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Agroforestry has an indispensable role in food and livelihood security in addition to its capacity to combat the detrimental effects of climate change. However, agroforestry has not been properly promoted and exploited due to lack of precise extent, geographical distribution, and carbon sequestration (CS) assessment. The recent advent of geospatial technologies, as well as free availability of spatial data and software, can provide new insights into agroforestry resources assessment, decision-making, and policy development despite agroforestry's small spatial extent, isolated nature, and higher structural and functional complexity of agroforestry. In this review, the existing application of geospatial technologies together with its constraints and limitations as well as the potential future application for agroforestry has been discussed. The review reveals that the application of optical remote sensing in agroforestry includes spatial extent mapping, production of tree species spectral signature, CS assessment, and suitability mapping. Simultaneously, the recent surge in the use of synthetic aperture radar in conjunction with algorithms based on vegetation photosynthesis and optical data enables a more accurate estimation of gross primary productivity at different scales. However, unmanned aerial vehicles equipped with sensors, such as multispectral, LiDAR, hyperspectral, and thermal, offer a considerably higher potential and accuracy than satellite-based datasets. In the future, the health monitoring of agroforestry systems can be a key concern that may be addressed by utilizing hyperspectral and thermal datasets to analyze plant biochemistry, chlorophyll fluorescence, and water stress. Additionally, current (GEDI, ECOSTRESS) and future space agency missions (BIOMASS, FLEX, NISAR, TRISHNA) have enormous potential to shed fresh light on agroforestry systems. [ABSTRACT FROM AUTHOR]

Polyethyleneimines find many applications in products such as detergents, adhesives, cosmetics, and for processes such as tissue culture, gene therapy, and CO2 capture. The current state‐of‐the‐art technology for the production of the branched polyethyleneimines involves aziridine feedstock which is a highly toxic, volatile and mutagenic chemical and raises significant concern to human health and environment. We report here a novel method for the synthesis of branched polyethyleneimine derivative from ethylene glycol and ethylenediamine which are much safer, environmentally benign, commercially available and potentially renewable feedstock. The polymerisation reaction is catalysed by a complex of an earth‐abundant metal, manganese and liberates H2O as the only by‐product. Our mechanistic studies using a combination of DFT computation and experiment suggest that the reaction proceeds by the formation and subsequent hydrogenation of imine intermediates. [ABSTRACT FROM AUTHOR]

Carbon sequestration is an important aspect of expelling greenhouse gases from the atmosphere and decelerating the rate of global warming. Agroforestry plays an important role in carbon sequestration. Keeping this in mind, the current study was carried out between 2017 and 2021 to assess the effect of integrated nutrient management on biomass production, carbon sequestration, and carbon credit in a mango and turmeric agroforestry system. The study used randomized block design (RBD) with four treatments and five replications. According to the findings of this study, the rate of fertilizer application has a significant impact on the growth of turmeric and mango crops. The physiochemical characteristics of soil show an improvement in soil composition with the application of urea (CO(NH2)2), single super phosphate [Ca(H2PO4)2.2H2O] 226 kg ha−1, MOP [KCl] 309 kg ha−1 100 kg ha−1. The carbon density of the agrihorticulture land use system was six to seven times higher than that of the open agriculture-based land use system. The highest turmeric production (8.98 t ha−1) was reported under the mango-turmeric system rather than turmeric alone (6.36 t ha−1) in the T2-N100kg treatment. Total biomass production (61.2 t ha−1 and 64.6 t ha−1), carbon stock (38.6 t ha−1 and 41.06 t ha−1), carbon sequestration (246.5 t ha−1 and 299.5 t ha−1), and carbon credit (246.57 credits and 299.5 credits) were found to be highest in mango and turmeric-based agroforestry land use system treatments T2-N100 kg and T3-N80 Kg, respectively. The net additional profit from the agrihorticulture land use system was 299.5 carbon credits, which is equivalent to 4,49,250 INR. [ABSTRACT FROM AUTHOR]

