Start of funding 01.07.2021

ValidBio: Comparison and Validation of different Biomass characterization Methods

Dr. Sebastian Fendt
Technische Universität München
Fakultät für Maschinenwesen

Prof. Bryan M. Jenkins
University of California, Davis
Biological and Agricultural Engineering Department (BAED)



Chemical analysis is an important step for predicting the characteristics of biomass, both in the use as a fuel and in the further utilization of biomass ashes. The characterization of solid biomass is especially challenging due to a high heterogeneity of the feedstock. Thus, an extra step of sample preparation such as leaching or evaporation is usually required. In both collaborating institutes different methods are used for characterization that each have their strengths and limitations. With an Electrothermal Vaporization unit (ETV) connected to an Inductive Coupled Plasma Optical Emission Spectrometer (ICP-OES) solid biofuels can be analyzed without an extra preparation step at TU Munich. UC Davis uses a Differential-Thermal-Analyzer connected to an Inductively Coupled Plasma Mass Spectrometer (DTA-ICPMS). Especially these two state-of-the-art measurement techniques allowing temperature resolved mass-change and elemental release will be compared and validated.
The goal of the collaboration is to significantly deepen the scientific knowledge in both institutes as well as to improve general fuel analysis by sharing expertise on highly advanced analytical methods and validate both systems.

Final report:
In the course of the BaCaTeC-funded ValidBio project, the characterization of solid biomass was investigated using an innovative method for temperature-resolved analysis. For this purpose, the Chair of Energy Systems at the Technical University of Munich (TUM) and the Department of Biological and Agricultural Engineering at the University of California, Davis (UCD) cooperated. For five months Theresa Hauth (B.Sc.) was working with the working group of Bryan Jenkins (Ph.D.) (Distinguished Professor Emeritus) and collaborated closely with Peter Thy (Ph.D.) and Li Wang (M.Sc). Additionally, the funding enabled a research stay abroad for three weeks of Hendrik Mörtenkötter (M.Sc.) who supervised the research project of Ms. Hauth.

For the analysis, a thermobalance (TG/DTA) was linked to a mass spectroscope with inductively coupled plasma (ICP-MS) at UCD. The biomass sample was first evaporated and the released elements were then detected with temperature resolution.

In order to investigate the comparability of the chemical analysis of the biomass and its use in existing biomass power plants with regard to the atmosphere, measurements were carried out in argon and air. It was found that an oxidizing atmosphere increases the element release of the volatile components and leads to a greater mass loss during heating. At higher temperatures, however, hardly any differences were found. Consequently, the results indicate that measurements in an argon atmosphere can be transferred to existing power plants with an oxidizing atmosphere.

To ensure the reliability of the ICP-MS measurements, a laser ablation system was added to the experimental setup. By ablating platinum in the laser, an internal standard was introduced to overcome variable plasma conditions due to the release of volatiles. Experiments with different sample quantities were used to illustrate the behavior of the plasma and to find a possible further development of the existing methodology.

Due to different limitations of the measuring equipment at UCD and TUM, the measuring techniques could not be conclusively validated, but comparable results could be obtained and the advantages and disadvantages of the respective experimental set-ups could be highlighted. In addition to the purely technical exchange, which will be included in future publications, the project also led to intensive professional exchange regarding the future of energy supply and the role of biomass in California and Bavaria.