Carbon Energy Sources Research Articles

System Modeling-Based Investigation of SMR Operations Using Variable T-avg Control for Cost-Effective Electricity Generation in a Grid

Given the importance of nuclear power as low carbon energy source, this study conducted techno-economic evaluation of flexible use (baseload as well as load-following) of small modular reactors (SMRs) in an electric grid. The load-following operation of SMR (SMART-100) was restricted to the use of variable T-avg control, a least disruptive and cost minimizing method of load follow control. A system model was developed to describe the reactivity feedback effects of coolant temperature variations due to electric demand-based turbine load changes. Using the system model, conservative output ranges and maximum ramp rates that allow load-following operation without violating axial offset limits were derived. Assuming the introduction of SMR in Jeju Island in South Korea, a semi-independent grid region, with highly dependency on fossil fuel energy and power imports along with significant renewable energy generation (15–20 %), as a test case, this study evaluated the economic contribution of SMR using LPM to minimize the grid electricity generation costs. The results indicate that in regions with a high penetration of renewable energy in their grid systems, flexible energy generation of SMR can make a significant contribution in reducing electricity generation cost and carbon emissions.

Screening and characterization of integration sites based on CRISPR-Cpf1 in Pichia pastoris

Pichia pastoris, a methylotrophic yeast, can utilize methanol as a carbon source and energy source to synthesize high-value chemicals, and is an ideal host for biomanufacturing. Constructing the P. pastoris cell factory is somewhat impeded due to the absence of genetic tools for manipulating multi-gene biosynthetic pathways. To broaden its application in the field of metabolic engineering, this study identified and screened 15 novel integration sites in P. pastoris using CRISPR-Cpf1 genome editing technology, with EGFP serving the reporter protein. These integration sites have integration efficiencies of 10–100 % and varying expression strengths, which allow for selection based on the expression levels of genes as needed. Additionally, these integrated sites are applied in the heterologous biosynthesis of P. pastoris, such as the astaxanthin biosynthetic pathway and the carbon dioxide fixation pathway of the Calvin-Benson-Bassham (CBB) cycle. During the three-site integration process, the 8 genes of the CBB cycle were integrated into the genome of P. pastoris. This indicates the potential of these integration sites for integrating large fragments and suggests their successful application in metabolic engineering of P. pastoris. This may lead to improved efficiency of genetic engineering in P. pastoris.

Oxygen-enriched carbon molecular sieve hollow fiber membrane for efficient CO2 removal from natural gas

Natural gas is considered one of the most attractive low carbon energy sources while the separation of CO2 is a crucial process for the natural gas purification. Herein, cellulose-based carbon molecular sieve (CMS) hollow fiber membranes with high CO2 affinity capability were fabricated through a post-treatment strategy of hydrogen-induced reduction followed by oxygen-doped modification (H-O treatment), and show good potential for high pressure natural gas purification. The CMS membranes were reduced by H2 at high temperatures (500–600 °C) to form active sorption sites in the carbon matrix, and subsequently chemically absorbed O2 to generate oxygen-containing functional groups, which are favorable for CO2 adsorption and diffusion. After being treated at 600 °C (CMS-600), the CMS membrane presented a high CO2 adsorption capacity of 62.78 cm3/g (298 K). As a result, the CO2 permeability was enhanced from 264 to 1125 Barrer, with approximately 400 % improvement. Moreover, mixed gas separation performances (CO2/N2 and CO2/CH4) were investigated at high pressure and impurities feedings. The CMS membrane exhibited a remarkable CO2/CH4 separation factor of 104 when operated at 20 bar and 500 ppm heptane existed.

Biodegradation of Nitrile Gloves as Sole Carbon Source of Pseudomonas aeruginosa in Liquid Culture.

