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Accident Tolerant Fuels (ATF) have emerged as a promising solution to improve safety during reactor accidents by enhancing fuel performance in light water reactors (LWRs). This paper investigates the performance of different ATF concepts, including Chromium-coated Zircaloy (CrZry), advanced steel (FeCrAl), and Silicon Carbide (SiC) as cladding materials, paired with Uranium Dioxide (UO 2 ), Uranium Silicide (U 3 Si 2 ), and Uranium Nitride (UN) fuels, under spectrum shift regulation conditions in a VVER-S reactor. Using the GETERA program, a series of calculations were conducted to compare multiplying factors and isotopic concentrations under spectrum-shifted conditions. The results demonstrate significant differences in fuel cycle characteristics and isotopic behavior, with SiC emerging as the optimal cladding material for maximizing neutron economy and minimizing parasitic absorption.

How much carbon does it take to make nitric acid? The counterintuitive answer nowadays is quite a lot. Nitric acid is manufactured by ammonia oxidation, and all the hydrogen to make ammonia via the Haber-Bosch process comes from methane. That's without even accounting for the fossil fuels burned to power the process. Chen et al. review research prospects for more sustainable routes to nitrogen commodity chemicals, considering developments in enzymatic, homogeneous, and heterogeneous catalysis, as well as electrochemical, photochemical, and plasma-based approaches. Science , this issue p. eaar6611 Nitrogen is fundamental to all of life and many industrial processes. The interchange of nitrogen oxidation states in the industrial production of ammonia, nitric acid, and other commodity chemicals is largely powered by fossil fuels. A key goal of contemporary research in the field of nitrogen chemistry is to minimize the use of fossil fuels by developing more efficient heterogeneous, homogeneous, photo-, and electrocatalytic processes or by adapting the enzymatic processes underlying the natural nitrogen cycle. These approaches, as well as the challenges involved, are discussed in this Review.

The study of the electrochemical catalyst conversion of renewable electricity and carbon oxides into chemical fuels attracts a great deal of attention by different researchers. The main role of this process is in mitigating the worldwide energy crisis through a closed technological carbon cycle, where chemical fuels, such as hydrogen, are stored and reconverted to electricity via electrochemical reaction processes in fuel cells. The scientific community focuses its efforts on the development of high-performance polymeric membranes together with nanomaterials with high catalytic activity and stability in order to reduce the platinum group metal applied as a cathode to build stacks of proton exchange membrane fuel cells (PEMFCs) to work at low and moderate temperatures. The design of new conductive membranes and nanoparticles (NPs) whose morphology directly affects their catalytic properties is of utmost importance. Nanoparticle morphologies, like cubes, octahedrons, icosahedrons, bipyramids, plates, and polyhedrons, among others, are widely studied for catalysis applications. The recent progress around the high catalytic activity has focused on the stabilizing agents and their potential impact on nanomaterial synthesis to induce changes in the morphology of NPs.

Due to the large quantities of carbon emissions generated by the transportation sector, cleaner automotive technologies are needed aiming at a green energy transition. In this scenario, hydrogen is pointed out as a promising fuel that can be employed as the fuel of either a fuel cell or an internal combustion engine vehicle. Therefore, in this work, we propose the design and modeling of a fuel cell versus an internal combustion engine passenger car for a driving cycle. The simulation was carried out using the quasistatic simulation toolbox tool in Simulink considering the main powertrain components for each vehicle. Furthermore, a brief analysis of the carbon emissions associated with the hydrogen production method is addressed to assess the clean potential of hydrogen-powered vehicles compared to conventional fossil fuel-fueled cars. The resulting analysis has shown that the hydrogen fuel cell vehicle is almost twice as efficient compared to internal combustion engines, resulting in a lower fuel consumption of 1.05 kg-H2/100 km in the WLTP driving cycle for the fuel cell vehicle, while the combustion vehicle consumed about 1.79 kg-H2/100 km. Regarding using different hydrogen colors to fuel the vehicle, hydrogen-powered vehicles fueled with blue and grey hydrogen presented higher carbon emissions compared to petrol-powered vehicles reaching up to 2–3 times higher in the case of grey hydrogen. Thus, green hydrogen is needed as fuel to keep carbon emissions lower than conventional petrol-powered vehicles.

