Category: Publications

Moser, Peter and Stahl, Knut and Wiechers, Georg, Closing the Carbon Cycle – Demonstrating Back-Up Power Production from E-Fuels in Gensets and Recycling of the Engine Exhaust Gas (September 26, 2024). Available at SSRN: https://ssrn.com/abstract=5016150 or http://dx.doi.org/10.2139/ssrn.5016150

Abstract

For the first time the concept of back-up power production by combustion of a fuel blend using e-Fuels in a stationary engine (electric output 200 kW) and feeding back the exhaust gas of the engine upstream of an amine-based CO2 capture plant (capture capacity 7.2 t/day CO2 at a capture rate of 90%) was demonstrated at RWE’s Innovation Center at Niederaussem, Germany. The captured CO2 will be later the feedstock for the large 1 MW ECO2Fuel demonstrator to produce carbonaceous e-Fuels, which can again be used in the engine genset, closing the carbon loop. As the exhaust gas has an attractive high temperature level of >400°C that is typically for combined heat and power applications also the potential of the heat reuse and efficiency enhancement was investigated. The analysis and evaluation comprised especially the effect of the changes in the flue gas composition by the exhaust gas recycling (increased O2 and reduced CO2 concentration) on the capture plant performance (specific heat demand for the solvent regeneration, emissions; solvent CESAR1) and the potential of the set-up for combined heat and power applications.

Researchers Sabrina C. Zignani and Antonino S. Aricò have made significant strides in the field of renewable energy with their latest study on CO₂ conversion to synthetic fuels. Utilizing a flow cell reactor with copper and silver-based cathodes, they demonstrate improved selectivity and efficiency in converting carbon dioxide into valuable chemicals, including ethylene, ethanol, and propanol. This innovative approach holds promise for sustainable fuel production, contributing to efforts in reducing atmospheric CO₂ and combating climate change. 

Abstract

As a result of electrochemical conversion of carbon dioxide (CO₂), value-added chemicals like as synthetic fuels and chemical feedstocks can be produced. In the current state of the art, copper-based materials are most widely used being the most effective catalysts for this reaction. It is still necessary to improve the reaction rate and product selectivity of CuOx for electrochemical CO₂ reduction reaction (CO₂RR). The main objective of this work was synthesized and evaluate the copper oxide electrocatalyst combined with silver (CuO 70% Ag 30%) for the conversion of carbon dioxide into synthetic fuels. The catalysts have been prepared by the oxalate method and assessed in a flow cell system. The results of electrochemical experiments were carried out at room temperature and at different potentials (-1.05 V–0.75 V vs. RHE in presence of 0.1 M KHCO₃) and gas and liquid chromatographic analysis are summarized. The CuOx-based electrodes demonstrated the selective of ~ 25% at -0.55 V for formic acid (HCOOH) and over CuO -Ag and selective of ethylene at ~ 20% over CuOx at -1.05 V. Other products were formed as ethylene, ethanol, and propanol (C₂H₄, EtOH, PrOH) at more positive potentials. On the other hand, carbon monoxide, acetate, ethylene glycol, propinaldehyde, glycoaldehyde and glyoxal (CO, CH₃COO, C₂H₆O₂, C₃H₆O, C₂H₄O₂, C₂H₂O₂) have been formed and detected. Based on the results of these studies, it appears that the formation of synthetic fuels from CO₂ at room temperature in alkaline environment can be very promising.

For more detailed insights, read the full study here.