Primary Energy Input Research Articles

An Improved Bio-Physical Parameterization for Ocean Radiant Heating in Conditions of Near-Surface Stratification.

Solar heating of the upper ocean is a primary energy input to the ocean-atmosphere system, and the vertical heating profile is modified by the concentration of phytoplankton in the water, with consequences for sea surface temperature and upper ocean dynamics. Despite the development of increasingly complex modeling approaches for radiative transfer in the atmosphere and upper ocean, the simple parameterizations of radiant heating used in most ocean models can be significantly improved in cases of near-surface stratification. There remains a need for a parameterization that is accurate in the upper meters and contains an explicitly spectral dependence on the concentration of biogenic material, while maintaining the computational simplicity of the parameterizations currently in use. Here, we assemble observationally-validated physical modeling tools for the key controls on ocean radiant heating, and simplify them into a parameterization that fulfills this need. We then use observations from 64 spectroradiometer depth casts across 6 cruises in diverse water bodies, 13 surface hyperspectral radiometer deployments, and broadband albedo from 2 UAV flights to probe the accuracy and uncertainty associated with the new parameterization. A novel case study using the parameterization demonstrates the impact of chlorophyll concentration on the structure of diurnal warm layers. The parameterization presented in this work will allow for better modeling of global patterns of sea surface temperature, diurnal warming, and freshwater lenses, without a prohibitive increase in complexity.

Visible-Light-Mediated Photoredox Radical Cyclization Reaction with Alkyl Boronic Acids Using Molecular Oxygen as a Sole Oxidant

AbstractIndolo[2,1-b]quinazolin-12(6H)-one derivatives are prevalent in many synthetic intermediates, pharmaceuticals, and organic materials. Herein, we developed a photoredox radical cascade cyclization reaction that uses visible light as the primary energy input to promote the reaction, leading to a series of indolo[2,1-b]quinazolin-12(6H)-one derivatives under oxygen conditions.

Species Richness Net Primary Productivity and the Water Balance Problem.

Species energy theory suggests that, because of limitations on reproduction efficiency, a minimum density of plant individuals per viable species exists and that this minimum correlates the total number of plant individuals N with the number of species S. The simplest assumption is that the mean energy input per individual plant is independent of the number of individuals, making N, and thus S as well, proportional to the total energy input into the system. The primary energy input to a plant-dominated ecosystem is estimated as its Net Primary Productivity (NPP). Thus, species energy theory draws a direct correspondence from NPP to S. Although investigations have verified a strong connection between S and NPP, strong influences of other factors, such as topography, ecological processes such as competition, and historical contingencies, are also at play. The lack of a simple model of NPP expressed in terms of the principal climate variables, precipitation P, and potential evapotranspiration, PET, introduces unnecessary uncertainty to the understanding of species richness across scales. Recent research combines percolation theory with the principle of ecological optimality to derive an expression for NPP(P, PET). Consistent with assuming S is proportional to NPP, we show here that the new expression for NPP(P, PET) predicts the number of plant species S in an ecosystem as a function of P and PET. As already demonstrated elsewhere, the results are consistent with some additional variation due to non-climatic inputs. We suggest that it may be easier to infer specific deviations from species energy predictions with increased accuracy and generality of the prediction of NPP(P, PET).

A simplified approach to modeling temperature dynamics in photovoltaic systems – Validation, case studies, and parametric analysis

This paper presents a simplified theoretical model for analyzing the temperature dynamics of photovoltaic (PV) modules. The model is built on an energy balance approach, considering solar irradiation as the primary energy input. It accounts for the conversion of solar power into electricity and the storage of thermal energy within the PV module, which subsequently increases the PV temperature leading to decay in its electrical efficiency. Heat loss from the top and bottom surfaces of the module, with variations for cooling techniques, is also included. The model is validated against three different experimental studies, demonstrating good agreement with the experimental temperature variations, with a maximum discrepancy ranging from 4 % to 16 %. This simplified model is then applied to two case studies: one representing typical daytime conditions and another simulating cold weather events. By comparing the PV temperature dynamics between the model and the experimental data, it is shown that the model accurately captures the dynamic response of the PV temperatures to changes in solar irradiation and ambient temperatures. Moreover, a parametric analysis is conducted to investigate the effects of key parameters on PV temperature and efficiency. Higher cooling rates from the bottom surface significantly boost electric power output, aligning closely with solar irradiance variations. Enhanced upper surface cooling, through increased convection, reduces PV temperature and thereby improves electric efficiency and power production. The PV temperature increases quasi-linearly with ambient temperature, especially at lower wind speeds, and decreases with higher wind speeds, eventually stabilizing at high values. Additionally, both ambient temperature and solar irradiance contribute to rising PV temperatures, with ambient temperature having a slightly greater effect. These findings underscore the critical role of cooling techniques in optimizing PV performance amidst varying environmental conditions.