This study demonstrates that using spin-polarized deuterium-tritium (D-T) fuel with more deuterium than tritium can increase tritium burn efficiency (TBE) by at least an order of magnitude without compromising fusion power output, compared to unpolarized fuel. Although previous studies show that a low tritium fraction can enhance TBE, this strategy resulted in reduced fusion power density. The surprising improvement in TBE at fixed power reported here is due to the TBE increasing nonlinearly with decreasing tritium fraction but the fusion power density increasing roughly linearly with D-T cross section. A study is performed for an ARC-like tokamak producing 481 MW of fusion power with unpolarized 53:47 D-T fuel, finding the minimum startup tritium inventory ( Istartup,min) is 0.69 kg. By spin-polarizing half of the fuel and using a 60:40 D-T mix, Istartup,min is reduced to 0.08 kg, and fully spin-polarizing the fuel with a 63:37 D-T mix further reduces Istartup,min to 0.03 kg. Some ARC-like scenarios are predicted to achieve plasma ignition with relatively modest spin polarization. These findings indicate that, with advancements in helium divertor pumping efficiency, TBE values of approximately 10%–40% could be achieved using low-tritium-fraction and spin-polarized fuel with minimal power loss. This would dramatically lower tritium startup inventory requirements and reduce the amount of on-site tritium. More generally than just for spin-polarized fuels, increased plasma performance can be used to increase TBE. This strongly motivates the development of spin-polarized fuels and low-tritium-fraction operation for burning plasmas.

PurposeThe goal of this study was to provide a holistic, reliable, and transparent comparison of battery electric vehicles (BEVs) and fuel cell electric vehicles (FCVs) regarding their environmental impacts (EI) and costs over their whole life cycle. The comprehensive knowledge about EI and costs forms the basis on which to decide which technology should be favored for the future of mobility.MethodsTherefore, a holistic and transparent comparative life cycle assessment (LCA), using the ReCiPe 2016 method, and a life cycle costing were conducted. Special attention was paid to the fuel supply infrastructure for BEV and FCV as these have not been sufficiently considered in previous research. The required infrastructure was calculated for six million electric vehicles (EVs) and the EI and costs were allocated proportional on the functional unit of 1 km driven with an EV. Different scenarios regarding electricity mix, range of the BEV, and vehicle lifetime were calculated. In order to ensure transparency, all inventories and calculations were published in the attached Electronic supplementary material (ESM).Results and discussionDetailed results were presented for the impact categories global warming potential (GWP), human toxicity potential non-carcinogenic (HTPnc), surplus ore potential (SOP), and particulate matter formation potential (PMFP). Aggregated results for all midpoint impact categories of the ReCiPe method can be found in the ESM. It was shown that BEVs achieve lower EI than FCVs in most impact categories (e.g., GWP: BEV: 1.40E-01, FCV: 1.68E-01 kg CO2-eq./km) and that the total costs of ownership are as well lower for BEVs (68,900 € vs. 130,100 €). Further, it was found that the fuel supply infrastructure—without electricity supply—contributes a considerable amount to the overall impact per kilometer driven (e.g., 3.7% and 3.3% of the GWP for BEV and FCV, respectively).ConclusionsConsidering mid-size vehicles like the VW e-Golf, it was concluded that BEVs have today a better environmental and financial performance than FCVs. However, the range of the BEV is lower than the range of the FCV (200 vs. 530 km) and both technologies have different stages of maturity. Moreover, the study showed that the fuel supply infrastructure is an important contributor to the overall life cycle impacts and that it is therefore indispensable to include the infrastructure in LCA of electric vehicles. Based on the results, recommendations to utilize the advantage of both BEV (high energy efficiency, lower costs) and FCV (long-distance capability) were made.

Marine transportation facilitates the transportation of fuels and goods over long distances cost-effectively, but their environmental impact has increased due to the utilization of fossil fuels. This paper presents a new marine engine design comprising a steam Rankine cycle, gas Brayton cycle, and solid oxide fuel cell to replace a two-stroke internal combustion engine. Hydrogen, methane, dimethyl ether, ethanol, and methanol are selected as eco-friendly fuels. This hybrid combined engine is attached to a multi-effect desalination unit to take the advantage of waste energy from the exhaust gases. The engine is thermodynamically analyzed using the Aspen Plus software to assess its performance energetically and exergetically. It is found that the engine's total power is increased by 40% to an average of 15,546 kW with average thermal and exergetic efficiencies of 61% and 43%, respectively. The maximum power reaches 16,780 kW with maximum carbon emission reductions of 53% and a minimum specific fuel consumption of 337 g kWh −1 which is a reduction of 17%. In addition, the waste energy is used to deliver 20.3 kg s −1 freshwater by desalinating seawater. The proposed engine system has better performance and less environmental impact, which makes it a better choice than traditional engines.