The emergence of algal biorefineries has garnered considerable attention to researchers owing to their potential to ensure carbon neutrality via mitigation of atmospheric greenhouse gases. Algae-derived biofuels, characterized by their carbon-neutral nature, stand poised to play a pivotal role in advancing sustainable development initiatives aimed at enhancing environmental and societal well-being. In this context, algae-based wastewater treatment systems are greatly appreciated for their efficacy in nutrient removal and simultaneous bioenergy generation. These systems leverage the growth of algae species on wastewater nutrients—including carbon, nitrogen, and phosphorus—alongside carbon dioxide, thus facilitating a multifaceted approach to pollution remediation. This review seeks to delve into the realization of carbon neutrality through algae-mediated wastewater treatment approaches. Through a comprehensive analysis, this review scrutinizes the trajectory of algae-based wastewater treatment via bibliometric analysis. It subsequently examines the case studies and empirical insights pertaining to algae cultivation, treatment performance analysis, cost and life cycle analyses, and the implementation of optimization methodologies rooted in artificial intelligence and machine learning algorithms for algae-based wastewater treatment systems. By synthesizing these diverse perspectives, this study aims to offer valuable insights for the development of future engineering applications predicated on an in-depth understanding of carbon neutrality within the framework of circular economy paradigms. • Utilization of algae in wastewater treatment helps in acheiving carbon neutrality. • Research trend of algal wastewater treatment is analyzed via bibliometric analysis. • Chlorella vulgaris is the most investigated species in wastewater treatment system. • Binary culture approach has shown significant benefits over conventional systems. • AI and ML integration in algal system has potential benefits in carbon neutrality. [ABSTRACT FROM AUTHOR]

Deep soil carbon (C) plays an important role in the global carbon cycle because it is more recalcitrant and remains in the soil for a longer period. Yet, very few studies have reported the impact of long‐term fertilization on soil organic carbon (SOC) dynamics in deep soil in a rice‐wheat system (RWS). Hence, the objectives of this study were to evaluate the long‐term fertilization impact on carbon sequestration and C pools in RWS in the Indo‐Gangetic Plain (IGP) of India. Application of 90 kg N, 20 kg P and 25 kg K ha−1 through mineral fertilizers (NPK) + green gram incorporation (GR) + 30 kg N ha−1 through farmyard manure (FYM) sequestered more C (25.86 Mg ha−1) in the 0–105 cm soil depth compared with mineral fertilizer alone (1.25 Mg ha−1). The C‐sequestration rate ranged between 0.61 to 1.23 Mg C ha−1 yr−1 under treatments having organic fertilizer and mineral fertilizer, whereas it varied from 0.06 to 0.39 Mg C ha−1 yr−1 in the treatments receiving mineral fertilizer only. Total C and critical C input were 197 Mg kg−1 and 1.94 Mg C ha−1 yr−1, respectively under NPK + GR + FYM treatment. Integrated application of mineral fertilizers and organics in treatments NPK + FYM, NPK + SPM (sulphitation press mud), NPK + GR, NPK + GR + FYM and NPK + CR (crop residue) resulted in higher sustainable yield index of RWS compared to mineral fertilizer alone. We conclude that application of organic material along with mineral fertilizers is essential to mitigate the atmospheric C load through C‐sequestration in deep soils and to attain sustainable RWS productivity in the IGP. [ABSTRACT FROM AUTHOR]

