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39 pages, 1403 KiB

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Research Needs and Pathways to Advance Hydrothermal Carbonization Technology

by Chau Huyen Dang, Giovanna Cappai, Jae-Wook Chung, Changyoon Jeong, Beatrice Kulli, Filippo Marchelli, Kyoung S. Ro and Silvia Román

Agronomy 2024, 14(2), 247; https://doi.org/10.3390/agronomy14020247 - 24 Jan 2024

Cited by 11 | Viewed by 3716

Abstract

Hydrothermal carbonization (HTC) is a proven cost-effective and energy-efficient method for waste management and value-added product recovery. There are, however, several issues that require further improvement or research. Identifying the strengths and weaknesses of HTC in comparison to traditional pyrolysis is crucial for scientists to choose between them or use both (complementary) to achieve specific product properties. Additionally, sharing information on diverse modeling approaches and scales is crucial to enhance the robustness and universality of HTC process models. In addition, the study on the applicability of hydrochars on target applications such as soil amendment is crucial to give back nutrients to soils and face the dependence on finite specific feedstocks in this field. Also, proper management of the process by-products, especially process water, must be addressed to improve the carbon and hydric footprint of the process. Reviewing the suitability of HTC to treat specific challenging wastes, whose strength is not related to their calorific value but to their nutrient composition (i.e., manures), is also an appealing topic for HTC research. This paper aims to tackle the above-mentioned issues through an updated review and discussion of research gaps that require further investigation. Full article

(This article belongs to the Special Issue Innovative Hydrothermal Systems to Valorize Agricultural Residuals for Sustainable Crop Production and Environmental System)

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17 pages, 13328 KiB

Open AccessArticle

Geothermal Heat Pumps for Slurry Cooling and Farm Heating: Impact and Carbon Footprint Reduction in Pig Farms

by Cristina Sáez Blázquez, David Borge-Diez, Ignacio Martín Nieto, Miguel Ángel Maté-González, Arturo Farfán Martín and Diego González-Aguilera

Sustainability 2022, 14(10), 5792; https://doi.org/10.3390/su14105792 - 10 May 2022

Cited by 14 | Viewed by 3211

Abstract

The pig farm sector has been developing rapidly over recent decades, leading to an increase in the production of slurry and associated environmental impacts. Breeding farms require the maintenance of adequate indoor thermal environments, resulting in high energy demands that are frequently met by fossil fuels and electricity. Farm heating systems and the storage of slurry constitute considerable sources of polluting gases. There is thus a need to highlight the advantages that new green heating solutions can offer to reduce the global environmental impact of pig farming. This research presents an overview of alternative pig farm slurry technology, using geothermal heat pumps, which reduces the harmful effects of slurry and improves the energy behavior of farms. The results reflect the environmental benefits of this solution in terms of reducing carbon and hydric footprints. Reducing the temperature of slurry with the geothermal heat pump of the system also reduces the annual amount of greenhouse gases and ammonia emissions, and, via the heat pump, slurry heat is used for installation heating. Annual emissions of CO₂e could be reduced by more than half, and ammonia emissions could also experience a significant reduction if the slurry technology is installed. Additional advantages confirm the positive impact that the expansion of this renewable technology could have on the global pig farm sector. Full article

(This article belongs to the Special Issue Sustainable Use and Techniques of Geothermal Energy)

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26 pages, 2476 KiB

Open AccessArticle

Benefit of Unsaturated Soil Mechanics Approach on the Modeling of Early-Age Behavior of Rammed Earth Building

by Parul Chauhan, Noémie Prime and Olivier Plé

Materials 2022, 15(1), 362; https://doi.org/10.3390/ma15010362 - 4 Jan 2022

Cited by 5 | Viewed by 2238

Abstract

Rammed earth has the potential to reduce the carbon footprint and limit the energy consumption in the building sector due to its sustainable characteristics. Still, its use is not generalized due to a lack of understanding of the material behavior, notably its sensitivity to water. The coupled hydro-mechanical behavior has been recently studied in the framework of unsaturated soil mechanics, using suction as the parameter to represent the hydric state. This dependency of the mechanical behavior on the hydric state leads to uncertainty of the drying period required to progress in the construction process. Notably, the drying period before building the next floor is unknown. To determine the drying period, thermo-hydro-mechanical coupled finite element method simulations were carried out on a single wall by using the unsaturated soil mechanics approach and safety criterion recommendations from the practical guide for rammed earth construction in France. It was determined that it takes significant time for the construction of additional floor both in ‘summer-like’ and ‘winter-like’ environmental conditions, whereas the walls were far away from the ultimate failure state. Thus the drying periods were overestimated. It was concluded that the safety criterion from the practical guide is very conservative and drying periods can be reduced without significantly compromising the safety factor. Full article

(This article belongs to the Special Issue Sustainable Building Materials: Novelties, Characteristics and Applications)

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