Waste from olive oil processing can be converted into energy for fuel cells, helping to power the processing plant and also reducing environmental damage.

It's a much more sustainable approach than the current process, in which the olive mash — containing pesticides and toxic organic compounds — is dumped into sludge pits, introducing toxins to the surrounding environment.

An experimental system that generates heating and power from the processing waste has been set up in Spain. It was developed by scientists from Sweden's KTH Royal Institute of Technology.

The small-scale prototype is fully operational in an olive oil production facility operated by a cooperative in San Isidro de Loja, Granada, KTH said on Monday. At the moment it produces around 1kW of power, but the project partners are planning to scale the operation up to create 200kW, which would be enough to supply 50 percent of the facility's energy needs.

The priority for this project was to find a solution for the toxic waste left over from olive oil production, said Carina Lagergren, research leader in applied electrochemistry.

The waste is converted to heat and power in a three-stage process. First, a digester tank breaks the material down and releases methane, carbon dioxide and sulfur compounds. A reformer converts the biogas into carbon dioxide and hydrogen, which can then be converted in fuel cells. In the final stage, oxygen mixes with the hydrogen and CO2 to create heat and electricity.

Any remaining olive mash is no longer toxic and can safely go to landfill.