This study is particularly aimed at investigating the influence of hydrogen chloride traces in biogas on direct internal reforming in solid oxide fuel cells (SOFCs). The experiments are performed with simulated biogas containing methane to carbon dioxide ratio of 3:2, the usual average proportion in biogas. To the best of our knowledge, there are no reported studies that investigated the effect of hydrogen chloride on direct internal reforming by clearly establishing the effect of reforming with outlet gas composition measurements. The experiments at SOFC operating temperature of 850 °C reveals no negative effect on reforming or cell performance, with 4, 8, and 12 ppm(v) of hydrogen chloride in biogas. At 800 °C, there is no visible performance degradation, but a negligible amount of methane (∼ 1%) is detected in the anode off gas. Both the reforming and electrochemical performance are marginally affected at 750 °C. Further, post-test analyses (FESEM-EDS, XRD) of the used SOFC reveals no damage to the cell at microstructure level or chlorine poisoning. All the experiments are performed in the context of utilizing the biogas generated from sewage treatment plants in an SOFC system. The reported level of chlorine traces in biogas generated from sewage sludge is < 10 ppm(v) and hence the limit set for experiments is at par with this value.

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In the face of the rapidly dwindling carbon budgets, negative emission technologies are widely suggested as required to stabilize the Earth’s climate. However, finding cost-effective, socially acceptable, and politically achievable means to enable such technologies remains a challenge. We propose solutions based on negative emission technologies to facilitate wealth creation for the stakeholders while helping to mitigate climate change. This paper comes up with suggestions and guidelines on significantly increasing carbon sequestration in coffee farms. A coffee and jackfruit agroforestry-based case study is presented along with an array of technical interventions, having a special focus on bioenergy and biochar, potentially leading to “negative emissions at negative cost.” The strategies for integrating food production with soil and water management, fuel production, adoption of renewable energy systems and timber management are outlined. The emphasis is on combining biological and engineering sciences to devise a practically viable niche that is easy to adopt, adapt and scale up for the communities and regions to achieve net negative emissions. The concerns expressed in the recent literature on the implementation of emission reduction and negative emission technologies are briefly presented. The novel opportunities to alleviate these concerns arising from our proposed interventions are then pointed out. Our analysis indicates that 1 ha coffee jackfruit-based agroforestry can additionally sequester around 10 tonnes of CO2-eq and lead to an income enhancement of up to 3,000–4,000 Euros in comparison to unshaded coffee. Finally, the global outlook for an easily adoptable nature-based approach is presented, suggesting an opportunity to implement revenue-generating negative emission technologies on a gigatonne scale. We anticipate that our approach presented in the paper results in increased attention to the development of practically viable science and technology-based interventions in order to support the speeding up of climate change mitigation efforts.@en

Clean energy transition via utilizing biomass resources has been projected as an important climate change mitigation strategy. A vital characteristic of biomass is its localized nature; therefore, bioenergy utilization should follow decentralized planning. Agrarian countries like India can take benefit of its large agricultural biomass waste pool to produce clean renewable energy. However, prior knowledge of spatio-temporal distribution, competing uses, and biomass characteristics are necessary for successful bioenergy planning. This paper assesses biomass resource and its power generation potential at different agro-climatic zone levels in the state of Rajasthan, India considering crop residue biomass (25 different crop residues from 14 crops) and livestock manure (from cattle, buffalo, and poultry). Uncertainties associated with the availability of biomass and the power generation potential are assessed for each agro-climatic zone under different scenarios. Greenhouse gases (GHGs) emissions from biomass-based power generations are also estimated and compared with biomass-equivalent coal power plants. It is observed that the annual biomass power potential of Rajasthan is 3056 MW (2496 MW from crop residues and 560 MW from livestock manure). Scenario analysis suggests that the potential varies from 2445 to 6045 MW under different biomass availability and power plant operating conditions. Annual GHGs emissions due to biomass power generation is 5053 kt CO₂eq. Replacing coal-based power with biomass power would result in annual GHGs savings of 11412 kt CO₂eq. The paper also discusses various carriers and barriers viz. logistics, institutional, financial and technical in setting up decentralized bioenergy plants. Outcomes of the present study are expected to assist renewable energy planners in India.

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Increasing pressure on farming systems due to rapid urbanization and population growth has severely affected soil health and fertility. The need to meet the growing food demands has also led to unsustainable farming practices with the intensive application of chemical fertilizers and pesticides, resulting in significant greenhouse gas emissions. Biochar, a multifunctional carbon material, is being actively explored globally for simultaneously addressing the concerns related to improving soil fertility and mitigating climate change. Reviews on biochar, however, mainly confined to lab-scale studies analyze biochar production and its characteristics, its effects on soil fertility, and carbon sequestration. The present review addresses this gap by focusing on biochar field trials to enhance the current understanding of its actual impact on the field, w.r.t. agriculture and climate change. The review presents an overview of the effects of biochar application as observed in field studies on soil health (soil’s physical, chemical, and biological properties), crop productivity, and its potential role in carbon sequestration. General trends from this review indicate that biochar application provides higher benefits in soil properties and crop yield in degraded tropical soils vis-a-vis the temperate regions. The results also reveal diverse observations in soil health properties and crop yields with biochar amendment as different studies consider different crops, biochar feedstocks, and local climatic and soil conditions. Furthermore, it has been observed that the effects of biochar application in lab-scale studies with controlled environments are not always distinctly witnessed in corresponding field-based studies and the effects are not always synchronous across different regions. Hence, there is a need for more data, especially from well-designed long-term field trials, to converge and validate the results on the effectiveness of biochar on diverse soil types and agro-climatic zones to improve crop productivity and mitigate climate change.

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Sugarcane bagasse-based cogeneration contributes significantly to bioenergy conversion in India and therefore, appropriate performance analysis is required considering the regional factors. Further increase of sugarcane bioenergy is expected in India with the Government's mandate to enhance the share of renewable energy by 2030. Herein this study, district-wise sugarcane bagasse cogeneration potential is assessed in the state Maharashtra, India. Variations in energy, carbon and water footprint of energy generated from bagasse-based cogeneration plants are also assessed for all the districts considering farm to gate attributional life cycle assessment (ALCA). Avoided product function (also called as System expansion) of simaPro 9.2 LCA software is used to assess the environmental benefits of sugarcane waste or by-products (leaves and tops, press-mud and bagasse ash). The annual bagasse production potential in Maharashtra is 19 million tonne, equivalent to 8206 GWh of cogenerated electricity. The potential varies markedly among the districts (2–1500 GWh). Nearly 81 % of cogeneration potential is concentrated in 6 districts alone. The life cycle carbon footprint (0.075–0.2 kg CO₂e/kWh), the energy footprint (0.75–2.12 MJ/kWh) and the water footprint (206–516 L/kWh)-all the three estimated on the life cycle basis- differ considerably among the districts. The nexus among water, energy, and carbon footprint for sugarcane bioenergy is also analyzed to understand the complex interconnectivities among these individual resources. Cultivating high yielding varieties, use of renewable energy-based micro-irrigation, and installing modern cogeneration technology can lower the estimated carbon, energy and water footprint by up to 50 %. Such measures will help enhance farmers' income while addressing the sustainability issues in India.

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