Local Biomass Research Articles

Optimizing pyrolysis and Co-Pyrolysis of plastic and biomass using Artificial Intelligence

The rapid increase in biomass and plastic waste poses significant environmental challenges. Co-pyrolysis of biomass with plastic wastes offers a promising avenue for sustainable waste management and renewable energy generation. This study covers several novel aspects: First, it investigates the impacts of feedstock composition and operating conditions in pyrolysis (individual feedstock) and co-pyrolysis (biomass and plastic wastes). The study reveals that synergistic effects, specifically improved yields and optimized temperature, exist in the co-pyrolysis of biomass and plastic wastes compared to individual feedstock. Secondly, a suitable blended machine learning predictive model (with Random Forest, Gradient Boosting Regressor, and XGBoost) and robust optimization framework are developed to address model accuracy, non-linear interactions, and uncertainties in pyrolysis such as temperature, heating rate, and biomass-to-plastic ratio. This study predicts the bio-oil yield quantitatively (amount) and qualitatively (composition) with high accuracy (R2 > 0.97). Thirdly, key factors contributing to yield include plastic content (18 %) and biomass type (13 %) have been identified through Gini feature importance and Shapley Additive Explanation (SHAP) analysis. Furthermore, multi-objective optimization techniques reveal the most optimal bio-oil yield under specific conditions, supported by uncertainty analysis, which confines bio-oil yield to a range of 30–50 %. Finally, it also demonstrates a case study to find the optimal bio-oil yield and quality conditions using co-pyrolysis of local resources, i.e., biomass (wood and bagasse) and plastic wastes. The case study suggests optimal conditions like > 50 °C heating rate, <50 min pyrolysis time, and > 60 % plastic content in a blend of wood and HDPE. This study assists industries and policymakers to assess and understand the viability of co-pyrolysis, optimal design parameters, and process impacts.

Fuel for collective action: A SWOT analysis to identify social barriers and drivers for a local woody biomass supply chain in an Italian alpine valley

The role of woody biomass in the clean energy transition is substantial in the EU. Forest residues are one of the main biomass sources that can be used for energy production, but their use to support the energy transition is still limited for several reasons. Research has shown that the use of forest residues in energy production can be effectively stimulated through collective actions that aim to develop short and local supply chains. This study aims to identify the barriers and drivers for the development of a local supply chain for forest residues in an Italian alpine valley, gathering and analysing the perspectives of all involved local actors, that is, (i) suppliers - the communities that own the forest resources, (ii) intermediaries - the forest professionals providing extension and advice services to owners and the harvesting companies; and (iii) the final consumers, in this case the local municipalities and hospitality enterprises. Data are analysed using a SWOT analysis. The results show that the suppliers identified opportunities especially, while the final consumers focused more on strengths, weaknesses, and threats. The SWOT categories in terms of the number of different factors were weaknesses (37 %), strengths (27 %), threats (18 %), and opportunities (17 %). Opportunities and strengths were considered as drivers, while threats and weaknesses were barriers. Several drivers emerged, such as a general predisposition toward the development of a local supply chain for forest residues, social homogeneity in terms of knowledge and management of the land, and common challenges. Barriers also emerged in the form of limited know-how on the supply chain potential, but also in limited availability to concede control between different forest owners over their property. The SWOT results are useful to design strategies to support the development of the supply chain: four possible strategies, amongst which flexible cooperation processes between different categories of stakeholders, and the organisation of a buying group of the hospitality enterprises, were suggested.

Biomass-Derived Carbons as Friction Reducing Additives for Lubricants: Tribological Properties of Biochars and Activated Carbons Obtained from Sugar Cane Bagasse

Activated carbons are commonly used for adsorption/depollution applications, but only a few studies are related to their lubricating properties. In order to investigate a new family of friction reducers, the tribological properties of biochars and derived activated carbons obtained from sugar cane bagasse are investigated. Activated carbons are obtained from either a physical (steam water) or chemical (with phosphoric acid) activation process. The tribological tests show that the activated carbons present very low friction coefficients, close to 0.08. The correlation of textural and tribological investigations shows that the specific surface area of the compounds as well as the microporous and mesoporous domain extensions are key parameters to optimize the friction reduction properties of activated carbons. The friction properties of the compounds are improved if the mesoporous domain extension is above 40% of the total porous volume. This study shows that local biomass waste valorization is possible and that sugar cane bagasse-derived activated carbons appear as interesting new friction reduction additives for lubricants.

