Orfeas Karountzos, Georgios Kagkelis, K. Kepaptsoglou

Journal of Geovisualization and Spatial Analysis • 2023

Sustainability of maritime operations is a topic widely considered in recent years, as the shipping industry attempts to limit its environmental impact and meet the decarbonization goals set by the International Maritime Organization (IMO). As alternative fuels and newer ship technologies are gaining interest, the shift to more environmentally friendly fleets is quickly becoming a reality. In this context, potential areas for such shifts need to be determined, to expedite decarbonization efforts and provide passengers with a more sustainable way of travel. Greece is an insular country, with a complex coastal shipping network connecting the mainland with the islands and being of paramount importance for their economic growth. Recognizing accessibility and decarbonization needs, this paper examines whether the Greek coastal shipping network (GCSN) can be restructured, by introducing zero-emission sub-networks operated by electric ferries. The aim is to propose a methodological framework for the spatial analysis and evaluation of coastal networks, with the implementation of exploratory spatial data analysis (ESDA) methods and determination of local indicators of spatial association (LISA) with the help of geographic information systems (GIS). The proposed framework provides insight on whether and where such a restructuring is possible, with the introduction of new transshipment port hubs in the islands from which electric ferries could operate, thus determining potential electrification areas with additionally high renewable resource potential. Final conclusions indicate that a potential electrification of certain parts of the GCSN could be possible, while results for GHG emissions reduced by the introduction of electric ferries are calculated.

E. Van Rheenen, J. T. Padding, J. Slootweg et al.

Journal of Marine Engineering & Technology • 2023

Green hydrogen combined with PEM fuel cell systems is a viable option to meet the demand for alternative maritime fuels. However, hydrogen storage faces challenges, including low volumetric density, fire and explosion risks and transport challenges. We assessed over fifteen hydrogen carriers based on their maritime performance characteristics to determine their suitability for shipboard use. Evaluation criteria included energy density, locally zero-emission, circularity of process, safety, dehydrogenation process, logistic availability and handling. Thus, excluding ammonia and methanol because of these constraints, we found that borohydrides, liquid organic hydrogen carriers and ammoniaborane are the most promising hydrogen carriers to use on ships with PEM fuel cells. Borohydrides, specifically sodium borohydride, have high energy densities but face regeneration issues. The liquid organic hydrogen carrier dibenzyltoluene has a lower energy density but exhibits easy hydrogenation and good handling. Given varying operational demands, we developed a framework to assess the suitability of hydrogen carriers for use in different ship categories. Evaluating the three types of hydrogen carriers, using our framework and considering current practices, shows that these are viable options for almost all ship types. Thus, we have identified three types of hydrogen carriers, which should be the focus of future research.

Gihan Gamage, Nishan Mills, Daswin De Silva et al.

2024 IEEE International Conference on Industrial Technology (ICIT) • 2024

Modern energy platforms are increasingly leveraging Artificial Intelligence (AI) for effective decision-making and efficient operations. This has led to the development of expansive data spaces that comprise both structured and unstructured energy data in various modalities. Conversational agents with the most recent advancements in Large Language Models (LLM) are primed to facilitate the efficient retrieval of this diverse information for decision support. In this paper, we propose a multi-agent chatbot architecture for decision support in net-zero emissions energy systems, leveraging LLMs and Retrieval-Augmented Generation (RAG). This architecture consists of a Chatbot User Interface (UI), an advanced Natural Language Understanding (NLU) module for precise entity and intent recognition, a robust Chatbot Core with four specialized agents: Observer, Knowledge Retriever, Behavior Analyzer, and Visualizer and Response Construction Module. These components work together to address diverse decision support needs in energy environments, specifically for net zero carbon emissions initiatives that need to consider diverse parameters and large volumes of data. We showcase the chatbot's successful integration and evaluation for decision support in the net-zero emissions energy system of a large tertiary education institution.

Priyanka Saha, Faysal Ahamed Akash, Shaik Muntasir Shovon et al.

International Journal of Green Energy • 2023

ABSTRACT Energy is the linchpin for economic development despite its generation deficit worldwide. Hydrogen can be used as an alternative energy source to meet the requirement that it emits zero to near-zero impurities and is safe for the environment and humans. Because of growing greenhouse gas emissions and the fast-expanding usage of renewable energy sources in power production in recent years, interest in hydrogen is resurging. Hydrogen may be utilized as a renewable energy storage, stabilizing the entire power system and assisting in the decarbonization of the power system, particularly in the industrial and transportation sectors. The main goal of this study is to describe several methods of producing hydrogen based on the principal energy sources utilized. Moreover, the financial and ecological outcomes of three key hydrogen colors (gray, blue, and green) are discussed. Hydrogen’s future prosperity is heavily reliant on technology advancement and cost reductions, along with future objectives and related legislation. This research might be improved by developing new hydrogen production methods, novel hydrogen storage systems, infrastructure, and carbon-free hydrogen generation. GRAPHICAL ABSTRACT

A. Saha, V. Šimić, Tapan Senapati et al.

IEEE Transactions on Fuzzy Systems • 2023

For the first time, the critical worldwide problem of prioritizing zero-emission last-mile delivery (LMD) solutions for sustainable city logistics is addressed and solved in this article. It not only aims to help city logistics companies sustainably decarbonize urban freight distribution but also provide valuable practical guidelines. To evaluate zero-emission LMD solutions, this article presents a novel multicriteria group decision-making methodology with dual hesitant fuzzy (DHF) sets. First, we propose some improved operations on DHF elements and investigate their vital properties. Second, based on these operations, we develop DHF improved weighted averaging operator to overcome the drawbacks of the existing operators on DHF sets. Third, for measuring the weights of criteria, a new model called the cross-entropy-based optimization model (CEBOM) is developed. Fourth, for the rational aggregation of the preferences, we formulate a new method namely score-based double normalized measurement alternatives and ranking according to the compromise solution (SDNMARCOS). The proposed DNMARCOS method couples the linear and vector normalization techniques. It is composed of the complete compensatory model and the incomplete compensatory model. Thus, SDNMARCOS is more robust compared to the available state-of-the-art approaches. To exhibit the applicability of the proposed DHF-CEBOM-SDNMARCOS methodology in real-world settings, a case study for one of the largest Austrian logistics companies in Serbia is provided. The research findings show that electric light commercial vehicles are the best LMD solution. Also, it is recommended to consider electric cargo bikes as a viable mid-term solution. The superiority of the introduced methodology is demonstrated through the comparative investigation.

Yati Nurhayati, Ifrani, M. Said et al.

