Swedish scientists are testing a prototype heating and power generating system running on residues from olive oil manufacturing.
Designed to improve current processes of converting organic waste into energy, the system relies on fuel cells digesting gas separated from the olive mash to produce heat and power for a small olive oil refining facility in Spain.
Located in San Isidro de Loja in the Spanish province of Granada, the experimental olive oil waste power plant consists of three components. First the toxic olive oil waste enters a digester tank, which breaks down mash and releases methane, carbon dioxide and sulphur compounds. The biogas further travels into a reformer, where it is purified to contain only carbon dioxide and hydrogen. In the final step, the fuel cells get involved, burning the carbon dioxide and hydrogen with oxygen to create heat and electricity.
"The idea behind the project is to show that it is possible to connect these processes together – starting with olive oil waste – and end up with electrical energy," said Carina Lagergren, a researcher from Sweden's KTH Royal Institute of Technology.
"For this project, the most important thing was finding a solution for all of the toxic waste left over from olive oil production.”
The system currently produces around 1kW of power but plans are already underway to scale up the operation to generate 200kW, which would be enough to supply 50 per cent of the processing plant's energy needs.
In addition to addressing the need for clean renewable energy, the system also solves the issue of toxic olive oil production waste. Conventionally, after olives are milled and the oil is extracted, the waste containing pesticides and toxic organic compounds is dumped into sludge pits, releasing toxins to the surrounding environment. On the contrary, the leftovers from the new processing system developed by KTH in cooperation with PowerCell Sweden AB, are rather harmless.
The team is currently analysing how possible impurities in the biogas generated by the system could affect the fuel cells.
"We fed the cells with the contaminants that are found in the fuel from the olive oil, or from the environment where the fuel cells operate, such as hydrogen sulphide and ammonia," said Lagergren.
The KTH team led by Lagergren is studying possible improvements to fuel cell, focusing on bringing down the cost and increasing the efficiency.
"There are other ways to decrease the cost, such as work with the electrolytes. We try to do small improvements with the different components," she said.