Integration of photovoltaic panels and biomass-fuelled CHP in an Italian renewable energy community

This study presents the first attempt to explore the technical and financial feasibility of combining incentives for Italian Renewable Energy Communities (REC) with those for high-efficiency cogeneration. The community has local wooden biomass availability and was assembled around two prosumers: an industrial laundry with biomass-fuelled CHP and a school with photovoltaic panels. Other members include residential users. Electric loads were derived from available quarter-hour meters and electric bills. Thermal demand for the laundry was reconstructed from an energy audit. First, the CHP optimal mode of operation was selected among the two suggested by the manufacturer (matching the electric or the thermal load), providing energy, financial and environmental performance in both scenarios. Then the photovoltaic system of the school was sized. Finally, an optimal number of users was selected using a genetic algorithm, with financial performance of the REC as objective functions. Energy, economic and environmental impact performance of prosumers and REC are discussed, finding that the optimal configuration reduces CO2 emissions by 722 tons/year, with further 1360 tons/year coming from biomass combustion. In an optimal REC configuration members cut 250 €/year of electric bills, with an overall performance of 21 % in valorization of shared energy, while a social-focused REC can increase its NPV from 233 to 769 k€. The scenario can be applied to other prosumers with similar thermal demand and can be replicated or adjusted to local requirements.

Assessing the Economic and Environmental Impacts of Anaerobic Digestion for Municipal Organic Waste: A Case Study of Minamisanriku Town, Japan

Anaerobic digestion (AD), or biogas technology, is an optimal method for municipal organic waste (MOW) treatment, recovering both material and energy. This study takes a life cycle assessment perspective and examines the economic and environmental impacts of a BIO facility in Minamisanriku Town, Japan, which has utilized MOW (kitchen/food waste and surplus sludge from sewage) as local biomass resources since 2012. Stakeholder interviews were conducted to gather data on material flows and impacts. Scenario analysis considered various conditions, such as pre- and post-operation of the BIO facility, the use and non-use of digestate as liquid fertilizer, and the facility’s 100% operational efficiency. The results indicate that full operation of the BIO facility and marketing of value-added products, such as branded rice grown using liquid fertilizer, could significantly reduce greenhouse gas (GHG) emissions, lower integrated environmental costs, improve the regional economy, and increase net income. In the business as usual (BAU) scenario with a 56% operation rate of the BIO facility, there is an over 10% improvement in economic and environmental impacts compared to the pre-operation baseline. This study underscores the importance of maximizing biomass utilization to develop value-added uses by enhancing, extending, and expending stakeholder collaboration.

Unprecedented Harmful algal bloom in the UK and Ireland’s largest lake associated with gastrointestinal bacteria, microcystins and anabaenopeptins presenting an environmental and public health risk

