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 MW_e) power generation from biomass. The analysis is based on the preliminary experimental performance of a 500 kW_th 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%.

CO₂-derived methanol and dimethyl ether can play a very important role as fuels, energy carriers, and bulk chemicals. Methanol production from CO₂ and renewable hydrogen is considered to be one of the most promising pathways to alleviate global warming. In turn, methanol could be subsequently dehydrated into DME; alternatively, one-step CO₂ conversion to DME can be obtained by hydrogenation on bifunctional catalysts. In this light, four oxide catalysts with the same Cu and Zn content (Cu/Zn molar ratio = 2) were synthesized by calcining the corresponding CuZnAl LDH systems modified with Zr and/or Ce. The fresh ex-LDH catalysts were characterized in terms of composition, texture, structure, surface acidity and basicity, and reducibility. Structural and acid–base properties were also studied on H₂-treated samples, on which specific metal surface area and dispersion of metallic Cu were determined as well. After in situ H₂ treatment, the ex-LDH systems were tested as catalysts for the hydrogenation of CO₂ to methanol at 250 °C and 3.0 MPa. In the same experimental conditions, CO₂ conversion into dimethyl ether was studied on bifunctional catalysts obtained by physically mixing the ex-LDH hydrogenation catalysts with acid ferrierite or ZSM-5 zeolites. For both processes, the effect of the Al/Zr/Ce ratio on the products distribution was investigated.

In this work, we propose two bifunctional nanocomposite catalysts based on acidic mesostructured γ-Al₂O₃ and a Cu/ZnO/ZrO₂ redox phase. γ-Al₂O₃ was synthesized by an Evaporation-Induced Self-Assembly (EISA) method using two different templating agents (block copolymers Pluronic P123 and F127) and subsequently functionalized with the redox phase using an impregnation method modified with a self-combustion reaction. These nanocomposite catalysts and their corresponding mesostructured supports were characterized in terms of structural, textural, and morphological features as well as their acidic properties. The bifunctional catalysts were tested for the CO₂-to-DME process, and their performances were compared with a physical mixture consisting of the most promising support as a dehydration catalyst together with the most common Cu-based commercial redox catalyst (CZA). The results highlight that the most appropriate Pluronic for the synthesis of γ-Al₂O₃ is P123; the use of this templating agent allows us to obtain a mesostructure with a smaller pore size and a higher number of acid sites. Furthermore, the corresponding composite catalyst shows a better dispersion of the redox phase and, consequently, a higher CO₂ conversion. However, the incorporation of the redox phase into the porous structure of the acidic support (chemical mixing), favoring an intimate contact between the two phases, has detrimental effects on the dehydration performances due to the coverage of the acid sites with the redox nanophase. On the other hand, the strategy involving the physical mixing of the two phases, distinctly preserving the two catalytic functions, assures better performances.