Environmental Policy and Law • 2024

The Nationally Determined Contribution (NDC) of Indonesia in the Paris Agreement targeted emission reductions of 29% on its own and 41% with international cooperation in 2030, followed by Net Zero Emissions (NZE) in 2060. To achieve NZE, Indonesia enacted a carbon tax policy on April 1, 2022. The 2022–2024 carbon tax is limited to Steam Power Plants and will be imposed on other sectors by 2030. This research examines the ratio legis of carbon cost policies in Indonesia and compares the core of carbon tax policies in Indonesia with Sweden and Finland. Indonesia is starting to implement a Carbon Pricing policy under the ‘Cap-and-Tax’ scheme. The Cap scheme will be a means to force changes in the business culture in Indonesia, so the companies will pay attention to and reduce the carbon emission produced to avoid paying penalties for carbon exceeding the limits. Meanwhile, the Carbon Tax will provide economic resources to Indonesia to develop environmentally friendly technologies, fund research on renewable energy, and provide incentives for environmentally friendly businesses during the transition process to a carbon culture in Indonesia. Referring to the results of the comparison of carbon pricing policies in Finland and Sweden, Indonesia can gradually increase the cost of carbon taxes starting from Rp30,000/US$2 per ton CO2 equivalent to US$10 per ton CO2 equivalent. Meanwhile, for the imposition of high carbon tax rates, such as in Finland (US$73.02 per ton CO2 equivalent) and Sweden (US$137 per ton CO2 equivalent), Indonesia must carry out tax reforms, so the applied carbon tax is able to reduce carbon emissions without causing adverse impacts for the Indonesian economy.

Namireddy Praveen Reddy, R. Skjetne, Oliver Stugard Os et al.

IEEE Journal of Emerging and Selected Topics in Industrial Electronics • 2024

Zero-emission ships (ZESs) have gained interest to comply with the stringent regulations of international maritime organization. One way to build ZES is the hybridization of fuel cells with batteries. Traditionally, for a newly built ship, the energy and emissions management system (EEMS) is designed based on the initial condition of the fuel cells and batteries and used with fixed parameters in future execution. However, for a fuel cell and battery ZES, the EEMS gradually becomes suboptimal since the characteristics of fuel cells and batteries are continuously changing due to aging and degradation. In this article, a reinforcement learning (RL)-based EEMS is developed such that it can learn and adapt continuously to changes in the fuel cell/battery characteristics. Within RL, different types of algorithms, such as double deep <inline-formula><tex-math notation="LaTeX">$Q$</tex-math></inline-formula>-learning (DDQL), soft actor–critic (SAC), and proximal policy optimization (PPO) are implemented. The results are benchmarked against those of a typical rule-based EEMS. Each RL algorithm is trained with four reward function formulations; negative cost (<inline-formula><tex-math notation="LaTeX">$r_{1}$</tex-math></inline-formula>), negative quadratic cost (<inline-formula><tex-math notation="LaTeX">$r_{2}$</tex-math></inline-formula>), inverse cost (<inline-formula><tex-math notation="LaTeX">$r_{3}$</tex-math></inline-formula>), and inverse quadratic cost (<inline-formula><tex-math notation="LaTeX">$r_{4}$</tex-math></inline-formula>). The results demonstrate that health-aware EEMS can minimize fuel consumption and component degradation costs. <inline-formula><tex-math notation="LaTeX">$r_{1}$</tex-math></inline-formula> has led to the lowest operational expenses (OPEX) followed by <inline-formula><tex-math notation="LaTeX">$r_{2}$</tex-math></inline-formula>, while <inline-formula><tex-math notation="LaTeX">$r_{3}$</tex-math></inline-formula> and <inline-formula><tex-math notation="LaTeX">$r_{4}$</tex-math></inline-formula> have high OPEX. Among the three algorithms, the DDQL led to the lowest reward followed by the SAC and then the PPO, when trained with <inline-formula><tex-math notation="LaTeX">$r_{1}$</tex-math></inline-formula> and <inline-formula><tex-math notation="LaTeX">$r_{2}$</tex-math></inline-formula>.

Hui Li, Zhouyang Ren, Anupam Trivedi et al.

IEEE Transactions on Smart Grid • 2024

This paper proposes an optimal planning method for the dual-zero microgrid (DZMG) on an island. The DZMG is the off-grid microgrid that exchanges zero power with entity grids and operates in a net-zero carbon emission mode. A net-zero emission operating strategy is designed considering the positive interaction between $\rm CO_{2}$ flow and energy flow. The multi-scale circulation of $\rm CO_{2}$ flow is realized by coordinating the carbon capture system, solvent storage tank (SST), and direct air capture (DAC), while the seasonal shift of energy flow is completed by the hydrogen storage system (HSS) and DAC. An optimization planning model for DZMG is developed to size the SST, DAC, and HSS optimally. The net-zero emission target and the net-zero operating strategy are involved in the model to balance the environmental and economic concerns in the planning. Numerical experiments are carried out on two IEEE test systems and a real-world island microgrid to validate the effectiveness and adaptability of the proposed method. Simulation results reveal that the proposed method reduces the planning cost by over 25% compared with the extant zero-carbon-based method. Besides, the economy of the DZMG positively correlates to carbon prices and technological maturity, while inversely relates to fuel prices.

Kaiqi Jiang, Hai Yu, Zening Sun et al.

Environmental Science &amp; Technology • 2024

Decarbonization of the cement sector is essentially required to achieve carbon neutrality to combat climate change. Amine-based CO2 capture is a leading and practical technology to deeply remove CO2 from the cement industry, owing to its high retrofittability to existing cement plants and extensive engineering experience in industrial flue gas decarbonization. While research efforts have been made to achieve low-carbon cement with 90% CO2 removal, a net-zero-emission cement plant that will be required for a carbon neutrality society has not yet been investigated. The present study proposed an advanced amine-based CO2 capture system integrated with a cement plant to achieve net-zero CO2 emission by pushing the CO2 capture efficiency to 99.7%. Monoethanomaine (MEA) and piperazine/2-amino-2-methyl-1-propanol (PZ-AMP) amine systems, which are considered to be the first- and second-generation capture agents, respectively, were detailed investigated to deeply decarbonize the cement plant. Compared to MEA, the advanced PZ-AMP system exhibited excellent energy performance with a regeneration duty of ∼2.6 GJ/tonne CO2 at 99.7% capture, 39% lower than the MEA process. This enabled a low CO2 avoided cost of $72.0/tonne CO2, which was 18% lower than that of the MEA-based zero-emission process and even 16.2% lower than the standard 90% MEA process. Sensitivity analysis revealed that the zero-emission capture cost of the PZ-AMP system would be further reduced to below $56/tonne CO2 at a $4/GJ steam production cost, indicating its economic competitiveness among various CO2 capture technologies to achieve a zero-emission cement plant.