Nitrile gloves have become a significant environmental pollutant after the COVID-19 pandemic due to their single-use design. This study examines the capability of P. aeruginosa to use nitrile gloves as its sole carbon energy source. Biodegradation was determined by P. aeruginosa adapting to increasing nitrile glove concentrations at 1%, 3%, and 5% (w/v). The growth kinetics of P. aeruginosa were evaluated, as well as the polymer weight loss. Topographic changes on the glove surfaces were examined using SEM, and FT-IR was used to evaluate the biodegradation products of the nitrile gloves. Following the establishment of a biofilm on the glove surface, the nitrile toxicity was minimized via biodegradation. The result of the average weight loss of nitrile gloves was 2.25%. FT-IR analysis revealed the presence of aldehydes and aliphatic amines associated with biodegradation. SEM showed P. aeruginosa immersed in the EPS matrix, causing the formation of cracks, scales, protrusions, and the presence of semi-spherical particles. We conclude that P. aeruginosa has the capability to use nitrile gloves as its sole carbon source, even up to 5%, through biofilm formation, demonstrating the potential of P. aeruginosa for the degradation of nitrile gloves.

Planning incapacitated: Environmental planning and the political ecology of austerity

Coal mining in the UK, once central to its political economy, has been in terminal decline for decades for both political and more recently environmental reasons. Against the grain of this decline, the proposal of a new metallurgical coal mine near Whitehaven (on the north west coast of England) has caused significant controversy. Those supporting the mines development say it is necessary to ‘level up’ from the previous decade of austerity, whereas opponents argue that new coal mining would severely undermine the transition to low carbon energy sources. Through a discourse analysis and open-ended interviews, this paper analyses the contestation of the mine through the environmental planning process, identifying how both the discursive contestation and decision-making practices are shaped by political logics (austerity/levelling up) and ecological logics (climate change). The paper finds that, as states turn towards greater levels of public subsidies as a new form of crisis management, the environmental decision-making processes which can determine the shape of investments have been severely undermined through a decade or more of reduced public investment, policy streamlining and a lack of public expertise. The paper argues that even though states may be turning towards policies subsidising energy projects, they are doing so in a context where there is a lack of state capacity due to a ‘political ecology of austerity’, limiting public capacity to plan for a better future.

Technoeconomic and Emissions Analysis of the Hybrid Redox Process for the Production of Acetic Acid with CO2 Utilization

AbstractThe production of oxygenated hydrocarbons, such as acetic acid, using captured CO2 is a promising pathway to reduce greenhouse gas emissions in the chemical industry. The use of a chemical looping‐based hybrid redox process (HRP) is proposed to convert CO2 and natural gas into separate CO and syngas streams that can be used to produce various commodity oxygenates, while allowing the beneficial utilization of captured CO2. Here, a detailed technoeconomic analysis of HRP applied to the production of acetic acid is presented. Emissions and energy analyses show the ability of HRP to lower the CO2 emissions for acetic acid synthesis by 74% compared to a conventional steam and autothermal reforming route. HRP also offers a potential 34% reduction in capital costs. Compared to a dry reforming based acetic acid production route, HRP has the potential for significantly lower costs. If integrated with a low carbon energy source, HRP has the potential to achieve a negative emission of greenhouse gas (‐0.50 kg CO2 per kg acetic acid).

In pursuit of thermal comfort: An exploration of smart heating in everyday life

Smart Home Heating Technologies (SHHT) have been designed to improve demand flexibility and energy conservation. SHHT rely on rational theories of energy use postulating that people will use less energy when the energy cost is higher. The inclusion of AI within SHHT is poised to optimise energy use in the future as the introduction of lower carbon energy sources place new demands on the grid. When SHHT is introduced in the home, however, they become situated in temporal heating practices that are shaped by an interplay of materiality, meanings, and competencies. We report findings from a mixed methods field study involving eleven households utilising an AI-enabled SHHT probe ‘Squid’. Taking a temporal focus throughout, our study contributes a new lens as to why households may not fully engage with SHHT's rational design, given that energy conversation is already embedded in their ongoing socio-material practices with heating. Focusing on the AI-human relation, we articulate the necessity for human agency where heating is involved, whilst also advancing an understanding of the new forms of hidden labour that households incur before they can engage with the AI. Crucially, our research informs the ongoing HCI concern over how humans understand AI, raising the question of who is responsible to assess the appropriateness of AI when the effects of human-AI performance remain opaque. Our findings contribute a new theoretical perspective into the intricate relationship between individuals and AI in the home and raise several new design implications for SHHT.

