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Special Issue "Small-Scale Energy Conversion of Agro-Forestry Residues for Local Benefits and European Competitiveness"

A special issue of Sustainability (ISSN 2071-1050).

Deadline for manuscript submissions: 30 September 2018

Special Issue Editors

Guest Editor
Prof. Andrea Colantoni

Department of Agricultural and Forestry scieNcEs (DAFNE), University of Tuscia, Via S. Camillo de Lellis, SNC, 01100 Viterbo, Italy
Website | E-Mail
Interests: agricultural mechanics and mechanization; renewable energy, safety and health
Guest Editor
Prof. Danilo Monarca

Department of Agriculture and Forest Sciences (DAFNE) University of Tuscia, Via San Camillo De Lellis, 01100 Viterbo, Italy
Website | E-Mail
Phone: +39 0761357364
Interests: Renewable energies; forestry and agricultural mechanization; safety and health in agriculture; processing plants and food quality
Guest Editor
Prof. Dr. Massimo Cecchini

Department of Agricultural and Forestry scieNcEs (DAFNE), University of Tuscia, Via S. Camillo de Lellis, SNC, 01100 Viterbo, Italy
Website | E-Mail
Interests: agricultural mechanics and mechanization; renewable energy, safety and health
Guest Editor
Prof. Dr. Enrico Maria Mosconi

Department of Economics and Entrepreneurship (DEIM), University of Tuscia, Via del Paradiso, 01100 Viterbo, Italy
E-Mail
Interests: green economy; renewable energy; circular economy
Guest Editor
Dr. Letizia Magaldi

Member of the board, Magaldi Power S.p.A., Via Irno, 219, 84135 Salerno SA, Italy
E-Mail
Interests: waste to energy; biomass power plants, renewable energy
Guest Editor
Dr. Stefano Poponi

Department of UNISU, Niccolò Cusano University, Via Don Carlo Gnocchi, 3, 00166 Rome, Italy
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Interests: green economy; renewable energy; circular economy
Guest Editor
Dr. Flavio Andreoli Bonazzi

President, EPICO Biomass Ltd, Viale Degli Ammiragli 67, 00136 Roma, Italy
E-Mail
Interests: renewable energy; hydroelectric energy; biomass

Special Issue Information

Dear Colleagues,

The current way to produce, convert and consume energy throughout the world is not sustainable. However, our economic growth and social development can be implemented only by means of an appropriate availability of energy services. Large-size plants present several problems: 1. high biomass supply; 2. authorization problems for the large-size plants; 3. Biomass conversion technologies more adapted to change biomass residual in energies. The small size plants are a technology for future energy supply systems. The unique and advantageous point in the combination of residual biomass and small-size plants results from the fact that biomass is a renewable source of energy which can be utilized most efficiently using gasification technology. Thermo-chemical processes can be seen as an energy-efficient technology for the transformation of biomass, especially lignocellulosic feedstock, into a syngas which can be used for various utilization routes (heat, heat and power, gaseous as well as liquid biofuels, chemicals, etc.).  The use of biomass for energetic purposes within Europe varies widely from country to country and from region to region, depending on the climate, the traditions in the use of the land, the available biomass and on the political and financial support for energy from biomass. In some European countries where the energetic use of biomass is considerably supported by national programs (e.g., Austria, Denmark, Finland and Sweden), biomass as a source of energy is already used to a remarkable amount. In Finland, biomass contributes with 17% to the fossil primary energy consumption. In Sweden, Portugal and Austria the share of biomass use is between 12 and 14%. The main biomass resources that are already widely used in Europe are:

  • fuel wood in households for heating and for cooking;
  • wood chips from thinnings and tree harvesting in district heating plants;
  • wood processing residues in the wood processing industry and in district heating plants;
  • residual wood and bark from wood processing including recovered wood products (i.e., demolition wood) in the wood processing industry and power generation sector and pulping liquors in the pulp and paper industry (particularly in the Scandinavian countries).