V. Aryanpur, F. Rogan

Scientific Reports • 2024

The road freight sector faces significant challenges in decarbonisation, driven by high energy demand and limited availability of low-emission fuels and commercialised zero-emission vehicles. This study investigates intangible costs associated with advanced electric and hydrogen-powered trucks, including recharging/refuelling time, cargo capacity limitations, and buyer reluctance towards emerging technologies. Utilising a comprehensive whole-systems modelling approach considering low- and zero-emission fuels, inter-sectoral dynamics, and the carbon budget, we explore cost-optimal decarbonisation pathways for heavy, medium, and light trucks. Scenario and sensitivity analyses reveal the following insights: (1) Electric trucks dominate the market under mitigation pathways across all weight categories. However, the inclusion of intangible costs triggers a shift, leading to the emergence of hydrogen fuel cell vehicles for heavy trucks, while battery electric vehicles are preferred for medium and small trucks. (2) Prioritising heavy truck decarbonisation and taking early action are crucial to avoid carbon lock-in effects. (3) Considering limited decarbonisation options, where electric and hydrogen-fuelled trucks are pivotal, this research highlights the significance of policy instruments targeting operational expenditures over conventional purchase price incentives. Such policies offer dual benefits by supporting truck owners and directing incentives more precisely towards achieving measurable emission reductions.

Sirine Saadaoui, B. Erable, Luc Etchevery et al.

Fermentation • 2023

Bioelectrochemical systems (BESs), rather than physicochemical processes, are used for wastewater remediation, electricity production, and zero carbon dioxide emission. Textile effluents contain organic and inorganic compounds that can fuel BESs. The main goal of this study was to understand the interplay between the anode material, its surface area, the potential applied to the working electrode (WE), and the concentration of the co-substrate, and how these factors lead to the formation of highly efficient thermohalophilic bioanodes (THB) retrieved from Chott El Djerid (SCD) hypersaline sediment for the treatment of synthetic textile wastewater. To this end, twenty-seven bioanode formation experiments were designed using a Box-Behnken matrix and response surface methodology to understand concomitant interactions. All experiments were conducted in electrochemical reactors of final volume 750 mL inoculated with 80% of enrichment medium containing three azo dyes at a concentration of 300 ppm and 20% of biocatalyst microbial SCD source, at 45 °C. The optimal levels were predicted using NemrodW software as carbon felt (CF) anode material, 6 cm2 anode surface, 7 g/L glucose concentration, and −0.1 V applied potential. These theoretical results were experimentally validated, using maximum current output of 5.23 ± 0.30 A/m2, decolorization rate of 100%, and a chemical oxygen demand (COD) removal rate of 96 ± 1%. Illumina Miseq results revealed that bacterial community harbored the bioanode was dominated at phylum level by Firmicutes (67.1%). At the species level, the biofilm was mainly colonized by Orenia metallireducens species (59.5%). Obtained findings show a promising application of THB in the degradation of recalcitrant molecules as well as for the energy recovery.

Arian Loli, Chiara Bertolin

Buildings • 0

<jats:p>Nowadays, restoration interventions that aim for minimum environmental impact are conceived for recent buildings. Greenhouse gas emissions are reduced using criteria met within a life-cycle analysis, while energy saving is achieved with cost-effective retrofitting actions that secure higher benefits in terms of comfort. However, conservation, restoration and retrofitting interventions in historic buildings do not have the same objectives as in modern buildings. Additional requirements have to be followed, such as the use of materials compatible with the original and the preservation of authenticity to ensure historic, artistic, cultural and social values over time. The paper presents a systematic review—at the intersection between environmental sustainability and conservation—of the state of the art of current methodological approaches applied in the sustainable refurbishment of historic buildings. It identifies research gaps in the field and highlights the paradox seen in the Scandinavian countries that are models in applying environmentally sustainable policies but still poor in integrating preservation issues.</jats:p>

Piotr F. Borowski

Energies • 0

<jats:p>The energy transition requires substantial financial investments and the adoption of innovative technological solutions. The aim of this paper is to analyze the economic and technological aspects of implementing zero-emission strategies as a key component of the transition toward a carbon-neutral economy. The study assesses the costs, benefits, and challenges of these strategies, with a particular focus on wind farms and nuclear power, including small modular reactors (SMRs). The paper presents an in-depth examination of key examples, including onshore and offshore wind farms, as well as nuclear energy from both large-scale and small modular reactors. It highlights their construction and operating costs, associated benefits, and challenges. The investment required to generate 1 MW of energy varies significantly depending on the technology: onshore wind farms range from $1,300,000 to $2,100,000, offshore wind farms from $3,000,000 to $5,500,000, traditional nuclear power plants from $3,000,000 to $5,000,000, while small modular reactors (SMRs) require between $5,000,000 and $10,000,000 per MW. The discussion underscores the critical role of wind farms in diversifying renewable energy sources while addressing the high capital requirements and technical complexities of nuclear power, including both traditional large-scale reactors and emerging SMRs. By evaluating these energy solutions, the article contributes to a broader understanding of the economic and technological challenges essential for advancing a sustainable energy future.</jats:p>

Thorsten Schuetze

Sustainability • 0

<jats:p>This paper discusses the history, status quo, and future prospects of Zero Emission Buildings (ZEBs) in the Republic of Korea. The advantages of, and requirements for ZEBs are described, concerning the factors of energy, water, nutrients, and biomass. ZEBs are characterized by net zero energy consumption through the minimization of the energy demand, as well as the onsite production and use of renewable energy. The direct water footprint is reduced by up to 100% through on-site water supply and wastewater management according to the principles of Sustainable Sanitation. The fresh water demand is reduced by using water saving technologies and by recycling of wastewater. Rainwater harvesting, utilization, and infiltration facilitates for onsite drinking water production. Nutrients and biomass from sanitation systems are recycled for local soil application. While traditional Korean buildings can be generally regarded as ZEBs, traditional know-how has been overlooked in the process of modernization and implementation of centralized infrastructure systems in the 20th century. However, the growing interest in sustainability issues in Korea since the beginning of the 21st century is reflected in a growing number of research and development activities, including the design, construction, and operation of ZEBs. The widespread implementation of ZEBs would significantly contribute to sustainable development in the Republic of Korea.</jats:p>

Deger Saygin, Dolf Gielen

Energies • 0

<jats:p>The chemical and petrochemical sector relies on fossil fuels and feedstocks, and is a major source of carbon dioxide (CO2) emissions. The techno-economic potential of 20 decarbonisation options is assessed. While previous analyses focus on the production processes, this analysis covers the full product life cycle CO2 emissions. The analysis elaborates the carbon accounting complexity that results from the non-energy use of fossil fuels, and highlights the importance of strategies that consider the carbon stored in synthetic organic products—an aspect that warrants more attention in long-term energy scenarios and strategies. Average mitigation costs in the sector would amount to 64 United States dollars (USD) per tonne of CO2 for full decarbonisation in 2050. The rapidly declining renewables cost is one main cause for this low-cost estimate. Renewable energy supply solutions, in combination with electrification, account for 40% of total emissions reductions. Annual biomass use grows to 1.3 gigatonnes; green hydrogen electrolyser capacity grows to 2435 gigawatts and recycling rates increase six-fold, while product demand is reduced by a third, compared to the reference case. CO2 capture, storage and use equals 30% of the total decarbonisation effort (1.49 gigatonnes per year), where about one-third of the captured CO2 is of biogenic origin. Circular economy concepts, including recycling, account for 16%, while energy efficiency accounts for 12% of the decarbonisation needed. Achieving full decarbonisation in this sector will increase energy and feedstock costs by more than 35%. The analysis shows the importance of renewables-based solutions, accounting for more than half of the total emissions reduction potential, which was higher than previous estimates.</jats:p>