[Display omitted] • The pH-swing cold capture chloralkali process improves energy efficiency threefold over the benchmark process. • Integrating pH-swing cold capture chloralkali in eFuel synthesis moves most of the energy consumption to the electrolyzer. • We attain ∼ 76 % carbon capture efficiency and 79.5 % overall process efficiency. Renewable Fuels of Non-Biological Origin (RFNBOs, a.ka. "eFuels") are drop-in replacements for fossil fuels in the "hard-to-abate" sectors, and utilise existing distribution and storage infrastructure, but suffer from low synthetic efficiency. In particular, the low efficiency and high energy consumption of hydrogen synthesis by freshwater electrolysis remains a problem to be addressed. In the current study, we explore the potential of saltwater electrolysis (chloralkali) for the synthesis of eFuels generally, and specifically eMethanol. The study explores the use of chlorinated water in carbonate-loop pH-swing "cold capture" of carbon dioxide, and the resulting synergetic integration of the chloralkali process in eFuel syntheses. Doing so eliminates the high energy consumption of the calciner and the slaker of the benchmarked carbonate-loop thermal-swing method. It is replaced with a spontaneous chemical process in which chlorine is neutralized in the presence of carbonates. This allows the simultaneous solution of "The Chlorine Problem" of saltwater electrolysis, and a lower overall energy consumption of direct air capture when combined with green hydrogen synthesis. The only limitation on the comparison is that a large amount of carbon dioxide is over-captured when using chloralkali. That is, the ratio of hydrogen generated to carbon dioxide captured is fixed by the stoichiometry of chloralkali and not that of the eFuel. This results in an excess of carbon captured and thus a carbon-negative eFuel. We examine one configuration of secondary revenue and use it to inform the marginal cost of CO 2 capture. In the system proposed by Aeon Blue Technologies (ABT), carbon dioxide is absorbed into caustic according to the standard method. Hydrogen gas is produced in a standard chloralkali electrolyzer, along with caustic for the contactor, and chlorine. Water oxidation by chlorine gives the strong acid, hydrochloric acid, and the weak acid, hypochlorous acid, which react directly with wet carbonate to release CO 2. H 2 and CO 2 react in a methanol reactor to produce eFuel. H 2 is the limiting reagent for eFuel synthesis, giving an excess of cold captured CO 2. Thus, the current study underscores significant advancements in renewable fuel synthesis, particularly eMethanol, and evaluates the carbon capture and energy efficiency of a novel method. The simulation indicates that the marginal energy cost for a tonne of CO 2 is ∼ 184kWh. This gives ∼ 76 % theoretical carbon capture efficiency and an overall process efficiency of 79.5 % (approximately a threefold improvement over the benchmark). The authors are unaware of a comparable method. The overall system yields a tonne of carbon-neutral e-methanol (eMeOH) while capturing an additional 3 tonnes of carbon dioxide, which means the modelled process captures over 300 % more carbon dioxide than is released upon combustion of the eFuel. In summary, this research contributes valuable insights into carbon-negative eFuel production, representing a significant scientific step in sustainable fuel production. [ABSTRACT FROM AUTHOR]

The targets of limiting global warming levels below 2°C or even 1.5°C set by Paris Agreement heavily rely on bioenergy with carbon capture and storage (BECCS), which can remove carbon dioxide in the atmosphere and achieve net zero greenhouse gas (GHG) emission. Biomass and coal co‐firing with CCS is one of BECCS technologies, as well as a pathway to achieve low carbon transformation and upgrading through retrofitting coal power plants. However, few studies have considered co‐firing ratio of biomass to coal based on each specific coal power plant's characteristic information such as location, installed capacity, resources allocation, and logistic transportation. Therefore, there is a need to understand whether it is worth retrofitting any individual coal power plant for the benefit of GHG emission reduction. It is also important to understand which power plant is suitable for retrofit and the associated co‐firing ratio. In order to fulfill this gap, this paper develops a framework to solve these questions, which mainly include three steps. First, biomass resources are assessed at 1 km spatial resolution with the help of the Geography Information Science method. Second, by setting biomass collection points and linear program model, resource allocation and supply chain for each power plants are complete. Third, is by assessing the life‐cycle emission for each power plant. In this study, Hubei Province in China is taken as the research area and study case. The main conclusions are as follows: (a) biomass co‐firing ratio for each CCS coal power plant to achieve carbon neutral is between 40% and 50%; (b) lower co‐firing ratio sometimes may obtain better carbon emission reduction benefits; (c) even the same installed capacity power plants should consider differentiated retrofit strategy according to their own characteristic. Based on the results and analysis above, retrofit suggestions for each power plant are made in the discussion. [ABSTRACT FROM AUTHOR]