Operating Energy Needed for Desalination Systems in Cogeneration Plants

This study investigated the energy requirement for running desalination units coupled to cogeneration plants. Various cogeneration systems were explored using power- and heat-allocated approaches. The specific work and heat necessary for operating different desalination systems were determined. The investigation revealed that the specific work and heat remain consistent regardless of the desalination daily capacity. It was observed that the energy demand for operating a desalination system mainly relies on power plant efficiency. The investigation revealed that the energy demand for a plain multi-effect desalination system was lower than that for multi-effect desalination with thermal vapor compression. Additionally, the energy requirement for a multi-effect desalination system with preheaters was lower than that for plain multi-effect desalination. Comparisons also indicated that the energy demand of multi-stage flash exceeds that of different multi-effect desalination systems. Based on the primary thermal energy input, a universal performance ratio was used to evaluate the desalination unit performance. Furthermore, a new correlation was proposed to predict the universal performance ratio.

Estimation of Spectral Solar Irradiance in the Ecliptic Plane Using Synthetic Solar Surface Magnetograms

AbstractThe primary external energy input to planetary atmospheres comes from solar radiation. Accurate estimates of solar irradiance are needed in order to understand atmospheric conditions at other planets. Many studies have interpolated Earth‐based irradiance measurements at other planets, disregarding the evolution of solar features, which are responsible for the irradiance variability. We present an approach for assessing solar irradiance at other planets by using synthetic full surface magnetograms of the Sun, generated by the Surface Flux Transport Model, and then converted into sunspots and faculae areas. Following the Spectral And Total Irradiance REconstruction approach, we compute the irradiance as the sum of contributions from sunspots, faculae, and the quiet Sun. We calculate the S‐index, which is a proxy for near‐ultraviolet irradiance, and the total solar irradiance (TSI), which is the wavelength‐integrated value. We demonstrate that a simple phase shift of the Earth‐observed TSI does not produce reliable estimates in the ecliptic. By comparing and correlating our results with the interpolated measurements, we find that the two models agree in the S‐index variability, because faculae have a long lifetime, so the effect of the solar rotation becomes less important. Conversely, the methods disagree strongly in the TSI, since sunspots have a short lifetime, and the interpolation does not take into account their emergence and evolution on the far‐side of the Sun, as it only uses the information of the disc visible for an Earth‐bound observer.

Simulation Process for Allyl Alcohol Production via Deoxydehydration of Glycerol

A process for the deoxydehydration (DODH) of glycerol to allyl alcohol in 2-hexanol as solvent was modelled with Aspen Plus. Experimental results for the DODH reaction, the liquid vapour equilibria and the catalytic hydrogenation were employed for the development of the model. The whole process consists of four subsystems: allyl alcohol production (S1), solvent recovery (S2), allyl alcohol purification (S3) and solvent regeneration (S4). Based on the results of the process model, allyl alcohol with 96% yield and a purity of 99.99% with product loss of only 0.2% was obtained. The optimisation of the energy consumption through an integrated heat exchange network resulted in a net primary energy input of 863.5 kW, which corresponded to a carbon footprint of 1.89 kgCO2/kgAllylOH.