Biomass already contributes to the European energy supply to a certain extent, though, according to the assessments made above about the potential of biomass as a source of energy, this share could be considerably higher than it is today. From the shares of the currently used fossil energy carriers and the calculated biomass potential, the maximum reachable share of biomass to cover the energy demand can be calculated. The following enumeration shows the results of such calculations: i) Biomass resources below 10 % of the fossil energy supply in the Netherlands, Belgium and Luxembourg, United Kingdom, Germany, and Italy; ii) biomass resources between 10 and 30% of the fossil primary energy consumption in Denmark, Spain, France, Greece, Portugal and Austria; iii) biomass resources above 30% of the fossil primary energy consumption in Ireland, Sweden, and Finland.

Additionally, the share of the already-used biomass is analyzed against the background of the overall available biomass resources. This shows that, in nearly all of the EU-countries, only slightly more than 25% of the available biomass resources are currently used. In most countries, the share is even significantly lower. It is only higher in countries where the energetic use of biomass is promoted by governmental measures.

The increasing demand for energy and related environmental concerns are the main drivers for the strong interest in biomass residues in the agro-forestry sector and in appropriate small- scale energy conversion. Biomass residues (e.g., prunings, thinnings and forest residues) constitute a highly promising (and currently largely under-utilized) feed stock with a significant potential to be converted into useful end products. This Special Issue proposal has the overall aim of developing a network around technologies for small-scale energy conversion of forestry residues for local benefit and European competitiveness. The following targets will be addressed: i) to improve knowledge of different energy conversion processes for forest residues; ii) to develop an expert group on forest biomass supply chains; iii) to identify best practice for sampling of available forest biomass residues; and iv) to create agro-forestry-scale energy districts.

The purpose of this Special Issue is to publish high-quality research papers, as well as review articles, addressing recent advances on systems, processes, and materials for work safety, health, and environment. Original, high-quality contributions that have not yet been published, or that are not currently under review by other journals or peer-reviewed conferences, are sought.

Dr. Andrea Colantoni
Prof. Dr. Danilo Monarca
Prof. Dr. Massimo Cecchini
Prof. Dr. Enrico Maria Mosconi
Dr. Letizia Magaldi
Dr. Stefano Poponi
Dr. Flavio Andreoli Bonazzi
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Sustainability is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Published Papers (12 papers)

