e-XPlore – Portable research platform for SOC electrolysis and fuel cell operation at pressures of up to 25 bar
The e-XPlore portable research platform, developed by the DLR Institute of Technical Thermodynamics in Stuttgart, enables the investigation of SOC reactors comprising multiple solid oxide cell stacks (SOC) under pressurised electrolysis and fuel cell operating conditions. Operating pressures between 4 and 25 bar can be set.
Research tasks
The aim is to test and characterise the electrochemical SOC reactors in high-pressure operation in order to develop operating strategies and enable low degradation rates and high power and energy densities. The focus is on investigations in electrolysis mode. The hydrogen produced during the electrolysis of water or the synthesis gas produced from carbon monoxide and hydrogen during the simultaneous electrolysis of water and carbon dioxide (co-electrolysis) can then be further processed in various chemical processes. One example is the Fischer-Tropsch synthesis, which is carried out at approx. 25 bar. The high outlet pressures of the gases produced in high-pressure electrolysis make it possible to efficiently supply the coupled processes with educts without additional intermediate steps. By coupling the processes, electrical energy can be converted with high efficiency into easily storable liquid or gaseous chemicals with high energy density.
The construction of the test environment was self-funded by the DLR at a cost of just under €3.7 million and was integrated with a transportable synthesis system developed by the project partner KIT-IMVT as part of the H2Mare: PtX-Wind project and its follow-up project, PtX@Sea.
Mode of operation
Various operating modes can be analysed:
- Electrolysis mode (SOE) for the production of hydrogen or synthesis gas from hydrogen and carbon monoxide using electrical energy of up to 10 kWel
- Fuel cell mode (SOFC) for electricity generation of up to 3 kWel
- Reversible operation (rSOC), e.g. for the temporary storage of electrical energy, whereby the system switches between SOFC and SOE operation
Media supply and disposal
On the fuel gas side, H₂, CO₂, CO, N₂ and CH₄ are available. The gas mixture is preheated and blended with steam (up to 7.5 kg/h). The gas mixture is then heated to operating temperature. Up to 30 m³/h of filtered ambient air is used for the air supply. The gases are heated to an operating temperature of up to 850 °C by several heaters with a total electrical power of 15 kW. Buffer tanks and pressure differential regulators are fitted to prevent fluctuations in pressure. The thermal energy from the products is not recovered via heat exchangers in order to maintain maximum flexibility for operation and the simulation of system operating conditions.
Extended examination options
In-situ characterisation methods, such as online gas analysis of the product gases and high-temporal-resolution voltage measurements using an oscilloscope, provide a detailed insight into the system’s performance. Rapid load cycling can be achieved by controlling the load via PWM.
Projects
- H2Mare: PtX-Wind (completed)
- PtX@Sea (ongoing)