European olives are treasured for their oil, and as a zesty snack in their own right. Now researchers are also using them to make biofuel. They're hoping to reduce CO2 output while making olive growing more profitable.
Scientists and engineers at Vienna's University of Technology are laboring over a shiny steel construction standing almost two storeys high. It's a new generation "gasification plant," which the university pioneered a couple of decades ago. It turns biomass into gas, and in Austria and a number of other European countries, that gas is used to run generators and produce electricity.
The problem operators now face is buying biomass to feed these power plants at a price which makes them competitive with other renewable and fossil fuel energy sources. With prices for wood and biofuel crops on the increase, the European Union is funding a project called Phenolive which aims to turn the pomace - what's left of the olive after its oil is pressed out - into biofuel.
"When you look at the olive mill operator he wants to get as much as possible out of the olive, and he tries everything he can to get as much out if it as possible," Stefan Müller, a senior researcher at the university's Institute of Chemical Engineering, told DW.
Müller is part of a team exploring the energy potential of olive pomace. He lines up bottles of the olive residue on his desk. Some are identifiable as the remains of olives, others look more like dark beach sand. Müller calls the dark sand material "olivine," and explains it's the feed stock for the gasification plant.
"At the end we have these residues and there isn't much olive oil left in there. So this is a kind of waste material from an olive mill, but it still has quite a high energy content."
More than just a canapé
The Phenolive project, co-funded by the European Union, involves pressing every last drop of value out of the olive. At the Phenobio Laboratory, a start-up enterprise begun by the University of Bordeaux, scientists also play a role in the Phenolive project. They are identifying compounds which can be taken from the olive pomace after it has given up its oil and before it's turned into energy.
"The laboratory specializes in the analysis of phenols in different types of raw materials for finished products such as cosmetics, food supplements or food," Director Xavier Vitrac told France's LaBiotech web site. He added that extracting the polyphenols will add value to the pomace.
The polyphenols from olive residue are used as antioxidant additives in foods as well as nutritional supplements and cosmetics. In Europe it's estimated the market will be worth 290 million euros ($404 million) annually within a few years, according to the Phenolive web site.
"We're very conscious about using the resources we have and that's why these waste materials are in focus now, to use them to provide high valuable products," adds Stefan Müller.
Keeping energy down on the farm
The new gasification plant being developed at Vienna's University of Technology is small enough to be built on site at large olive plantations and olive presses. The energy it produces is intended for use within the olive oil enterprise.
"It's important that you use the energy nearby the plant where you generate the residues so the plan is to cover the electricity demand and the heat demand of the olive oil mill with the gasification of these residues," says Müller, adding that it also relieves the olive processors of the cost of disposing of their residues.
Some olive pomace is already burnt as a fuel in olive producing areas of Europe however Müller's aim is to analyze the residue and fully investigate its energy potential. Other uses for pomace include compost and fertiliser.
The university's research team also points to the work they are doing on producing liquid fuels from biomass, and say this has the potential to allow the olive industry to run its transport vehicles on fuel produced from the olive residue. A gasification plant the team developed at Güssing, Austria, is already producing liquid fuels for vehicles.
"It's a bio-refinery, that's the idea. It's renewables producing our fuels for the future," says engineer Johannes Schmid. His aim, he says, is to demonstrate refineries do not have to burn fossil fuels.
Europe produces 80 million tonnes of olive oil pomace every year, according to the Phenolive project. If the scientists are successful, the venture could boost the olive growing industry and see costs, particularly for energy, significantly reduced.