Energetic Sustainability Research Articles

Energetic and Environmental Sustainability of the food agriculture system

Il sistema agricolo-alimentare nazionale nella sua accezione piu ampia di agricoltura e industria alimentare, ha assunto nell’ultimo decennio, una configurazione fortemente sistemica, che gli ha consentito di raggiungere posizioni ragguardevoli, se consideriamo che complessivamente risulta caratterizzato da volumi economici di circa 270 miliardi di Euro. Significativi sono anche i valori occupazionali che, secondo indagini recenti, fanno registrare oltre 900.000 occupati nel settore agricoltura e circa 500.000 posti di lavoro nell’industria alimentare. Questo lavoro e focalizzato principalmente sulle conseguenze che, nell’ultimo ventennio hanno prodotto la globalizzazione dei mercati e le trasformazioni commerciali sul sistema agricolo-alimentare nazionale, con particolare attenzione alle interazioni del mondo agricolo con l’industria alimentare a livello della produzione, della trasformazione e della commercializzazione dei beni alimentari. Sono brevemente analizzate le iniziative e le strategie messe in atto dalle aziende agricole, dalle imprese, dalle associazioni e dagli stessi consumatori per contrastare gli eccessi degli impatti della globalizzazione nei confronti della sostenibilita energetica ed ambientale del mercato dei prodotti agroalimentari. A questo riguardo si riportano i dati di mercato e di diffusione delle cosiddette Reti Alternative Alimentari e si discutono le implicazioni socio-culturali ed economiche di questi nuovi modelli di produzione e consumo anche ai fini dello sviluppo economico sostenibile della societa. Vengono riportati, inoltre, i risultati dei Progetti Tesla e SCOoPE che l’ENEA ha sviluppato per sostenere la tematica dell’efficienza energetica come strumento prioritario per l’introduzione di innovazione per ammodernamento tecnologico delle imprese sia per diminuire gli elevati consumi di energia finale, attualmente stimati in circa 15 Mtep, sia per sostenere lo sviluppo socio-economico sostenibile del sistema agricolo-alimentare del nostro Paese.

Macrophytes as a Digestion Substrate. Assessment of a Sonication Pretreatment

Biomethane potential (BMP) test was performed to access the anaerobic degradation of three macrophytes (Eichhornia crassipes, Pistia stratiotes and Salvinia molesta). Sonication pretreatment was evaluated in order to pre-hydrolyze the plants, aiming to remove the lag time and potentially increase the methane production. Two sonication energies were tested: 40,000 and 80,000 kJ kgTS− 1. Results indicated that not all the aquatic plants presented the same behavior. Raw biomass of Eichhornia and Pistia required a long lag-phase (11 and 8 days, respectively), while Salvinia did not, being the faster and most productive raw biomass (64% of biomethanization factor). Pretreated biomass was solubilized, however the results did not have a direct translation to the digestion performance. In fact, no substantial improvement on the amount of methane production occurred. The main experimental evidence was the full reduction of the lag-phase for Eichhornia and Pistia, while Salvinia did not exhibited a substantial change neither in methane production or in kinetics. The high biodegradability of Salvinia biomass without pretreatment indicated that ultrasound pretreatment is not required. Energetic Sustainability Index evidenced that sonication pretreatment process was not sustainable, due to the required high water content of the bulk.

Automatic Parametrization and Shadow Analysis of Roofs in Urban Areas from ALS Point Clouds with Solar Energy Purposes

A basic feature of modern and smart cities is their energetic sustainability, using clean and renewable energies and, therefore, reducing the carbon emissions, especially in large cities. Solar energy is one of the most important renewable energy sources, being more significant in sunny climate areas such as the South of Europe. However, the installation of solar panels should be carried out carefully, being necessary to collect information about building roofs, regarding its surface and orientation. This paper proposes a methodology aiming to automatically parametrize building roofs employing point cloud data from an Aerial Laser Scanner (ALS) source. This parametrization consists of extracting not only the area and orientation of the roofs in an urban environment, but also of studying the shading of the roofs, given a date and time of the day. This methodology has been validated using 3D point cloud data of the city of Santiago de Compostela (Spain), achieving roof area measurement errors in the range of ±3%, showing that even low-density ALS data can be useful in order to carry out further analysis with energetic perspective.

