Energy Balance Analysis Research Articles

The bar-resonator interaction in mallet percussion instruments: A multi-modal model and experimental validation

In some mallet percussion instruments, like vibraphones and marimbas, acoustical resonators are placed under the tuned bars to enhance acoustic radiation. Despite its wide use in commercial instruments, the vibro-acoustic interaction between the tuned bars and their acoustic resonators has not been studied extensively, and previous modeling attempts often neglect important aspects of the coupling dynamics. This work presents a physical model describing the two-way vibro-acoustic interaction between a vibrating beam and an acoustic resonator. The proposed formulation leads to a system composed of a set of mechanical oscillators coupled to a set of acoustical oscillators, representing bar and resonator modes, respectively. The simplicity of the proposed model provides an intuitive understanding of the physics occurring in real instruments and show how specific design parameters will affect their behavior. The dynamics of the system are analyzed through energy balance, time-domain simulations and eigenvalue analysis, revealing a number of interesting features and highlighting three dimensionless parameters: the ratio of frequencies and quality factors, as well as a coupling “strength” coefficient, dependent on the bar-resonator distance, the placement of the resonator along the bar length, bar and resonator mode shapes, amongst others. The proposed model is also shown to be a useful tool for the design of instruments optimized for multi-modal coupling, where several resonator modes are tuned to bar frequencies. Finally, experimental results are presented to validate various aspects of the proposed model and demonstrate its capacity to emulate real instruments, both qualitatively and quantitatively.

Microwave-boosted elemental mercury removal using natural low-grade pyrolusite

Utilizing natural minerals to remove Hg0 from flue gas was regarded as a preferable route to control mercury pollution. This paper purposed a novel microwave (MW)-boosted removal method using natural low-grade pyrolusite (NLP), by which over 85 % of Hg0 was removed and approximately 10–20 % of the increment of efficiency was obtained. Compared with thermo-catalysis, MW also empowered NLP with a wider active-temperature range (100–250 °C) and better H2O and SO2 resistances. Kinetic analysis showed that MW increased the rate constant and reduced the activation energy, Hg-TPD and material balance analyses demonstrated that major Hg0 was chemisorbed as HgO. Via the thermal treatment experiments, the regeneration performance of NLP was confirmed to be good. From the experiments and characterizations, the mechanism was preliminarily speculated: (i) the contribution order of the active components was MnO2 > Mn3O4 > Fe2O3; (ii) the redox pairs of Fe(II)/Fe(III) and Mn(III)/Mn(IV), as well as the O-species, involved in the conversion from Hg0 to HgO. Density functional theory calculations revealed the pathway and mechanism: (i) MnO2 exhibited higher oxidation activity, whereas Mn3O4 showed higher adsorption activity; (ii) Odis derived from Oads enhanced the removal of Hg0 by increasing the adsorption energies and amounts of transferred electron; (iii) Oads had advantages over Olat in term of desorbing HgO, which was the rate-determining step.

A green pretreatment strategy using CO2 and acidogenesis liquid digestate as reagents for biomethane enhancement from corn stover

Pretreatment is a key step for the conversion of lignocellulosic biomass to biomethane via anaerobic digestion (AD). Though various chemical pretreatment strategies have been developed, most of them are costly and environmentally unfriendly, which seriously prevents them from practical applications. This study provides an innovative strategy that uses two kinds of AD byproducts, i.e., CO 2 and acidogenesis liquid digestate (ALD), to replace conventional chemical reagents for pretreating corn stover . The effect of CO 2 -ALD pretreatment at different temperatures (35, 55, and 100 °C) on biomethane production as well as characteristics of pretreated solid and liquid products were studied. Results showed that the highest biomethane yield was obtained after using 1 Mpa CO 2 in ALD at 55 °C pretreatment, which was 63.85% higher than the untreated sample. Meanwhile, CO 2 -ALD pretreatment could destroy the stubborn structure of lignocellulose and separate partially cellulose and hemicellulose , from the stover . The microbial community analysis indicated that this pretreatment strategy enhanced the abundance of hydrolytic bacteria and promoted the acetotrophic pathway. Further energy balance analysis proved that using 1 Mpa CO 2 in ALD at 55 °C for pretreatment had the highest energy gain ( E out /E in ), which was 30.51 % higher than that without any pretreatment. • Acidogenesis liquid digestate and carbon dioxide were used to pretreat corn stover. • The stubborn obstruction of lignocellulose was eliminated after pretreatment. • A 63.85 % methane enhancement was achieved by this pretreatment. • Microbial community changes revealed that the acetotrophic pathway was promoted. • The energy ratio increased by 30.51 % under the best pretreatment conditions.