The effects of crude glycerol addition on biogas production

Crude glycerol is a by-product of biodiesel production in which the number increases every year and is quite an expensive purification process to meet the technical standards required by consumer industries. To overcome this, it is important to find alternatives for crude glycerol utilization to increase the economic feasibility of the biodiesel industry. This study aimed to evaluate the technical feasibility of biogas production with the addition of crude glycerol from a Palm Oil Plant. The glycerol was introduced into 500mL Anaerobic Digester (AD) as a carbon source and energy source for the growth of methanogenic bacteria along with cow dung and Distilled Water with a ratio of 1:1. The addition of crude glycerol was 5% wt (GL5), 10% wt (GL10) dan 15% wt (GL15), and one control reactor without crude glycerol addition (GL0). AD was operated in a batch system at mesophilic conditions for 30 days. The highest biogas yield was obtained in the experimental set GL10 as much as 380 mL/g VS and was formed on the 3rd day but the highest percentage of methane gas (CH4) was obtained from the control set GL0 as much as 60.2%. In addition to the identification of bacteria, it was found that the type of Bacillus sp in the GL10 treatment was the most biogas producer, and based on the results of its bio-slurry analysis it could be used as organic fertilizer and soil improvement for agriculture and degraded soil.

Syngas optimization and tar reduction via multistage catalytic gasification: Effects of catalyst pore, catalyzer stage, and temperature profile

Biomass stands out as a promising availability source of sustainable carbon energy due to its low pollution profile and versatile applications. This study investigates the multistage catalytic gasification (MCG) of coconut shells, employing thermal and catalytic cracking processes in a two-step gasification approach. Local source catalysts, including dolomite, kaolin, and zeolite, were utilized as eco-friendly additives at temperatures ranging from 200 to 300 °C. Zeolite emerged as the most effective catalyst, producing the highest energy content at 6.21 MJ/kg. Conversely, kaolin resulted in higher CO2 emissions. A blend of zeolite and kaolin achieved the highest energy content at 5.43 MJ/kg. However, the combined use of catalysts showed negligible improvements compared to individual catalysts. The study demonstrates that multistage catalytic gasification enhances syngas production and reduces tar content during the gasification of coconut shells. Optimal pyrolysis temperatures were identified within the 500–600 °C range. In conclusion, the introduction of multiple stages in the catalytic cracking process ensures a stable breakdown of hydrocarbon chains, promoting the exposure of gasification products to lighter compounds. Multistage catalytic gasification enhances oxygen supply for oxidation, thereby improving syngas production while mitigating tar and ash content.

In situ community transcriptomics illuminates CO2-fixation potentials and supporting roles of phagotrophy and proton pump in plankton in a subtropical marginal sea.

Lineage-wise physiological activities of plankton communities in the ocean are important but challenging to characterize. Here, we conducted whole-assemblage metatranscriptomic profiling at continental shelf and slope sites in the South China Sea to investigate carbon fixation potential in different lineages. RuBisCO expression, the proxy of Calvin carbon fixation (CCF) potential, was mainly contributed by Bacillariophyta, Chlorophyta, Cyanobacteria, and Haptophyta, which was differentially affected by environmental factors among lineages. CCF potential exhibited positive or negative correlations with phagotrophy gene expression, suggesting phagotrophy possibly enhances or complements CCF. Our data also reveal significant non-Calvin carbon fixation (NCF) potential, as indicated by the active expression of genes in all five currently recognized NCF pathways, mainly contributed by Flavobacteriales, Alteromonadales, and Oceanospirillales. Furthermore, in Flavobacteriales, Alteromonadales, Pelagibacterales, and Rhodobacterales, NCF potential was positively correlated with proton-pump rhodopsin (PPR) expression, suggesting that NCF might be energetically supported by PPR. The novel insights into the lineage-differential potential of carbon fixation, widespread mixotrophy, and PPR as an energy source for NCF lay a methodological and informational foundation for further research to understand carbon fixation and the trophic landscape in the ocean.IMPORTANCEMarine plankton plays an important role in global carbon cycling and climate regulation. Phytoplankton and cyanobacteria fix CO2 to produce organic compounds using solar energy and mainly by the Calvin cycle, whereas autotrophic bacteria and archaea may fix CO2 by non-Calvin cycle carbon fixation pathways. How active individual lineages are in carbon fixation and mixotrophy, and what energy source bacteria may employ in non-Calvin carbon fixation, in a natural plankton assemblage are poorly understood and underexplored. Using metatranscriptomics, we studied carbon fixation in marine plankton with lineage resolution in tropical marginal shelf and slope areas. Based on the sequencing results, we characterized the carbon fixation potential of different lineages and assessed Calvin- and non-Calvin- carbon fixation activities and energy sources. Data revealed a high number of unigenes (4.4 million), lineage-dependent differential potentials of Calvin carbon fixation and responses to environmental conditions, major contributors of non-Calvin carbon fixation, and their potential energy source.