Hybrid Building as Social and Energy Hub for Smart Cities: Unitè 2.0, a Prototype

The purpose of the master degree project «Living in the time of crisis: Unite d’habitation 2.0» designed by Eleonora Barsanti and tutored by Luca Lanini and Sergio Russo Ermolli aims to offer a possible definition for a new housing model based on concepts like affordability and social living, but above all of flexibility, adaptability, versatility, energetic sustainability and/or production: a prototype that can be placed in any context and adapted to meet specific needs as being a node in a smart city grid. In our opinion, this process would allow us to accomplish diversity within the same building, attaining a kind of chameleon like organism which is flexible, adaptable, versatile and an active energy hub.

Modeling oxygen requirements in ischemic cardiomyocytes

Heart disease remains the leading cause of death globally. Although reperfusion following myocardial ischemia can prevent death by restoring nutrient flow, ischemia/reperfusion injury can cause significant heart damage. The mechanisms that drive ischemia/reperfusion injury are not well understood; currently, few methods can predict the state of the cardiac muscle cell and its metabolic conditions during ischemia. Here, we explored the energetic sustainability of cardiomyocytes, using a model for cellular metabolism to predict the levels of ATP following hypoxia. We modeled glycolytic metabolism with a system of coupled ordinary differential equations describing the individual metabolic reactions within the cardiomyocyte over time. Reduced oxygen levels and ATP consumption rates were simulated to characterize metabolite responses to ischemia. By tracking biochemical species within the cell, our model enables prediction of the cell's condition up to the moment of reperfusion. The simulations revealed a distinct transition between energetically sustainable and unsustainable ATP concentrations for various energetic demands. Our model illustrates how even low oxygen concentrations allow the cell to perform essential functions. We found that the oxygen level required for a sustainable level of ATP increases roughly linearly with the ATP consumption rate. An extracellular O2 concentration of ∼0.007 mm could supply basic energy needs in non-beating cardiomyocytes, suggesting that increased collateral circulation may provide an important source of oxygen to sustain the cardiomyocyte during extended ischemia. Our model provides a time-dependent framework for studying various intervention strategies to change the outcome of reperfusion.

Energetic Sustainability and the Environment: A Transdisciplinary, Economic–Ecological Approach

The paper combines original concepts about eco-energetic systems, in a transdisciplinary sustainable context. Firstly, it introduces the concept of M.E.N. (Mega-Eco-Nega-Watt), the eco-energetic paradigm based on three different but complementary ecological economic spaces: the Megawatt as needed energy, the Ecowatt as ecological energy, and the Negawatt as preserved energy. The paper also deals with the renewable energies and technologies in the context of electrical energy production. Secondly, in the context of the M.E.N. eco-energetic paradigm, comprehensive definitions are given about eco-energetic systems and for pollution. Thirdly, the paper introduces a new formula for the eco-energetic efficiency which correlates the energetic efficiency of the system and the necessary newly defined ecological coefficient. The proposed formula for eco-energetic efficiency enables an interesting form of relating to different situations in which the input energy, output energy, lost energy, and externalities involved in an energetic process, interact to produce energy in a specific energetic system, in connection with the circular resilient economy model. Finally, the paper presents an original energetic diagram to explain different channels to produce electricity in a resilience regime, with high eco-energetic efficiency from primary external energetic sources (gravitation and solar sources), fuels (classical and radioactive), internal energetic sources (geothermal, volcanoes) and other kind of sources. Regardless the kind of energetic sources used to obtain electricity, the entire process should be sustainable in what concerns the transdisciplinary integration of the different representative spheres as energy, socio-economy, and ecology (environment).