Numerical analyses of energy balance and installation mechanisms of large-diameter tapered monopiles by impact driving

Large-diameter monopiles are widely used as the foundation to support offshore wind turbines (OWTs) in shallow coastal waters. The benefits of small-to-medium diameter tapered piles have been reported in the past. The potential use of large-diameter tapered monopiles installed by impact driving to support OWTs is thus presented, and then comparatively assessed by numerical analyses in terms of energy balance and installation mechanisms. A three-dimensional large deformation finite element (3D-LDFE) model of monopiles driven in clay was developed using a Coupled Eulerian-Lagrangian (CEL) approach. An advanced user-defined hypoplasticity clay (HC) model was employed to model undrained kaolin clay, featuring nonlinear behavior from small strain to large strain. The force-time curve defined by the operating data of a state-of-the-art hammer in the offshore industry was inputted to explicitly model impact driving. Better agreement between the measured and the simulated results was observed to validate the accuracy of the numerical model. The numerical results obtained give greater confidence to the future use of large diameter tapered monopiles for OWTs.

The effect of heat pre-treatment on the anaerobic digestion of high-solid pig manure under high organic loading level.

Since more and more large-scale farms appear in China and changes in fecal sewage source disposal, the production of high-concentration solid manure waste is also increasing, and its conversion and utilization are gaining attention. This study investigated the effect of heat pre-treatment (HPT) on the thermophilic anaerobic digestion (AD) of high-solid manure (HSM). Pig manure (PM) feed with a total solids of 13% was used for the HPT and subsequent anaerobic digestion (AD) test. The HPT was carried out at 60°C, 80°C, and 100°C, respectively, for 15min after the heating reached the set temperature. The results show that HPT led to PM feed COD solubilization, observing a maximum increase of 24.57% after pretreated at 100°C, and the treated PM feed under this condition received the maximum methane production potential of 264.64 mL·g-1 VS in batch AD test, which was 28.76% higher than that of the untreated group. Another semi-continuous AD test explored the maximum volume biogas production rate (VBPR). It involves two organic loading rates (OLR) of 13.4 and 17.8g VSadded·L-1·d-1. The continuous test exhibited that all the HPT groups could produce biogas normally when the OLR increased to the high level, while the digester fed with untreated PM showed failure. The maximum VBPR of 4.71LL-1·d-1 was observed from PM feed after pre-treated at 100°C and running at the high OLR. This reveals that thermal treatment can weaken the impact of a larger volume of feed on the AD system. Energy balance analysis demonstrates that it is necessary to use a heat exchanger to reuse energy in the HPT process to reduce the amount of energy input. In this case, the energy input to energy output (E i /E o ) ranged from 0.34 to 0.55, which was much less than one, suggesting that biogas increment due to heat treatment can reasonably cover the energy consumption of the pre-treatment itself. Thus combining HPT and high-load anaerobic digestion of PM was suitable.

