Electrical energy from CO2 emissions by direct gas feeding in capacitive cells

Abstract

This work demonstrates the possibility to harvest electrical power from CO2 emissions by feeding CO2 and air gas directly into a capacitive cell. Hamelers et al. previously showed, that the available mixing energy of CO2 emitted into the air can be converted into electricity, but at high energy costs for gas-sparging in the process. In the present work, electrical power is generated by feeding the gas directly into the capacitive cell. We investigated three different cell designs (namely, “conventional”, “flow-by(wire)”, and “flow-by(flat)”), by changing both electrode and cell geometry. The flow-by(flat), inspired from fuel cell design, showed the best performance thanks to a high membrane potential (≈190 mV), which is the highest value so far reported from CO2 and air. A maximum membrane permselectivity between CO2 and air of 90% was obtained, i.e., almost double of values reported in previous studies. On the contrary, the “conventional” cell design gave poor performance due to non-optimal gas flow in the cell. We highlight the importance of water management and internal electrical resistance, to indicate directions for future developments of the technology.