Investigating the immobilization of CO2, previous basalt‐water‐CO2 interaction studies revealed the formation of carbonates over a short period, but with the extensive formation of secondary silicates (SS). The mechanisms involved in these processes remain unresolved, so the present study was undertaken to understand secondary mineral formation mechanisms. XRPD and Rietveld refinement data for neo‐formed minerals show a drastic decrease in the Ca‐O bond length, with the calcite structure degenerating after 80 h (hours). However, SEM images and EDS data revealed that a longer interaction time resulted in the formation of chlorite and smectite, adjacent to basalt grains which prevent basalt‐water‐CO2 interaction to form carbonates, thus restricting carbonate formation. As a result of this, the CO2 mineralization rate is initially high (till 80 h), but it later reduces drastically. It is evident that, for such temperature‐controlled transformations, low temperature is conducive to minimizing SS surface coating at the time of mineral carbonation. [ABSTRACT FROM AUTHOR]

Fluctuations in conventional crude oil price globally and initiatives towards the phase-out of coal-based power have initiated a focus on alternative sources of liquid fuels from natural gas and coal. Gas-to-liquid (GTL) and coal-to-liquid (CTL) processes are two liquefaction technologies that could be used. There is a limited work on either the development of scale factors to estimate capital costs or on techno-economic assessments of the plants. This study addresses this gap and focusses on western Canada, which has large deposits of coal and natural gas. The capital costs of the plants' key equipment are estimated through the development of cost scale-up factors. The production cost for 50,000 bbl/day of liquid fuels from GTL and CTL plants is estimated through modelling using a bottom-up approach. The developed scale-up factors for the GTL and CTL plants were found to be 0.70 and 0.65, respectively. For both plants, most of the benefits of economies of scale are achieved at a capacity of 20,000 bbl/day. The production costs of the GTL and CTL processes are 44.61 and 57.65 Canadian cents/liter respectively. With carbon capture and sequestration (CCS), the production cost of fuel from the CTL plant is higher than from the GTL plant. [ABSTRACT FROM AUTHOR]

As per international policy agendas on mitigation of greenhouse gas emission, the impact change in land use on soil organic carbon (SOC) stocks is of major concern. There has been no systematic study carried out to estimate SOC pool in the catchment of hydroelectric reservoirs. An assessment of SOC stock along altitudinal gradient was carried out in the catchment of proposed Kotli Bhel 1A hydroelectric reservoir located in Uttarakhand, India. The SOC stocks were found to be decreasing with altitude, ( i.e. soil under high altitude forests having more SOC and vice versa). The SOC map developed from the normalized difference vegetation index also verified the results and allowed for spatially explicit targeting of potential climate change mitigation efforts through soil carbon sequestration. The results also revealed that the alpine forest soil has a greater potential of C sequestration compared to devdar, oak, and chir species found in the catchment. This information will help policymakers or environmentalists to take preventive measures for afforestation of forest species that can sequester more C. [ABSTRACT FROM AUTHOR]

Agricultural residues (wheat/barley/oat straw) can be used to produce charcoal, which can then be either landfilled off-site or spread on the agricultural field as a means for sequestering carbon. One centralized and five portable charcoal production technologies were explored in this paper. The centralized system produced 747.95 kg-CO 2 eq/tonne-straw and sequestered 0.204 t-C/t-straw. The portable systems sequestered carbon at 0.141–0.217 t-C/t-straw. The net energy ratio (NER) of the portable systems was higher than the centralized one at 10.29–16.26 compared to 6.04. For the centralized system, the carbon sequestration and the cumulative energy demand were most sensitive to the charcoal yield. Converting straw residues into charcoal can reduce GHG emissions by 80% after approximately 8.5 years relative to the baseline of in-field decomposition, showing these systems are effective carbon sequestration methods. [ABSTRACT FROM AUTHOR]