Influence of Vegetation on Simulation of the Water Balance and Hydrological Response to El Niño–Southern Oscillation in Western Tropical South America

Abstract Land surface models (LSMs) rely on vegetation parameters for use in hydrological and energy balance analysis, monitoring, and forecasting. This study examines the influence that vegetation representation in the Noah-Multiparameterization (Noah-MP) LSM has on hydrological simulations across the diverse climate zones of western tropical South America (WTSA), with specific consideration of hydrological variability associated with El Niño–Southern Oscillation (ENSO). The influence of model representation of vegetation on simulated hydrology is evaluated through three simulation experiments that use 1) satellite-derived constant MODIS; 2) satellite-derived time-varying MODIS; and 3) the Noah-MP dynamic leaf model. We find substantial differences in vegetation fields between these simulations, with the Noah-MP dynamic leaf model diverging significantly from satellite-derived vegetation fields in many ecoregions. Impacts on simulated hydrology were, however, found to be modest across climate zones, except for select extreme events. Also, although impacts on hydrology under ENSO-induced variability were small, we find that the Noah-MP dynamic leaf model simulates a positive relationship between rainfall and vegetation in humid ecoregions of WTSA, where satellite observations may indicate the opposite. The relatively small sensitivity of simulated hydrology to vegetation scheme suggests that the performance of hydrological monitoring and forecasting in WTSA that uses Noah-MP is largely unaffected by the choice of vegetation scheme, such that using a simple climatological default is generally no worse than adopting more complicated options. The presence of some differences between the time-varying and constant MODIS simulations for hydrologic extremes, however, indicates that time-varying MODIS configuration might be more suitable for hydrological hazards applications.

Biorefining of ethanol and methane from NaOH pretreated poplar residues: Mass balance and energy flow analyses

Poplar, a crucial player in lignocellulosic biofuel production worldwide, can be divided into five types. The feedstock variability would significantly impact the scale-up and commercialization of biofuel technologies from poplar. To date, few studies were found comparing ethanol and biogas production from different types of poplar. This study compared the conversion efficiency of NaOH pretreated five types of poplar residues to ethanol and biogas under three biological conversion processes (namely ethanol fermentation process, anaerobic digestion (AD) process, and cascading ethanol fermentation and AD process); the flow of mass, carbon, nitrogen and energy were also analyzed by material flow analysis. 48.4–60.1 % of theoretical ethanol yield, and the specific methane yield of 201 ± 11.0–270 ± 3.40 mL/g volatile solids were obtained under the co-production process, with the highest yield from Populus trichocarpa (N2). These results showed that the co-production process (cascading ethanol fermentation and AD process) of poplar N2 outperformed ethanol fermentation and AD in terms of energy conversion efficiency, which was 121 % and 42.9 % higher than the ethanol fermentation process and AD process, respectively. Mass and energy balance analysis showed that under the co-production process, 158 g ethanol and 103 g methane could be obtained from 1 kg pretreated poplar N2, corresponding to a total energy output of 9.5 MJ, with an energy conversion efficiency of 54.3 %. This study may provide new insights into the breeding of new poplar species for the current biorefinery process.

Analysis on the results of CAP1400 passive containment cooling system during LOCA scenario via integral test

As an important means of removing decay heat from containment, whether the existing water film coverage design could meet integrity requirements needs to be determined. An integral experiment is carried out to validate this by adjusting the cooling water flow and film coverage associated with the DEGB LOCA scenario. The results show that the current design could ensure the residual heat removal, inhibit the temperature and pressure rise in the containment, even the cooling water flow and film coverage as low as 50% of design values. The energy balance analysis shows that the energy in the current test is derived from the “condensation-conduction-evaporation” path at the containment shell, which undertakes 1/3–2/3 energy removal in the initial stage and almost all rest energy removal in the long-term stage. That is, the condensation and evaporation heat transfer process on the shell is the dominant factor affecting the long-term cooling of the containment incorporated steel internal containment and its passive cooling system via external surface.