Investigation and optimization of performance of nano-scale Stirling refrigerator using working fluid as Maxwell–Boltzmann gases

The motivation behind this work is to explore a nanoscale irreversible Stirling refrigerator with respect to size impacts and shows two novel thermo-ecological criteria. Two distinct strategies were suggested in the optimization process and the consequences of every strategy were examined independently. In the primary strategy, with the purpose of maximizing the energetic sustainability index and modified the ecological coefficient of performance (MECOP) and minimizing the dimensionless Ecological function, a multi-objective optimization algorithm (MOEA) was used. In the second strategy, with the purpose of maximizing the ECOP and MECOP and minimizing the dimensionless Ecological function, a MOEA was used. To conclude the final solution from each strategy, three proficient decision makers were utilized. Additionally, to quantify the deviation of the results gained from each decision makers, two different statistical error indexes were employed. Finally, based on the comparison between the results achieved from proposed scenarios reveals that by maximizing the MECOP the maximum values of ESI, ECOP, and a minimum of ecfare achieved.

Energetic Sustainability Using Renewable Energies in the Mediterranean Sea

The paper is focused on the analysis of the electrical energy sector in the Maltese islands, focusing on the employment of Renewable Energies in order to increase its energy independence. The main renewable source here proposed is wave energy: thanks to its strategic position, Malta will be able to generate electrical energy through the use of an innovative type of Wave Energy Converter (WEC) based on the prototype of linear generator designed and developed by the University of Palermo. This new technology will be able to cut down the electrical energy production from traditional power plants and, consequently, the greenhouse gas emissions (GHG). Wave energy source and off-shore photovoltaic (PV) technology are proposed here. Particularly, the installation of 18 wave farms, for a total installed capacity of 130 MW, will generate about 5.7% of Malta’s energy requests in 2025, while the installation of 60 MW of off-shore PV will generate about 4.4%.

Finding Resilient and Energy-saving Control Strategies in Smart Homes

Evolutionary computing has demonstrated its effectiveness in supporting the development of robust and intelligent systems: when used in combination with formal and quantitative models, it becomes a primary tool in critical systems. Among the modern critical infrastructures, smart energy grids are getting a growing interest from many communities (academic, industrial and political) fostering the development of a robust energy distribution infrastructure. Energy grids are also an example of critical cyber physical social systems since their equilibrium can be perturbed not only by cyber and physical attacks but also by economical and social crises as well as changes in the consumption profiles. The paper illustrates a practical framework supporting the run-time evolution of the control logic inside the Smart Meter: the centre of modern Smart Homes. By combining the modeling and analysis capabilities of Fluid Stochastic Petri Nets and the flexibility of Genetic Programming, this approach can be used to adapt the control logic of the Smart Meters to the changes of the structure and functionalities of the Smart Home as well as of the operational environment. While the main objective of the evolution is to guarantee the energetic sustainability of the Smart Home, the fulfilment of the user's requirements about the energetic need of the home allows to preserve the identity of the Smart Meter during its evolution.

Performance and energy aspects of single and two phase thermophilic anaerobic digestion of waste activated sludge

The study reported in this paper considered the results of pilot-scale experiments on single and 2-phase anaerobic digestion of waste activated sludge at high rate. Both single and 2-phase digesters were conducted at the same conditions of organic loading and retention time. The 2-phase anaerobic system showed clear increases in terms of organic matter removal and biogas production compared to the single stage system. Particularly, the volatile solids removal rose from 34% in the single stage system to 38% in the 2-phase system. Hence, the global specific biogas production increased 32%, moving from 0.21 to 0.31 m3/kgTVS·d respectively for the single and 2-phase systems. The 2-phase system produced 15% more energy than the single stage system. Furthermore, the heat produced in a CHP unit satisfied all heat requirements insuring more than the complete energetic sustainability of the process. Finally, both single and 2-phase digestates showed to meet requirements established for sludge reuse in agriculture regarding pathogens, metals and organic contaminants. A preliminary economic analysis showed the possibility to pay back the investment for the implementation of a second anaerobic reactor in 3 years because of both the increased biogas production and reduced quantity of excess sludge to be disposed of.