• The soil stoichiometric ratios (C:N:P) were invariant in lower Himalaya. • The studied region has low C:N ratio indicating prospect for N 2 O emission. • Abies species have a higher C sequestration potential and carbon credit. • The findings are helpful to understand nutrient dynamics in forest. Understating of forest functioning is crucial for ensuring the sustainable flow of forest ecosystem services. Climate regulation service of a forest ecosystem can be ensured through emission reduction by increasing carbon sequestration in forests. However, understanding about the functioning of forests for carbon sequestration is constrained due to lack of information on nutrient stocks and stoichiometry of soils of forests of India. Present study focuses to examine the stoichiometry of major nutrients; nitrogen (N), phosphorus (P), carbon (C) of forest soil to understand the dynamics of the forests of Uttarakhand, India. The study also attempted to supplement the information about the soil carbon sequestration potential of important tree species of the forest. Soil samples were collected randomly for the evaluation of physico-chemical characteristics and stoichiometry of forest soil at four altitudinal ranges i.e., <1000, 1000–1500, 1500–2000, and >2000 m a.s.l in the Himalayan region of Uttarakhand, India. The analysis shows that total nitrogen, total phosphorous, and soil organic carbon contents in forest soil were 0.35 ± 0.11%, 0.10 ± 0.04% and 3.36 ± 0.84%, respectively, which increases with altitude. The stoichiometric ratios viz., C:N:P, N:P, C:N, and C:P, and N:P were reported of 51.6:5.4:1, 4.30 ± 2.39, 9.60 ± 1.48, and 41.94 ± 23.35, respectively which were invariant with altitude. The low C:N ratio may be attributed to either increase in the nitrous oxide (N 2 O) emissions with an increase in nitrogen, or low in carbon stock leading to decrease in carbon dioxide (CO 2) and methane (CH 4) emissions. Moreover, the soil C sequestration potential in the forest tree species follow the order of Abies pindrow > Cedrus deodara > Quercus leucotrichophora > Pinus roxburghii. The information of the study would facilitate for broadening the understanding about the soil properties and stoichiometry of forest ecosystem and would provide an aid to forest management besides contributing to the mitigations strategies of the forests. [ABSTRACT FROM AUTHOR]

Heavy carbon industries produce solid side stream materials that contain inorganic chemicals like Ca, Na, or Mg, and other metals such as Fe or Al. These inorganic compounds usually react efficiently with CO 2 to form stable carbonates. Therefore, using these side streams instead of virgin chemicals to capture CO 2 is an appealing approach to reduce CO 2 emissions. Herein, we performed an experimental study of the mineral carbonation potential of three industrial steel slags via aqueous, direct carbonation. To this end, we studied the absorption capacities, reaction yields, and physicochemical characteristics of the carbonated samples. The absorption capacities and the reaction yields were analyzed through experiments carried out in a reactor specifically designed to work without external stirring. As for the physicochemical characterization, we used solid-state Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscope (SEM). Using this reactor, the absorption capacities were between 5.8 and 35.3 g/L and reaction yields were in the range of 81–211 kg CO 2 /ton of slag. The physicochemical characterization of the solid products with solid FTIR, XRD and SEM indicated the presence of CaCO 3. This suggests that there is potential to use the carbonated products in commercial applications. • Mineral aqueous carbonation of three industrial steel slags. • Absorption capacities are between 5.8 and 35.3 g/L. • Reaction yields obtained were in the range of 81–211 kg CO 2 /ton of slag. • In situ analysis showed evidence for the formation of carbonate ions. • The physicochemical characterization showed CaCO 3 in the solid products. [ABSTRACT FROM AUTHOR]

