Fuel oil quality of biomass pyrolysis oils - State of the art for the end user

Biomass pyrolysis oils have potential to be used as a fuel oil substitute. Combustion tests have shown that the oils burn efficiently in standard or s lightly modified boilers and engines with rates similar to those for commer cial fuels. However, these tests also identified several challenges in bio- oils applications resulting from their properties. The oils have heating va lues of only 40-50% of that for hydrocarbon fuels. They have a high water c ontent that is detrimental for ignition. Organic acids in the oils are corr osive to common construction materials. Solids (char) can block injectors o r erode turbine blades. Over time, reactivity of some components in the oil s leads to formation of larger molecules that results in high viscosity and in slower combustion. This paper discusses physical and chemical character istics of bio-oils relevant to fuel applications as well as some low-cost m ethods for improvement of these properties. It also provides bio-oil specif ications proposed by some industrial users and recommendations for storage and handling.