Harmful Algal Blooms (HABs) are outbreaks of aquatic toxic microalgae emerging as a global problem driven by nutrient enrichment, global climate change and invasive species. We uniquely describe a HAB of unprecedented duration, extent and magnitude during 2023 in Lough Neagh; the UK and Ireland’s largest freshwater lake, using an unparalleled combination of satellite imagery, nutrient analysis, 16S rRNA gene sequencing and cyanotoxin profiling. The causative agent Microcystis aeruginosa accounted for over a third of DNA in water samples though common bacterioplankton species also bloomed. Water phosphate levels were hypertrophic and drove local algal biomass. The HAB pervaded the entire ecosystem with algal mats accumulating around jetties, marinas and lock gates. Over 80 % of bacterial DNA isolated from algal mat samples consisted of species associated with wildfowl or livestock faeces and human-effluent wastewater including 13 potential pathogens that can cause serious human illness including: E. coli, Salmonella, Enterobacter and Clostridium among others. Ten microcystins, nodularin and two anabaenopeptin toxins were confirmed as present (with a further microcystin and four anabaenopeptins suspected), with MC-RR and -LR in high concentrations at some locations (1,137–18,493 μg/L) with MC-LR exceeding World Health Organisation (WHO) recreational exposure guidelines in all algal mats sampled. This is the first detection of anabaenopeptins in any waterbody on the island of Ireland. Notwithstanding the ecological impacts, this HAB represented an environmental and public health risk, curtailing recreational activities in-and-around the lake and damaging local businesses. Reducing agricultural runoff and discharge from human-effluent wastewater treatment to manage nutrient loading, and the public health risk, should be the top priority of stakeholders, especially government. Key recommendations include Nature-based Solutions that avoid conflict with the productivity and profitability of the farming sector enhancing sustainability. We hope this stimulates real-world action to resolve the problems besetting this internationally important ecosystem.

Enhancing sustainable energy production in the Canary Islands: Valorization of local biomass resources through thermochemical processes

Diverse biomass sources from the Canary Islands (vineyard, tomato plant residues, Canary pine needles and Pennisetum setaceum) were assessed due to their local abundance, availability, and low supply cost. Based on their physico-chemical properties, various thermochemical processes were conducted to assess their thermal degradation behaviour, using simultaneous thermal analysis, and their potential for energy production. The results indicate that while tomato plant biomass is unsuitable for thermochemical processes because of its elevated ash content and limited volatile matter, the other biomass sources show promising potential for pyrolysis and gasification, characterized by high fixed carbon content and reactivity. The yearly production of residual biomass in the Canary Islands was quantified at 87,253 tonnes. This biomass could generate an estimated 88.5 GWh of electricity annually. Considering that electricity consumption in the Canary Islands reached 8750 GWh in 2023, biomass-derived electricity could contribute approximately 1.0 % to the archipelago's energy needs. These findings highlight the significant role of local biomass resources in advancing renewable energy goals and reduce dependence on non-renewable sources, promoting a greener energy landscape for the Canary Islands.

Thermal performance of solar ground source heat pump system for rural buildings in Chinese cold zone

In response to China's national policy of “achieving carbon peak by 2030 and carbon neutrality by 2060″, and to promote the heating system of rural buildings in China's severe cold zone. Two heating schemes of the GSHP (Ground Source Heat Pump) system and the SGSHP (Solar Ground Source Heat Pump) system are designed and simulated for a single rural residential building in Harbin city. The results present that the outlet temperature of buried pipe in SGSHP system is 13.86 % higher than that in GSHP system, and coefficient of performance (COP) correspondingly increases 9.2 %. There is a better comprehensive performance for the SGSHP system in cold climates. The standard coal consumption of SGSHP system is about 72.35 % less than that of biomass boiler system, showing a greater energy efficiency. Compared to the local conventional biomass boiler system, the dynamic cost payback period of the SGSHP system amounts to 11 years, while yielding a net present value (NPV) of 10,800 CNY throughout the project's life cycle. The emissions of CO2, SO2, and dust are reduced by 2617.13 kg, 19.38 kg, and 14.535 kg respectively. The results indicate a great overall performance of the SGSHP system for residential heating in the cold climate zone. This research offers an energy efficient and eco-friendly alternative for the space heating of Chinese rural buildings in cold climates.