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Research

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Open AccessArticle Sustainable Land Management, Adaptive Silviculture, and New Forest Challenges: Evidence from a Latitudinal Gradient in Italy
Sustainability 2018, 10(7), 2520; https://doi.org/10.3390/su10072520
Received: 12 June 2018 / Revised: 12 July 2018 / Accepted: 16 July 2018 / Published: 18 July 2018
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Abstract
Aimed at reducing structural homogeneity and symmetrical competition in even-aged forest stands and enhancing stand structure diversity, the present study contributes to the design and implementation of adaptive silvicultural practices with two objectives: (1) preserving high wood production rates under changing environmental conditions
[...] Read more.
Aimed at reducing structural homogeneity and symmetrical competition in even-aged forest stands and enhancing stand structure diversity, the present study contributes to the design and implementation of adaptive silvicultural practices with two objectives: (1) preserving high wood production rates under changing environmental conditions and (2) ensuring key ecological services including carbon sequestration and forest health and vitality over extended stand life-spans. Based on a quantitative analysis of selected stand structure indicators, the experimental design was aimed at comparing customary practices of thinning from below over the full standing crop and innovative practices of crown thinning or selective thinning releasing a pre-fixed number of best phenotypes and removing direct crown competitors. Experimental trials were established at four beech forests along a latitudinal gradient in Italy: Cansiglio, Veneto; Vallombrosa, Tuscany; Chiarano, Abruzzo; and Marchesale, Calabria). Empirical results indicate a higher harvesting rate is associated with innovative practices compared with traditional thinning. A multivariate discriminant analysis outlined significant differences in post-treatment stand structure, highlighting the differential role of structural and functional variables across the study sites. These findings clarify the impact of former forest structure in shaping post-treatment stand attributes. Monitoring standing crop variables before and after thinning provides a basic understanding to verify intensity and direction of the applied manipulation, the progress toward the economic and ecological goals, as well as possible failures or need for adjustments within a comprehensive strategy of adaptive forest management. Full article
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Open AccessArticle Operator Dermal Exposure to Pesticides in Tomato and Strawberry Greenhouses from Hand-Held Sprayers
Sustainability 2018, 10(7), 2273; https://doi.org/10.3390/su10072273
Received: 7 June 2018 / Revised: 28 June 2018 / Accepted: 29 June 2018 / Published: 2 July 2018
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Abstract
Protection of greenhouse crops in southern Italy usually requires 15–20 phytosanitary treatments per year, with volume rates in the range of 1000–2000 L ha−1, depending on the plant growth stage. The most widespread sprayers are hand-held, high-pressure devices, which may expose
[...] Read more.
Protection of greenhouse crops in southern Italy usually requires 15–20 phytosanitary treatments per year, with volume rates in the range of 1000–2000 L ha−1, depending on the plant growth stage. The most widespread sprayers are hand-held, high-pressure devices, which may expose operators to high levels of pesticides. This paper, also with the aim to lead toward a more sustainable use of greenhouses in agricultural productions, including some aspects of workers’ safety, reports the results of experimental tests aimed at measuring the amount of the mixture deposited on the worker’s body (potential dermal exposure, PDE) during pesticide applications to tomato and strawberry plants in a protected environment. Experimental tests on tomatoes were carried out taking into account two plant growth stages (flowering and senescence), two types of spray lance, two working pressures (1 and 2 MPa), and two walking directions (forwards and backwards). Those on the strawberries were carried out at the maturity of the fruit growth stage, comparing two hand-held sprayers (a standard spray gun and a short hand-held spray boom equipped with two nozzles) and working according to the common practice: forwards movement of the operator and high pressure (2 MPa). The results showed that with the tomato plants, the most important factor in reducing the deposit on the operator was the walking direction: on average, the PDE was 718 mL per 1000 L of the sprayed mixture (0.72‰) while walking forwards and 133 mL (0.13‰) while walking backwards. The reduction factor ranged from 3.0 at the flowering growth stage to 7.2 at the senescence growth stage. With respect to the strawberry plants, the PDE was significantly higher when the operator used the short hand-held spray boom (887 mL per 1000 L of the sprayed mixture, equivalent to 0.89‰), rather than the spray gun (344 mL, 0.34‰). In both cases, the most exposed body parts were the lower limbs, which accounted for 89–94% of the total PDE. Full article
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Open AccessArticle Machine Vision Retrofit System for Mechanical Weed Control in Precision Agriculture Applications
Sustainability 2018, 10(7), 2209; https://doi.org/10.3390/su10072209
Received: 26 April 2018 / Revised: 21 June 2018 / Accepted: 26 June 2018 / Published: 28 June 2018
Cited by 1 | PDF Full-text (4530 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents a machine vision retrofit system designed for upgrading used tractors to allow the control of the tillage implements and enable real-time field operation. The retrofit package comprises an acquisition system placed in the cabin, a front-mounted RGB camera sensor, and
[...] Read more.