Justin Kramer, Anjaneyulu Krothapalli, Brenton Greska

ASME 2007 Energy Sustainability Conference • 2007

<jats:p>This paper deals with the Off-Grid Zero Emissions Building (OGZEB), a project undertaken by the Sustainable Energy Science &amp; Engineering Center (SESEC) at Florida State University (FSU). The project involves the design, construction and operation of a completely solar-powered building that achieves LEED-NC (Leadership in Energy and Environment Design-New Construction) platinum certification. The resulting 1000 square foot building will be partitioned such that 750 square feet will be a two bedroom, graduate student style flat with the remaining 250 square feet serving as office space. This arrangement will allow the building to serve as an energy efficient model for campus designers in student living and office space. The building will also serve as a prototype for developing and implementing cutting edge, alternative energy technologies in both residential and commercial settings. For example, hydrogen will be used extensively in meeting the energy needs of the OGZEB. In lieu of high efficiency batteries, the excess electricity produced by the building’s photovoltaic (PV) panels will be used to generate hydrogen via water electrolysis. The hydrogen will be stored on-site until needed for either generating electricity in a Proton Exchange Membrane (PEM) fuel cell stack or combusted in natural gas appliances that have been modified for hydrogen use. Although commercial variants already exist, a highly efficient water electrolysis device and innovative PEM fuel cell are currently under development at SESEC and both will be implemented into the OGZEB. The use of hydrogen in modified natural gas appliances, such as an on-demand hot water heater and cook top, is unique to the OGZEB.</jats:p>

Mikko Pihlatie, Mikaela Ranta, Pekka Rahkola et al.

• 0

<jats:p>Zero-emission trucks for regional and long haul missions are an option for fossil-free freight. The viability of such powertrains and system solutions was studied conceptually in project ESCALATE for trucks with GVW of 40 tonnes and beyond through various prime mover combinations. The study covers battery and fuel cell power sources with different degrees of battery electric as well as H2 and fuel cell operation. As a design basis, two different missions with a single-charge/H2 refill were analysed. The first mission was the VECTO long haul profile repeated up to 750 km, whereas the second was a real 520 km on-road mission in Finland. Based on the simulated energy consumption on the driving cycle, on-board energy demand was estimated, and the initial single-charge operational scenarios were analysed with five different power source topologies. The traction motors of the tractor were dimensioned so that a secondary mission of GVW up to 76 tons on a shorter route can be operated. Based on the powertrain and vehicle model, various infrastructure options for charging and H2 refuelling strategy as well as various operative scenarios with indicative total cost of ownership (TCO) were analysed.</jats:p>

Piotr F. Borowski, Barbara Karlikowska

Energies • 0

<jats:p>Hydrogen can be considered an innovative fuel that will revolutionize the energy sector and enable even more complete use of the potential of renewable sources. The aim of the paper is to present the challenges faced by companies and economies that will produce and use hydrogen. Thanks to the use of hydrogen in the energy, transport and construction sectors, it will be possible to achieve climate neutrality by 2050. By 2050, global demand for hydrogen will increase to 614 million metric tons a year, and thanks to the use of hydrogen in energy, transport and construction, it will be possible to achieve climate neutrality. Depending on the method of hydrogen production, the processes used and the final effects, several groups can be distinguished, marked with different colors. It is in this area of obtaining friendly hydrogen that innovative possibilities for its production open up. The costs of hydrogen production are also affected by network fees, national tax systems, availability and prices of carbon capture, utilization, and storage installations, energy consumption rates by electrolyzers and transport methods. It is planned that 1 kg of hydrogen will cost USD 1. The study used the desk research method, which made it possible to analyze a huge amount of descriptive data and numerical data.</jats:p>

Modeste Kameni Nematchoua, Sigrid Reiter

Zero-Energy Buildings - New Approaches and Technologies • 0

<jats:p>The buildings respecting the concept “Net Zero energy” are becoming more and more flowering in the world these last years. The main goal of this research is to evaluate the different possibilities of implementation of buildings with Net zero energy and low environmental impacts in Sub-Saharan Africa. The proposed building is 80% made of local materials with low carbon emissions and especially at lower cost. The optimization and modeling of the building is carried out by the Design Builder software, which is a world-renowned software in the field of optimization of comfort, cost, carbon reduction, etc. By fixing the insulation thickness up to 11 cm, cooling and heating energy are found equal to zero during the different operating seasons in this residential building. The results show that the optimal solution to consider a net zero energy building in Antananarivo city requires an additional expense estimated at 40% of the cost of buildings more conventional encountered in the island. This will save $475 each year starting in 2030, with 99% reduction in the CO2 release. The choice of local materials with low conductivity, low emissions, and low cost, has a significant impact on the implementation of a sustainable building, and more adapted to climate change concept.</jats:p>

Shah Ali Adnan, Akanksha .

ADHYAYAN: A JOURNAL OF MANAGEMENT SCIENCES • 0

<jats:p>Every other day we hear about environmental and climate issues and the effect of global warming or carbon emission. Many companies are shifting their concerns from making profits to making sustainable profits. The idea of saving the environment has propelled many start-ups also. Organizations worldwide are concerned about the consequences of wasting natural resources and trying their best to find a solution as soon as possible. The Paris Agreement and the Net Zero Coalition are some of the treaties the UN organization is trying to implement. The problem is that some people are ignoring climate change altogether or still think this is not a big concern. So, this article answers the following questions: what is net zero or net zero emission, how does it create an impact on our lives, and what, as an individual, do we could do about it?</jats:p>

A. Sharma

Water Science and Technology • 2003

<jats:p>Innovative application of a systematic approach to reduce freshwater intake and achieve zero emissions could help in reducing the adverse impact of industrial activity on world water resources. Cleantech is a strategic enviro-management technique to reduce the generation of pollutants in a process at source, through minor process modification, material substitution, improved manufacturing practices or low cost treatment.</jats:p>

