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Membranes obtained by adding small amounts (1 wt %) of nanoplatelets of graphene (G) and graphene oxide (GO) to poly­(1-trimethylsilyl-1-propyne) (PTMSP) were fabricated with a simple route, and their gas permeability was measured at 30 °C over 9 months. In most cases, variations of PTMSP permeability due to the addition of filler are limited, while the ideal selectivity of CO2/He, CH4/He, and CH4/N2 is slightly enhanced by addition of filler. Specific measurements indicate that the CO2 and CH4 diffusivity are more strongly affected by addition of graphene than their solubility: such behavior indicates that the filler modifies mainly the microstructure of the polymer rather than its interactions with the gas, as it is reasonable. The most significant quantitative effect observed after filler incorporation is the reduction of PTMSP aging, that was monitored by studying gas permeability after 9 months of aging at room temperature and after annealing at 200 °C. The reduction of aging observed after adding graphene is more significant than that obtained with large amounts (up to 20 vol %) of other inorganic fillers, like MgO and TiO2, even though the amount of filler added in this work is small (<1 wt %). Such behavior, coupled to the generally favorable effect of filler on gas permeability and selectivity, makes such materials extremely promising for real applications.

Among the carbon capture and storage (CCS) technologies suitable for power generation plants, partial oxy-combustion coupled with post combustion CO 2 capture is gaining interest, since such a hybrid configuration could allow to reduce the size and enhance the performance of postcombustion CO 2 capture by operating combustion with air enriched with oxygen and reducing the dilution of flue gas. Moreover, partial oxy-combustion is a potential candidate for the retrofit of existing steam plants because it could be based on an almost conventional boiler and requires a smaller CO 2 capture section. This work presents the results of a comparative techno-economic analysis of a 1000 MW th partial oxy-combustion plant based on an ultra-supercritical pulverized coal combustion power plant integrated with a post-combustion CO 2 capture system and geological storage in saline aquifer. In particular, plant performance is assessed by using simulation models implemented through Aspen Plus 7.3 and Gate Cycle 5.40 commercial tools, whereas economic performance are evaluated on the basis of the expected annual cash flow. The analysis shows that, for new plants, this hybrid approach is not feasible from the economic point of view and full oxy-combustion potentially remains the most profitable technology even if, in the short-term period, the lack of commercial experience will continue to involve a high financial risk.

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In order to limit global warming to around 1.5–2.0 °C by the end of the 21st century, there is the need to drastically limit the emissions of CO2. This goal can be pursued by promoting the diffusion of advanced technologies for power generation from renewable energy sources. In this field, biomass can play a very important role since, differently from solar and wind, it can be considered a programmable source. This paper reports a techno-economic analysis on the possible commercial application of gasification technologies for small-scale (2 MWe) power generation from biomass. The analysis is based on the preliminary experimental performance of a 500 kWth pilot-scale air-blown bubbling fluidized-bed (BFB) gasification plant, recently installed at the Sotacarbo Research Centre (Italy) and commissioned in December 2017. The analysis confirms that air-blown BFB biomass gasification can be profitable for the applications with low-cost biomass, such as agricultural waste, with a net present value up to about 6 M€ as long as the biomass is provided for free; on the contrary, the technology is not competitive for high-quality biomass (wood chips, as those used for the preliminary experimental tests). In parallel, an analysis of the financial risk was carried out, in order to estimate the probability of a profitable investment if a variation of the key financial parameters occurs. In particular, the analysis shows a probability of 90% of a NPV at 15 years between 1.4 and 5.1 M€ and an IRR between 11.6% and 23.7%.