Browsing by Author "Tregambi, Claudio"

Now showing 1 - 2 of 2
  • Thumbnail Image
    ItemOpen Access
    Modelling of an integrated process for atmospheric carbon dioxide capture and methanation
    (Elsevier, 2022-04-29) Tregambi, Claudio; Bareschino, Piero; Hanak, Dawid P.; Montagnaro, Fabio; Pepe, Francesco; Mancusi, Erasmo
    Negative-emission technologies are largely investigated to better control atmospheric carbon dioxide concentration driving global warming. Calcium looping has been proposed in literature for direct air capture, but a comprehensive system analysis is still missing. Methanation of carbon dioxide can represent an alternative to geological storage, widely investigated within the power-to-gas framework. In this study, an integrated process considering the catalytic methanation of the concentrated carbon dioxide stream after capture from ambient air by a pure hydrogen stream from water electrolysis was proposed and numerically investigated. The system relies on packed bed reactors and uses calcium oxide as sorbent, and a nickel-based catalyst for methanation. A comprehensive study on the overall system performance was carried out, assuming a carbon dioxide capture target of 100 t y−1. Model computations suggest that roughly 50-in-parallel reactors, 0.5 m diameter each, are required for a continuous operation. The overall energy demand of the integrated process ranges within 344–370 GJ tCH4−1, or 215–293 GJ tCH4−1 if neglecting the humidifier. The methanation process requires 3-in-series reactors and can yield a continuous gas stream with a flow rate of 5 kg h−1 and a methane molar fraction of nearly 91%. If this stream is exploited for heat generation, a return of energy index of 16%, or 23% if neglecting the humidifier, is foreseen. The proposed process stems as viable solution towards a circular carbon economy.
  • Thumbnail Image
    ItemOpen Access
    Technoeconomic analysis of a fixed bed system for single/two–stage chemical looping combustion
    (Wiley, 2021-07-31) Tregambi, Claudio; Bareschino, Piero; Hanak, Dawid P.; Mancusi, Erasmo; Pepe, Francesco
    Chemical looping combustion (CLC) is a promising carbon capture technology allowing integration with high-efficiency Brayton cycles for energy production and yielding a concentrated CO2 stream without requiring air separation units. Recently, dynamically operated fixed bed reactors have been proposed and investigated for CLC. This study deals with the technoeconomic assessment of a CLC process performed in packed beds. Following a previously published work on the topic, two different configurations are considered: one relying on a single oxygen carrier (Cu/CuO based) and the other on two in–series oxygen carriers (Cu/CuO based first, Ni/NiO based later). For both configurations, relevant process schemes are devised to obtain continuous power generation. Despite slightly larger capital costs, two-stage CLC performs better in terms of efficiency, levelized cost of electricity, and avoided CO2 costs. Fuel price and high–temperature valves costs are identified as the main variables influencing the economic performance. The use of two in–parallel packed bed reactors (2.0 m length, 0.7 m internal diameter) enables a power output of 386 kWe, a net electric efficiency of 37.2%, a levelized cost of electricity of 91 € MWhe −1, and avoided CO2 costs of 55 € tonCO2 −1 with respect to a reference pulverized coal power plant.