Preliminary Investigation of Possible Biochar Use as Carbon Source in Polyacrylonitrile Electrospun Fiber Production

Electrospinning with consequent thermal treatment consists in a carbon fiber production method that spins a polymer solution to create fibers with diameters around a few hundred nanome-ters. The thermal treatments are used for the cyclization and then carbonization of the material at 1700◦C for one hour. The unique structure of micro-and nano-carbon fibers makes them a promis-ing material for various applications ranging from future battery designs to filtration. This work investigated the possibility of using milled gasification biochar, derived from a 20 kW fixed-bed gasifier fueled with vine pruning pellets, as an addictive in the preparation of electrospinning solu-tions. This study outlined that solvent cleaning and the consequent wet-milling and 32 µm sifting are fundamental passages for biochar preparation. Four different polyacrylonitrile-biochar shares were tested ranging from pure polymer to 50–50% solutions. The resulting fibers were analyzed via scanning electron microscopy, and energy-dispersive X-ray and infrared spectroscopy. Results from the morphological analysis showed that biochar grains dispersed themselves well among the fiber mat in all the proposed shares. All the tested solutions, once carbonized, exceeded 97%wt. of carbon content. At higher carbonization temperatures, the inorganic compounds naturally showing in biochar such as potassium and calcium disappeared, resulting in an almost carbon-pure fiber matrix with biochar grains in between. © 2022 by the authors. Licensee MDPI, Basel, Switzerland

Spent Coffee Grounds in the Production of Lightweight Clay Ceramic Aggregates in View of Urban and Agricultural Sustainable Development

This paper presents an innovative application for spent coffee grounds (SCGs) used as filler for the formulation of lightweight clay ceramic aggregates (LWA). LWA can be used for urban and agricultural purposes as a sustainable solution. Spent coffee grounds were tested as a pore forming agent partially acting as a replacement for red clay in material formulation before firing. Substitutions of 10, 15, and 20 wt.% of red clay were tested. The properties of lightweight aggregates with 15 wt.% of SCGs were improved using a specifically tailored fertilizer glass due to its low pH and conductivity within the soil tolerance range. Packaging glassy sand, cattle-bone flour ash, and potassium carbonate were mixed and melted in order to obtain this glass, which when added to the clayey batch functionalized the aggregates by phosphorus and potassium nutrients. The results (in particular, porosity and bulk density) show that the lightweight aggregates obtained have interesting properties for possible uses both in urban (e.g., green roofs as a drainage layer) and agricultural purposes. Moreover, pH and conductivity are in line with the Italian Standard regarding soil amendment (D.lgs. 75/2010). In addition, several leaching tests were performed in a solution containing 2 vol.% citric acid (C6H8O7) to evaluate the release capacity not only of nutrients (P and K)mbut also to check the presence and release of heavy metals, such as lead (Pb), that may come from the glassy precursor. The results obtained showed that nutrients are effciently released in 21 days (P = 87.73% and K = 25.74% of released percentage) and Pb release is under the standard threshold of 30 ppm

Approaching sustainable development through energy management, the case of Fongo Tongo, Cameroon

This work is aimed at defining a possible solution for sustainable energy development in the Menoua Department, West Cameroon. The purpose of the cooperation between ALA Milano Onlus and the Biomass Energy Efficiency Laboratory of the University of Modena and Reggio Emilia was to analyze the case study in order to propose a solution for energy production capable of meeting the needs of the Cameroonian society while also heading towards a sustainable development. Primary researches suggested that the most viable solution was to integrate the corn food processing with the gasification of the cobs. The thermo-conversion process was modeled with a black-box approach; the results of the model were further compared with the energy required for corn processing, therefore demonstrating the sustainability and virtuosity of the chosen solution. A commercial 20 kW$$_el$$el gasifier was selected for supplying electrical power to three central buildings: the city hall, the Chaufferie and the school. This solution is a security measure assuring continue power supply to these vital buildings. Furthermore, it will bind the relation between the rural and the city areas through the energy exchange process

Combined Effects of LED Lights and chicken manure on Neochloris oleoabundans Growth

In this study a photobioreactor prototype is presented for the culture growth of microalgae model organism Neochloris oleoabundans by using chicken manure waste as feedstock along with the optimum combination of led light wavelengths and light intensity. Particularly interesting results are observed on the strains fed by chicken manure medium under the proper combination of red and blue LED light illumination, the microalgal growth resulted comparable with the strains fed by the costly commercial microalgal growth medium (BG 11 medium). Cell concentration, optical density, growth rate, cell size, total lipid and photosynthetic pigment content have been monitored during a time-course experiment. The data suggest that there are difficulties due to white light diffusion into the dark chicken medium, which leads to a generally lower intensity scattered along all wavelengths; blue or combined red and blue lights resulted in a higher irradiation density, affecting microalgae cell growth

Energy Generation Potential Through Cattle Manure Solid Phase Gasification

A common practice for cattle manure management, especially for farms with a small number of animals, is simply the separation of the manure solid phase from the liquid one and the subsequent spreading on the land. However, this biomass has a chemical composition similar to more valuable ones like woodchips, with the downside of the high ash content. For this reason, gasification of cattle manure solid phase in a small-scale gasifier was explored. Through this solution it is possible to provide both electrical and thermal energy to the farm, constantly throughout both the day and the year as opposed to other renewable sources like solar and wind power. In addition, a byproduct of this process is biochar, whose main application is in agriculture as soil improver and therefore it could be a valuable substitute of a fraction of the manure currently used as fertilizer. The quantity of manure available was assumed considering the typical size of an Italian dairy farm while the efficiency of the CHP system was calculated through an experimental test with a gasifier prototype. The results have been utilized for a basic comparison between the energy available through gasification and through anaerobic digestion