Devi Bühler, Thorsten Schuetze, Ranka Junge

Sustainability • 0

<jats:p>The operation of so-called Zero Emission Buildings (ZEB) does not result in harmful emissions to water, soil and air. In contrast, ZEBs produce energy, water and resources. Therefore, the definition of ZEBs in this paper goes well beyond the definition of (Net) Zero Energy Buildings, which focuses primarily on greenhouse gas emissions resulting from the combustion of fossil fuels. The concept of ZEB is based on the decentralization of urban infrastructure systems on the building level. The aim is to avoid environmental impacts during the building operation through sustainable production, management, consumption, and recycling of resources. In order to facilitate an easy evaluation of ZEBs a ZEB assessment tool needed to be developed. This paper discusses the development of the general framework, the assessment method, and the ZEB Assessment Tool (ZEBAT), which facilitates the evaluation of the environmental performance of potential ZEBs. The exemplary evaluation of selected case studies from Switzerland and South Korea illustrates the method and the practicability of the ZEBAT for the evaluation of potential ZEBs. The holistic integration of environmental performance factors and their specific environmental impacts facilitates the successful application of the ZEBAT independently from the specific use of a building and its geographical location.</jats:p>

M. E. M. Hassouna, Marzooka Shaban Abdel‐Tawab, Adel Ahmed Mohamed Abdel‐Aleem

Environmental Quality Management • 2024

Phenol bioremediation was investigated using two bacteria (primarily cocci) Dermacoccus nishinomiyaensis, Kocuria rosea strains and the one actinomycetes Nocardiopsis lucentensis which were isolated from samples of activated sludge from the wastewater treatment plant (WWTP) in Beni‐Suef, Egypt as sole carbon and energy sources. This was applied on real industrial wastewater sample taken from Ul HAWA textile plant, Middle Egypt. Degradation of phenol by microbes adsorbed on natural kaolin clay was studied compared with free microbes. In case of 50 mg/L as starting phenol concentration, the percentage removal using free microbes was 68%, corresponding to 98% in case of microbes adsorbed on kaolin clay after the passage of 48 h under incubation at 30°C and neutral pH at 150 rpm. Also, 300 mg/L of phenol achieved degradation frequency of 80% compared to 38% after ≈48 h without clay addition. High concentrations of an organic pollutant are usually inhibitory for the microorganisms. Kaolin clay has a pronounced effect in accelerating phenol degradation through biofilm formation resulting in decreasing the degradation time, increasing the percentage of removing efficiency under high phenol concentration conditions due to its buffering effects on pH fluctuations of the degradation system. Kaolin clay protects microorganisms against unfavorable environment, resists the adverse effects of substrate inhibition and accelerates the degradation process. The adsorption process was demonstrated by the pseudo‐first‐order, pseudo‐second‐order, Weber–Morris adsorption kinetic models, and four isotherm models namely, Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich have been applied to express the adsorption process. The SEM images of microbes adsorbed on kaolin clay explain their adsorption mode on the clay surface as biofilm (Bio kaolinite).

María E. Alcamán-Arias, C. Pedrós-Alió, J. Tamames et al.

Frontiers in Microbiology • 2018

Composition, carbon and nitrogen uptake, and gene transcription of microbial mat communities in Porcelana neutral hot spring (Northern Chilean Patagonia) were analyzed using metagenomics, metatranscriptomics and isotopically labeled carbon (H13CO3) and nitrogen (15NH4Cl and K15NO3) assimilation rates. The microbial mat community included 31 phyla, of which only Cyanobacteria and Chloroflexi were dominant. At 58°C both phyla co-occurred, with similar contributions in relative abundances in metagenomes and total transcriptional activity. At 66°C, filamentous anoxygenic phototrophic Chloroflexi were >90% responsible for the total transcriptional activity recovered, while Cyanobacteria contributed most metagenomics and metatranscriptomics reads at 48°C. According to such reads, phototrophy was carried out both through oxygenic photosynthesis by Cyanobacteria (mostly Mastigocladus) and anoxygenic phototrophy due mainly to Chloroflexi. Inorganic carbon assimilation through the Calvin–Benson cycle was almost exclusively due to Mastigocladus, which was the main primary producer at lower temperatures. Two other CO2 fixation pathways were active at certain times and temperatures as indicated by transcripts: 3-hydroxypropionate (3-HP) bi-cycle due to Chloroflexi and 3-hydroxypropionate-4-hydroxybutyrate (HH) cycle carried out by Thaumarchaeota. The active transcription of the genes involved in these C-fixation pathways correlated with high in situ determined carbon fixation rates. In situ measurements of ammonia assimilation and nitrogen fixation (exclusively attributed to Cyanobacteria and mostly to Mastigocladus sp.) showed these were the most important nitrogen acquisition pathways at 58 and 48°C. At 66°C ammonia oxidation genes were actively transcribed (mostly due to Thaumarchaeota). Reads indicated that denitrification was present as a nitrogen sink at all temperatures and that dissimilatory nitrate reduction to ammonia (DNRA) contributed very little. The combination of metagenomic and metatranscriptomic analysis with in situ assimilation rates, allowed the reconstruction of day and night carbon and nitrogen assimilation pathways together with the contribution of keystone microorganisms in this natural hot spring microbial mat.

Haobo Ya, Tian-Shu Zhang, Yi Xing et al.

• 2023

Microplastics are plastic particles with particle size less than 5 mm in the environment. As an emerging organic pollutant, the presence of microplastics in the soil environment has been widely noticed. Secondly, due to the overuse of antibiotics, a large amount of antibiotics that cannot be fully absorbed by humans and livestock enter the soil environment in the form of urine or manure, making the soil suffer from serious antibiotic contamination problems. To address the environmental problems of microplastics and antibiotic contamination in soil, this study was conducted to investigate the effects of PE microplastics on antibiotic degradation, microbial community characteristics and ARGs in tetracycline-contaminated soils. The results showed that the addition of PE microplastics inhibited the degradation of tetracycline, and significantly increased the organic carbon content and decreased the neutral phosphatase activity. The addition of PE microplastics significantly reduced the alpha diversity of soil microbial community. Compared to the single tetracycline contamination. In addition, combined contamination with PE microplastics and tetracycline significantly affected bacterial genera such as Aeromicrobium, Rhodococcus, Mycobacterium and Intrasporangium. Metagenome sequencing studies revealed that the addition of PE microplastics inhibited the dissipation of ARGs in tetracycline-contaminated soils. There were strong positive correlations between Multidrug, Aminoglycoside and Clycopeptide resistance genes and Chloroflexi and Proteobacteria in tetracycline contaminated soils, and there was a strong positive correlation between Aminoglycoside resistance genes and Actinobacteria in combined contamination of PE microplastics and tetracycline. This study will provide some data support for the current environmental risk assessment of the coexistence of multiple contaminants in soil.

Anjali Chandrol Solanki, N. Gurjar, Satish Sharma et al.

