Special Issue "Biochar-Bioenergy Production Systems"

A special issue of Processes (ISSN 2227-9717). This special issue belongs to the section "Environmental and Green Processes".

Deadline for manuscript submissions: closed (30 November 2021) | Viewed by 4549

Special Issue Editor

Dr. Ali Mohammadi
E-Mail Website
Guest Editor
Department of Engineering and Chemical Sciences, Karlstad University, 651 88 Karlstad, Sweden
Interests: biochar; agricultural waste management; sustainable cropping systems; soil toxicity and environmental impact; carbon cycling
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The effects of biochar on soil vary widely depending on soil type and biochar properties. Moreover, the characteristics of biochar when used as an additive in the processes of anaerobic digestion and composting considerably affect the outcomes. In order for biochar technology to benefit the environment and society, it is critical to understand the key production factors that affect the physicochemical properties of biochars. Biochar characteristics depend on the feedstock source, production conditions, and post-production treatments. Therefore, to maximize agronomic and soil benefits and improve bio-based processes whose functions can be affected by biochar application, carbonization should be engineered to address specific constraints in each target application. However, variation in responses to biochar and performance of biochar technologies such as pyrolysis and hydrothermal carbonization (HTC) can lead to uncertain environmental and economic results of biochar amendment. Therefore, it is imperative to analyze biochar implementation from techno-economic and life cycle perspectives to judge whether biochar would be an effective strategy to reduce the environmental impacts of energy production while increasing economic productivity.

This Special Issue "Biochar–Bioenergy Production Systems" aims to fill the gaps in the scientific literature concerning this crucial area as much as possible, to highlight its importance, and to provide a platform for the dissemination of state-of-the-art advances in this field. Topics include, but are not limited to:

  • Engineering biochar–bioenergy processes to raise benefits in high-value production systems;
  • Development of material flow analysis models to evaluate energy and resource recovery from using organic waste in biochar systems;
  • Properties of biochar from novel sources and different production conditions;
  • Synergetic/antagonistic effects of biochar as an additive in bio-processes;
  • Novel trends and developments in biochar technologies
  • Development of life cycle assessment models to quantify the sustainability (environmental, exergetic, economic, and social) benefits that the adoption of the biochar could deliver;
  • Designing sustainable biochar supply chains

Dr. Ali Mohammadi
Guest Editor

Manuscript Submission Information

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Keywords

  • Biochar
  • Bioenergy
  • Pyrolysis
  • HTC
  • Biochar pellet
  • Sustainability
  • Physicochemical properties
  • Resource recovery
  • Bioprocesses

Published Papers (4 papers)

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Research

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Article
Temperature-Programmed Reduction of NiO/Al2O3 by Biochar In Situ Generated from Citric Acid
Processes 2022, 10(8), 1542; https://doi.org/10.3390/pr10081542 - 05 Aug 2022
Viewed by 256
Abstract
The reduction of metal oxides by biochar is an important reaction for many biomass utilization technologies. This work investigated the temperature–programmed reduction (TPR) of NiO/Al2O3 by in situ generated biochar from citric acid pyrolysis. Firstly, NiO/Al2O3 was [...] Read more.
The reduction of metal oxides by biochar is an important reaction for many biomass utilization technologies. This work investigated the temperature–programmed reduction (TPR) of NiO/Al2O3 by in situ generated biochar from citric acid pyrolysis. Firstly, NiO/Al2O3 was loaded with citric acid by impregnation and then heated from ambient temperature to 900 °C in a N2 flow. The process was on–line analyzed by the TGA–FTIR technique. Secondly, a series of intermediates was obtained and characterized by XRD, CHNO elemental analysis, and temperature programmed oxidation (TPO). Lastly, a control experiment of unsupported NiO was conducted to show the influence of Al2O3 support on the NiO reduction. Results showed that the whole heating process could be resolved into two parts that is citric acid pyrolysis and NiO reduction at a heating rate of 5 °C/min. The NiO reduction occurred above 400 °C with the biochar from citric acid pyrolysis as reductant. In the temperature–programmed reduction process, the Al2O3–supported NiO exhibited three reduction phases in contrast with only one reduction phase for the unsupported NiO. A hypothesis was proposed to explain this. The presence of Al2O3 support may result in different deposition sites of biochar (on NiO or on Al2O3), and consequently different reduction mechanisms. Full article
(This article belongs to the Special Issue Biochar-Bioenergy Production Systems)
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Article
Sensitivity Analysis of the Climate Effect of Using Pyrochar Biofuel for Heat and Electricity Generation
Processes 2021, 9(10), 1744; https://doi.org/10.3390/pr9101744 - 29 Sep 2021
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Abstract
This study aims to quantify the climate change impact of pyrochar production from pulp and paper mill sludge and the subsequent utilisation in combined heat and power (CHP) plants for co-generation of heat and electricity using the environmental life cycle assessment (E-LCA) method. [...] Read more.
This study aims to quantify the climate change impact of pyrochar production from pulp and paper mill sludge and the subsequent utilisation in combined heat and power (CHP) plants for co-generation of heat and electricity using the environmental life cycle assessment (E-LCA) method. In the Pyrochar Scenario, in which the sludge is pyrolyzed into pyrochar, the authors have assumed that pyrochar would replace coal. In the Reference Scenario, sludge is incinerated with a subsequent low rate of energy recovery. A comprehensive sensitivity analysis was performed to determine the conditions in which the sludge pyrochar would offer the greatest climate-effect benefits. The parameters selected for the said analysis are the form of pyrochar (pellet or powder), fuels replaced by it in the CHP plant (solid waste and peat vis-à-vis coal), and the utilisation of the pyrochar fuel in another European country (Germany and Spain vis-à-vis Sweden). The results of this E-LCA clearly show that using pyrochar as a biofuel in CHP plants delivered a considerable reduction in greenhouse gas (GHG) emissions (−1.87 tonne CO2-eq per 2.8 tonne dry sludge). Contribution analysis reveals that the process accounting for the biggest share of the reduction is the pyrochar combustion (a negative contribution of 76%), which results in a displacement of coal-based fuels. The authors conclude that the utilisation of pyrochar in firing units would provide the highest reduction in GHG emissions, while recommending a comprehensive economic analysis in addition to climate effect assessment, before making a decision regarding the introduction of sludge pyrochar to the energy sector. Full article
(This article belongs to the Special Issue Biochar-Bioenergy Production Systems)
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Review

