix of waste material to obtain the right calorific value is a fiddly process. Getting the right amounts to the right place at the right time can be a logistical nightmare. Often, long-term supply cannot be assured. Last but not least, the public remains suspicious about waste of all types. As a result, explains Skerratt, "Most energy producers prefer to stick with what they know, what's predictable in terms of supply and demand."
But the recent rapid run-up in the price of crude oil has reminded everyone of the vagaries of fossil fuel supplies. And alternative fuels raise fewer safety concerns than nuclear power. Skeptics may dismiss endeavors like Endesa's as quixotic, but they may soon find that what is now an experimental curiosity has become a commercial reality.
With reporting by Jane Walker/Madrid