Biomass

Bioenergy with carbon capture and utilization (BECCU) can decarbonize industrial steam, but the conversion plant only works if the feedstock reaches it. This study tests, for a design scenario, whether the catchment area of a fixed oxy-fuel bubbling fluidized bed boiler at a refinery in Puertollano, central Spain, can supply its fuel. The boiler needs 20.94–52.34 MW of thermal input and therefore 35.2–88.0 kt/y of dry matter, that is 59–147 kt/y of class-2 wood chips at 40% moisture. Forest cover, forest formations and potential forest productivity were characterized from open national cartography inside 50 and 100 km buffers and inside road-network service areas, and the residue availability values were taken from two public assessments, one national and one for the surrounding district, used to cross-check the GIS characterization. Wooded land covers 42.7% of the 100 km buffer, but only 0.77 Mha of it lies within 100 km of road and 400 m of a road, and about half of that is in Natura 2000 sites or protected areas. The forest residue accessible within 100 km of road is about 18.5 kt/y of dry matter, 53% of the minimum demand, and a delivered-cost supply curve shows that the shortfall is one of quantity, not of price. The residue potential of the whole region, 40.8 kt/y, is a theoretical upper bound rather than an available supply, and even all of it would cover less than half of the maximum demand. Olive and vine by-products are the only local resources of sufficient magnitude, but they are already used by an existing 50 MW plant and are candidates for further evaluation rather than a proven supply. Biomethane for start-up would need less than 0.3% of the regional 2030 production target.

Municipal solid waste (MSW) is a heterogeneous mixture of plastics, biomass-derived materials, moisture, inorganics and contaminants. Microwave-assisted catalytic pyrolysis (MACP) combines volumetric dielectric heating with catalytic upgrading and is increasingly proposed for such residual streams. This critical narrative review examines what has actually been demonstrated for MSW and what is extrapolated from single-polymer, biomass and mixed-model studies. A structured literature search (418 records screened to 77 core sources, 2015–2026) was combined with an explicit three-tier classification of evidence by feedstock realism. Only a handful of studies used real or model MSW, so most mechanistic and performance conclusions rest on extrapolated evidence. The main findings are: (i) dielectric heterogeneity is a first-order design variable, with calculated penetration depths at 2.45 GHz ranging from a few millimeters to centimeters for wet organics, char and susceptors to tens of meters for dry polyolefins; (ii) susceptor–catalyst arrangement and contaminant management (Cl, N, ash) govern selectivity and catalyst lifetime more than microwave power alone; (iii) hydrogen yields of about 9–12 wt% of feed have been reported for clean polyolefins but remain unproven for real MSW; (iv) published techno-economic analysis (TEA), life cycle assessment (LCA) and machine learning results cannot be compared directly because boundaries, functional units, electricity assumptions and datasets differ; and (v) no study reporting weeks-to-months continuous operation on MSW-type feed was identified. A prioritized roadmap is proposed, comprising standardized feed and reporting protocols, contamination-tolerant catalysts, coupled electromagnetic–thermal–reaction design and a long-duration pilot campaign.

Environmental and economic assessments of syngas chains from residual woody biomass are rarely integrated in Mediterranean regions. Attributional life cycle assessment and life cycle costing were combined for three prospective configurations in the Lazio Region, central Italy: a regional feedstock mix (S1), residues from widespread coppicing (S2) and a pruning hub (S3). Impacts were characterized with Environmental Footprint 3.1; costs were discounted over 15 years at a pre-tax rate of 6.75%. In deterministic terms, S2 was lowest in fifteen of sixteen midpoint categories; its single score (an illustrative aggregate) was 0.47 µPt MJ⁻¹, 18% below S1. Quicklime for syngas cleaning was the largest contributor among the inventoried flows (65–80%). The advantage of S2 rests on cut-off allocation and, on the single score, passes to S3 once more than 18% of upstream forest burdens are attributed to residues. With delivered heat valued at 0.20 € kWh⁻¹ and a conversion efficiency of 0.90, S2 and S3 were profitable, and S1 was not (break-even 0.221, 0.171 and 0.182 € kWh⁻¹). Profitability was sensitive to both: S3 became unprofitable at an efficiency of 0.80 or with feedstock-specific conversion. Forest-residue chains required at least 100 kg h⁻¹ and the pruning hub 250 kg h⁻¹, and procurement cost outweighed transport distance almost fourfold.