Comparative life cycle energy, water consumption and carbon emissions analysis of deep in-situ gasification based coal-to-hydrogen with carbon capture and alternative routes

In order to clarify the competitiveness of deep in-situ gasification based coal-to-hydrogen (deep IGCtH) in the context of carbon-constrained development, based on simulation results, the energy, water consumption and carbon emissions were quantitatively assessed and compared with large-scale fossil energy based routes, using life cycle assessment model from feedstock to hydrogen that covers process energy production and utilization. The results indicate when producing 1 kg of hydrogen, deep IGCtH requires 349.55 MJ of external primary fossil energy input and generates 30.47 kg CO2-eq of emissions, which are 24.88% and 16.32% lower than 465.34 MJ and 36.41 kg CO2-eq of Lurgi surface gasification based coal-to-hydrogen (Lurgi SGCtH), and also 7.38% lower than 377.39 MJ of coke-oven gas-to-hydrogen (COGtH). Furthermore, deep IGCtH can not only reduce coal consumption by 19.7% compared with Lurgi SGCtH, but also reduce oil consumption required to obtain process energy by 81.84%, which also reaches 80.09% compared with COGtH. Due to the high methane content, the exhaust gas and flue gas of deep IGCtH contributes 9.78 kg and 8.84 kg of CO2 emissions, and under the CO2 capture rate of 80%, the carbon emissions adopting exhaust gas and flue gas simultaneous capture reach 25.88 kg CO2-eq, higher than the 23.1 kg CO2-eq adopting exhaust gas single capture, of which waste gas only contributes 3.87 kg of emissions, but electricity consumption causes 15.11 kg CO2-eq of emissions, indicating the key to adopting such scheme to achieve further emissions reduction lies in reducing emissions caused by electricity consumption.

Visible-light-driven reversible shuttle vicinal dihalogenation using lead halide perovskite quantum dot catalysts

Dihalogenation of alkenes to the high-added value vicinal dihalides is a prominent process in modern synthetic chemistry. However, their effective conversion still requires the use of expensive and hazardous agents, sacrificial half-reaction coupling or primary energy input. Here, we show a photocatalytically assisted shuttle (p-shuttle) strategy for redox-neutral and reversible vicinal dihalogenation using low-cost and stable 1,2-dihaloethane under visible light illumination. Energetic hot electrons from metal-halide perovskite QDs enable the challenging photocatalytic reactions. Ultrafast laser transient absorption spectroscopy have unveiled the energy matching of the hot electrons with the high reduction potential of 1,2-dihaloethane, via two consecutive photoexcitation process. Powered by the sustainable energy as the only energy input, our new catalytic system using metal-halide perovskite QDs for dibromination, dichlorination and even unexplored hetero-dihalogenation, shows good tolerance with a wide range of alkenes at room temperature. In contrast to homogeneous photocatalysts, chalcogenide QDs and other semiconductor catalysts, perovskite QDs deliver previously unattainable performance in photoredox shuttle vicinal dihalogenation with the turnover number over 120,000. This work provides new opportunities in visible-light-driven heterogeneous catalysis for unlocking novel chemical transformations.

Taguchi optimization and analysis of variance for thermoelectric generators with forced convection air cooling

In recent years, humanity has experienced the effects of using unsustainable energy sources that pollute the environment while being inefficient. Most of the primary energy input used in energy conversion processes is lost in the form of heat. Thermoelectric generators (TEGs) have the potential to recover some of this wasted heat; however, their low energy conversion efficiency needs to be addressed. Previous literature has shown effective optimization of thermoelectric generation systems through statistical tools such as the Taguchi method that optimized all the parameters that affect the outcome of the system. To this date, no research has considered wind speed for convection heat transfer as one of the optimizable parameters. This study aims to optimize the operating conditions of commercially available TEGs that are cooled by forced convection simulating naturally occurring wind speeds and operate under low-quality waste heat temperatures to improve the TEG performance further. Two commercially available TEGs are optimized via the Taguchi method. The Taguchi method is implemented with three parameters and three levels, making an L9 orthogonal array. The objective function is the maximum output power. The optimized parameters are the hot side temperature, the heat sink size, and the wind airspeed. Analysis of variance (ANOVA) is used alongside the Taguchi orthogonal array for the statistical analysis of the results. The optimization results show that the hot side temperature is the most influential parameter to the output power. In addition, the change in the heat sink size also significantly influences the output power, whereas the impact of the wind speed is not as significant. In addition, interaction analysis between the parameters is performed. The Taguchi method yields satisfactory optimization results. The optimized system yields 0.65 W of power at 140 °C hot side temperature, Model K402 heat sink, and 3.7 m·s−1 wind speed. The influence of the air velocity of 1.73% is minimal on the output power compared to the hot side temperature, with a level of influence of 75.67% and a heat sink size of 22.43% for the shorter module. The results also show that the TEG with a smaller TE leg height yields the best output power at low load resistance ranging from 0.2 Ω to 2 Ω, as the TEG with a taller TE leg renders better performance at higher load resistance ranging from 3 Ω to 16 Ω at the optimal conditions. The results show that the hot side temperature remains the most important parameter in the optimization process. Furthermore, convection cooling from naturally occurring winds has a minimal but positive effect on the output of the presented TEG system.