Growth Performance of Tilapia Fed Commercial Feed with Cellulolytic Bacteria from Ruminants

Bacteria have the ability to decompose cellulose into glucose monomers and make it a carbon source and energy source. Cellulolytic bacteria are found in the digestive tract of ruminants. Utilization of cellulolytic bacteria as a producer of cellulase enzymes can be applied to fish to increase feed digestibility so that it can support growth. Cellulolytic bacteria isolated from ruminant were introduced to tilapia through feed. The study used a completely randomized design with four treatments and three replications. A total of 25 tilapia with a length of 10 cm were kept in each aquarium with a capacity of 250 L for 2 mo. During feed maintenance, cellulolytic bacteria were added at a dose of 1 %, 2 %, 3 % and without bacteria as a control. The specific growth rate of tilapia treated with 2 % and 3 % bacteria significantly increased. The feed was more efficiently utilized by tilapia when compared to that without the addition of cellulolytic bacteria or at a dose of 1 %. The amount of feed consumption did not differ between treatments, while the survival rate of tilapia treated with bacteria was significantly higher than without bacteria. Cellulolytic bacteria isolated from the digestive tract of ruminants added to commercial feed significantly improved the growth performance of tilapia.

Novel Phospholipase C with High Catalytic Activity from a Bacillus stearothermophilus Strain: An Ideal Choice for the Oil Degumming Process

A novel thermoactive phosphatidylcholine-specific phospholipase C (PC-PLCBs) was identified from Bacillus stearothermophilus isolated from a soil sample from an olive oil mill. Enhanced PLCBs production was observed after 10 h of incubation at 55 °C in a culture medium containing 1 mM of Zn2+ with an 8% inoculum size and 6 g/L glucose and 4/L yeast extract as the preferred carbon energy and nitrogen sources, respectively. PLCBs was purified to homogeneity by heat treatment, ammonium sulfate fractionation, and anion exchange chromatography, resulting in a purification factor of 17.6 with 39% recovery. Interestingly, this enzyme showed a high specific activity of 8450 U/mg at pH 8–9 and 60 °C, using phosphatidylcholine PC as the substrate, in the presence of 9 mM sodium deoxycholate and 0.4 mM Zn2+. Remarkable stability at acidic and alkali pH and up to 65 °C was also observed. PLCBs displayed a substrate specificity order of phosphatidylcholine > phosphatidylethanolamine > phosphatidylserine > sphingomyelin > phosphatidylinositol > cardiolipin and was classified as a PC-PLC. In contrast to phospholipases C previously isolated from Bacillus strains, this PLCBs substrate specificity was correlated to its hemolytic and anti-bacterial potential against erythrocytes and Gram-positive bacterial membranes, which are rich in glycerophospholipids and cardiolipin. An evaluation of PLCBs soybean degumming process efficiency showed that the purified enzyme reduced the phosphorus content to 35 mg/kg and increased the amount of diacylglycerols released, indicating its ability to hydrolyze phospholipids in the crude soybean oil. Collectively, PLCBs could be considered as a potential catalyst for efficient industrial oil degumming, advancing the edible oil industry by reducing the oil gum volume through transforming non-hydratable phospholipids into their hydratable forms, as well as through generating diacylglycerols, which are miscible with triacylglycerols, thereby reducing losses.

