Bio-oil Production - Process Optimization and Product Quality

The concurrent increase in global primary energy demand by an annual 1.8% (2012) and depletion of conventional resources combine with climate issues and the desire for national/regional energy independence to lead to an urgent need for renewable as well as sustainable energy sources. In 2012, fossil fuels still accounted for 87% of global and 81% of EU primary energy consumption. In an effort to reduce the carbon footprint of a continued supply of liquid fuels, processes utilizing biomass in general, and lignocellulosic biomass in particular, are being developed to replace their fossil counterparts. For some sectors of transportation, notably the marine, aviation and heavy duty land transport sectors, sustainably produced biofuels seem to be the most promising pathway in the near and medium term. This is especially so, if the biofuels possess drop-in properties, i.e. are completely miscible with the existing hydrocarbon fuel at the drop-in point in such a way that neither logistics nor end user technology must be replaced in order to accommodate the increasing blend fraction of biofuels. However, as biomass will also become the primary feedstocks for carbon containing chemicals, plastics, nutritional and pharmaceutical products, it will become a high-cost commodity. Therefore it is of great importance to develop a sustainable and marketable process for the conversion of biomass, which is feedstock flexible and energy efficient and offers high conversion efficiency. Only a process like this has the ability to produce a drop-in product that is commercially compatible to conventional fuels as wells as has the capability to endure. Furthermore, liquid biofuels in future need to be produced in bulk to meet demand; thus, the challenge becomes one of finding the right process with high feedstock flexibility. One such candidate is hydrothermal liquefaction (HTL), a thermochemical process that converts low-value biomass feedstocks to a high-value bio-through the use of hot compressed water and catalysts. As there is typically residual oxygen left in the bio-crude from HTL, further processing involves upgrading in order to be further treated in existing refineries. The design of an efficient, low input procedure for this requires an accurate understanding of the nature of the bio-crude along with corresponding upgrading pathways as well as existing refinery structure assessment. Once pathways have been identified the optimal configuration for refining can be designed.