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This paper deals with the design, operation, modeling, and grid integration of bioelectrochemical systems (BES) for power-to-gas application, through an electromethanogenesis process. The paper objective is to show that BES-based power-to-gas energy storage is feasible on a large scale, showing a first approximation that goes from the BES design and operation to the electrical grid integration. It is the first study attempting to cover all aspects of a BES-based power-to-gas technology, on authors’ knowledge. Designed BES reactors were based on a modular architecture, suitable for a future scaling-up. They were operated in steady state for eight months, and continuously monitored in terms of power consumption, water treatment, and biomethane production, in order to obtain data for the following modeling activity. A black box linear model of the BES was computed by using least-square methods, and validated through comparison with collected experimental data. Afterwards, a BES stack was simulated through several series and parallel connections of reactors, in order to obtain higher power consumption and test the grid integration of a real application system. The renewable energy surplus and energy price variability were evaluated for the grid integration of the BES stack. The BES stack was then simulated as energy storage system during low energy price periods, and tested experimentally with a real time system.

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In dye-sensitised solar cells developed to-date, ultraviolet blocking layers (UV-BL) is employed to avoid photocatalysis effects on the dye and consequent reduction in PV energy output over time due to UV exposure in outdoor conditions. Use of a UV-BL increases stability but, power conversion efficiency decreases as incident UV photons are not converted. The organolanthanide complex Eu(tta) 3 phen is examined for inclusion in large Stokes shift downshifting (LSS DS) layers. It is shown that such LSS DS layers can be used as a UV blocking layer in DSSCs. A ray-trace numerical model is used to optimise the thickness and concentration of the LSS DS layers for the specific N719 DSSC. EQE is significantly increased in the UV spectral region compared to DSSCs utilizing a passive, non-luminescent, UV-BL. High Eu(tta) 3 phen film transparency in the visible range minimises DSSC EQE losses at visible wavelengths. The photostability of the blended LSS DS polymer films is not sufficient to be useful for medium-long term outdoor PV applications. However, the results demonstrate that significant efficiency enhancement can be realized. Short circuit current enhancement due to downshifting is demonstrated (~1%) in small scale LSS DS polymer films prepared and attached to DSSC devices, where the specific geometry limits the photon collection efficiency and overall enhancement. Model predictions indicate that 2-3% enhancement is realizable in DSSC minimodules, compared to minimodules using passive, non-luminescent, UV-BL. Predicted enhancement in energy produced in outdoor conditions is 3-5%.