This paper presents a machine vision retrofit system designed for upgrading used tractors to allow the control of the tillage implements and enable real-time field operation. The retrofit package comprises an acquisition system placed in the cabin, a front-mounted RGB camera sensor, and a rear-mounted Peiseler encoder wheel. The method combines shape analysis and colorimetric k-nearest neighbor (k-NN) clustering for in-field weed discrimination. This low-cost retrofit package can use interchangeable sensors, supplying flexibility of use with different farming implements. Field tests were conducted within lettuce and broccoli crops to develop the image analysis system for the autonomous control of an intra-row hoeing implement. The performance showed by the system in the trials was judged in terms of accuracy and speed. The system was capable of discriminating weed plants from crop with few errors, achieving a fairly high performance, given the severe degree of weed infestation encountered. The actuation time for image processing, currently implemented in MATLAB integrated with the retrofit kit, was about 7 s. The correct detection rate was higher for lettuce (from 69% to 96%) than for broccoli (from 65% to 79%), also considering the negative effect of shadows. To be implementable, the experimental code needs to be optimized to reduce acquisition and processing times. A software utility was developed in Java to reach a processing time of two images per second. Full article
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Open AccessArticle A New Approach to Land-Use Structure: Patch Perimeter Metrics as a Spatial Analysis Tool
Sustainability 2018, 10(7), 2147; https://doi.org/10.3390/su10072147
Received: 1 June 2018 / Revised: 20 June 2018 / Accepted: 22 June 2018 / Published: 24 June 2018
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Abstract
This work introduces a new class of landscape metrics characterizing basic features of patch perimeters. Specific computation on patch perimeters was carried out on fine-grained land-use maps with the aim to characterize spatial patterns of neighbor patches, evidencing contact points and perimeter length
[...] Read more.
This work introduces a new class of landscape metrics characterizing basic features of patch perimeters. Specific computation on patch perimeters was carried out on fine-grained land-use maps with the aim to characterize spatial patterns of neighbor patches, evidencing contact points and perimeter length between two (or more) land-use types. A detailed set of class and landscape metrics were derived from such analysis. This approach is complementary to classical landscape metrics and proved to be particularly useful to characterize complex, fragmented landscapes profiling metropolitan regions based on integrated evaluations of their structural (landscape) and functional (land-use) organization. A multivariate analysis was run to characterize distinctive spatial patterns of the selected metrics in four metropolitan regions of southern Europe reflecting different morphological configurations (Barcelona: compact, polycentric; Lisbon: dispersed, mono-centric; Rome: dispersed, polycentric; and Athens: compact, mono-centric). Perimeter metrics assumed different values for each investigated land-use type, with peculiar characteristics associated to each city. Land-use types assessing residential, discontinuous urban patches were associated to particularly high values of perimeter metrics, possibly indicating patch fragmentation, spatially-associated distribution of land-use types and landscape complexity. Multivariate analysis indicates substantial differences among cities, reflecting the range of morphological configurations described above (from compact mono-centric to dispersed polycentric) and suggesting that urban expansion is accompanied with multiple modifications in the use of the surrounding non-urban land. The computational approach proposed in this study and based on spatially-explicit metrics of landscape configuration and proximity may reflect latent changes in local socio-spatial structures. Our results demonstrate that scattered urban expansion determines a polarization in suburban areas with highly fragmented and more homogeneous landscapes, respectively, associated with mixed cropland and forest systems. Full article
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Open AccessArticle Building Energy Opportunity with a Supply Chain Based on the Local Fuel-Producing Capacity
Sustainability 2018, 10(7), 2140; https://doi.org/10.3390/su10072140
Received: 20 May 2018 / Revised: 13 June 2018 / Accepted: 21 June 2018 / Published: 22 June 2018
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Abstract
Studying and modeling plants for producing electric power obtained from vegetal wood cellulose biomass can become an opportunity for building a supply chain based on the local fuel-producing capacity. Focusing on energy-producing technologies, such as pyrolysis or gasification, the present work assessed the
[...] Read more.
Studying and modeling plants for producing electric power obtained from vegetal wood cellulose biomass can become an opportunity for building a supply chain based on the local fuel-producing capacity. Focusing on energy-producing technologies, such as pyrolysis or gasification, the present work assessed the amount of vegetal biomass that may be used as fuel, both in terms of actual availability and supply price, in the Province of Rieti (Italy). The aim is to draw up a supply plan that has an intrinsic relationship with the local area. The results confirmed a production of 24 MW of project thermal power and 4 MW of project electric power. The ensuing plant was then studied following current norms about renewable energy, environmental consistency, and atmospheric emissions. An economic analysis of the cost investment was also carried out, where the total return is approximately of 19%. The results exposed that plant costs are acceptable only if short-supply chain fuel is purchased. The costs of generating energy from agroforestry biomass are certainly higher; however, the plant represents a significant territorial opportunity, especially for the economic sectors of agriculture and forestry. The employment effect plays a central role in the concession process, which is relevant for the interaction among renewable energy production and agriculture. The environmental impact of a biomass plant from agroforestry residues can be measured exclusively on atmospheric emissions: the plant must be placed in industrial areas without any landscape or naturalistic value. Full article
