Research

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12 pages, 1062 KiB

Open AccessArticle

Chemical Characterization of Microcystis aeruginosa for Feed and Energy Uses

by Larissa Souza Passos, Éryka Costa Almeida, Claudio Martin Pereira de Pereira, Alessandro Alberto Casazza, Attilio Converti and Ernani Pinto

Energies 2021, 14(11), 3013; https://doi.org/10.3390/en14113013 - 23 May 2021

Cited by 6 | Viewed by 2238

Abstract

Cyanobacterial blooms and strains absorb carbon dioxide, drawing attention to its use as feed for animals and renewable energy sources. However, cyanobacteria can produce toxins and have a low heating value. Herein, we studied a cyanobacterial strain harvested during a bloom event and [...] Read more.

Cyanobacterial blooms and strains absorb carbon dioxide, drawing attention to its use as feed for animals and renewable energy sources. However, cyanobacteria can produce toxins and have a low heating value. Herein, we studied a cyanobacterial strain harvested during a bloom event and analyzed it to use as animal feed and a source of energy supply. The thermal properties and the contents of total nitrogen, protein, carbohydrate, fatty acids, lipid, and the presence of cyanotoxins were investigated in the Microcystis aeruginosa LTPNA 01 strain and in a bloom material. Microcystins (hepatotoxins) were not detected in this strain nor in the bloom material by liquid chromatography coupled to mass spectrometry. Thermogravimetric analysis showed that degradation reactions (devolatilization) initiated at around 180 °C, dropping from approximately 90% to 20% of the samples’ mass. Our work showed that despite presenting a low heating value, both biomass and non-toxic M. aeruginosa LTPNA 01 could be used as energy sources either by burning or producing biofuels. Both can be considered a protein and carbohydrate source similar to some microalgae species as well as biomass fuel. It could also be used as additive for animal feed; however, its safety and potential adverse health effects should be further investigated. Full article

(This article belongs to the Special Issue Valorisation of Wastes: Environmental Sustainability and Production of Biofuels by Advanced Technologies)

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14 pages, 7127 KiB

Open AccessArticle

Co-Incineration of Rice Straw-Wood Pellets: A Sustainable Strategy for the Valorisation of Rice Waste

by Cristina Moliner, Dario Bove and Elisabetta Arato

Energies 2020, 13(21), 5750; https://doi.org/10.3390/en13215750 - 03 Nov 2020

Cited by 12 | Viewed by 2341

Abstract

Agricultural activities produce an estimated amount of 32.7 MToe/year of residues in EU countries. They are mostly disposed in landfills, incinerated without any control, or abandoned in fields, causing severe impacts on human health and environment. Rice is one of the most consumed [...] Read more.

Agricultural activities produce an estimated amount of 32.7 MToe/year of residues in EU countries. They are mostly disposed in landfills, incinerated without any control, or abandoned in fields, causing severe impacts on human health and environment. Rice is one of the most consumed crops worldwide with an annual production of 782 million tons according to the Food and Agriculture Organization of the United Nations database. In this context, the EU-funded project LIFE LIBERNITRATE promotes the use of renewable residual sources (i.e., rice straw) to obtain new materials with an added value. The methodology is based on the incineration of rice straw in an own-designed and constructed valorization system. Rice straw/wood pellets are burned in optimized conditions to produce a maximized quantity of ashes with high silica content. These materials will be then used to treat water polluted with nitrates, representing an optimal example of circular economy strategy. In this work, the own-designed valorization unit is described, with special focus on its main constituting elements. The theoretical study of the co-incineration of rice straw and wood pellets identified the optimised combustion conditions. Experimental tests using the theoretical inputs confirmed the most adequate operational conditions (10 g rice straw pellets/min + 10 g wood pellets/min, 6–7 Nm³/h of air, T = 500 °C) and helped in the definition of improvements on the experimental plant. Full article

(This article belongs to the Special Issue Valorisation of Wastes: Environmental Sustainability and Production of Biofuels by Advanced Technologies)

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17 pages, 3081 KiB

Open AccessArticle

Thermocatalytic Pyrolysis of Exhausted Arthrospira platensis Biomass after Protein or Lipid Recovery

by Elena Spennati, Alessandro Alberto Casazza, Attilio Converti and Guido Busca

Energies 2020, 13(20), 5246; https://doi.org/10.3390/en13205246 - 09 Oct 2020

Cited by 7 | Viewed by 1680

Abstract

Microalgae and cyanobacteria are unicellular microorganism that contain high-added-value compounds. To make their extraction economically feasible, the biorefinery concept is the only solution. In this study, the residues resulting from lipid or protein extraction from Arthrospira platensis biomass were valorized by catalytic pyrolysis [...] Read more.