Energetic sustainability of three arabica coffee growing systems used by family farming units in Espírito Santo state

Three growing systems of Arabica coffee were evaluated under the energy perspective, in the state of Espírito Santo in Brazil. The systems are conventional cultivation (CC), cultivation with good agricultural practices (CGP) and organic farming (OF). It was made a comparison of the energy flows within these three systems to show sustainable levels of each one based on production average data of several family-farming units. Therefore, we analyzed crop yield, total energy efficiency reverse (TEER), energy efficiency of ripe coffee (EERC) and non-renewable energy efficiency (NREE). OF system had values for TEER, EERC and NREE of 3.3 4.7 and 7.9 respectively. Yet CC showed values of 1.8, 1.9 and 1.6 for TEER, EERC and NREE respectively. Furthermore, CGP presented values for TEER, EERC and NREE of 0.7, 1.3 and 1.4 respectively. The highest yield was observed in CGP, reaching an amount of 1794 kg ha-1(17,455 MJ); however, this system expends more energy than it converts. Thus, over those points, OF is the most sustainable system.

Direct Energy Balance of Anaerobic Digestion (ad) Toward Sustainability

Currently, the biogas production from organic waste (OW) refuses through AD has been and continues to be one of the most widely used processes for energy production. Usually, AD is carried out in thermophilic (TC) or mesophilic conditions (MC); some authors claim that it is far better to work in TC than MC, others explain that there are no major differences, while some others affirm that the MC has highest performance. Even if each in of single case, the statement is true, it is necessary nowadays to have a valid and objective criterion in order to compare different studies and mainly to assess the energetic sustainability of AD. To this purpose, in this paper, an Energy Sustainability Index (ESI) parameter is candidate. The ESI is the ratio between the energy obtained under form of H2 and/or CH4, and that spent as direct energy to heat the fermenting broth at the working temperature and when present, the energy spent as heat in the broth pretreatment. In Author's opinion this fact is the first check toward sustainability of AD technology as mean to produce energy. Only in the case of ESI > 1, it is possible to consider others energy spent to produce the energy, in fact, for ESI 1. The ESI here proposed represents the first step of a more detailed energy sustainability evaluation procedure, performed using a LCA (life cycle assessment) approach

Applying the concept of "energy return on investment" to desert greening of the Sahara/Sahel using a global climate model

Abstract. Altering the large-scale dynamics of the Earth system through continual and deliberate human intervention now seems possible. In doing so, one should question the energetic sustainability of such interventions. Here, from the basis that a region might be unnaturally vegetated by employing technological means, we apply the metric of "energy return on investment" (EROI) to benchmark the energetic sustainability of such a scenario. We do this by applying EROI to a series of global climate model simulations where the entire Sahara/Sahel region is irrigated with increased rates of desalinated water to produce biomass. The energy content of this biomass is greater than the energy input rate for a minimum irrigation rate of about 200 mm yr−1 in the winter and 500 mm yr−1 in the summer, thereby yielding an EROI ratio >1 : 1, expressing energetic sustainability. Quantified annually, the EROI was >1 : 1 for irrigation rates more than 500 mm yr−1, progressively increasing to a maximum of 1.8 : 1 with 900 mm yr−1, and then decreasing with further increases in the irrigation rate. Including the precipitation feedback arising from changes in moisture recycling within the study region approximately doubles these EROI ratios. This overall result varies spatially and temporally, so while the entire Sahara/Sahel region is irrigated equally, the western coastal region from June to August had the highest EROI. Other factors would complicate such a large-scale modification of the Earth system, but this sensitivity study concludes that with a required energy input, desert greening may be energetically sustainable. More specifically, we have shown how this type of EROI analysis could be applied as a metric to assess a diverse range of human alterations to, and interventions within, the Earth system.

Producción de biodiesel y bioetanol: ¿una alternativa sustentable a la crisis energética?