Frontiers in Microbiology • 2024

In dry deciduous tropical forests, both seasons (winter and summer) offer habitats that are essential ecologically. How these seasonal changes affect soil properties and microbial communities is not yet fully understood. This study aimed to investigate the influence of seasonal fluctuations on soil characteristics and microbial populations. The soil moisture content dramatically increases in the summer. However, the soil pH only gradually shifts from acidic to slightly neutral. During the summer, electrical conductivity (EC) values range from 0.62 to 1.03 ds m-1, in contrast to their decline in the winter. The levels of soil macronutrients and micronutrients increase during the summer, as does the quantity of soil organic carbon (SOC). A two-way ANOVA analysis reveals limited impacts of seasonal fluctuations and specific geographic locations on the amounts of accessible nitrogen (N) and phosphorus (P). Moreover, dehydrogenase, nitrate reductase, and urease activities rise in the summer, while chitinase, protease, and acid phosphatase activities are more pronounced in the winter. The soil microbes were identified in both seasons through 16S rRNA and ITS (Internal Transcribed Spacer) gene sequencing. Results revealed Proteobacteria and Ascomycota as predominant bacterial and fungal phyla. However, Bacillus, Pseudomonas, and Burkholderia are dominant bacterial genera, and Aspergillus, Alternaria, and Trichoderma are dominant fungal genera in the forest soil samples. Dominant bacterial and fungal genera may play a role in essential ecosystem services such as soil health management and nutrient cycling. In both seasons, clear relationships exist between soil properties, including pH, moisture, iron (Fe), zinc (Zn), and microbial diversity. Enzymatic activities and microbial shift relate positively with soil parameters. This study highlights robust soil-microbial interactions that persist mainly in the top layers of tropical dry deciduous forests in the summer and winter seasons. It provides insights into the responses of soil-microbial communities to seasonal changes, advancing our understanding of ecosystem dynamics and biodiversity preservation.

Kriangsak Ketpang, A. Boonkitkoson, Nattawan Pitipuech et al.

E3S Web of Conferences • 2020

The major technical obstacles in commercialization of microbial fuel cell technology are the sluggish kinetic, high cost, and poor durability of an air cathode electrocatalyst. This research aimed to synthesize the highly active, stable and low cost non-precious metal catalyst to replace the expensive Pt electrocatalyst using a simple, low cost and scalable method. The Fe3C and Fe-N-C catalysts were prepared by direct heating the precursors under autogenic pressure conditions. X-ray diffraction pattern revealed the phase of Fe3C sample was cohenite Fe3C and graphitic carbon, while the phase of Fe-N-C catalyst was only graphitic carbon. The morphology of the synthesized catalysts was a highly porous structure with nanoparticle morphology. The surface area of the Fe3C and the Fe-N-C catalysts was 295 and 377 m2 g-1, respectively. The oxygen reduction reaction (ORR) activity of Fe-N-C catalyst was more active than Fe3C catalyst. The ORR performance of Fe-N-C catalyst exhibited about 1.6 times more superior to that of the noble Pt/C catalyst. In addition, the Fe-N-C catalyst was durable to operate under neutral media. Thus, a novel autogenic pressure technique was a promising method to effectively prepare an highly active and durable non-precious metal catalyst to replace the precious Pt/C catalyst.

A. Mentges, C. Deutsch, C. Feenders et al.

Frontiers in Marine Science • 2020

Dissolved organic carbon (DOC) forms one of the largest active organic carbon reservoirs on Earth and reaches average radiocarbon ages of several thousand years. Many previous large scale DOC models assume different lability classes (labile to refractory) with prescribed, globally constant decay rates. In contrast, we assume that all DOC compounds are equally degradable by a heterotrophic microbial community. Based on this central assumption, we simulate DOC concentrations using a simple biogeochemical box model. Parameterized correctly, the simple model of neutral DOC uptake produced a recalcitrant carbon pool of 33 mmolC/m3, throughout the entire virtual ocean. The spatial distribution of DOC in the model was independent of the distribution of DOC sources from primary production and particle degradation. Instead, DOC concentrations were primarily driven by spatial gradients in microbial physiology, e.g., mortality rate or growth efficiency. Applying such a gradient, we find DOC concentrations of ~70 mmolC/m3 at the surface and ~35 mmolC/m3 in the deep ocean. Introducing model variations, such as seasonally-varying supply rates or temperature-dependent DOC uptake did not significantly alter model results. DOC spatial patterns are thus not necessarily shaped by the co-cycling of separate reactivity fractions, but can also arise from gradients in physiological parameters determining DOC uptake. We conclude that neutral DOC uptake can lead to realistic large-scale patterns of DOC concentration in the ocean.

S. B. Jilani, Daniel G. Olson

Microbial Cell Factories • 2023

Lignocellulosic biomass represents a carbon neutral cheap and versatile source of carbon which can be converted to biofuels. A pretreatment step is frequently used to make the lignocellulosic carbon bioavailable for microbial metabolism. Dilute acid pretreatment at high temperature and pressure is commonly utilized to efficiently solubilize the pentose fraction by hydrolyzing the hemicellulose fibers and the process results in formation of furans—furfural and 5-hydroxymethyl furfural—and other inhibitors which are detrimental to metabolism. The presence of inhibitors in the medium reduce productivity of microbial biocatalysts and result in increased production costs. Furfural is the key furan inhibitor which acts synergistically along with other inhibitors present in the hydrolysate. In this review, the mode of furfural toxicity on microbial metabolism and metabolic strategies to increase tolerance is discussed. Shared cellular targets between furfural and acetic acid are compared followed by discussing further strategies to engineer tolerance. Finally, the possibility to use furfural as a model inhibitor of dilute acid pretreated lignocellulosic hydrolysate is discussed. The furfural tolerant strains will harbor an efficient lignocellulosic carbon to pyruvate conversion mechanism in presence of stressors in the medium. The pyruvate can be channeled to any metabolite of interest by appropriate modulation of downstream pathway of interest. The aim of this review is to emphasize the use of hydrolysate as a carbon source for bioproduction of biofuels and other compounds of industrial importance.

H. Seelajaroen, M. Haberbauer, Christine Hemmelmair et al.

ChemBioChem • 2019

Microbial electrosynthetic cells containing Methylobacterium extorquens were studied for the reduction of CO2 to formate by direct electron injection and redox mediator‐assisted approaches, with CO2 as the sole carbon source. The formation of a biofilm on a carbon felt (CF) electrode was achieved while applying a constant potential of −0.75 V versus Ag/AgCl under CO2‐saturated conditions. During the biofilm growth period, continuous H2 evolution was observed. The long‐term performance for CO2 reduction of the biofilm with and without neutral red as a redox mediator was studied by an applied potential of −0.75 V versus Ag/AgCl. The neutral red was introduced into the systems in two different ways: homogeneous (dissolved in solution) and heterogeneous (electropolymerized onto the working electrode). The heterogeneous approach was investigated in the microbial system, for the first time, where the CF working electrode was coated with poly(neutral red) by the oxidative electropolymerization thereof. The formation of poly(neutral red) was characterized by spectroscopic techniques. During long‐term electrolysis up to 17 weeks, the formation of formate was observed continuously with an average Faradaic efficiency of 4 %. With the contribution of neutral red, higher formate accumulation was observed. Moreover, the microbial electrosynthetic cell was characterized by means of electrochemical impedance spectroscopy to obtain more information on the CO2 reduction mechanism.