Novel Microfluidic Septum to Optimize Energy Recovery in Single-Chamber Microbial Fuel Cells

This study proposes a redesign of asymmetric single-chamber microbial fuel cells (a-SCMFCs) with the goal of optimizing energy production. In the present work, the new approach is based on the introduction of a novel intermediate microfluidic septum (IMS) inside the electrolyte chamber. This IMS was designed as a relatively simple and inexpensive method to optimize both electrolyte flow and species transfer inside the devices. a-SCMFCs, featuring the IMS, are compared to control cells (IMS-less), when operated with sodium acetate as the carbon energy source. Performances of cells are evaluated in terms both of maximum output potential achieved, and energy recovery (Erec) as the ratio between the energy yield and the inner electrolyte volume. The a-SCMFCs with the novel IMS are demonstrated to enhance the energy recovery compared to control cells exhibiting Erec values of (37 ± 1) J/m3, which is one order of magnitude higher than that achieved by control cells (3.0 ± 0.3) J/m3. Concerning the maximum output potential, IMS cells achieve (2.8 ± 0.2) mV, compared to control cells at (0.68 ± 0.07) mV. Furthermore, by varying the sodium acetate concentration, the Erec and maximum potential output values change accordingly. By monitoring the activity of a-SCMFCs for over one year, the beneficial impact of the IMS on both the initial inoculation phase and the long-term stability of electrical performance are observed. These improvements support the effectiveness of IMS to allow the development of efficient biofilms, likely due to the reduction in oxygen cross-over towards the anode. Electrochemical characterizations confirm that the presence of the IMS impacts the diffusion processes inside the electrolytic chamber, supporting the hypothesis of a beneficial effect on oxygen cross-over.

Transcriptomics and metabolomic profiling identify molecular mechanism for Aspergillus flavus infection in grain

AbstractAspergillus flavus is a ubiquitous saprophyte and opportunistic fungal pathogen with worldwide distribution, which causes diseases commonly in agricultural commodities and seriously threatens food security and human health. In this study, we try to reveal the mechanisms of A. flavus infection in grain from the perspective of apparent changes in physicochemical properties, microscopic structure, and ultrastructural changes at transcriptome–metabolomics levels. The results showed that the A. flavus infection included the preinfection (1–3 days) and postinfection period (4–7 days). The downregulated expression of creA promoted the cellulase expression and initiated infection. The metabolite oleic acid promoted infection as a nutrient carbon source and energy source. Then the entry of acetate units into the aflatoxin synthesis pathway was inhibited, whereas aflH, hypD, and hypB were significantly upregulated (p < .05) to stimulate the aflatoxin synthesis to complete the infection on the surface. During the postinfection period, the upregulation of aflS and other toxin‐producing regulatory genes accelerated aflatoxin synthesis and completed the internal infection. At the same time, the upregulation of vitamin B6 and allysine involved in amino acid metabolism, and galactose 1‐phosphate involved in energy metabolism ensured the production of acetyl‐CoA and the energy supply for A. flavus infection. The research findings highlight the underlying mechanisms of A. flavus infection at the transcriptome–metabolomics levels, which is important for developing effective strategies to prevent postharvest contamination.

The asymmetric effect of renewable and non-renewable energy on carbon emissions in OECD: new evidence from non-linear panel ARDL model