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Open AccessArticle Worrying about ‘Vertical Landscapes’: Terraced Olive Groves and Ecosystem Services in Marginal Land in Central Italy
Sustainability 2018, 10(4), 1164; https://doi.org/10.3390/su10041164
Received: 16 March 2018 / Revised: 6 April 2018 / Accepted: 11 April 2018 / Published: 13 April 2018
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Abstract
Terraced Mediterranean areas are distinctive man-made landscapes with historical and cultural relevance. Terraced land abandonment driven by physical and economic constraints had important ecological consequences. This study focuses on a marginal agricultural district in southern Latium, central Italy, where terracing dated back to
[...] Read more.
Terraced Mediterranean areas are distinctive man-made landscapes with historical and cultural relevance. Terraced land abandonment driven by physical and economic constraints had important ecological consequences. This study focuses on a marginal agricultural district in southern Latium, central Italy, where terracing dated back to the Roman period and olive groves are the main agricultural use. A diachronic assessment of land-use transformations was carried out to identify landscape dynamics and drivers of change around terraced land. Terraced landscape systems (TLS), derived from spatial aggregation of neighboring terraced patches, have been analyzed for landscape transformations considering slope as the main stratification variable. Structural and functional characteristics of TLS were analyzed using a landscape ecology approach. Soil bio-chemical indicators were finally assessed to study the impact of terraced olive agro-ecosystems on soil-related ecosystems services. The empirical findings outlined that TLS in central Italy are sensitive to urbanization and land abandonment. Cultivated terraces prevailed up to gentle-medium slope land, uncultivated and wooded areas dominated terraces on steep slopes. In this context, poly-cultural olive groves proved to be a cropping system particularly resilient to global change, irrespective of land slope. Terraced systems and extensive poly-cultural olive groves play a role in preserving ecosystem integrity, landscape quality, soil functionality and, therefore, environmental sustainability. Full article
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Open AccessArticle Rural Districts between Urbanization and Land Abandonment: Undermining Long-Term Changes in Mediterranean Landscapes
Sustainability 2018, 10(4), 1159; https://doi.org/10.3390/su10041159
Received: 20 March 2018 / Revised: 5 April 2018 / Accepted: 11 April 2018 / Published: 12 April 2018
Cited by 1 | PDF Full-text (3572 KB) | HTML Full-text | XML Full-text
Abstract
The present study investigates changes in the rural landscapes of a Mediterranean country (Greece) over a long time period (1970–2015) encompassing economic expansions and recessions. Using a spatial distribution of 5 basic agricultural land-use classes (arable land, garden crop, vineyards, tree crop and
[...] Read more.
The present study investigates changes in the rural landscapes of a Mediterranean country (Greece) over a long time period (1970–2015) encompassing economic expansions and recessions. Using a spatial distribution of 5 basic agricultural land-use classes (arable land, garden crop, vineyards, tree crop and fallow land) derived from official statistics at 6 years (1970, 1979, 1988, 1997, 2006, 2015), a quantitative analysis based on correlation and multivariate techniques was carried out to identify recent changes in the Greek agricultural landscape at prefectural level during different economic waves. Empirical results evidenced both intuitive and counter-intuitive landscape transformations, including: (i) a progressive, spatially-homogeneous reduction of cropland; (ii) a (more or less) rapid decrease in the surface of high-input crops, including arable land, horticulture and vineyards; (iii) a parallel increase in the surface of tree crops, especially olive; (iv) a spatially-heterogeneous decrease of fallow land concentrated in metropolitan and tourism districts, especially in the last decade; and, finally, (v) increasingly diversified landscapes in rural, accessible areas close to the sea coast. Based on a correlation analysis with background socioeconomic indicators, our findings reflect the multiple impacts of urbanization and land abandonment on the composition and diversity of rural landscapes. Changes in agricultural land-use were moulded by multiple drivers depending on latent transformations in rural systems and inherent conflicts with expanding urban regions. Together with market conditions and the Common Agricultural Policy subsidy regime, social contexts and the economic cycle are important when identifying long-term changes in agricultural landscapes, especially in transitional socio-ecological systems. Full article
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Open AccessArticle Solar Radiation Distribution inside a Greenhouse Prototypal with Photovoltaic Mobile Plant and Effects on Flower Growth
Sustainability 2018, 10(3), 855; https://doi.org/10.3390/su10030855
Received: 13 February 2018 / Revised: 7 March 2018 / Accepted: 14 March 2018 / Published: 18 March 2018
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Abstract
The diffusion of renewable energy requires the search for new technologies useful for obtaining good energy and production efficiency. Even if the latter is not always easy to obtain, the integration of photovoltaic panels on the roof of greenhouses intended for floriculture can
[...] Read more.
The diffusion of renewable energy requires the search for new technologies useful for obtaining good energy and production efficiency. Even if the latter is not always easy to obtain, the integration of photovoltaic panels on the roof of greenhouses intended for floriculture can represent an alternative. The present paper evaluates climatic conditions inside a greenhouse, in which 20% of its roof surface has been replaced with mobile photovoltaic (PV) panels. The PV system implemented in this study can vary the light energy collection surface in relation to the degree of insolation. The aim is to observe the shading effects of the PV system on the growth of several varieties of flowers (iberis, mini-cyclamens and petunias) to ensure the use of solar energy as an income integration deriving from floricultural production. In fact, in agronomic terms, it has ensured: (i) to be able to shade the underlying environment in most lighting conditions; and (ii) to let through more light when it is required for the needs of crop plants or in cloudy weather. Results have described the distribution of solar radiation, variability of temperature and humidity and lighting in a solar year and the observed outcomes on floristic production. Full article