Combined Effects of Dewatering, Composting and Pelleting to Valorize and Delocalize Livestock Manure, Improving Agricultural Sustainability

An agronomic strategy to mitigate climate change impact can be the build-up of soil organic carbon. Among agronomic management approaches, the administration of organic fertilizers like livestock manure represents an eective strategy to increase soil organic carbon. However, livestock manure usually contains a high amount of water, reducing its sustainable delocalization and impacting on greenhouse gas emissions and nutrient leaching. Furthermore, the possible presence of weed seeds and harmful microorganisms could reduce the agronomic value of the manure. To overcome these issues, the combined eects of dewatering, composting and pelleting were investigated on livestock manure to produce sustainable organic fertilizers. Our results showed that composting and pelleting can represent a feasible and sustainable solution to reduce the potential risks related to the presence of weed seeds and harmful bacteria, concentrating nutrients and allowing a sustainable valorization and delocalization of the livestock manure. In addition, the processed manures were assessed as fertilizers in the growing medium (GM), displaying an increase in water retention and nutrient availability and a decrease of GM temperature and weed seed emergences. However, further study is needed to validate, both in open field and greenhouse productions, the eects of the proposed fertilizers in real cropping systems

An experimental analysis of a stand-alone standing-wave thermoacoustic refrigerator

In the last years, the thermoacoustic phenomena had risen the scientific community interest due to its implications in thermodynamics, heat transfer and acoustic matters, that make possible the conversion between sound and heat. This work aimed at exploring the Russell\u2013Weibull refrigerator, analyzing the behavior of the different parts to achieve a good level of thermal separation, together with the capability of working standalone. Special attention was paid to all those parts that need to be designed properly with explanation of the physics that ruled them, such as the sound generator, the woofer box, the stack and the tube insulation. During the second part of the work, the results obtained are discussed, consistently showing that, if some expedients are adopted, this simple refrigerator can achieve a temperature difference of 24 \ub0C. The design choices concerning materials and geometries had great influence on the device behavior

Effects of upgrading systems on energy conversion efficiency of a gasifier - fuel cell - gas turbine power plant

This work focuses on a DG-SOFC-MGT (downdraft gasifier - solid oxide fuel cell - micro gas turbine) power plant for electrical energy production and investigates two possible performance-upgrading systems: polyphenylene oxide (PPO) membrane and zeolite filters. The first is used to produce oxygen-enriched air used in the reactor, while the latter separates the CO2 content from the syngas. In order to prevent power plant shutdowns during the gasifier reactor scheduled maintenance, the system is equipped with a gas storage tank. The generation unit consists of a SOFC-MGT system characterized by higher electrical efficiency when compared to conventional power production technology (IC engines, ORC and EFGT). Poplar wood chips with 10% of total moisture are used as feedstock. Four different combinations with and without PPO and zeolite filtrations are simulated and discussed. One-year energy and power simulation were used as basis for comparison between all the cases analyzed. The modeling of the gasification reactions gives results consistent with literature about oxygen-enriched processes. Results showed that the highest electrical efficiency obtained is 32.81%. This value is reached by the power plant equipped only with PPO membrane filtration. Contrary to the PPO filtering, zeolite filtration does not increase the SOFC-MGT unit performance while it affects the energy balance with high auxiliary electrical consumption. This solution can be considered valuable only for future work coupling a CO2 sequestration system to the power plant

Experimental assessment and modeling of energy conversion effectiveness in a gasification power plant

National and international energy scenarios seem to be rediscovering a new confidence in gasification power plants as a valuable technology for biomass conversion. Their adaptability, in both direct power production and biofuels synthesis, has been manifested into the development of wide varieties of reactor models and sizes. An appropriate modeling of the system, supported by experimental analysis, is necessary to achieve the high level of efficiency of the gasifier and the proper effectiveness of the entire energy plant conversion. This work is aimed at studying a stratified downdraft gasifier coupled to two IC engines with the total nominal power of 250 kWel. The model of the system is based on mass and energy balance; the model outputs are compared here with those coming from the experimental campaign. All the major thermo-chemical parameters are monitored, these include: air and gas flow rate, biomass moisture content, consumption and ultimate analysis, reaction zones temperatures, tars and char production. In this paper, the model outputs have been compared with the data to evaluate the sensitivity of the model. Moreover, the difference between the theoretical data and the experimental data have been exanimate

Aige conference: A kinetic model for a stratified downdraft gasifier

A model for a stratified downdraft gasifier has been developed. It has been adapted from two different models from literature with appropriate modifications and improvements. The new “interacting” model is able to predict the syngas composition, input and output flow rates and the gasifier cold efficiency under different working condition and with different biomass input. It works assuming a constant biomass consumption. The results of the model has been compared to experimental data taken from a downdraft gasifier power plant system with nominal power output of 200 kWel. The plant has been set at 160 kWel in order to avoid system instabilities related to high power runs.A model for a stratified downdraft gasifier has been developed. It has been adapted from two different models from literature with appropriate modifications and improvements. The new "interacting" model is able to predict the syngas composition, input and output flow rates and the gasifier cold efficiency under different working condition and with different biomass input. It works assuming a constant biomass consumption. The results of the model has been compared to experimental data taken from a downdraft gasifier power plant system with nominal power output of 200 kWel. The plant has been set at 160 kWel in order to avoid system instabilities related to high power runs