Lasse Rosendahl

Abstract:

Biomass conversion through direct liquefaction has been investigated for decades. Specifically for hydrothermal liquefaction (HTL), in which organic material is converted in an aqueous medium under the application of pressure and temperature, focus has been on converting inherently wet organic materials into an oil – a bio-crude – typically maximizing mass yields and operating at pressure-temperature combinations below the critical point of water. For inherently dry materials, pyrolysis has been more favored. However, recent work not only indicates that HTL is an efficient method to convert not only wet feedstocks, defined by humidity contents greater than, say, 70%, but also for feedstocks commonly considered dry such as lignocellulosics. This opens up for a vast range of organic material – aquatic biomass, terrestrial biomass, non-plant organic material and various liquid organic waste streams – all of which can be processed by the same technology platform. Recent focus, however, has been directed not only at technical processing aspects such as temperature and heating rate, pressure, dry matter concentration, reaction environment pH etc, but also at establishing individual reaction mechanisms for the macro-compounds in the organic material, subject to a given set of reaction conditions. Thus, rather than focusing on mass yield as the single quality parameter, the reaction product composition (mainly in the bio-crude) forms the platform for a more holistic understanding of what constitutes an “optimal process”, allowing for a more coherent approach to building knowledge about how to apply HTL to one or multiple available sources of organic material, and to operate the process to maximize certain fuel compounds or platform chemicals. This presentation will address supercritical HTL and it’s application to lignocellulosics as well as certain aquatic biomasses and contaminated waste fractions, separate and mixed, from the perspective of understanding the biocrude composition and maximizing desired fuel precursors in the bio-crude. Furthermore, the talk will explore utilization of potential value-added compounds in the bio-crudes, as well as methods to reach fuel grade quality from selected fractions of bio-crude.