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Review
Overview of the Benefits and Challenges Associated with Pelletizing Biochar
Processes 2021, 9(9), 1591; https://doi.org/10.3390/pr9091591 - 05 Sep 2021
Cited by 6 | Viewed by 1116
Abstract
Biochar can be derived from a wide variety of organic materials including agricultural wastes and residues, animal wastes, municipal solid wastes, pulp and paper mill wastes, and sewage sludge. Its productivity relies on feedstock type and thermochemical conditions of production. Biochar has many [...] Read more.
Biochar can be derived from a wide variety of organic materials including agricultural wastes and residues, animal wastes, municipal solid wastes, pulp and paper mill wastes, and sewage sludge. Its productivity relies on feedstock type and thermochemical conditions of production. Biochar has many application advantages in several fields and has been widely studied in recent years. However, most of these studies are mainly on the powder form of biochar, while its pelleted form is sparsely reported. Even with the reported studies on biochar pellets, there is still lack of knowledge and awareness of the effects of different feedstock on the densification behavior of biochar. The mechanisms of biochar densification, which appear to be sensitive to the conditions predominating during its thermochemical production, are affected by the material from which the biochar is derived. This partly accounts for why biochar pellets have not been widely adopted in various application fields. Therefore, this paper presents an overview of the benefits associated with the use of biochar pellets and discusses the challenges encountered when pelleting biochars that are derived from different feedstock under various carbonization conditions. Research priority areas needed to overcome the challenges are also identified and discussed. The purpose is to contribute to better understanding on biochar pelletization behavior, and to offer insights useful to comprehend some basic principles that may occur in the pelleting process and to ease further and more thorough investigations. Full article
(This article belongs to the Special Issue Biochar-Bioenergy Production Systems)
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Review
A Critical Review on Advancement and Challenges of Biochar Application in Paddy Fields: Environmental and Life Cycle Cost Analysis
Processes 2020, 8(10), 1275; https://doi.org/10.3390/pr8101275 - 12 Oct 2020
Cited by 16 | Viewed by 1909
Abstract
Paddy fields emit considerable amounts of methane (CH4), which is a potent greenhouse gas (GHG) and, thereby, causes significant environmental impacts, even as they generate wealth and jobs directly in the agricultural sector, and indirectly in the food-processing sector. Application of [...] Read more.
Paddy fields emit considerable amounts of methane (CH4), which is a potent greenhouse gas (GHG) and, thereby, causes significant environmental impacts, even as they generate wealth and jobs directly in the agricultural sector, and indirectly in the food-processing sector. Application of biochar in rice production systems will not just help to truncate their carbon footprints, but also add to the bottom-line. In this work, the authors have reviewed the literature on climate change, human health, and economic impacts of using organic residues to make biochar for the addition to croplands especially to rice paddy fields. Biochar-bioenergy systems range in scale from small household cook-stoves to large industrial pyrolysis plants. Biochar can be purveyed in different forms—raw, mineral-enriched, or blended with compost. The review of published environmental life cycle assessment (E-LCA) studies showed biochar has the potential to mitigate the carbon footprint of farming systems through a range of mechanisms. The most important factors are the stabilization of the carbon in the biochar and the generation of recoverable energy from pyrolysis gases produced as co-products with biochar as well as decreased fertiliser requirement and enhanced crop productivity. The quantitative review of E-LCA studies concluded that the carbon footprint of rice produced in biochar-treated soil was estimated to range from −1.43 to 2.79 kg CO2-eq per kg rice grain, implying a significant reduction relative to rice produced without a biochar soil amendment. The suppression of soil-methane emission due to the biochar addition is the dominant process with a negative contribution of 40–70% in the climate change mitigation of rice production. The review of the life cycle cost studies on biochar use as an additive in farmlands demonstrated that biochar application can be an economically-feasible approach in some conditions. Strategies like the subsidization of the initial biochar capital cost and assignment of a non-trivial price for carbon abatement in future pricing mechanisms will enhance the economic benefits for the rice farmers. Full article
(This article belongs to the Special Issue Biochar-Bioenergy Production Systems)
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