The sustainability of biofuels as a renewable energy source has been boosted with the development of a new water-free process for the production of biodiesel from waste vegetable oils.
The global production of biofuels - such as ethanol and biodiesel - has increased by over 600 per cent in a decade to more than 100 billion litres in 2011. Biofuels are used widely in the transport sector and account for three per cent of total road transport fuel globally.
However, biofuels production has been criticized for causing deforestation, adding to the pressure on agricultural land needed for food production and the environmental impact of wastewater produced during their production.
Traditional methods of biodiesel production use high volumes of water to remove impurities or 'soaps' to meet stringent quality standards. For palm oil production, 50 per cent of water used becomes palm oil mill effluent - the largest pollutant of rivers in Malaysia.
However, researchers from the University of Porto, Portugal, are now looking at water-free methods for purifying biofuels, including those made from waste cooking oils, animal fats and other fatty wastes derived from industrial activities.
Instead of water, researchers used catalysts to pre-treat and target impurities such as calcium 'soaps' in the biodiesel. The impurities were then removed by absorption into resins or passing through ceramic membranes.
The researchers were able to produce good quality biodiesel from both virgin vegetable oil and, importantly, waste oils used for frying. The new process could provide significant economic and environmental benefits compared to other more energy intensive water-based production methods.
The Institution of Chemical Engineers (IChemE) chief executive, Dr David Brown, said: "In some countries like Brazil, biofuels provide nearly a quarter of their road transport needs. In the European Union, negotiations are under way to increase biofuels for transport to ten per cent. And Indonesia - the world's largest producer of palm oil - has announced plans to increase biodiesel production to reduce its reliance on crude oil imports.
"However, current production processes do not always deliver the full potential of biofuels to help reduce greenhouse gas emissions and there are continuing challenges including economic and environmental.
"But demand for biofuels is clearly increasing and advancement in chemical engineering processes, such as the use of heterogeneous catalysis4 and water-free methods using membranes, are very welcome to consolidate biofuels as a globally accepted and sustainable source of renewable energy."
The role of chemical engineers in the health, water, food and energy sectors is explored in IChemE’s latest technical strategy, Chemical Engineering Matters.