Microalgae and cyanobacteria are unicellular microorganism that contain high-added-value compounds. To make their extraction economically feasible, the biorefinery concept is the only solution. In this study, the residues resulting from lipid or protein extraction from Arthrospira platensis biomass were valorized by catalytic pyrolysis using ZSM5 zeolite or amorphous silica–alumina as catalyst. The reaction was performed in a quartz reactor, and the catalysts were placed in a fixed bed, to force the reaction gases to pass through it. The reaction products were analyzed by FTIR and GC–MS analyses. The reaction gases and liquids obtained from the extraction residues had higher hydrocarbon contents compared with the untreated biomass. Moreover, the pyrolysis of biomass after protein extraction led to fractions with lower nitrogenated component contents, while that after lipid extraction to fractions with lower oxygenated component contents. This study showed that the pyrolysis process could be used to valorize the microalgae extraction residues, aiming to make biofuels production and extraction of high-added-value products more economically feasible. Full article

(This article belongs to the Special Issue Valorisation of Wastes: Environmental Sustainability and Production of Biofuels by Advanced Technologies)

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35 pages, 4057 KiB

Open AccessArticle

Selection of Temporal Lags for Predicting Riverflow Series from Hydroelectric Plants Using Variable Selection Methods

by Hugo Siqueira, Mariana Macedo, Yara de Souza Tadano, Thiago Antonini Alves, Sergio L. Stevan, Jr., Domingos S. Oliveira, Jr., Manoel H.N. Marinho, Paulo S.G. de Mattos Neto, João F. L. de Oliveira, Ivette Luna, Marcos de Almeida Leone Filho, Leonie Asfora Sarubbo and Attilio Converti

Energies 2020, 13(16), 4236; https://doi.org/10.3390/en13164236 - 16 Aug 2020

Cited by 27 | Viewed by 2380

Abstract

The forecasting of monthly seasonal streamflow time series is an important issue for countries where hydroelectric plants contribute significantly to electric power generation. The main step in the planning of the electric sector’s operation is to predict such series to anticipate behaviors and [...] Read more.

The forecasting of monthly seasonal streamflow time series is an important issue for countries where hydroelectric plants contribute significantly to electric power generation. The main step in the planning of the electric sector’s operation is to predict such series to anticipate behaviors and issues. In general, several proposals of the literature focus just on the determination of the best forecasting models. However, the correct selection of input variables is an essential step for the forecasting accuracy, which in a univariate model is given by the lags of the time series to forecast. This task can be solved by variable selection methods since the performance of the predictors is directly related to this stage. In the present study, we investigate the performances of linear and non-linear filters, wrappers, and bio-inspired metaheuristics, totaling ten approaches. The addressed predictors are the extreme learning machine neural networks, representing the non-linear approaches, and the autoregressive linear models, from the Box and Jenkins methodology. The computational results regarding five series from hydroelectric plants indicate that the wrapper methodology is adequate for the non-linear method, and the linear approaches are better adjusted using filters. Full article

(This article belongs to the Special Issue Valorisation of Wastes: Environmental Sustainability and Production of Biofuels by Advanced Technologies)

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19 pages, 3356 KiB

Open AccessFeature PaperArticle

Heterogeneous Catalysis in (Bio)Ethanol Conversion to Chemicals and Fuels: Thermodynamics, Catalysis, Reaction Paths, Mechanisms and Product Selectivities

by Gabriella Garbarino, Giovanni Pampararo, Thanh Khoa Phung, Paola Riani and Guido Busca

Energies 2020, 13(14), 3587; https://doi.org/10.3390/en13143587 - 11 Jul 2020

Cited by 19 | Viewed by 4590

Abstract

In gas/solid conditions, different chemicals, such as diethylether, ethylene, butadiene, higher hydrocarbons, acetaldehyde, acetone and hydrogen, can be produced from ethanol with heterogeneous catalytic processes. The focus of this paper is the interplay of different reaction paths, which depend on thermodynamic factors as [...] Read more.

In gas/solid conditions, different chemicals, such as diethylether, ethylene, butadiene, higher hydrocarbons, acetaldehyde, acetone and hydrogen, can be produced from ethanol with heterogeneous catalytic processes. The focus of this paper is the interplay of different reaction paths, which depend on thermodynamic factors as well as on kinetic factors, thus mainly from catalyst functionalities and reaction temperatures. Strategies for selectivity improvements in heterogeneously catalyzed processes converting (bio)ethanol into renewable chemicals and biofuels are also considered. Full article

(This article belongs to the Special Issue Valorisation of Wastes: Environmental Sustainability and Production of Biofuels by Advanced Technologies)

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13 pages, 1535 KiB

Open AccessArticle

Study of the Antioxidant Power of the Waste Oil from Palm Oil Bleaching Clay

by Katiane Cunha de Melo, Ingrid Silva de Oliveira, Luiza Helena de Oliveira Pires, Luís Adriano Santos do Nascimento, José Roberto Zamian, Geraldo Narciso da Rocha Filho, Marcele Fonseca Passos, Alessandra Santos Lopes, Attilio Converti and Carlos Emmerson Ferreira da Costa

Energies 2020, 13(4), 804; https://doi.org/10.3390/en13040804 - 12 Feb 2020

Cited by 3 | Viewed by 2920

Abstract

Palm oil is one of the most consumed oils, one of whose refining steps is the removal of pigments and other substances using bleaching clay as adsorbent. Worldwide production of this oil was 70 million tons in 2017, requiring 1 t of clay [...] Read more.