La presente contribución pretende dar una visión general de la situación energética actual y sugerir algunas alternativas sustentables de energía. En primer lugar, se muestra una breve historia sobre las materias primas utilizadas para la producción de energía a través del tiempo, teniendo una alta dependencia de combustibles fósiles, ya que ha sido estimado que más del 90% de la energía consumida proviene de recursos no renovables como el petróleo, gas y carbón. También se menciona que el petróleo es sin duda la principal fuente de energía utilizada en la actualidad y por ende sus reservas se agotan inevitablemente. Además de ocasionar y aumentar los problemas de contaminación ambiental. Posteriormente, se sugiere que para lograr la sustentabilidad energética es necesario el desarrollo de fuentes alternativas que puedan reducir la emisión de gases de efecto invernadero (GEI) que son tóxicos, así como también disminución en el uso de agua y disminución en los costos de producción de energía. Una de las alternativas que se proponen es la producción de biocombustibles como son: biodiesel y bioetanol, se citan principales características de ellos a nivel de materias primas utilizadas y sistemas de producción. Finalmente, se sugieren algunas soluciones que están siendo desarrolladas a nivel mundial para hacer frente a esta actual situación energética.

Virtual Sense: A Java-Based Open Platform for Ultra-Low-Power Wireless Sensor Nodes

Idleness has to be carefully exploited in wireless sensor networks (WSNs) to save power and to accumulate the energy possibly harvested from the environment. State-of-the-art microcontroller units provide a wide range of ultra-low-power inactive modes with sub-millisecond wakeup time that can be effectively used for this purpose. At the same time they are equipped with 16-bit RISC architectures clocked at tens of MHz, which make them powerful enough to run a Java-compatible virtual machine (VM). This makes it possible to bring the benefits of a virtual runtime environment into power-constrained embedded systems. VMs, however, risk to impair the effectiveness of dynamic power management as they are seen as always-active processes by the scheduler of the operating system in spite of the idleness of the threads running on top of them. Avoiding to keep sensor nodes busy when they could be idle is mandatory for the energetic sustainability of WSNs. While most of the tasks of a sensor node are inherently event-driven, the functioning of its hardware-software components is not, so that they require to be redesigned in order to exploit idleness. This paper presents VirtualSense, an open-hardware open-source ultra-low-power reactive wireless sensor module featuring a Java-compatible VM.

Analisi multitemporale dei flussi energetici nel paesaggio di Castagneto Carducci (LI) fra il XIX e XX secolo

Abstract: Using the energy flow account and the input/output analysis is possible to assess the “energetic sustainability” of landscape, in order to define policies as well as planning and management tools of the rural territory. The study area is the municipality of Castagneto Carducci, located on the Tuscan coastline, in the Leghorn district. The area, 14.000 hectares wide, is characterized by wooded hills in the inner part, a narrow dunal band along the coastline with mixed pine woods, and a flat area in the middle where all the major infrastructures and agricultural activities are located. The economy is based on tourism and on high quality wine production. The energy balance is not only referred to the present situation, but we have carried out the balances for the years 1832 and 1954, in order to assess the energy use evolution through the last 180 years, according to a multitemporal methodology develop for monitoring the dynamics of Tuscan landscape The energy balances examine all the energy flows result from the various activities in agriculture, forestry and animal husbandry. The study area must be considered as a close system, and we have to value the energy flows between the inside and the outside of this system, and how this energy is used inside of it. The three periods show different landscapes, due to the different socio-economic situation. In 1832 we find a traditional agricultural structure, based on large estate and on mezzadria management; in 1954 the mezzadria gives way to the diffusion of industrial agriculture and animal husbandry, while olive orchards became one of the main elements of the landscape. From the ’70s we attend at the proliferation of vineyards, and in few years Castagneto will become the area where some of the best Italian wines are produced (Sassicaia, Ornellaia). The wooded areas have undergone a dramatic change in their spatial location, specific composition, density and structure, but the extension remains the same, and it is approximately the half of the total communal area. In the 19th century the system was completely self-reliant about the production and the use of energy, but, with the intensification of agriculture after the Second World War, the local system consume more energy then it is produced, because of the energy imports coming from outside. Using a lot of energy brings to high productivity, but also to a less energetic efficiency compared to the 19th century and to a degradation of the landscape. The wooded areas can have an important role in mitigating the energy inefficiency, although only few of these are periodically managed; wooded areas and agricultural areas are not managed together, but they seems to be two different worlds, there is a lack of integrated approach.