Two-Phase improves Bio-hydrogen and Bio-methane production of anaerobic membrane bioreactor from waste activated sludge with digestate recirculation

The conventional recirculated two-phase anaerobic digestion (R-TPAD) equipped with two continuous stirred tank reactors (CSTR) usually shows poor water quality, insufficient bioconversion degree and low methane productivity. In this study, a new R-TPAD with CSTR as acidogenic phase and anaerobic membrane reactor (AnMBR) as methanogenic phase was constructed to digest waste activated sludge (WAS) for renewable energy recovery (H2 and CH4). The effects of recirculation ratio (R) on start-up time, long-term performance, membrane fouling behaviors, microbial community evolution, and energy recovery efficiencies were investigated systematically. Result showed that the R-TPAD possessed high H2 (6.1 mL/g-COD) and CH4 (67.9 mL/g-COD) yields with the corresponding COD removal of up to 96.1% at R0.2. During the whole process, the transmembrane pressure was lower than −3.3 kPa with negligible membrane fouling observed. The 16S rRNA gene analysis revealed that the synergistic role of membrane separation and recirculation system promoted the proliferation of fatty acids-producing and organics-degrading bacteria (i.e. Coprothermobacteraeota, Bacteroidetes, etc.) in acidogenic phase and CH4-producing methanogens (i.e. Methanobacterium, Methanosaeta, etc.) in methanogenic phase, thus accelerating the biodegradation of WAS. This positive stimulation sustained the high diversity and the dynamic balance of key microorganisms in the R-TPAD process. Energy balance analysis further indicated that the R-TPAD with R0.2 could increase net energy output by 77.9% compared to the control TPAD without recirculation. This work provides a fundamental data base for the scientific management of WAS and push forward the real-world application of R-TPAD technology in the real-world scenarios.

Long term performance of pilot methanogenic digester filled with seashell wastes treating slaughterhouse wastes: Biogas production and environmental impact

High ammonia and organic acids contents of decomposed slaughterhouse waste (SHW) often result in the severe inhibition or even failure of the anaerobic digestion (AD). The two-stage AD system can alleviate the ammonia inhibition; however, addition of alkali is often needed to maintain the neutral condition. In this study, seashell wastes containing high percentage of calcium carbonate (CaCO3) were for the first time added in a pilot scale methanogenic digester treating chicken blood waste to retain the microorganisms and provide pH buffers for the substrate. A long-duration performance of this digester was conducted for 400 days under different organic loading rates (OLRs). The results show that methane yields of the digester were 244.8 and 224.9 mL g−1 CODadded at OLR of 0.4 and 0.6 g COD L−1 d−1, respectively, higher than the results of previous studies treating the similar feedstock. An AD system treating blood wastes of a typical poultry slaughterhouse was also proposed for which energy balance and carbon footprint analyses were conducted. The energy production of 0.35 MJ kg−1 blood and carbon emissions reduction of 0.05 kg CO2-eq kg−1 blood can be achieved from treating blood waste of the broiler chicken. This study reveals that using seashell wastes in an AD treating SHW can facilitate the reuse of aquaculture wastes and improve the sustainability of meat industry.

An 11-year record of wintertime snow-surface energy balance and sublimation at 4863 m a.s.l. on the Chhota Shigri Glacier moraine (western Himalaya, India)