Assessment and selection of a micro-hybrid renewable energy system for sustainable energy generation in rural areas of Zambia

This research focuses on the implementation of micro-hybrid renewable energy systems (MHRES) in rural Zambia, where a large part of the population lacks adequate electrical infrastructure. Using a multi-criterion decision-making approach (MCDM), specifically the Technique for Preference Order by Similarity to an Ideal Solution (TOPSIS) with an entropy-weighted method, this research aims to identify an optimal MHRES solution to replace dependence on wood and fossil fuels. Analysis is carried out in 14 scenarios, taking into account technical, economic, social, and environmental criteria. The results show that a biogas-solar photovoltaic integrated with Energy System Power Safe Storage Battery Systems 190 (SBS 190) is the most visible option, demonstrating a relative proximity of 0.98556. In contrast, a diesel generator-solar PV system is the least favorable, with a relative proximity of 0.02576. Validation of the results through a convergent distance assessment (CODAS), an evaluation based on the distance from the average solution (EDAS), and the weighted aggregate sum of the product assessment (WASPAS) confirm its robustness. The proposed MHRES solution is designed to meet the energy needs of rural communities using local biomass and solar resources, free of obstacles by high buildings and structures. This research highlights the potential of MHRES to meet energy needs and promote sustainable development in developing countries, providing valuable insights for policymakers and energy stakeholders.

Detection differences between eDNA and mid‐water trawls are driven by fish biomass and habitat preferences

AbstractMarine scientific trawl surveys are commonly used to assess the distribution and population size of fisheries‐related species, yet the method is effort‐intensive and can be environmentally destructive. Sequencing environmental DNA (eDNA) from water samples can reveal the presence of organisms in a community without capturing them; however, we expect the detectability of taxa to differ between eDNA and trawl surveys, and understanding how species traits and population variables contribute to detection differences can help calibrate our expectations from each form of sampling. Here, we coupled eDNA metabarcoding and capture trawl surveys in British Columbia, Canada, to examine species traits that explain recurrent differences in detectability between the two methods, including habitat, body size, and biomass. At the regional scale, 17 of 23 fish species (74%) captured by the trawl were detected by eDNA metabarcoding, and 39 additional species were detected by eDNA sampling only. We found that eDNA metabarcoding disproportionately detected trawl‐caught species with greater local biomass (i.e., greater biomass in the adjacent trawl). Fish detected only in eDNA had a greater range of body lengths and a broader range of habitat preferences outside the trawls' target size and sampling areas. Our results suggest that with our level of sampling, eDNA metabarcoding can adequately recapitulate detection of fish communities detected by trawl surveys, but with a bias toward fish of high population biomass and greater inclusion of fish from outside the trawled area.

Modeling and thermodynamic optimization of distributed combined heat and power system based on biomass chemical looping hydrogen generation process

Distributed biomass combined heat and power (CHP) system is becoming an important way to use local biomass for ensuring regional energy supply and reducing CO2 emissions. In this work, a high-efficient CHP system based on a new separated-type biomass gasification process is proposed. The gasification system includes a chemical looping hydrogen generation (CLHG) process combined and a tar catalytic steam reforming (TCSR) unit, in which the general CLHG process includes a fuel reactor (FR), a steam reactor (SR) and an air oxidation reactor (AR), but in this study, the AR is removed and instead, the FR is decoupled into two reaction stages, namely, pyrolysis and gasification. In addition, the biomass pyrolysis-gasification-hydrogen generation (BPGH) combined cycle system is established by using oxygen carrier to couple pyrolysis, gasification and hydrogen generation stages. The TCSR process is used to convert volatiles generated by pyrolysis into syngas. To maximize thermodynamic efficiency of the system, the influences of temperature for the catalytic steam reforming (TCSR) and the ratio of steam to carbon (S/C) on the overall energy and exergy efficiency are mainly studied. The results show that the overall energy and exergy efficiencies reach the highest values of 75.93% (LHV) and 32.61%, respectively, when TSCR=800 °C and S/C = 3 while the net power generation energy and exergy efficiencies are 27.43% (LHV) and 27.54%, respectively.