Palm oil is one of the most consumed oils, one of whose refining steps is the removal of pigments and other substances using bleaching clay as adsorbent. Worldwide production of this oil was 70 million tons in 2017, requiring 1 t of clay to produce 1000 t of refined oil. The residual bleaching clay, having an oil fraction (12.70%) rich in phenolics, carotenoids and tocopherols, was extracted in this study with ethanol to obtain an antioxidant-rich palm oil bleaching extract (POBE), with the aim of using it as a natural antioxidant source. The POBE antioxidant capacity determined by the DPPH method corresponded to a 20.29% inhibition of radical formation. The POBE was also tested for its potential to enhance oxidative stability of passion fruit, pracaxi and Brazil nut oils used as reference oils, and compared to common synthetic antioxidants (tert-butylhydroquinone and propyl gallate), either separately as controls or in mixtures with them. Besides the increased oxidative stability of these oils induced by the POBE, a positive synergistic effect between it and the synthetic antioxidants was observed. These results taken together suggest that the exploitation of the waste oil from bleaching clay as an additive to improve the oxidative stability of biofuels or lubricating oils is feasible. Full article

(This article belongs to the Special Issue Valorisation of Wastes: Environmental Sustainability and Production of Biofuels by Advanced Technologies)

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Review

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20 pages, 2536 KiB

Open AccessReview

Small-Scale Biodiesel Production Plants—An Overview

by Maria Gabriela De Paola, Ivan Mazza, Rosy Paletta, Catia Giovanna Lopresto and Vincenza Calabrò

Energies 2021, 14(7), 1901; https://doi.org/10.3390/en14071901 - 30 Mar 2021

Cited by 16 | Viewed by 6261

Abstract

Small-scale plants that produce biodiesel have many social, economic and environmental advantages. Indeed, small plants significantly contribute to renewable energy production and rural development. Communities can use/reuse local raw materials and manage independently processes to obtain biofuels by essential, simple, flexible and cheap [...] Read more.

Small-scale plants that produce biodiesel have many social, economic and environmental advantages. Indeed, small plants significantly contribute to renewable energy production and rural development. Communities can use/reuse local raw materials and manage independently processes to obtain biofuels by essential, simple, flexible and cheap tools for self-supply. The review and understanding of recent plants of small biodiesel production is essential to identify limitations and critical units for improvement of the current process. Biodiesel production consists of four main stages, that are pre-treatment of oils, reaction, separation of products and biodiesel purification. Among lots of possibilities, waste cooking oils were chosen as cheap and green sources to produce biodiesel by base-catalyzed transesterification in a batch reactor. In this paper an overview on small-scale production plants is presented with the aim to put in evidence process, materials, control systems, energy consumption and economic parameters useful for the project and design of such scale of plants. Final considerations related to the use of biodiesel such as renewable energy storage (RES) in small communities are discussed too. Full article

(This article belongs to the Special Issue Valorisation of Wastes: Environmental Sustainability and Production of Biofuels by Advanced Technologies)

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22 pages, 2124 KiB

Open AccessReview

Prospects for the Improvement of Bioethanol and Biohydrogen Production from Mixed Starch-Based Agricultural Wastes

by Gabriel S. Aruwajoye, Alaika Kassim, Akshay K. Saha and Evariste B. Gueguim Kana

Energies 2020, 13(24), 6609; https://doi.org/10.3390/en13246609 - 15 Dec 2020

Cited by 12 | Viewed by 2999

Abstract

The need for fossil fuel alternatives keeps increasing. Bioethanol and biohydrogen have emerged as significant renewable options. However, these bioprocess routes have presented various challenges, which constantly impede commercialization. Most of these bottlenecks are hinged on feedstock logistics, low biofuel yield and enormous [...] Read more.

The need for fossil fuel alternatives keeps increasing. Bioethanol and biohydrogen have emerged as significant renewable options. However, these bioprocess routes have presented various challenges, which constantly impede commercialization. Most of these bottlenecks are hinged on feedstock logistics, low biofuel yield and enormous process costs. Meanwhile, a large output of renewable energy can be generated from mixed starch-based agricultural wastes due to their intrinsic bioenergy characteristics. This study, therefore, focuses on the production of bioethanol and biohydrogen from mixed starch-based agricultural wastes. The content further highlights the current challenges of their individual processes and elucidates the prospects for improvement, through an integrated biofuel approach. The use of mixed starch-based agricultural wastes as substrates for integrated bioethanol and biohydrogen production was proposed. Furthermore, the use of mixture-based experimental design for the determination of optimal values of critical factors influencing biofuel production emerges as a viable prospect for profitable bioethanol production from the starch-based biomass. Additionally, biohydrogen production from effluents of the mixed starch-based waste bioethanol looked promising. Thus, the study proposed valuable insights towards achieving a cost-effective biofuel technology. Full article

(This article belongs to the Special Issue Valorisation of Wastes: Environmental Sustainability and Production of Biofuels by Advanced Technologies)

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