The level of economic income, population density and sources of energy supply is critical in assessing environmental quality. Recent empirical studies paid limited attention to the role of renewable (RE) and fossil energy (NRE) supply in carbon pollution regarding the Environmental Kuznets Hypothesis (EKC). Therefore, this study investigates the asymmetric relationships between carbon emissions and energy sources on the one hand and the environmental Kuznets hypothesis on the other hand for OECD countries, comprising countries with significant renewable energy supplies. The study includes the annual data from 1990 to 2021 and performs panel non-linear ARDL regression. The empirical results clearly show that RE and NRE have asymmetric effects on emissions in the long run but not in the short run. Both positive and negative shocks in RE reduce CO2 emissions in OECD economies, while asymmetric shocks in NRE substantially increase them. Increasing RE supply is clearly effective in reducing emissions. However, unlike most previous studies, this study shows that RE does not significantly reduce CO2 emissions in OECD countries. The error correction term (ect.) in the NARDL model is negative and significant. The magnitude of the term indicates that the system will return to long-term equilibrium about 4.2 years after any shock. Furthermore, we show that the EKC Hypothesis is supported in OECD countries. The turning point of the EKC is at $4085.77 per capita. Besides, regression with Driscoll-Kraay standard errors and Augmented Mean Group (AMG) estimator approach were used for robustness checks. The findings from the robustness check are consistent with the NARDL findings. Policies based on the promotion of a low-carbon and sustainable green environment should place greater emphasis on renewable resources even in OECD countries. Moreover, while many studies in the literature address asymmetric effects and EKC as energy consumption or utilisation, the novelty of this study is that it approaches the issue regarding energy supply with asymmetric effects for RE and NRE.

THE UPPER PERMIAN ZECHSTEIN SUPERGROUP OF NE ENGLAND AND THE ADJACENT SOUTHERN NORTH SEA: A REVIEW OF ITS ROLE IN THE UK'S ENERGY TRANSITION

As the United Kingdom reduces its CO2 emissions in order to meet its 2050 net zero greenhouse gas targets, there will be a significant evolution of the UK's energy mix. The reliance on hydrocarbons will decrease while there is predicted to be an increase in low carbon energy sources such as renewables and nuclear. In order to decarbonise and achieve the net zero emissions targets while concurrently producing enough energy to provide for national energy needs, large‐scale, low carbon energy generation projects need to be developed alongside energy storage facilities to provide flexibility within a low carbon energy supply. Robust CCUS programmes will need be developed in order to capture and store unavoidable carbon dioxide emissions. The subsurface geology of the UK provides opportunities for the development of low carbon energy generation, energy storage and CCS, and the Upper Permian Zechstein Supergroup deposited in eastern England and offshore in the Southern North Sea is a potential host for these new developments. In NE England, salt cavern gas storage sites have been developed in thick Zechstein evaporites since the mid 20th centrury. In this paper we present new isopach maps and well correlation panels which will help to outline optimal locations for the development of additional salt caverns for gas storage. A review of the Zechstein Supergroup indicates that it does not exhibit great potential for the development of CCS, due both to its complex reservoir characteristics and to difficulties with both subsurface imaging and monitoring. However thick Zechstein evaporites could provide an excellent seal for CO2 storage in the underlying Lower Permian Rotliegend Group.

Niche differentiation of microbial community shapes vertical distribution of recalcitrant dissolved organic matter in deep-sea sediments

Sedimentary organic matter provides carbon substrates and energy sources for microorganisms, which drive benthic biogeochemical processes and in turn modify the quantity and quality of dissolved organic matter (DOM). However, the molecular composition and distribution of DOM and its interactions with microbes in deep-sea sediments remain poorly understood. Here, molecular composition of DOM and its relationship with microbes were analyzed in samples collected from two sediment cores (∼40 cm below the sea floor), at depths of 1157 and 2253 m from the South China Sea. Results show that niche differentiation was observed on a fine scale in different sediment layers, with Proteobacteria and Nitrososphaeria dominating the shallow sediments (0–6 cm) and Chloroflexi and Bathyarchaeia prevailing in deeper sediments (6–40 cm), indicating correspondence of microbial community composition with both geographical isolation and the availability of organic matter. An intimate link between the DOM composition and microbial community further indicates that, microbial mineralization of fresh organic matter in the shallow layer potentially resulted in the accumulation of recalcitrant DOM (RDOM), while relatively low abundance of RDOM was linked to anaerobic microbial utilization in deeper sediment layers. In addition, higher RDOM abundance in the overlying water, as compared to that in the surface sediment, suggests that sediment might be a source of deep-sea RDOM. These results emphasize the close relation between the distribution of sediment DOM and different microbial community, laying a foundation for understanding the complex dynamics of RDOM in deep-sea sediment and water column.