Biomass distribution patterns of salt marshes: A detailed spatial analysis in central China's coastal wetlands

Wetland vegetation plays a critical role in the health of coastal ecosystems, serving pivotal roles in disaster mitigation and blue carbon sequestration. While extensive research on the effects of sea-level rise on the aboveground biomass of salt marsh vegetation, the spatial patterns of biomass distribution related to surface elevation remain less explored. This study investigates the growth patterns and spatial distribution of Spartina alterniflora in central coast of China through field surveys and the analysis of remote sensing data via Google Earth Engine. We have found a significant parabolic relationship between vegetation biomass and distance from the sea, with the optimal biomass influenced by the location of the marsh front edge. Further, we observe that biomass distribution varies with surface elevation and is influenced by geomorphological features notably creeks, which introduce significant elevation differences and local biomass fluctuations. These findings offer new insights into the spatial distribution of tidal flat vegetation, which are vital for effective coastal management and for modeling the evolution of tidal flats.

Temperature and water availability drive insect seasonality across a temperate and a tropical region.

The more insects there are, the more food there is for insectivores and the higher the likelihood for insect-associated ecosystem services. Yet, we lack insights into the drivers of insect biomass over space and seasons, for both tropical and temperate zones. We used 245 Malaise traps, managed by 191 volunteers and park guards, to characterize year-round flying insect biomass in a temperate (Sweden) and a tropical (Madagascar) country. Surprisingly, we found that local insect biomass was similar across zones. In Sweden, local insect biomass increased with accumulated heat and varied across habitats, while biomass in Madagascar was unrelated to the environmental predictors measured. Drivers behind seasonality partly converged: In both countries, the seasonality of insect biomass differed between warmer and colder sites, and wetter and drier sites. In Sweden, short-term deviations from expected season-specific biomass were explained by week-to-week fluctuations in accumulated heat, rainfall and soil moisture, whereas in Madagascar, weeks with higher soil moisture had higher insect biomass. Overall, our study identifies key drivers of the seasonal distribution of flying insect biomass in a temperate and a tropical climate. This knowledge is key to understanding the spatial and seasonal availability of insects-as well as predicting future scenarios of insect biomass change.

Optimal sizing of hybrid PV–diesel–biomass gasification plants for electrification of off-grid communities: An efficient approach based on Benders’ decomposition

Nowadays, millions of people in remote areas do not enjoy an uninterrupted power supply due to the lack of connectivity to the main power grid. Under such circumstances, the only feasible way to access electricity is typically local power generation, often relying on diesel engine–generator sets or photovoltaic arrays. However, on many occasions, this configuration does not fully exploit all available local resources, including biomass. Indeed, most isolated areas have access to local biomass production from agricultural activities, which can be used for local electricity generation through gasification. This paper addresses this challenge by developing an innovative optimal sizing tool for hybrid power plants integrating biomass gasifiers, specifically designed for isolated areas with access to local biomass production. The novel approach models the particular features of biomass gasification technologies, including long on/off times or restrictive ramping limits. To this end, an efficient methodology based on representative weeks is proposed, which is combined with a solution strategy based on the multi-cut Benders’ decomposition, thus resulting in a tractable framework that can deal with a huge amount of data efficiently. One of the most salient features of the new proposal is the consideration of local biomass production, which is included in the methodology through an original algorithm. Accordingly, a certain amount of biomass is sourced locally, leading to more accurate and reliable results. The new methodology is applied to a benchmark off-grid community in Ghana. The results demonstrate that the use of gasifiers reduces the project cost notably (by 90%) driven by the reduced biomass cost, which can be supplemented by locally generated biomass from agricultural activities. In addition, this technology constitutes a clean source of energy, reducing the total CO2 emissions by 83% compared to a baseline case in which only diesel generators are used. Moreover, it is demonstrated that biomass gasification can effectively act as base load power generation technology to reliably cover most of the local demand, thereby enabling a clean and inexpensive dispatchable local power generation. Finally, a sensitivity analysis reveals that the economic feasibility of the plant is more sensitive to the biomass cost than the selling price of biochar, resulting in a 33% increment in the total project cost when the price of biomass increases from 0 to 0.4 $/kg. Nevertheless, gasification remains as the predominant power generation technology even under unfavorable prices.

