Quality problems caused by water in biofuel
While the negative effects of particle contamination in fuels is well-known, the effects of water contamination were widely underestimated. Depending on the water content, water exists as dissolved water, dispersed throughout the oil, as emulsified microscopic droplets or as a separate phase of free water. Besides the reduction of the calorific value of the bulk fuel resulting in slower acceleration, less power and harder starting, the contamination with water enhances rust formation and corrosion of vital fuel system components. At temperatures below 0 °C the forming of ice crystalls can clog fuel lines and enhances crystallisation processes within the biodiesel.
The presence of water not only reverses the FAME to fatty acids, but it significantly promotes the growth of bacteria and fungi oxidizing the biodiesel to corrosive degradation products (organic acids). Additionally, water hydrolyses certain stabilisers, such as phenolic antioxidans, thus overruling their interceptive character. Resulting oxidation products can cause disturbances in the injection system and in the engine itself. In view of this, the EN 14214 standard specifies a maximum water content of 500 ppm for biodiesel.
- Brochure: Quality Assurance of Biofuels with Metrohm instruments (pdf)