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Open AccessArticle Photovoltaic and Hydrogen Plant Integrated with a Gas Heat Pump for Greenhouse Heating: A Mathematical Study
Sustainability 2018, 10(2), 378; https://doi.org/10.3390/su10020378
Received: 11 January 2018 / Revised: 28 January 2018 / Accepted: 30 January 2018 / Published: 1 February 2018
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Abstract
Nowadays, the traditional energy sources used for greenhouse heating are fossil fuels such as LPG, diesel and natural gas. The global energy demand will continue to grow and alternative technologies need to be developed in order to improve the sustainability of crop production
[...] Read more.
Nowadays, the traditional energy sources used for greenhouse heating are fossil fuels such as LPG, diesel and natural gas. The global energy demand will continue to grow and alternative technologies need to be developed in order to improve the sustainability of crop production in protected environments. Innovative solutions are represented by renewable energy plants such as photovoltaic, wind and geothermal integrated systems, however, these technologies need to be connected to the power grid in order to store the energy produced. On agricultural land, power grids are not widespread and stand-alone renewable energy systems should be investigated especially for greenhouse applications. The aim of this research is to analyze, by means of a mathematical model, the energy efficiency of a photovoltaic (8.2 kW), hydrogen (2.5 kW) and ground source gas heat pump (2.2 kW) integrated in a stand-alone system used for heating an experimental greenhouse tunnel (48 m2) during the winter season. A yearlong energy performance analysis was conducted for three different types of greenhouse cover materials, a single layer polyethylene film, an air inflated-double layer polyethylene film, and a double acrylic or polycarbonate. The results of one year showed that the integrated system had a total energy efficiency of 14.6%. Starting from the electric energy supplied by the photovoltaic array, the total efficiency of the hydrogen and ground source gas heat pump system was 112% if the coefficient of the performance of the heat pump is equal to 5. The heating system increased the greenhouse air temperatures by 3–9 °C with respect to the external air temperatures, depending on the greenhouse cover material used. Full article
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Open AccessArticle Rethinking Sustainability within the Viticulture Realities Integrating Economy, Landscape and Energy
Sustainability 2018, 10(2), 320; https://doi.org/10.3390/su10020320
Received: 18 December 2017 / Revised: 22 January 2018 / Accepted: 23 January 2018 / Published: 26 January 2018
Cited by 5 | PDF Full-text (3693 KB) | HTML Full-text | XML Full-text
Abstract
Sustainability is often explained through three dimensions (society, economy and environment). However, such a definition currently appears to be restricted. Sustainable development often includes the energy issue. An example of realities founded on bioenergy are agro-energy districts. These realities involve all the three
[...] Read more.
Sustainability is often explained through three dimensions (society, economy and environment). However, such a definition currently appears to be restricted. Sustainable development often includes the energy issue. An example of realities founded on bioenergy are agro-energy districts. These realities involve all the three dimensions of sustainability, integrating also the energy dimension and fueling a potential circular economy. Based on these premises, the most affluent rural subdivision in Italy is that of wine. The wine sector has experienced a recent growth of its economic market, diverging from other agricultural activities and enlarging its cultivated surface areas. In this sense, the local landscape has also changed. Owing to the strong inclination of the wine sector in adopting sustainable strategies and measures, agro-energy districts can be the following future phase in viticulture realities as a cutting-edge business in the modern agricultural sector, implementing new strategies and opportunities. Full article
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Open AccessArticle Thermal and Fluid Dynamic Analysis within a Batch Micro-Reactor for Biodiesel Production from Waste Vegetable Oil
Sustainability 2017, 9(12), 2308; https://doi.org/10.3390/su9122308
Received: 24 October 2017 / Revised: 27 November 2017 / Accepted: 6 December 2017 / Published: 12 December 2017
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Abstract
Biofuels represent an alternative solution to petroleum-based fuels. In particular, biodiesel is very interesting, especially if it is produced from waste vegetable oil. Biodiesel can be used in diesel engines. The aim of this work is to implement a 2D numerical analysis in
[...] Read more.
Biofuels represent an alternative solution to petroleum-based fuels. In particular, biodiesel is very interesting, especially if it is produced from waste vegetable oil. Biodiesel can be used in diesel engines. The aim of this work is to implement a 2D numerical analysis in Comsol Multiphysics in order to verify an uniform temperature field within a non-isothermal batch mixed micro-reactor. An immersion heater system has been studied as a suitable solution to increase the temperature of WVO (Waste Vegetable Oil) before the start of the transesterification reaction. Thus, the efficiency of the immersion heating system has been investigated. The results show that the temperature field is not uniform within the fluid domain, because of the convective flux with the external environment. These conditions could lead to a low overall conversion rate. Full article
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Review

