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This study evaluates the environmental impacts associated with the conversion of garden organic waste into value-added products, namely compost or biochar, employing various processes. Three distinct scenarios are considered: composting garden organic waste followed by screening of oversized materials (CBP), pyrolysis of oversized screenings of compost into biochar AP(I), and in-situ conversion of garden organics into biochar AP(II). A comprehensive Life Cycle Assessment (LCA) was conducted using OpenLCA software and life cycle impact assessment was conducted using Recipe 2016 midpoint methodology. The environmental ramifications of each scenario were assessed, optimising transport distances in AP(II) to achieve a functional unit of one tonne of biochar produced within a cradle-to-gate system boundary. For the first time, this study offers a holistic exploration of the benefits of soil biochar application, extending its scope to climate change mitigation, incorporating the optimisation of transport distance and its influence when scaling up the technology. The results revealed that global warming was increased from 125 kgCO 2 eq during composting of garden waste to 232 kgCO 2 eq where oversized screenings of compost is converted to biochar at an off-site facility. However, direct conversion of the oversized organic waste to biochar, without composting, showed reduced global warming impact of 56 kgCO 2 eq, and is thus the most favourable scenario to limit climate impacts of this fraction of organic garden waste. However, among 18 environmental impact indicators studied, eight indicators were either not influenced or did not significantly increase by transport distance to an off-site pyrolysis facility, while the magnitude of 10 impact indicators increased with transport distance. The insights and methodologies presented in this study hold global relevance, based on an actual case study in regional Australia, offering valuable recommendations for sustainable waste management practices and establishing biochar as a carbon-neutral or carbon-negative solution. The findings contribute to existing waste management knowledge and provide guidance for accessible carbon dioxide removal and soil carbon sequestration technologies. [Display omitted] • A comprehensive LCA for valorisation of garden organics was conducted. • Direct conversion of garden organics to biochar showed least potential environmental impacts. • Biochar provides opportunities for avoided, reduced, and removed carbon from atmosphere. • Maximum transport distance has been identified for individual impact categories. [ABSTRACT FROM AUTHOR]

Rapid climate change mitigation requires carbon sequestration in addition to greenhouse gas emission reductions. Agriculture may have a high potential for carbon sequestration due to improved practices. However, it is not known how the global warming impacts of crop production could be mitigated especially within an agricultural system. The aim of this study is to evaluate possibilities to neutralize global warming impacts in crop production using biochar produced from side flows and buffer zone biomass. A life cycle assessment methodology is utilized in this research for oat production in the boreal climate zone. Global warming impact reductions are compared for three different side flow utilization options. Traditionally, side flows have been utilized in energy or fodder production, and these options are compared to biochar production at a system level. The potential to use buffer zone biomass for biochar production is also studied. Willow has been selected as a biomass source in buffer zones. Oat production leads to greenhouse gas emissions especially due to the use of fossil and mineral fertilizers in cultivation and heat energy, electricity and fuels in various process phases. The production of one metric ton of oat flakes from cradle to gate generates 700 kg of CO 2 eq emissions. Biochar and energy production from side flows enables a greater reduction in global warming impacts than the feed use of side flows. Buffer zones in willow biomass and biochar production may enable the full neutralization of the global warming potential of oat production within an agricultural system. Further research with actual measurements is required especially on biochar impacts on soil emissions such as N 2 O. This research shows that it could be possible to neutralize global warming impacts from crop production using available technologies and available biomass in agricultural systems. A framework is created for carbon neutral crop production using side flows and buffer zone biomass through biochar. • Global warming potential of oat production is studied using LCA methodology. • Oat flakes production generates emissions of 700 kgCO 2eq t−1. • Side flow use for biochar production leads to the lowest overall GWP impacts. • Buffer zone biomass use for biochar production could mitigate the GWP impacts of oat production. [ABSTRACT FROM AUTHOR]

Besides being an opportunity to valorize biomass residues, biochar (i.e., the solid product of biomass pyrolysis) has many potential environmental benefits, such as climate change mitigation and reduced nutrient leaching. Even though the academic interest in biochar has increased, it is not being used at a large scale yet, mainly because of its economic infeasibility compared to fertilizers and because farmers are either unaware of or skeptical about its effects. In this paper, the economics of biochar are examined by performing a systematic review, following the guidelines of the Collaboration for Environmental Evidence. Specifically, it has been examined to which extent the production and application of biochar are yet profitable from an investor's perspective and desirable from a societal perspective. For the first time, this review investigates the extent to which previous studies have included external costs and benefits. We find that profitability and desirability of biochar production and use are highly uncertain and case-specific, depending on factors like location, feedstock, scale, pyrolysis conditions, biochar price, cultivated crop, and the potential internalization of externalities, which hampers private investment. To advance biochar development and deployment, those factors must be considered carefully for each case. Although externalities are included in the literature to some extent, the focus is mostly on external benefits rather than external costs, often focusing on its carbon sequestration potential. The inclusion of externalities in economic assessments is necessary to provide solid arguments to develop policies for the acceleration of market uptake of biochar technology. [ABSTRACT FROM AUTHOR]

The biochar is a solid carbon-rich, porous material produced by the thermochemical conversion of a diverse range of biomass feedstocks under an inert atmosphere (i.e., in the absence of oxygen). We can produce the biochar at all likely scales, ranging from the industrial to the domestic level and even at individual farms, thus, the biochar industry is leading as a most appropriate at different socioeconomic settings. The possibility of sustainable biochar production practices and multi-functionality features make it a promising candidate to fulfill an increasing demand in the fields of soil amendment, agricultural sustainability, environmental protection, cutting-edge materials, and to achieve circular bioeconomy and mitigation of climate change. An available fraction of waste biomass (agroforestry waste, biomass crops, agricultural residues, mill residues, and animal manure, and many more) can be used efficiently in pyrolysis and converted into desired biochar materials, besides this alternative energy products, such as syngas, bio-oil, electricity generation, and process heat. This report emphasizes the fate of biomass composition, pyrolysis mechanisms, and applications of modern analytical and characterization techniques that are being adopted, applied, and standardized to improve understandings of molecular, structural, and surface properties characteristics of biochar. To achieve precisely designed biochar, there is a need to understand the latest advances in biochar materialization mechanisms and structure-application relationships to speed up their agronomic applications and to achieve a zero-waste dream. This report also summarizes a wide range of literature published on feedstocks, pyrolysis, and biochar and suggests several practical recommendations appropriate to implement and bring together specific details on the thermochemical conversion of biomass, desired biochar properties, organic and inorganic phases, and the significance to the agronomic applications. A schematic illustration of sustainable biochar production, application, and impact on global climate. [Display omitted] • Sustainability is motivating aspect in management of biomass feedstocks supply chain. • Report examines relationships of biomass feedstock composition and pyrolysis products. • Physicochemical properties of biochar influences structure-application relationships. • Current challenges covered to achieve viable biochar production and desired biochar. [ABSTRACT FROM AUTHOR]