According to the Institution of Chemical Engineers (IChemE), the global production of biofuels has increased by over 600 percent in a decade, to more than 100 billion litres in 2011. Sounds like good news, except for the fact that the overall sustainability of biofuels as a renewable energy source has been hampered by, among other things, the water-intensiveness of their production.
Traditional methods of biodiesel production use high volumes of water to remove impurities or 'soaps' to meet stringent quality standards. For example, the production of palm oil — a contentious ingredient in many consumer products and increasingly cultivated for use as a biofuel — 50 percent of the water used becomes palm oil mill effluent — the largest pollutant of rivers in Malaysia.
But researchers from the University of Porto, Portugal, recently announced they are exploring water-free methods for purifying biofuels, including those made from waste cooking oils, animal fats and other fatty industrial wastes.
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, according to IChemE.
The researchers were able to produce high-quality biodiesel from both virgin vegetable oil and 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.
"In some countries like Brazil, biofuels provide nearly a quarter of their road transport needs,” said IChemE chief executive Dr David Brown. “In the European Union, negotiations are under way to increase biofuels for transport to ten percent. 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.”
These kinds of issues illustrate why the cultivation of biofuel from “waste” materials — including food, beverage, human and animal wastes, to name a few — while potentially only viable on a smaller scale, is an important alternative to the utilization of food crops.