Jump to: Research

Open AccessReview Monitoring and Optimization of the Process of Drying Fruits and Vegetables Using Computer Vision: A Review
Sustainability 2017, 9(11), 2009; https://doi.org/10.3390/su9112009
Received: 27 September 2017 / Revised: 18 October 2017 / Accepted: 28 October 2017 / Published: 2 November 2017
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Abstract
An overview is given regarding the most recent use of non-destructive techniques during drying used to monitor quality changes in fruits and vegetables. Quality changes were commonly investigated in order to improve the sensory properties (i.e., appearance, texture, flavor and aroma), nutritive values,
[...] Read more.
An overview is given regarding the most recent use of non-destructive techniques during drying used to monitor quality changes in fruits and vegetables. Quality changes were commonly investigated in order to improve the sensory properties (i.e., appearance, texture, flavor and aroma), nutritive values, chemical constituents and mechanical properties of drying products. The application of single-point spectroscopy coupled with drying was discussed by virtue of its potentiality to improve the overall efficiency of the process. With a similar purpose, the implementation of a machine vision (MV) system used to inspect foods during drying was investigated; MV, indeed, can easily monitor physical changes (e.g., color, size, texture and shape) in fruits and vegetables during the drying process. Hyperspectral imaging spectroscopy is a sophisticated technology since it is able to combine the advantages of spectroscopy and machine vision. As a consequence, its application to drying of fruits and vegetables was reviewed. Finally, attention was focused on the implementation of sensors in an on-line process based on the technologies mentioned above. This is a necessary step in order to turn the conventional dryer into a smart dryer, which is a more sustainable way to produce high quality dried fruits and vegetables. Full article
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