The nexus between global carbon and renewable energy sources: A step towards sustainability

The energy transition is at the core of sustainable development as it helps to combat global warming and climate change. Similarly, carbon markets also support the climate change mitigation. Therefore, by realizing the potential role of clean energy and carbon markets in ensuring environmental sustainability, this study analyzes the spillovers and connectedness between the environment (global carbon) and renewable energy sources (wind, solar, geothermal, biofuel, and fuel cell). The empirical analysis is conducted by applying the novel “TVP-VAR” connectedness framework of Balcilar et al. (2021) on the daily data over the period from August 1, 2014, to February 4, 2022. The findings show that solar and biofuel appear as the highest net shock transmitter among alternative renewable sources while global carbon is shown as the net receiver of shocks. The largest transmission of shocks to global carbon is observed from wind followed by solar. Although these findings support the connectedness between renewable energy and the environment, however this connectedness is influenced by economic crises such as the oil crisis and pandemic crisis. During COVID-19, the fuel cell was the highest transmitter of shocks. The results are important for policy formulation, investment, and portfolio management as they provide insights into the interconnectedness and help in boosting climate actions.

A comprehensive study for the identification of the requirements for an optimal H2 combustion engine

As part of the fight against global warming and to achieve greenhouse gas emission targets, it is crucial to reduce the carbon footprint of ground transportation. Mobility needs are continuously growing with increase in population. All these factors will lead to an upsurge in the energy demand for the mobility in the very next future. Consequently, the diversification of low carbon energy sources is urgently required. Hydrogen can be used for mobility solution in its two energy conversion mechanisms: The Fuel Cell technology or the Internal Combustion Engine (ICE). The latter option, studied in the present work, offers the advantages of current fossil fuel engines – existing and proven technology, lifetime, controlled cost – with a very low carbon footprint. The overall objective of the study is to define the specifications of a dedicated Hydrogen direct injection combustion system for ground transportation application with the best fuel efficiency and lower raw emissions, to minimize the aftertreatment needs. A complete experimental and numerical study was carried out to get valuable information on various phenomena occurring throughout the engine cycle. The very first step of the study consisted in performing experimental investigations. For this purpose, an all metal single cylinder engine originally designed for gasoline spark ignited combustion (tumble air motion, gasoline direct injection) was modified for hydrogen direct injection combustion. The gas-gas injection was experimentally studied in the High Pressure/High Temperature vessel available at IFPEN. Those experiments were used to calibrate the 3D CFD numerical approach. Based on a 0D pre-study (boundary conditions) and using the injection modeling calibration introduced before, 3D CFD simulations have been then carried out with specific hydrogen kinetics properties. Finally, this comprehensive study highlights the specificities of ICE running with hydrogen. It provides indications and guidelines for further developments and optimization of hydrogen combustion engines.

A review of the enhanced degradation of pesticides in tropical agricultural soils

Pesticides newly introduced into the soil are normally poorly degraded by native soil microbes. However, studies have demonstrated that repeated exposure of pesticides to soil microbes potentially enhances their biodegradation through selective enrichment of pesticide-metabolising microorganisms, particularly when the compound is used as a carbon (C) or nitrogen (N) and energy source. Enhanced degradation of recalcitrant compounds in soil has a significant environmental impact, as the chemicals are less likely to contaminate environmental ecosystems. The authors have undertaken several studies to isolate these adapted microbes that rapidly degrade chemicals hitherto known to be recalcitrant in soil. These microbes could potentially be used for bioremediation (bioaugmentation). In addition, other studies have shown their potential to remove pesticide contamination from the environment by the use of organic materials locally generated as organic amendments (biostimulation). In this review, the various methods used in the course of the authors’ studies in determining the utilisation of selected chemicals (pesticides) by adapted microbes as a source of carbon and nitrogen for growth and energy are discussed. This review also presents some of the compounds that the authors have worked with and the successes registered in isolating key degraders of the respective pesticides and the extent to which the locally generated organic materials are able to enhance the degradation of the respective chemicals in soil.