The use of low-carbon hydrogen is being considered to help decarbonize several jurisdictions around the world. There may be opportunities for energy-exporting countries to supply energy-importing countries with a secure source of low-carbon hydrogen. The study objective is to assess the delivered cost of gaseous hydrogen export from Canada (a fossil-resource rich country) to the Asia-Pacific, Europe, and inland destinations in North America. There is a data gap on the feasibility of inter-continental export of hydrogen from an energy-producing jurisdiction to energy-consuming jurisdictions. This study is aimed at addressing this gap and includes an assessment of opportunities across the Pacific Ocean and the Atlantic Ocean, based on fundamental engineering-based models. Techno-economics were used to determine the delivered cost of hydrogen to these destinations. The modelling considers energy, material, and capacity-sizing requirements for a five-stage supply chain comprising hydrogen production with carbon capture and storage, hydrogen pipeline transportation, liquefaction, shipping, and regasification at the destinations. The results show that the delivered cost of hydrogen to inland destinations in North America is between CAD$4.81/kg and CAD$6.03/kg , to the Asia-Pacific from CAD$6.65/kg to CAD$6.99/kg, and at least CAD$8.14/kg for exports to Europe. Delivering hydrogen by blending in existing long-distance natural gas pipelines reduced the delivered cost to inland destinations by 17%. Exporting ammonia to the Asia-Pacific provides cost savings of 28% compared to shipping liquified hydrogen. The developed information may be helpful to policymakers in government and the industry in making informed decisions about international trade of low-carbon hydrogen in both energy-exporting and energy-importing jurisdictions, globally. [Display omitted] • The supply chain cost of H 2 export from Alberta to viable destinations is assessed. • Exporting H 2 to the USA with new long-distance hydrogen pipelines costs 4.81/kg. • Exporting hythane to the USA can reduce H 2 delivered cost to $4.03/kg. • Exporting H 2 to Asia-Pacific and Europe costs $6.65/kg and $8.18/kg, respectively. • Exporting ammonia can reduce the overseas H 2 delivered cost by over 25%. [ABSTRACT FROM AUTHOR]

An algal biorefinery approach is today's need for commercialization of microalgal biodiesel production. In the present study, an indoor photobioreactor with Chlorella minutissima was evaluated to upgrade biogas produced from anaerobic digestion of cow dung. The potential of C. minutissima was assessed in two different growth media viz. BG 11 and wastewater. The significant CO 2 absorption reported by C. minutissima was in the range of 75–85.4% at 1296 μmol m −2 s −1 of light intensity and 0.33 vol per volume per minute (vvm) gas flows. The present study demonstrated that there is an increase in methane content from 63.5 to 86.4% in the effluent biogas. The highest biomass productivity was observed at 1296 μmol m −2  s −1 light intensity with the same gas flow and the productivity of 0.18 gL −1 and 2.2 gL −1 in the BG11 medium and wastewater respectively. Further, we reported that total lipid content based on dry biomass of C. minutissima were 22.4% and 26% in the BG11 medium and wastewater, respectively. The gross calorific value of treated biogas was also higher (8.15 kWh m −3 and 8.63 kWh m −3 ) in both BG11 and wastewater, respectively. [ABSTRACT FROM AUTHOR]

• Agroforestry forms an explicit part of the hill farming systems. • Mostly all the dominant agroforestry systems were prevalent in the study area. • Silvopastoral and agrohortosilviculture have the highest CO 2 mitigation potential. • Along elevation, the highest total carbon stock was recorded in Zone III. The estimation of carbon stock in agroforestry is crucial for curbing the global climate crisis. In this study, biomass production and carbon storage potential of the prevalent agroforestry systems along an altitudinal gradient in the Chamba district of Himachal Pradesh was carried out during 2019–2021. Agroforestry practices were categorized into eight land use systems viz., agrisilviculture, agrihorticulture, agrosilvohorticulture, agrohortisilviculture, hortiagriculture, silvopastoral, pastoralsilviculture and hortipastoral systems and were divided into four altitudinal ranges viz., <1000 m above sea level (m asl; Z-I), 1000–1500 m asl (Z-II), 1500–2500 m asl (Z-III) and > 2500 m asl (Z-IV). Results revealed that biomass production and total carbon storage (vegetation + soil) were significantly affected by the land use type along the altitudinal gradient. Among the different agroforestry systems, maximum aboveground biomass (47.48 Mg ha−1) and belowground biomass (12.20 Mg ha−1) were recorded for agrohortisilviculture. Biomass production was positively correlated with altitudes and increased with an increase in altitudes. Soil carbon density was the maximum (35.77 Mg ha−1) under silvopastoral showing a decreasing trend along the altitudinal gradient. The total carbon storage potential was observed the maximum (59.76 Mg ha−1) under silvopastoral system followed by agrohortisilvicuture > agrosilvohorticulture > agrisilviculture > pastoralsilviculture > hortiagriculture > hortipastoral > agrihorticulture. Along the elevation gradient, total carbon stock ranged from 43.99 to 51.13 Mg ha−1 with the maximum carbon stock corresponding to Z-III and the minimum for Z-IV. This study offers a useful approach for selecting different land use systems and vegetation patterns to maximize thecarbon stocks in a cost-effective manner, which will further help to mitigate global warming issues in other fragile Himalayan catchments. [ABSTRACT FROM AUTHOR]

