• Energy Research

Abstract In Italy 1.5 Tg dry matter of residues are estimated to be produced by the agri-food sector. Approximately 30% of them are represented by residues of wine industry sector: grape marc. Referring to its production, it is possible to evaluate about 10 Mg of grapes from each vineyard hectare that generate, as wine industry residue, 2.7 Mg of grape marc, corresponding to about 19 GJ in terms of energy content. This kind of biomass is heterogenous and composed of stalks, grape skins and seeds. In this paper, in order to investigate the possibility of an energy and industrial utilization, the physical-chemical characteristics of each single component of grape marc are examined. In addition, a mechanical extraction test on the seed was performed to evaluate the vegetable oil production and the characteristics of the cake. Results on grape marc components put in evidence some difference in terms of ash and chemical elements content, which represent, specifically for these materials, the most critical aspects to take into account in combustion heating systems.

In the latex production chain, rubber tree seeds (Hevea brasiliensis) represent an underutilized fraction with high potentialities, which can increase the sustainability of the whole process if rightly valorized. In the present study, the quality of all the fractions obtained from the rubber fruit were evaluated, with the aim to identify possible applications for their valorization with a circular economy perspective. Seeds from five different varieties of rubber tree were analyzed. Furthermore, a whole mass and energy balance was defined, which has allowed us to define hypothetical production scenarios. The obtained results show negligible differences among varieties. Shells and capsules have shown a composition similar to woody biomass, with high heating values (more than 16.5 MJ kg−1), low nitrogen content (below 0.5% on weight basis (w/w)) and reduced ash content (0.51% w/w and 1.90% w/w, respectively). Kernels were chemically extracted comparing two different solvents: n-hexane and ethanol. Both solvents showed similar extraction yields, i.e., 49% w/w and 46% w/w for n-hexane and ethanol, respectively. The resulting extraction flour was characterized by a high protein content (around 40% w/w) making it suitable for animal feeding. The rubber seed oil could be used in blends of different vegetable oils for biodiesel production. All this information is useful for improving the sustainability of the latex production chain and to assess the sustainability of possible bioenergy value chains.

Abstract Biomass is an important renewable energy source, in particular if obtained by residues it becomes even more sustainable. In Italy, residual biomass coming from olive oil industry, i.e. olive pomace, is produced in a significant amount and is concentrated in olive oil extraction sites, making interesting a possible valorisation of these residues. The different extraction processes employed influence the pomace quality and, consequently, it is fundamental to find a rapid technique to assess its physical and chemical characteristics for a correct valorisation. The aim of the work was to develop a NIR-based methodology to obtain in a fast and cheap way information about olive pomace. Several samples (n = 104) were collected in Marche region and analysed according to standards methods. NIR spectra were acquired using both fiberoptic probe and integrating sphere and subsequently were elaborated with multivariate techniques, i.e. principal component analysis (PCA) and partial least square regression (PLS). Results show that information on extraction process and composition of the pomace can be obtained. Prediction models with performance suitable for quality control applications were obtained for moisture and ash contents, whereas gross calorific value model was suitable only for screening application.

Abstract Vine is one of the most widespread crop cultivated in Italy. The management of these residues is linked to an additional cost for the operator and determines environmental issues mainly due to open field combustion. A better exploitation of these residues could be the use for thermal energy production in residential heating devices fuelled with pellet. In the present work vineyard pruning residues were collected, pelletised, then characterised according to the standard for solid biofuels. Combustion tests were performed in a 150 kWth boiler fuelled with pruning pellet and the related TSP, CO, NOx emissions were measured. In order to make a comparison with the open field combustion emissions of the vineyard pruning residues, simulation tests were conducted at lab scale. Open field emissions are up to 120 times for CO emission and 30 times for TSP more than the boiler emission. Results highlighted that by avoiding open field combustion and using this residual biomass for energy production, a significant reduction of environmental pollution together with an increase in renewable energy production can be obtained. The results can be useful as support for policy makers engaged in developing the strategy for the promotion of renewable energy and air quality improvement.

Abstract European policy promotes renewable energies and sets specific targets. Solid biofuels can play a significant role and the quality is an important aspect to be checked. Quality parameters such as origin and source are also required by specific biofuel standards. Therefore it could be useful to develop a rapid and cheap tool to distinguish between hardwoods and softwoods especially in unstructured, milled or densified wood in order to check the compliance of producer's declarations. Compared to other analytical methods, infrared spectroscopy is fast, non-destructive and low cost. In this study Fourier transform infrared (FTIR) spectroscopy coupled with Soft Independent Modelling of Class Analogy (SIMCA) has been evaluated as a method for discrimination purpose. A large dataset of 110 wood samples belonging to 12 species were analysed. In addition 4 blends were also analysed to test the discrimination performance of the tool. FTIR-SIMCA has correctly classified 93% of hardwood samples and 100% of softwood samples at high significance level. Furthermore, 100% of tested blends were associated with no class, showing a discrimination ability of the technique in recognizing blends from pure material. This method could be useful to verify the compliance of producer declarations about wood origin and source.

