(235b) Plasma and Fluidic Oscillation Assisted Electrolysis of CO2

Authors: 
Rothman, R. H., University of Sheffield
Call, A. V., University of Sheffield
Zimmerman, W. B., University of Sheffield
Butterworth, T., DIFFER
Holmes, T., Perlemax
Tse, L. H. H., Perlemax
Desai, P., Perlemax
The reduction in carbon emissions required for a sustainable future, and the resultant necessary decarbonisation of energy generation, inevitably lead to an increased focus on renewable energy sources. Natural intermittency of renewable electricity sources such as wind and solar, mean that technologies such as energy storage must play an increasingly fundamental role by smoothing the natural fluctuations in electricity production. Reversible Solid Oxide Cells (SOCs) are widely seen as a leading technology for future clean power generation, chemicals production, and energy storage. Renewable electricity can be utilised directly via electrolysis to reduce CO2 and/or H2O which can then be further reacted to produce a myriad of hydrocarbon related products. In times of low or no renewable electricity generation, the SOC can flexibly switch to run as a fuel cell to produce electricity.

Whilst single SOCs are easy to operate on a small scale in the laboratory, larger systems have found it difficult to compete with alternative energy technologies on cost, performance and durability. In particular, it is necessary to develop methods for lifetime extension of SOCs, minimisation of losses such as concentration polarisation, and faster chemical activation of CO2, using energy inputs close to the thermodynamic minimum.

We are developing a novel, hybrid, plasma and fluidic oscillation assisted electrolysis system, in which the plasma is used to radically improve the kinetics and energy efficiency of CO2 dissociation. The system is designed to reduce concentration polarisation by disrupting the gas boundary layer using fluidic oscillation and by utilizing ionic wind formed in plasmas (the gas flow generated by movement of ions in the plasma).

Non-thermal plasma catalysis has shown great potential for CO2 reduction in its own right due to the promotion of strongly endothermic reactions with low activation energy, so that little or no excess energy is required from the plasma for activation and thermodynamic efficiencies are high. The challenges are to dynamically control the reaction and to achieve high conversion.

Fluidic oscillation can disrupt boundary layer formation and therefore minimise, or remove completely, the effects of concentration polarisation on cell performance. Fluidic oscillation has never before been coupled to an SOC.

Reactor design and preliminary results will be presented, showing the effect of fluidic oscillation and plasma on CO2 electrolysis.