Renewable fuel production and the impact of hydrogen infrastructure — A case study of the Nordics

Hard-to-electrify sectors will require renewable fuels to facilitate the green transition in the future. Therefore, it is crucial to identify promising production locations while taking into account the local biomass resources, variable renewable energy sources, and the synergies between sectors. In this study, investments and dispatch operations are optimised of a large catalogue of renewable fuel production technologies in the open-source software SpineOpt, and this is soft-linked to the comprehensive energy system model Balmorel. We analyse future production pathways by comparing various levels of hydrogen infrastructure, including large-scale hydrogen storage, and assess system impacts. The results indicate that methanol may provide synergies in its multipurpose use as an early (2030–2040) shipping fuel and later as an aviation fuel through further refining if ammonia becomes more competitive (2050). We furthermore show that a hydrogen infrastructure increases the competitiveness of non-flexible, hydrogen-based fuel production technologies. Offshore electrolysis hubs decrease energy system impacts in scenarios with 105 TWh of Nordic hydrogen export. However, hydrogen export scenarios are much costlier compared to scenarios with no export unless a high hydrogen price is received. Finally, we find that emission taxes in the range of 250–265 €/tCO2 will be necessary for renewable fuels to become competitive.

Evaluation of a Local Heating Network Supplied by a Pyrolysis Plant

In order to mitigate climate change, a wide range of negative emission technologies, such as pyrolytic carbon capture and storage, must be used in the future. This study therefore examines a specific application example for the energy supply with a pyrolysis plant that is operated with locally available biomass in the smallest district of the city of Freiburg. It is shown that such a supply concept is feasible and that the economic efficiency of the supply concept depends on the system output as well as the amount of local biomass and the revenues from the sale of the biochar. Of the six pyrolysis plants examined, two proved to be a promising alternative to the current wood chip boiler. By switching to an energy supply with a pyrolysis plant, the district could save several hundred tons of CO2 per year. The resulting total negative emissions would amount to almost 1200 tons of CO2 per year.

Comprehensive evaluation on performance and local impact in energy, environment, and economy of different rural clean heating modes: A case study in Northeastern China

To improve the atmospheric environment, the clean heating projects such as “coal-to-electricity” and “coal-to-gas” have been implemented in China, while leading to significantly increase in heating costs for rural residents and the supply pressure of fossil fuels in some rural areas. As the local renewable energy, biomass briquette can be used for rural heating. However, the local resource feasibility for the biomass heating has not been paid enough attention to, besides, the performance and potential local impacts of different heating modes has not been comprehensively estimated. Based on multiple attribute decision-making, this paper proposes an evaluation system by integrating the performance comparison and local impact in energy, environment, and economy, especially including an assessment on local biomass resource feasibility. The clean heating modes of biomass, electricity, and gas are evaluated along with the current coal heating mode in Harbin and Qiqihar as case studies. Results show that in the case regions, the biomass mode has sufficient resources and achieves significant comprehensive benefits, with the relative proximity nearly twice that of the coal mode. All the three clean heating modes can achieve environmental benefits. Due to the best economic feasibility, the biomass mode is suitable for the current rural economic level, with the cost intensity of 0.01 yuan/MJ, and the ratio of heating cost to disposable income less than 1%. The electric mode hardly produces comprehensive benefits because of the high cost. The gas mode is the least recommended due to significant energy demand and great economic burden.

Submicron aerosol pollution in Greater Cairo (Egypt): A new type of urban haze?

Greater Cairo, the largest megacity of the Middle East North Africa (MENA) region, is currently suffering from major aerosol pollution, posing a significant threat to public health. However, the main sources of pollution remain insufficiently characterized due to limited atmospheric observations. To bridge this knowledge gap, we conducted a continuous 2-month field study during the winter of 2019–2020 at an urban background site, documenting for the first time the chemical and physical properties of submicron (PM1) aerosols. Crustal material from both desert dust and road traffic dust resuspension contributed as much as 24 % of the total PM1 mass (rising to 66 % during desert dust events), a figure not commonly observed in urban environments. Our observations showed significant decreases in black carbon concentrations and ammonium sulfate compared to data from 15 years ago, indicating an important reduction in both local and regional emissions as a result of effective mitigation measures. The diurnal variability of carbonaceous aerosols was attributed to emissions emanating from local traffic at rush hours and nighttime open biomass burning. Surprisingly, semi-volatile ammonium chloride (NH4Cl) originating from local open biomass and waste burning was found to be the main chemical species in PM1 over Cairo. Its nighttime formation contributed to aerosol water uptake during morning hours, thereby playing a major role in the build-up of urban haze. While our results confirm the persistence of a significant dust reservoir over Cairo, they also unveil an additional source of highly hygroscopic (semi-volatile) inorganic salts, leading to a unique type of urban haze. This haze, with dominant contributors present in both submicron (primarily as NH4Cl) and supermicron (largely as dust) modes, underscores the potential implications of heterogeneous chemical transformation of air pollutants in urban environments.