A. Mentges, C. Feenders, C. Deutsch et al.

Scientific Reports • 2019

Dissolved organic carbon (DOC) is the main energy source for marine heterotrophic microorganisms, but a small fraction of DOC resists microbial degradation and accumulates in the ocean. The reason behind this recalcitrance is unknown. We test whether the long-term stability of DOC requires the existence of structurally refractory molecules, using a mechanistic model comprising a diverse network of microbe-substrate interactions. Model experiments reproduce three salient observations, even when all DOC compounds are equally degradable: (i) >15% of an initial DOC pulse resists degradation, but is consumed by microbes if concentrated, (ii) the modelled deep-sea DOC reaches stable concentrations of 30–40 mmolC/m3, and (iii) the mean age of deep-sea DOC is several times the age of deep water with a wide range from <100 to >10,000 years. We conclude that while structurally-recalcitrant molecules exist, they are not required in the model to explain either the amount or longevity of DOC.

Y. Asensio, C. Fernández-Marchante, J. Villaseñor et al.

Journal of Chemical Technology &amp; Biotechnology • 2018

BACKGROUND This work compares the performance of three stacked Microbial Fuel Cells constructed with different number of single-MFC (MFC1 with two stacked-MFCs, MFC2 with ten stacked-MFCs and MFC3 with twenty stacked-MFCs), and operated under the same conditions for one month. RESULTS According to results, algae suspensions can be used as fuel of MFC-stacks, although current efficiencies obtained are low. In comparing the effect of number of cells stacked on the performance of the stacks, it was found that the higher the number of cells stacked, the higher was the energy harvested from algae. However, because of the very efficient consumption of COD in the first MFC of the stacks (not only by electrogenic but also by non-electrogenic microorganisms) and the sequential circulation of the fuel through the different cells of the stack, in all cases the systems were run out of fuel and this was reflected in a lower production of electricity, as compared to that expected taking into account the number of cells stacked. Results obtained from the polarization curves and the cathodic oxygen consumption also support this explanation. CONCLUSIONS Results demonstrate that algal biomass is a suitable fuel for energy generation using MFC technology and provides microorganisms not only of a carbon source but also with the required nutrients. However, the low coulombic efficiencies obtained in the three stacks indicate that feeding algae to MFC also promotes the formation of an important amount of non-electrogenic microorganisms that compete successfully with bioelectrogenic microorganisms for the substrate provided.

Haoming Ning, Zhi Zhang, C. Shi et al.

RSC Advances • 2022

In this study, Fe/N codoped porous graphitic carbon derived from macadamia shells was prepared at different temperatures as cathodic catalysts for microbial fuel cells (MFCs), with K2FeO4 as a bifunctional catalyst for porosity and graphitization. The catalyst prepared at 750 °C (referred to as MSAC-750) showed a large specific surface area (1670.3 m2 g−1), graphite structure, and high pyridine-N and Fe-NX contents. Through the electrochemical workstation test, MSAC-750 shows excellent oxygen reduction reaction (ORR) activity, with an onset potential of 0.172 V and a half-wave potential of −0.028 V (vs. Ag/AgCl) in a neutral medium, and the ORR electron transfer number is 3.89. When applied to the MFCs as cathodic catalysts, a higher maximum power density and voltage of 378.68 mW m−2 and 0.425 V were achieved with the MSAC-750 catalyst and is superior to that of the Pt/C catalyst (300.85 mW m−2 and 0.402 V). In this case, a promising method is hereby established for the preparation of an excellent electrochemical catalyst for microbial fuel cells using inexpensive and easily available macadamia shells.

A. Malik, J. Puissant, Kate M. Buckeridge et al.

Nature Communications • 2018

Soil microorganisms act as gatekeepers for soil–atmosphere carbon exchange by balancing the accumulation and release of soil organic matter. However, poor understanding of the mechanisms responsible hinders the development of effective land management strategies to enhance soil carbon storage. Here we empirically test the link between microbial ecophysiological traits and topsoil carbon content across geographically distributed soils and land use contrasts. We discovered distinct pH controls on microbial mechanisms of carbon accumulation. Land use intensification in low-pH soils that increased the pH above a threshold (~6.2) leads to carbon loss through increased decomposition, following alleviation of acid retardation of microbial growth. However, loss of carbon with intensification in near-neutral pH soils was linked to decreased microbial biomass and reduced growth efficiency that was, in turn, related to trade-offs with stress alleviation and resource acquisition. Thus, less-intensive management practices in near-neutral pH soils have more potential for carbon storage through increased microbial growth efficiency, whereas in acidic soils, microbial growth is a bigger constraint on decomposition rates. Land use intensification could modify microbial activity and thus ecosystem function. Here, Malik et al. sample microbes and carbon-related functions across a land use gradient, demonstrating that microbial biomass and carbon use efficiency are reduced in human-impacted near-neutral pH soils.

H. Seelajaroen, S. Spiess, M. Haberbauer et al.

Sustainable Energy &amp; Fuels • 2020

Microbial electrolysis cells (MECs) consisting of a bioanode and biocathode offer a promising solution for wastewater treatment. These systems can degrade organic substances at the bioanode while converting carbon dioxide (CO2), a major greenhouse gas, to a value-added fuel, methane (CH4) at the biocathode. The bioelectrodes were inoculated with a mixed culture under anaerobic conditions. By applying a constant potential of 0.40 V vs. Ag/AgCl (3 M NaCl), the long-term performance of MECs has been studied by monitoring the removal of chemical oxygen demand (COD) in the anolyte which contained synthetic wastewater and CH4 generation in the cathode chamber. To investigate the effect of electrode modification, poly(neutral red) and chitosan modified carbon felt electrodes were prepared, and applied in MECs. The results revealed that MECs with modified electrodes showed remarkably enhanced overall performance. The average COD removal efficiency, faradaic efficiency towards CO2 reduction to CH4 and CH4 production yield of modified MECs were up to 67%, 55% and 0.14 LCH4/gCOD, respectively.

Zhihui Shi, Zhaoyu Xu, Weihe Rong et al.

Nature Communications • 2025

Starch is a primary food ingredient and industrial feedstock. Low-carbon microbial manufacturing offers a carbon-neutral/negative arable land-independent strategy for starch production. Here, we reconfigure the oleaginous yeast as a starch-rich micro-grain producer by rewiring the starch biosynthesis and gluconeogenesis pathways and regulating cell morphology. With the CO2 electro-synthesized acetate as the substrate, the strain accumulates starch 47.18% of dry cell weight. The optimized system renders spatial-temporal starch productivity (243.7 g/m2/d) approximately 50-fold higher than crop cultivation and volumetric productivity (160.83 mg/L/h) over other microbial systems by an order of magnitude. We demonstrate tunable starch composition and starch-protein ratios via strain and process engineering. The engineered artificial strains adopt a cellular resources reallocation strategy to ensure high-level starch production in micro-grain and could facilitate a highly efficient straw/cellulose-to-starch conversion. This work elucidates starch biosynthesis machinery and establishes a superior-to-nature platform for customizable starch synthesis, advancing low-carbon nutritional manufacturing.