Stability improvement of aerobic granular sludge (AGS) based on Gibbs free energy change (∆G) of sludge-water interface

• Δ G sw a can normalize the stability of AGS . • Microbial and chemical properties were more important for Δ G sw a than physical ones. • Reasonable increase in OLR or HSF reduced Δ G sw a and enhanced stability of AGS. The stability of aerobic granular sludge (AGS) has been evaluated by lots of physicochemical and microbial characteristic indicators, but none of them could singly and comprehensively characterize the stability of AGS. Gibbs free energy change (∆G) could reflect the stable state of the whole system by the second law of thermodynamics, so ∆G of the sludge-water interface ( Δ G sw a ) was proposed to characterize the stability of AGS in this study. Organic loading rate (OLR) and hydraulic shear force (HSF) as the primary external energy inputs were selected at different levels in four reactors. Results showed that a reasonable increase in OLR or HSF could reduce Δ G sw a , and its influence on Δ G sw a had two paths: affecting the surface roughness of sludge directly (Path 1); on the other hand, EPS producers like denitrifiers were enriched, promoting the secretion of PN such as tryptophan and protein-like to affect Δ G sw a (Path 2). These indicators were correlated with Δ G sw a significantly, especially genus Paracoccus spp. (class Alphaproteobacteria) (-0.74, p <0.001) and Amide III (-0.81, p <0.001), indicating that Path 2 had a more significant influence on Δ G sw a . In addition, the absolute values of correlation between physical stability indicators and Δ G sw a were around 0.80 ( p <0.001). Therefore, Δ G sw a can be normalized to characterize the stability of AGS. This study establishes Δ G sw a as the normalized indicator for the stability of AGS, which provides specific theoretical guidance for operating parameter regulation in engineering application.

Carbon-neutral hydrogen production from natural gas via electrified steam reforming: Techno-economic-environmental perspective

This study proposes and evaluates a novel carbon-neutral hydrogen (H2) production process from natural gas through electrified steam methane reforming (e-SMR) with renewable electricity. The process model consists of different unit technologies such as reforming, water–gas shift, hydrogen pressure swing adsorption, and CO2 capture, along with heat recovery. Then, we evaluated the techno-economic-environmental performance of the proposed e-SMR process by comparing it with the conventional fired-heating steam methane reforming (f-SMR). By employing an electrically driven reformer using renewable energy, e-SMR outperforms f-SMR with less natural gas consumption, higher energy efficiency of 78.7%, and lower net CO2eq emission of 5.28 kg CO2eq/kg H2 and captured 5.58 kg CO2/kg H2; however, it has a drawback, i.e., higher H2 unit production cost (UPC) of 3.49 $/kg with a capacity of 7.06 ton/day. Sensitivity and uncertainty analyses identified the major cost drivers of UPC, such as the prices of natural gas, renewable electricity, and interest rates, as well as economic risks and uncertainties. The economic viability of e-SMR was determined by investigating multiple plant capacities, natural gas markets, renewable energy prices, and possible future CO2 selling prices. According to the investigation, currently, the US and India show promise for e-SMR, with abundant and affordable natural gas and renewable energy resources, both priced at around 3.49 $/kg of H2, respectively. Furthermore, the global 2030's scenario with 45 $/MWh of renewable electricity, and capture CO2 credit of 35 $/ton is observed at 3.40 $/kg H2, compared with that of 2050 at 2.91 $/kg H2. e-SMR is well adaptable to many countries' energy mix because it is flexible to utilize hybrid primary energy input, conventional natural gas as feedstock, and conventional/renewable energy for utilities.

Assessment of carbon emission and primary energy input of a gasoline combustion-powered 2.0T SUV in China.