Sustainability of a wind power plant: Application to different Moroccan sites

In this paper, three main steps allowing the definition of the sustainability of a wind power plant (WPP) are described in detail. The first step is to choose a site with a good wind potential. In this respect, two approaches have been introduced: traditional wind statistical estimations based on the identification of the Weibull probability density function on specific sites; and an innovative Kriging approach based on artificial neural networks to reconstruct the profile of the mean wind speed of the territory. In the second step, given technical details, the energetic sustainability of a WPP installation is assessed according to a model computing the wind energy production per year, as well as the details of its efficiency. Finally, as third step, a cost/benefit evaluation on the overall reduction in CO2 emissions with respect to traditional fossil fuel energy plants is reported. From a wind speed characterisation viewpoint, the case study is referred to the overall Moroccan territory. From a WPP model viewpoint, the case study is referred to the installation of a specific WPP, which would allow the production of more than 2 GWh per year in the south Atlantic coast and of nearly 1 GWh per year in the Mediterranean coast in the neighbourhood of Tangier.

Theoretical model and experimental analysis of a high pressure PEM water electrolyser for hydrogen production

This work aims at analysing the performances of a prototype of a high pressure Polymer Electrolyte Membrane water electrolyser. The whole work was funded in the framework of the Italian FISR (Research special supplementary funding) project. The high pressure electrolyser prototype was manufactured by Giner Inc. (Massachusetts, USA), whereas the test bench was expressly designed and built thanks to the collaboration with LAQ INTESE (High Quality Laboratory – Technological Innovation for Energetic Sustainability) and with Sapio SpA (Monza, Milan, Italy). An electrochemical model of the electrolyser stack is developed, which calculates the theoretical open-circuit voltage via a thermodynamic analysis of the process, and then obtains the expected real voltage during operation by calculating the different overvoltages as function of the current. The final result of the model is a theoretical polarisation curve. Experimental results are then presented and compared with the model theoretical results, and thanks to an experimental data fitting it is possible to obtain the estimated values of some important process parameters and their trend in different temperature and pressure conditions.

The local industrial complex? Questioning the link between local foods and energy use

Local food has become the rising star of the sustainable agriculture movement, in part because of the energy efficiencies thought to be gained when food travels shorter distances. In this essay I critique four key assumptions that underlie this connection between local foods and energy. I then describe two competing conclusions implied by the critique. On the one hand, local food systems may need a more extensive and integrated transportation infrastructure to achieve sustainability. On the other hand, the production, transportation, and consumption of local foods are fundamentally as reliant on fossil fuels as are long distance foods. A more holistic approach to energy use in the food system is needed to determine which particular sociotechnical factors optimize energetic sustainability.

Home Garden Production and Energetic Sustainability in Calakmul, Campeche, Mexico

Energy flows were studied for the 2002–2003 agricultural cycle in four households for which agriculture is part of a diversified survival strategy and four that practice agriculture as a business. Home garden inputs and outputs were measured monthly. Quantified inputs were: household labour, household agro-system production, and purchased external renewable and non-renewable energy. Outputs measured were: sales, family and animal foods. While both strategies had similar indicators in biomass and energy production, vegetable richness, and soil quality, household garden function and sustainability differed between subsistence and commercial householders. Subsistence gardens complemented family diet and contributed to household system resiliency. They relied heavily on renewable energy sources from within their agro-system. Gardens in commercial households reduced fruit tree area and increased animal husbandry for the market. They depended more on purchased non-renewable energy sources and were less sustainable and much less energy efficient than traditional gardens.