• Energy Research
• Restricted close
• CA close
• NL close
• CNR ExploRA close

The Authors tested a complete new system for recovering wood fuel from the termination of depleted orchards. This operation can generate between 25 and 80 fresh t ha?¹, that can be directed to the growing bioenergy sector. The new system is based on highly-mobile low-investment general-purpose equipment, which allows containing operational cost and speeding relocation between work sites. The new residue collection system is quite flexible, and achieves cost-effective recovery on relatively small fields, often smaller than 1 ha. Under the conditions of the study, trees are cut, chipped and delivered at a cost between 35 and 40 EUR t?¹ (40% water mass fraction), provided that fields are within a 20 km distance from the biomass plant. Use of a standard drum chipper results in a better product quality than if a grinders is used, as is the case for conventional orchard removal operations. Feeding the chipper with a separate loader allows a significant cost reduction, provided that the field offers at least 25 t of fresh wood. In the future, use of remote controls and electronic tethers may allow a further cost reduction, which is estimated at 15%.

For the design of ground-source heat-pump systems, the local subsoil is an invariant factor. To improve the evaluation of the local heat exchange capability, significant efforts recently have been devoted to identifying the ground thermal conductivity vertical profile. In recent years, an innovative method using hybrid optic fiber cables inserted into the ground has been developed. The technique relies on copper wires that thermally stimulate the ground. Optical fibers measure the temperature variation over time all along the cable at a high spatial and temporal resolution. In this work, the hybrid cable was grouted into a 125-m well located in the Po Plain in Northern Italy. The provided core defined the geological environment as a continuous succession of unconsolidated alluvial deposits of very limited thickness, grouped in 15 different granulometric units. Three enhanced thermal response test (ETRT) data sets were acquired in different seasons; for 5 days of heating followed by 5 days of recovery, the soil temperature was recorded continuously along the well, with a spatial resolution of 1 m. A new approach using a multiple linear regression is proposed to analyze the data sets to distinguish the thermal conductivity of each individual granulometric unit. The obtained thermal conductivity values were compared and discussed considering the standard thermal response test outputs and the thermal conductivity data obtained from direct measurements performed on the cores. The analytical method's reliability stands due to the high repeatability of the obtained results, despite the increased complexity of the treated geological setting.

While the effects of climate change unfold and become more visible, infrastructures - especially those related to the distribution of water and energy - are the most exposed to the deep changes expected in the next years. Water is fundamental for people, and for infrastructures like energy, waste, and food production. Water sustainability is therefore a fundamental aspect to be addressed by an efficient use of the resources and by mainteining high quality standards. Hence, water industry and water infrastructure need a deep transformation; in this paper we present a framework based on complex systems and management science as a possible pathway to reshape and optimize the performance of the water infrastructure to cope with the complexity of todays' challenges. To this aim, we propose the framework Acque 2.0 (Water 2.0), where we point out how the increase of the infrastructural resilience and of the overall quality of service can be attained by integrating models, algorithms and numerical methods like network simulations and big data analytics for the predictive maintenance of water networks. We discuss how Complexity Science is the natural glue allowing technical, management and social issues to be integrated in the holistic vision of the "water system" needed play to provide measures for an integrated sustainability reporting that involves utilities, regulators, policy makers, and citizens.

In this contribution, we discuss the implementation of a novel microelectromechanical-systems (MEMS)-based energy harvester (EH) concept within the technology platform available at the ISAS Institute (TU Vienna, Austria). The device, already presented by the authors, exploits the piezoelectric effect to convert environmental vibrations energy into electricity, and presents multiple resonant modes in the frequency range of interest (i.e. below 10 kHz). The experimental characterisation of a sputter deposited aluminium nitride piezoelectric thin-film layer is reported, leading to the extraction of material properties parameters. Such values are then incorporated in the finite element method model of the EH, implemented in Ansys Workbench (TM), in order to get reasonable estimates of the converted power levels achievable by the proposed device solution. Multiphysics simulations indicate that extracted power values in the range of several mu W can be addressed by the EH-MEMS concept when subjected to mechanical vibrations up to 10 kHz, operating in closed-loop conditions (i.e. piezoelectric generator connected to a 100 k Omega resistive load). This represents an encouraging result, opening up the floor to exploitations of the proposed EH-MEMS device in the field of wireless sensor networks and zero-power sensing nodes.