With the use of vehicles, large amounts of carbon dioxide are emitted by combustion of gasoline and energy consumes in their lifecycle. Therefore, the objective of this study is to evaluate the lifecycle carbon emission and primary energy input of a widely used sport utility vehicle (SUV) in China with the lifecycle assessment method. The results show that total petrol consumption of an SUV in lifetime is 21,300kg; the CO2 emissions and primary energy input in the manufacturing, assembly, operation, and decommissioning phase are respectively 8857, 443, 54,925, and 443kg and 123,413, 6171, 12,341, and 6171MJ. The average CO2 emission intensity and energy input intensity of materials are respectively 2.74kg/kg and 64.9MJ/kg. The primary energy input of materials in manufacturing phase occupies 83.3%, and CO2 emission in use phase is 64,267.3kg (occupied 92.62%), mainly attributed to the combustion of petrol.

Evaluation of carbon footprint and energy input of internal combustion engine vehicles in China

AbstractLarge amounts of carbon dioxide (CO2) are discharged into air by combustion of gasoline and energy is input in a passenger internal combustion engine vehicle (ICEV) system through lifecycle phases. Thus, this study aims to evaluate the lifecycle carbon emissions and primary energy input of passenger ICEVs. With the life cycle assessment method, the calculations of carbon emission intensity and energy input intensity of materials used in lifecycle phases were made. The results show that the total lifecycle gasoline consumption of a vehicle was estimated to be 33,000 kg and the lifecycle CO2 emissions reached 81,311 kg per vehicle. Lifecycle CO2 emissions in use period occupied 89.43%, mainly attributed to the combustion of petrol. The average lifecycle CO2 emission intensity of the materials used was 2.33 kg/kg. The lifecycle carbon footprint of the passenger ICEVs was 163 g/km. The total CO2 emissions of ICEVs in Beijing were largest of all cities due to the maximum owning amount. The ratio of total lifecycle CO2 emissions of ICEVs in 13 large cities studied in this work to those of nationwide ICEVs was 0.179. Thus, more new energy vehicles will be given the prioritized choice in the future.

A Conceptual Design and Analysis of a Novel Trigeneration System Consisting of a Gas Turbine Power Cycle with Intercooling, Ammonia–Water Absorption Refrigeration, and Hot Water Production

In this study, the performance of a novel trigeneration system with a gas turbine prime mover, an ammonia–water refrigeration system, and a hot water generation system is investigated from thermodynamic and economic standpoints. The effects of various operating conditions on energy efficiency and the levelized cost of energy are investigated. The proposed system has a production capacity of 45.4 kW power, 14.07 kW cooling rate, and 16.32 kW heat rate. The efficiency of the gas turbine cycle is 49.7%, and it becomes 83.0% after the implementation of the trigeneration system. Through combined heating, cooling, and power generation, primary energy input and the CO2 emissions will be 49% lower compared to separate production. According to the exergy analysis, the combustion chamber is the main component where the greatest exergy destruction occurs. Sensitivity analysis revealed that an increase in the ambient temperature results in a decrease in the energy utilization factor and the net power output. The LCOE of the system is around 0.02 $/kWh, whereas the unit price of the local electricity from the grid is 0.09 $/kWh. The payback period of the absorption sub-cycle is between 4 months and 4 years, depending on the annual operation time of the chiller.

Stand-alone micro-trigeneration system coupling electrolyzer, fuel cell, and heat pump with renewables

A micro hydrogen system in conjunction with renewable energy, namely a wind turbine, a photovoltaic array, and an air-source heat pump, is designed to satisfy the power, heating, and cooling needs of a stand-alone household in a Mediterranean climate. An hourly-based model is used to simulate its operation throughout the year. A unique power management strategy is applied to achieve optimum configuration and size of the components without shortage or excess energy. Unlike previous practices, there is no release of excess heat into the environment. An innovative combination of a fuel cell and a heat pump followed the household's electrical and thermal (domestic hot water/heating and space cooling) profile. Almost 80% of the energy for preparing hot water and household cooling/heating was obtained from waste heat from these devices. The system is compared to the most commonly used stand-alone hybrid renewable energy system with battery storage. The hydrogen system needs four time less batteries and it does not need a back-up diesel generator. Although the energy storage in batteries is more efficient than in hydrogen, the hydrogen system requires only 10% larger primary energy input than the system with only battery storage.