Tomato manufacturing industry originates substantial amounts of residues. If left without control these residues can constitute an environmental problem. Their energetic use can solve this problem and give added value to the process. In this research physical-chemical characteristics of this biomass and its components are studied to evaluate the possibility of an energy recovery. In general, the dry residues of tomato processing industry are suitable as solid biofuel for energy purposes in large size power plants. The separation of components that constitute tomato residues (peels and seeds) makes sense in case of production and exploitation of oil from tomato seeds. The results can be useful for developing standards on these materials.

Abstract The first generation biofuels still have the role of leader in global production of biofuels. In Europe biodiesel is produced mostly from rapeseed ( Brassica napus L. oleifera Metzg) and sunflower ( Helianthus annuus L.). The EU policy is giving attention to the valorization of residues deriving also from those chains. The present work had the objective of evaluating the quality of residues deriving from biodiesel chains based on rapeseed and sunflower crops as well as on other interesting crops in the Mediterranean area, such as Ethiopian mustard ( Brassica carinata A. Braun) and cardoon ( Cynara cardunculus L.). For this purpose an energetic characterization of straws, hulls and press cakes were performed following the official technical normative, as well as the evaluation of their energetic potential. The energy content of residues resulted to be interesting and their quality compatible in general with an energetic use. Crop residues seem to have the most energy potential in quantitative terms, and their exploitation can improve the energy balance of first generation biodiesel production chain improving their sustainability. Concerning quality, crop residues should be employed in medium-large sized plants to limit problems related to plant management and emissions.

The increase in the demand for energy supply during the past few decades has brought and will bring to a growth in the utilisation of renewable resources, in particular of solid biomasses. Considering the variability in the properties of biomass and the globalisation of the timber market, a chemical and physical characterisation is essential to determine the biomass quality. The specific international standards on solid biofuels (ISO 17225 series) describe proper specification and classification of wood chip and pellet, to ensure appropriate quality. Moreover, standard requires information about origin and source of the biomass, normally only to be declared by the producers. In order to fulfill the requirements for the biomass quality, the origin and the source should be assessed, even if currently is hard to determine, in particular on milled or densified biomass. Infrared spectroscopy can provide information on the biomass at the chemical level, directly linked also to its origin and source. This technique is fast and not destructive thus suitable also for online monitoring along the biofuel production chain. In this study, 60 samples belonging to 8 different species were collected and related spectra were acquired using a Fourier transform infrared (IR) spectrometer equipped with a module for solid analysis and analysed by principal component analysis. The results obtained show that the method is very efficient in the identification between coniferous and deciduous wood (99% confidence level) and good results were obtained in the recognition of coniferous/deciduous mixtures, too. Nevertheless, some clear differences have been also noted among intra-class grouping, but additional tests should be carried out. This technique can provide useful information to solid biofuel stakeholders about wood quality and origin, important especially for sustainability issues. Further work will be oriented to the development of IR methodologies for the fast measurement of other important biomass parameters (<em>e.g.</em>, ash content, high calorific value, nitrogen content, <em>etc</em>.).

Abstract The standardization is an important aspect for fuel products. Some residual biomass are highly heterogeneous making their energy use rather difficult. Torrefaction can represent an interesting process to improve the standardization and quality of the lignocellulosic biomass. In the present research torrefaction has been applied on tomato peels, an important Italian industry residue. Different residence times and torrefaction temperatures have been employed in a bench top torrefaction reactor. Proximate, ultimate, thermogravimetric and infrared analyses of raw and torrefied material have been performed to evaluate the influence of the process. From the mildest condition studied to the most severe one, mass yield, energy yield and energy densification vary in the ranges of 94.7–69.9%, 98.0–86.0% and 1.04–1.23 respectively. According to mass and energy yields, ultimate analysis and thermogravimetric profiles, temperature parameter results more significant than residence time. Torrefaction makes the material increasingly hydrophobic as torrefaction temperature increases. This results in a more biologically stable and standardized material suitable to be employed as fuel for energy application. The results of this paper provide useful indications and suggest a mild torrefaction.