Blends of pyrolysis oil, petroleum, and other bio-based fuels: A review

Pyrolysis oil is a promising renewable fuel. However, crude pyrolysis oil use in conventional engines or boilers can be limited without modifications to these systems. Other bio-oils such as oils from vegetables or animal wastes face similar issues. One option to enhance the applicability of bio-oils is blending with petroleum or other bio-based fuels. A literature review on the blending of bio-oils to enhance their fuel properties is presented. Included in the review is information on types of oils that have been blended, additives used to enhance blending, and engine/boiler performance. Upgrading, such as transesterification or hydroprocessing, of bio-oils is often used to improve fuel properties. However, there is limited work on blending of “crude” bio-fuels (e.g. unrefined), such as pyrolysis oils and bio-based waste oils, Therefore, included in this review is a preliminary study of blending of fast pyrolysis oil from hardwood with fish oil extracted from fish processing by-product. The heating value and pH of the blended pyrolysis/fish oil is increased relative to pure pyrolysis oil while the cold flow properties of the blends are better than the pure fish oil. However, the miscibility of the oils is limited and therefore, the next step is to determine if this can be enhanced through upgrading or additives.