Quantification of waste heat potential in China: A top-down Societal Waste Heat Accounting Model

The recovery of waste heat is important for energy saving and carbon reduction in China. Although numerous technologies for waste heat recovery in China have been analyzed, research is still insufficient to provide an overview of the waste heat potential within the entire energy system. To fill this gap, this paper applies a top-down energy efficiency analysis to develop a Societal Waste Heat Accounting Model to quantify the waste heat potential in China. By indicating the total amount, sector and temperature distribution, and the ability to perform work of waste heat for China in 2018, the results revealed that: a) waste heat occupies 42% of total primary energy inputs, and 26% of primary energy and carbon emissions can be theoretically saved by utilizing waste heat. b) the electricity generation sector is the main source of waste heat, accounting for 45% of the total, of which 88% is below 100 °C. c) the industry sector has a wide range of temperatures, mostly above 300 °C, highlighting the highest ability to perform work. Future studies can focus on the utilization of low-temperature waste heat, which is 66% of the total, for example, the Organic Ranking Cycle technology and the heat pump technology.

System-friendly process design: Optimizing blue hydrogen production for future energy systems

While the effects of ongoing cost reductions in renewables, batteries, and electrolyzers on future energy systems have been extensively investigated, the effects of significant advances in CO2 capture and storage (CCS) technologies have received much less attention. This research gap is addressed via a long-term (2050) energy system model loosely based on Germany, yielding four main findings. First, CCS-enabled pathways offer the greatest benefits in the hydrogen sector, where hydrogen prices can be reduced by two-thirds relative to a scenario without CCS. Second, advanced blue hydrogen technologies can reduce total system costs by 12% and enable negative CO2 emissions due to higher efficiencies and CO2 capture ratios. Third, co-gasification of coal and biomass emerged as an important enabler of these promising results, allowing efficient exploitation of limited biomass resources to achieve negative emissions and limit the dependence on imported natural gas. Finally, CCS decarbonization pathways can practically and economically incorporate substantial shares of renewable energy to reduce fossil fuel dependence. Such diversification of primary energy inputs increases system resilience to the broad range of socio-techno-economic challenges facing the energy transition. In conclusion, balanced blue-green pathways offer many benefits and deserve serious consideration in the global decarbonization effort.

Decentralizing the Centralized Energy System Using CCAM Model: Key to Greener Energy Mix and Sustainability in Nigeria

Nigeria energy system is strongly centralised and unsustainable, associated with waste of huge amount of primary energy input, full of insecurity and climatic change threat and crises. To averts these energy crises, the entire energy requires an urgent energy revolution and this could be achieved by decentralising the country strongly centralised energy using an appropriate model whose energy mix is more of renewable energy. This paper presents how the Community Choice Aggregation Model (CCAM) can decentralise the entire energy system of Nigeria and ensure sustainability. The sustainability criteria of Gibson and Jaccard were used to evaluate the sustainability capacity of CCAM in line with existing Nigeria energy policies. The criteria include potential risks to the environment and humanity, the scale, adaptive capacity and resilience of an energy system, avoided path dependency, intra and intergenerational equity, participatory and inclusive governance, efficiency, and cost-effectiveness. The results from the evaluations have proven CCAM with partnership/joint ownership structure a veritable energy decentralization tool for ensuring greener energy mix and sustainability in Nigeria and the globe. The essentials of this paper can be employed for future energy planning and policy implementation

Electro-Oxidative sp3 C-H Bond Functionalization and Annulation Cascade: Synthesis of Novel Heterocyclic Substituted Indolizines.

Indolizine derivatives are prevalent in many synthetic intermediates, pharmaceuticals, and organic materials. Herein, we report a novel electro-oxidative cascade cyclization reaction that uses electricity as the primary energy input to promote the reaction, leading to a series of heterocyclic substituted indolizine derivatives under exogenous-oxidant-free conditions. It is noteworthy that this electrochemical method provides a novel strategy for generating heterocyclic diversity of quinazolinones and quinolines on indolizines. In addition, the sole byproduct in the reaction was molecular hydrogen.