IMagerie Multiphysique des Piles A Combustible microfluidiques
In the current objective of massive deployment of renewable energies from wind turbines and solar panels, energy storage is the most critical issue to synchronize the electrical production to the consumption. Several studies in the literature have shown how energy storage can transform intermittent renewables into high-value energy on demand if cost and efficiency improvements of storage systems are obtained. A recent study from the French Energy Agency (ADEME) has shown that the installation of 600 MW of storage capacity by 2030 would lead to 150 M€/yr savings on the energy price in France. In this context, Microfluidic Fuel Cells (MFC) like flow batteries and electrolysers, appear to be promising energy storage technologies as a large quantity of chemical energy can be stored into tanks. The low cost of these technologies is their main asset – compared to Li-ion batteries for the same energy storage capacity – but their power density and fuel utilization still need to be improved (their current round-trip efficient is about 30%).
MFCs can be viewed as a stack of small microfluidic chips where chemical energy from fluids (in general liquids) is converted into electricity and conversely. To improve the MFC performances and to develop innovative MFC designs, a trade-off between the heat and mass transport, the electrochemical kinetics, and the ohmic resistance need to be found. This is the objective of the I2MPAC project where a new technique called Lock-In Thermospectroscopy (LIT) will be built based on multispectral thermospectroscopic imaging and electrochemical impedance spectroscopy (EIS). The LiT will be used in combination with numerical and analytical models of MFCs to analyse the energy losses and establish specific guidelines for the manufacturers concerning the optimal MFC designs (channels geometry, electrode positions…) and optimal operating and safety conditions.
The project is divided into 3 scientific work packages (WPs), following the classical structure: experiments, modelling, and characterization. The WP1 will be dedicated to the development of a new multiphysic imager. It will be based on an infrared (IR) camera and an IR source (Fourier transform IR spectrometer) to image simultaneously the temperature and concentration field in a MFC at the microscale. Images of the charge transport in the MFC electrolyte will then be obtained using EIS. The WP2 will be dedicated to the MFC modelling based on the equation of heat, mass and charge transfer at the microscale. Using a Fourier decomposition of these equations, it will be possible to obtain several analytical solutions in some specific regimes which will be used to rapidly process the large quantity of data produced by the LiT. Finally, the MFC properties will be characterized in the WP3 using image-based inverse processing methods. These data will feed the numerical MFC model established in WP2 to perform a numerical parametric study and link the MFC design and operating conditions to the energy losses. From this study, guidelines to manufacturers will be given to make efficient and reliable new MFCs.
The I2MPAC consortium gathers the TIFC team who has a strong expertise in spectroscopic IR imaging methods and inverse processing. Associated to the coordinator expertise in electrochemistry and MFC modelling, it will ensure the success of the project.
A lot of benefits are expected from I2MPAC. The improvement of MFC design will enable the manufacturing of more efficient large-scale energy storage plants to improve the worldwide energy storage capacity and decrease the energy cost from renewables. On the fundamental aspects, the development of the LiT will have a high impact in the spectroscopic imaging domain where many processes in microfluidic with combined heat, mass and charge transfer will be characterized, such as enzymatic reactions in biology or heterogeneous catalysis in chemistry. .
ANR JCJC. Global cost 515 k€, including 236 k€ from ANR