Goethite is known to contribute to the co-precipitation of rhizodeposits and thus benefit carbon (C) sequestration, while arbuscular mycorrhizal fungi (AMF) play significant role in soil organic C (SOC), however, the combined effect is less known. To address this paucity in knowledge, we compared the physicochemical stabilization and microbial mineralization of rhizodeposits from maize (Zea mays L.) and the rhizosphere priming effect (RPE) in soils with a combination of goethite addition and AMF inoculation. Here, we showed that compared to the control: i) Co-amendment of AMF and goethite resulted in a 0.6-fold decrease of rhizodeposit derived CO 2 , and a 2.8-fold larger allocation of rhizodeposits into macro-aggregates, most likely due to precipitation by goethite and macro-aggregate formation stimulated by AMF hyphae. Analyses using μ-FTIR confirmed the spatial distribution of polysaccharides overlapped with Fe–O minerals within macro-aggregates, supporting the concomitant processes of rhizodeposit stabilization and aggregate formation via hyphal-aggregate mineral interactions; ii) Inoculation with AMF accelerated SOC turnover by increasing the RPE (by 6.1 mg C kg−1 day−1, 74% increase) and rhizodeposit stabilization (by 6.2 mg C kg−1 soil day−1, 47% increase). The larger soil priming effect stimulated by AMF was associated with several genera including Solirubrobacter, Pseudomonas and Talaromyces , suggesting these hyper-symbionts were involved in nutrient acquisition (mining hypothesis). Our results enabled the comparison between rhizodeposit stabilization versus rhizodeposit and SOC mineralization, and highlighted the contributions of both goethite (abiotic contribution) and AMF (biotic contribution) to C accrual in a soil-plant system. • AMF and goethite stabilized rhizo-C via mineral-aggregate-hyphae interaction. • μ-FTIR confirmed the spatial distribution of polysaccharides overlapped with Fe–O. • AMF increased SOM priming via extended hyphae and hyper-symbiont activity. • AMF enhanced both rhizo-C stabilization and soil priming and thus faster SOC turnover. [ABSTRACT FROM AUTHOR]

Global warming, management of soil health, remediation of contaminated wastewater,and sustainable alternate source of energy are the major challenges of the 21st century. Biochar has an enormous potential in addressing these global issues and can act as a catalyst in achieving sustainable development goals (SDGs). Biochar produced from waste biomass (crop residues, algal biomass, municipal waste, etc.) has dual advantages of waste management along with its application in different sectors. The mineral contents and buffering capacity of biochar make it an ultimate catalyst for anaerobic digestion which significantly enhances bioenergy production. Supplementing anaerobic digestion with biochar can increase biogas and biological hydrogen production up to 57% and 118% respectively, over control. Biochar addition to soil improves soil health, porosity and aeration which mitigates greenhouse gas emission from soil. Addition of biochar at the optimum level in rice can reduce cumulative methane emission up to 60%. In this manuscript, the potential of biochar for bioenergy production (biogas and biological hydrogen production), greenhouse gases mitigation, carbon sequestration in soils, and waste water remediation is discussed in detail along with the challenges and future prospects of biochar. This review identifies the key issues which need to be addressed for sustainable utilization of biochar. [Display omitted] • Biochar is nutrient rich biomass and its use is economic and environment friendly. • Biochar enhances biogas and bio-hydrogen production in anaerobic reactors. • Biochar based MFCs are economically and environmentally sustainable. • Biochar addition in soil sequesters carbon and reduces CH 4 and N 2 O emissions. • Biochar use potentially removes several emerging contaminants from wastewater. [ABSTRACT FROM AUTHOR]