Catalytic potential of green ordered mesoporous carbons, obtained from biomass-derived xylose, glucose, and lignin

Green high-surface area Ordered Mesoporous Carbons (OMCs) (576–948 m2/g) were successfully synthesized by the hard template method using xylose, glucose and lignin solutions obtained from almond shells, a local biomass waste, as carbon precursors, and SBA-15 as a template. The catalytic potential of OMCs, as catalytic supports or as catalysts, has been preliminarily tested for different reactions of interest. A dried sulfonic-acid treated OMC, obtained from xylose extract, led to full conversion and 92% selectivity to di- and tri-ethers of glycerol for the glycerol etherification with isobutene at 80 °C. A sulfonic-acid treated OMC, obtained from glucose, presented a higher turnover frequency (TOF) value and slightly lower selectivity to levulinic acid than commercial Amberlyst-15 for the conversion of 5-hydroxymethylfurfural at 180 °C. The use of an OMC obtained from lignin as catalytic support of a nickel catalyst combined with H-Beta led to 78% of selectivity to cyclohexane at total conversion for the hydrodeoxygenation of guaiacol at 180 °C.

Nitrogen aerosols in New Delhi, India: Speciation, formation, and sources

Delhi, the capital city of India, experiences severe air pollution and suffers from its adverse effects on human health and ecosystems. This pollution is characterized by high levels of pollutants, including atmospheric nitrogen in both the gaseous and particulate phases. However, there is a lack of simultaneous measurement of chemical composition, tracers and 15N data in aerosols to understand the influence of different sources on N aerosols over Delhi. Here, we measured total nitrogen (TN), water-soluble total nitrogen (WSTN), water-soluble inorganic nitrogen (WSIN), and N stable isotope compositions (δ15N) in PM2.5 samples covering the post-monsoon, winter, and summer periods of the year 2018–19. NH4+-N was the major N species, accounting for an average 58% of TN and 68% of WSIN. The temporal variations of TN, WSTN, NH4+-N, NO3−-N, and WSON showed peaks in the post-monsoon and winter seasons, exhibiting seasonality similar to PM2.5 and levoglucosan (a biomass-burning tracer) indicating their co-genetic sources. Based on the correlation analysis between δ15N and N-species, we identified two distinct secondary chemical processes: i) in an NH4+-poor atmosphere, the gas-to-particle (NH3 → NH4+) conversion and subsequent formation of NH4HSO4 was the main process controlling the 15N and nitrogen enrichments in PM2.5; whereas ii) under NH4+-rich conditions, the formation and dissociation of NH4NO3 dominated. The coupled HYSPLIT and PSCF analyses highlighted the transport and contributions of open biomass burning emissions under a northwesterly atmospheric flow during post-monsoon as well as from local biomass combustion (from cooking and heating) during winter in the city and its vicinity. Our results suggested that i) both NH4+-N and NO3−-N were mainly impacted by biomass combustion during post-monsoon and winter seasons, and ii) NO3−-N resulted of dust transport from the Thar Desert in the summer season, but not NH4+-N. Finally, we recommend that future research focuses on the study of the seasonality of atmospheric nitrogen composition using 15N data from their different sources to design tailor-made measures and policies regarding the different potential sources, combining them within a comprehensive framework to ultimately improve air quality and the living environment in Delhi.