Hanaa M. Sabaa, K. El-Khatib, M. El-kady et al.

Journal of Solid State Electrochemistry • 2022

For more sustainability and marketing of microbial fuel cells (MFCs) in wastewater treatment, the sluggish kinetics of cathode oxygen reduction reaction (ORR) and platinum scarcity (with its high cost) should be swept away. So, this work aimed to synthesize metal ferrite (MFe2O4; M = Mn, Cu, and Ni) -based activated carbon composites as inexpensive ORR cathode catalysts. The composites were synthesized using a facile modified co-precipitation approach with low-thermal treatment and labeled as MnFe2O4/AC, CuFe2O4/AC, and NiFe2O4/AC. The as-synthesized catalysts are physicochemically characterized by X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared microscopy (FTIR), Barrett-Joyner-Halenda (BJH), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), and electron spin resonance (ESR). The electrochemical catalytic performance toward ORR was studied in a phosphate buffer solution (PBS) at neutral media via cyclic voltammetry (CV) and linear sweep voltammetry (LSV). MnFe2O4/AC has the highest onset potential (Eonset) value of − 0.223 V compared to CuFe2O4/AC (− 0.280 V) and NiFe2O4/AC (− 0.270 V). MnFe2O4/AC also has the highest kinetic current density (jK) and lowest Tafel slope (− 5 mA cm−2 and − 330 mV dec−1) compared to CuFe2O4/AC (− 3.05 mA cm−2 and − 577 mV dec−1) and NiFe2O4/AC (− 2.67 mA cm−2 and − 414 mV dec−1). The ORR catalyzed by MnFe2O4/AC at pH = 7 proceeds via a 4e− -kinetic pathway. The ESR is in good agreement with the electrochemical analysis due to the highest ∆Hppvalue for MnFe2O4/AC compared to CuFe2O4/AC and NiFe2O4/AC. Thus, MnFe2O4/AC is suggested as a promising alternative to Pt- electrocatalyst cathode for MFCs at neutral conditions.

Bi-Lin Lai, Hui Wei, Zirong Luo et al.

SSRN Electronic Journal • 2022

The development of bifunctional catalysts is an effective way to simultaneously address the slow kinetics of oxygen reduction reaction (ORR) on the cathode and biofilm contamination in the microbial fuel cells (MFC). Cu-N/C@Cu composites were synthesized as bifunctional cathode catalysts for MFC by doping, adsorption, and two calcinations by using Cu-ZIF-8 as the precursor. The higher Cu-Nx content confers excellent ORR catalytic activity to the optimized Cu-N/C@Cu-2 catalyst. The half-wave potential for Cu-N/C@Cu-2 in a neutral solution is 0.67 V vs. RHE, which is close to that of commercial 20 % Pt/C (0.70 V vs. RHE). The maximum power density of the MFCs assembled with Cu-N/C@Cu-2 reached 581 ± 13 mW m-2, which is even better than that using Pt/C (499 ± 13 mW m-2). Moreover, the results of antimicrobial activity and biomass test show that the higher Cu content made Cu-N/C@Cu-2 effective against the contamination of cathode biofilm. And the 16 s rDNA results find that the community structure of the biofilm is favorable for the power production and purification of MFC. This work shows that copper-based materials can be used as potential bifunctional catalysts to promote MFC applications in wastewater treatment.

Orpheus M. Butler, S. Manzoni, C. Warren

The ISME Journal • 2023

Many microorganisms synthesise carbon (C)-rich compounds under resource deprivation. Such compounds likely serve as intracellular C-storage pools that sustain the activities of microorganisms growing on stoichiometrically imbalanced substrates, making them potentially vital to the function of ecosystems on infertile soils. We examined the dynamics and drivers of three putative C-storage compounds (neutral lipid fatty acids [NLFAs], polyhydroxybutyrate [PHB], and trehalose) across a natural gradient of soil fertility in eastern Australia. Together, NLFAs, PHB, and trehalose corresponded to 8.5–40% of microbial C and 0.06–0.6% of soil organic C. When scaled to “structural” microbial biomass (indexed by polar lipid fatty acids; PLFAs), NLFA and PHB allocation was 2–3-times greater in infertile soils derived from ironstone and sandstone than in comparatively fertile basalt- and shale-derived soils. PHB allocation was positively correlated with belowground biological phosphorus (P)-demand, while NLFA allocation was positively correlated with fungal PLFA : bacterial PLFA ratios. A complementary incubation revealed positive responses of respiration, storage, and fungal PLFAs to glucose, while bacterial PLFAs responded positively to PO_4^3-. By comparing these results to a model of microbial C-allocation, we reason that NLFA primarily served the “reserve” storage mode for C-limited taxa (i.e., fungi), while the variable portion of PHB likely served as “surplus” C-storage for P-limited bacteria. Thus, our findings reveal a convergence of community-level processes (i.e., changes in taxonomic composition that underpin reserve-mode storage dynamics) and intracellular mechanisms (e.g., physiological plasticity of surplus-mode storage) that drives strong, predictable community-level microbial C-storage dynamics across gradients of soil fertility and substrate stoichiometry.

Yang Lei, Danlian Huang, Wei Zhou et al.

Critical Reviews in Environmental Science and Technology • 2023

Abstract Using carbon-based materials (CBMs) to facilitate phytoremediation shows great promise for simultaneously enhancing the restoration efficiency of contaminated soil and reducing carbon dioxide in the context of global warming, which is still in the exploring and attempting phase. In addition to direct degradation or alteration of pollutant bioavailability, CBMs can enhance phytoremediation by alleviating plant nutrient deprivation and oxidative stress, as well as by modulating soil microbial communities and root secretions. Photosynthetic carbon fixation predominantly affects both phytoremediation efficiency and carbon cycle turnover in terrestrial ecosystems. In this regard, CBMs have extremely positive properties in facilitating plant carbon capture, with intrinsic mechanisms including (1) promoting photosynthetic pigment synthesis and acting as artificial built-in antennae to improve photon capture efficiency, (2) accelerating the photosynthetic electron transport rate in photosystems, (3) improving the Calvin cycle, and (4) maintaining the structural integrity of chloroplasts. Besides, as an ultra-stable type of CBM derived from waste biomass, biochar can preserve the native biomass carbon in the soil environment for decades and attenuate the rhizosphere priming effect by influencing the structure of rhizosphere soil aggregates and microbial communities, thus retarding the native soil organic carbon efflux. This review critically elaborates on the mechanisms by which CBMs assist in improving the efficiency of phytoremediation and their positive effects on the plant-root soil carbon balance. Additionally, a simple full-life cycle analysis encompassing cost analysis as well as ecological, economic, and social benefits is concluded to evaluate the feasibility and sustainability of CBMs-phytoremediation systems. Graphical Abstract