According to day-by-day consumption increase, energy high costs and nonrenewable energy destroying effects, clean technologies such as fuel cells lead a remarkable decline in consumption. In the present study, waste heat recovery from a hybrid system of an 1180 kW low-temperature polymer electrolyte membrane fuel cell and a vapor compression refrigeration cycle is surveyed using a recuperative organic Rankine cycle. The fuel cell system is equipped with a metal hydride storage. The heat absorbed from stack is divided into two streams. One stream flows into the recuperative organic Rankine cycle to produce power, and the other goes for waste heat recovery of the refrigeration cycle condenser; then, it is utilized for other components of fuel cell system including metal hydride to release hydrogen and H 2 preheater to preheat the hydrogen to the stack temperature. Effects of operational parameters including fuel cell thermal efficiency, cooling load, pressure ratio, mass flow rate and working fluid of recuperative organic Rankine cycle were thermodynamically analyzed. Two working fluids were surveyed including R-245fa and R-134a. Results indicate that hybrid system thermal efficiency falls down by increase in turbine pressure ratio. The maximum system consumption power was dedicated in the case in which the fuel cell has its highest thermal efficiency in addition to minimum net produced power. Additionally, R-134a was determined as the best working fluid. Net output power and efficiency of the system with R-134a are about 1.2 and 20% more than R-245fa, respectively.

The Digital Product Passport (DPP) is a concept of a policy instrument particularly pushed by policy circles to contribute to a circular economy. The preliminary design of the DPP is supposed to have product-related information compiled mainly by manufactures and, thus, to provide the basis for more circular products. Given the lack of scientific debate on the DPP, this study seeks to work out design options of the DPP and how these options might benefit stakeholders in a product’s value chain. In so doing, we introduce the concept of the DPP and, then, describe the existing regime of regulated and voluntary product information tools focusing on the role of stakeholders. These initial results are reflected in an actor-centered analysis on potential advantages gained through the DPP. Data is generated through desk research and a stakeholder workshop. In particular, by having explored the role the DPP for different actors, we find substantial demand for further research on a variety of issues, for instance, on how to reduce red tape and increase incentives for manufacturers to deliver certain information and on how or through what data collection tool (e.g., database) relevant data can be compiled and how such data is provided to which stakeholder group. We call upon other researchers to close the research gaps explored in this paper also to provide better policy direction on the DPP.

The International Maritime Organization (IMO) has set decarbonisation goals for the shipping industry. As a result, shipowners and operators are preparing to use low- or zero-carbon alternative fuels. The greenhouse gas (GHG) emission performances are fundamental for choosing suitable marine fuels. However, the current regulations adopt tank-to-wake (TTW) emission assessment methods that could misrepresent the total climate impacts of fuels. To better understand the well-to-wake (WTW) GHG emission performances, this work applied the life cycle assessment (LCA) method to a very large crude carrier (VLCC) sailing between the Middle East and China to investigate the emissions. The life cycle GHG emission impacts of using alternative fuels, including liquified natural gas (LNG), methanol, and ammonia, were evaluated and compared with using marine gas oil (MGO). The bunkering site of the VLCC was in Zhoushan port, China. The MGO and LNG were imported from overseas, while methanol and ammonia were produced in China. Four production pathways for methanol and three production pathways for ammonia were examined. The results showed that, compared with MGO, using fossil energy-based methanol and ammonia has no positive effect in terms of annual WTW GHG emissions. The emission reduction effects of fuels ranking from highest to lowest were full solar and battery-based methanol, full solar and battery-based ammonia, and LNG. Because marine ammonia-fuelled engines have not been commercialised, laboratory data were used to evaluate the nitrous oxide (N2O) emissions. The GHG emission reduction potential of ammonia can be exploited more effectively if the N2O emitted from engines is captured and disposed of through after-treatment technologies. This paper discussed three scenarios of N2O emission abatement ratios of 30%, 50%, and 90%. The resulting emission reduction effects showed that using full solar and battery-based ammonia with 90% N2O abatement performs better than using full solar and battery-based methanol. The main innovation of this work is realising the LCA GHG emission assessment for a deep-sea ship.