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Graphical abstract Highlights • Energy balance (data and model) of a CO 2 injection facility is presented. • Heat flow and efficiency of ambient air vaporizers are analyzed. • Operation conditions are compared for single- and two phase CO 2 flux. • Warm and cold injection schemes are evaluated. Abstract Injection of 67 kt carbon dioxide was carried out between 2008 and 2013 at the test site for geological storage in Ketzin, Germany. The source carbon dioxide was delivered in liquid phase. The injection facility has had a three step process chain: (i) pressure increase by a liquid pump, (ii) temperature increase by ambient air vaporizers and (iii) temperature increase by an electrical vaporizer including phase change to gaseous conditions. The ambient vaporizers reduced electrical power demand but the weather dependence induced some kind of uncertainty, further their power could not be measured. In the cases when the carbon dioxide was evaporated within the ambient vaporizers, the heat demand increased such that the driving temperature was not enough for full vaporization. However, the gas to liquid ratio is unknown wherefore the heating power can not be calculated over the ambient vaporizer. This is addressed, as the electric energy consumption was most reduced during the two phase operation. For these intervals, two phase gas–liquid conditions prevailed in the pipeline. Unlike conjectured, flow conditions remained stable and did not vary significantly from single phase behavior. The current work – for the first time – presents a detailed analysis of energy input and losses of the carbon dioxide injection process based on field data and simulations. A modified process chain is proposed to switch the electric energy demand to an ambient heat source, reducing the electrical energy use per ton carbon dioxide by up to 90 %. The work provides insight for planning future injection devices that involve liquid carbon dioxide in the process chain. [ABSTRACT FROM AUTHOR]

Abstract Liquid Metal Batteries (LMBs) are a promising concept for cheap electrical energy storage at grid level. These are built as a stable density stratification of three liquid layers, with two liquid metals separated by a molten salt. In order to ensure a safe and efficient operation, the understanding of transport phenomena in LMBs is essential. With this motivation we study thermal convection induced by internal heat generation. We consider the electrochemical nature of the cell in order to define the heat balance and the operating parameters. Moreover we develop a simple 1D heat conduction model as well as a fully 3D thermo-fluid dynamics model. The latter is implemented in the CFD library OpenFOAM, extending the volume of fluid solver, and validated against a pseudo-spectral code. Both models are used to study a rectangular 10 × 10 cm² Li||Bi LMB cell at three different states of charge. [ABSTRACT FROM AUTHOR]