The biomimetic CCS strategy is based on the enhancement of CO2 absorption rate into aqueous solutions by the enzyme carbonic anhydrase (CA). Immobilized CA on fine dispersed solids promotes the heterogeneous biocatalysis close to the gas-liquid interface and the enhancement of CO2 absorption rate. In this work a theoretical model of a slurry absorption unit for the biomimetic CO2 capture in K2CO3 solutions was developed and solved using the commercial software package Comsol Multiphysics®. The staged bubble column (SBC) configuration was selected to capture CO2 in aqueous slurry containing immobilized CA under counter-current gas-liquid flow. The theoretical framework included: the 'tanks-in-series' model to describe the unit; the two films theory to describe the absorption rate at the gas-liquid interface; the pseudo-homogeneous approach and a reversible Michaelis and Menten kinetics to model CO2 conversion by the slurry biocatalyst. The simulations provided the CO2 capture rate and the CO2 concentration profiles in the liquid boundary layer. Simulation results showed that the CO2 capture rate poorly increased when dissolved CA was used within the solubility limit (≈100 mg/L). Remarkably, about three fold enhancement of the CO2 absorption rate with respect to pure alkaline solvent when absorption in the presence of CA immobilized on fine particles was simulated.

The termination of a fruit orchard generates a considerable amount of residues that can be used as fuel in biomass-fired power plants. Various studies have explored the separate collection of the above-ground tree portion and the rootstock. The present work analyses the potential of complete-tree harvesting (aboveground biomass and rootstock) from a depleted peach orchard and compares this technique with the collection of the aboveground biomass (pruning residues and stems) only. Complete trees were extracted and piled, then ground into chunks and cleaned to reduce contamination with dirt and stones. As an alternative, trees were cut, stacked and chipped, leaving the rootstocks in the ground for later disposal. Extracting complete trees and piling them at the field's edge proceeded at a pace of ca. 1 ha day-1. Grinding and cleaning allowed reducing soil contamination by 10-15%. The study showed that complete-tree harvesting is a viable approach to containing the costs of biomass recovery from depleted orchards. Supply chain efficiency is maximized by including biomass compaction during the loading of trucks.

Silicon has long been established as the material of choice for the microelectronics industry. This is not yet true in photonics, where the limited degrees of freedom in material design combined with the indirect bandgap are a major constraint. Recent developments, especially those enabled by nanoscale engineering of the electronic and photonic properties, are starting to change the picture, and some silicon nanostructures now approach or even exceed the performance of equivalent direct-bandgap materials. Focusing on two application areas, namely communications and photovoltaics, we review recent progress in silicon nanocrystals, nanowires and photonic crystals as key examples of functional nanostructures. We assess the state of the art in each field and highlight the challenges that need to be overcome to make silicon a truly high-performing photonic material.

Disposal of FBC solid residues currently represents one of the major issues in FBC design and operation, and contributes significantly to FBC operating cost. This issue has triggered research activities on the enhancement of sorbent utilization for in-situ sulfur uptake. The present study addresses the effectiveness of the reactivation by liquid water hydration of FB spent sorbents. Two materials are considered in the study, namely bottom ash from the operation of a full-scale utility FB boiler and the raw commercial limestone used in the same boiler. Hydration-reactivation tests were carried out at temperatures of 40°C and 80°C and for curing times ranging from 15min to 2d, depending on the sample. The influence of hydration conditions on the enhancement of sulfur utilization has been assessed. A combination of methods has been used to characterize the properties of liquid water-hydrated materials.