I am a post-doctoral researcher in the field of advanced energy conversion systems, based on high temperature fuel cells. Since my PhD, my activity addresses the utilization of biofuels into Solid Oxide Fuel Cells (SOFCs). I believe that for this application, scientific research and technological development are called for, because they can really play a role towards the energy transition.
I learned about BRISK2 from a colleague who applied during the first round. Then, I decided to get in touch with TU Graz because there was the possibility to establish a collaboration following the above mentioned research thread.
Together with my hosts, we preliminary shaped an experimental campaign merging scientific interests from both sides. Hence, our case-study had the purpose of defining safe operating conditions for SOFC long-term run downstream a wood gasifier, focusing issues like: i) the system size, ii) the likelihood of the fuel gas to produce carbon deposition at the SOFC anode, iii) the total amount of water in the produced gas and, iv) thermal integration. All of these may hinder significantly the techno-economic feasibility and the sustainability of the system concept.
Consequently, the Design of Experiments (DOE) was defined as summarized in Figure 1.
When I arrived in Graz, the test rig TUG3 was ready to perform tests and this made everything run efficiently. The experiments were performed on large planar anode supported SOFC, simulating wood-derived syngas according to the DOE.
During the first week, the tests performed aimed at screening SOFC performance variability in the cases listed in Figure 1. Upon each test condition, voltage measurement, polarization, electrochemical impedance spectroscopy (EIS) and off-gases analysis were conducted (Figure 2). As an example of the results obtained, all of the polarization curves measured with regard to the DOE are depicted in Figure 3.
On the outcome from the first part and a discussion about technological and systemic integration issues, we identified the most interesting condition to run a single test to investigate degradation (case B-2 from Figure 1). Downdraft reactors are better candidates for a matter of scale and higher gas quality (less tars). Then, operating the gasifier at 800°C, hot gas cleaning requires to cool down the producer gas below 400°C: hence, heat recovery is possible whether the SOFC is run at lower temperature compared to the gasifier (i.e. 750°C). Finally, since to completely remove water from the wood-syngas would increase the system complexity and reduce efficiency, un-conditioned gas was considered.
Thus, during the second week, a 100-h test was performed keeping the SOFC at constant current load (100 mAcm-2). A continuous degradation screening was done implementing EIS diagnosis. Upon experimental evidence after the observation period, no significant quick degradation phenomena was induced by operating the SOFC at 750°C on simulated wood-derived syngas (neither concerning ohmic behaviour, nor considering the increase of diffusion losses). A few black particles were found at the anode exhaust line, while purging water from the condenser (Figure 4). Hence, it is reasonable to assume that a small amount of carbon was formed, yet without heavy impact on SOFC performance.
The obtained results produced an advancement in the topic, but also pointed at new directions for further investigations. Additional degradation tests on single cells will be needed, pushing SOFC operating conditions towards higher degradation risk.
Last but not least, I would like to thank my hosts Andrés Anca Couce and Vanja Subotić (Figure 5), for the warm welcome in the cold Graz. It was a great experience to work with them, for we had such interesting scientific sharing … and also nice moments enjoying the city life. I do believe that this kind of experience is fundamental to broaden professional and human networks, in order to join energies and find new motivation in making advancements in the research.