Abstract. Analysis of surface energy balance (SEB) at the glacier/snow surface is the most comprehensive way to explain the atmosphere–glacier/snow interactions, but that requires extensive data. In this study, we have analysed an 11-year (2009–2020) record of the meteorological dataset from an automatic weather station installed at 4863 ma.s.l. (above sea level) on a lateral moraine of the Chhota Shigri Glacier, western Himalaya. The study was carried out over the winter months (December to April) to understand SEB drivers and snow loses through sublimation. Furthermore, this study examines the role of cloud cover on SEB and turbulent heat fluxes. The turbulent heat fluxes were calculated using the bulk-aerodynamic method, including stability corrections. The net short-wave radiation was the primary energy source. However, the turbulent heat fluxes dissipated a significant amount of energy. The cloud cover plays an important role in limiting the incoming short-wave radiation by about 70 %. It also restricts the turbulent heat fluxes by more than 60 %, resulting in lower snow sublimation. During winter, turbulent latent heat flux contributed the largest proportion (64 %) in the total SEB, followed by net radiation (25 %) and sensible heat flux (11 %). Sublimation rates were 3 times higher in clear-sky than overcast conditions, indicating a strong role of cloud cover in shaping favourable conditions for turbulent latent heat flux by modulating the near-surface boundary layer conditions. Dry air, along with high snow-surface temperature and wind speed, favours sublimation. Besides, we also observed that strong and cold winds, possibly through mid-latitude western disturbances, impede sublimation by bringing high moisture content to the region and cooling the snow surface. The estimated snow sublimation fraction was 16 %–42 % of the total winter snowfall at the study site. This study substantiates that the snow sublimation is an essential variable to be considered in glaciohydrological modelling at the high-mountain Himalayan glacierised catchments.

Novel ways for hydrogen production based on methane steam and dry reforming integrated with carbon capture

The combination of methane steam reforming technology and CCS (Carbon Capture and Storage) technology has great potential to reduce carbon emissions in the process of hydrogen production. Different from the traditional idea of capturing CO2 (Carbon Dioxide) in the exhaust gas with high work consumption, this study simultaneously focuses on CO2 separation from fuel gas and recycling. A new hydrogen production system is developed by methane steam reforming coupled with carbon capture. Separated and captured high-purity carbon dioxide could be recycled for methane dry reforming; on this basis, a new methane-dry-reforming-driven hydrogen production system with a carbon dioxide reinjection unit is innovatively proposed. In this study, the energy flow and irreversible loss in the two newly developed systems are analyzed in detail through energy and exergy balance analysis. The advantages are explored from the perspective of hydrogen production rate, natural gas consumption and work consumption. In addition, in consideration of the integrated performance, an optimal design analysis was conducted. In terms of hydrogen production, the new system based on dry reforming is better, with an advantage of 2.41%; however, it is worth noting that the comprehensive thermal performance of the new steam reforming system is better, reaching 10.95%. This study provides new ideas for hydrogen production from a low carbon emission perspective and also offers a new direction for future distributed energy system integration.

Enhancing methane production in anaerobic co-digestion of sewage sludge and food waste by regulating organic loading rate

This study presented mechanistic insights into the long-term effects of stepwise-increasing organic loading rates (OLRs) on anaerobic co-digestion (AcoD) of sewage sludge and food waste. The maximum methane (CH4) yield of 500.0 ± 10.5 mL CH4/g VSfed was achieved at medium OLR of 3.5 g VS/L/d. This excellent performance was associated with the high hydrolysis efficiency (78.4%), three-fold enhancement in the acidogenesis enzyme activity, and 87.0% enhanced methanogen activity. Soluble intermediates (carbohydrates and proteins) were largely degraded (>98.5%), especially tyrosine-like and tryptophan-like aromatic proteins. The particulates were effectively decomposed from macromolecules to micromolecules, and the crystallinity of cellulosic substances decreased by 24.5%. The newly-shaped combined syntrophic acetate oxidation-hydrogenotrophic methanogenesis pathway dominated enhanced CH4 production. Energy balance analysis based on medium OLR demonstrated the high energy recovery potential in full-scale AcoD. These findings suggest the optimal medium OLR can facilitate the bioconversion of organics to CH4 through a new metabolic pathway.

Refined crack propagation methodology and energy balance analysis in the Rubber Cord Adhesion Inflation Test

The Rubber Cord Adhesion Inflation Test (RCAIT) has been recently introduced to characterize the bond quality between coated steel wires and rubber as used in tires applications. In this experiment, a pressurized fluid is used to initiate and propagate a delamination along the reinforcement. A constant pressure is measured during the crack propagation regime so that using adequate energy balance analysis, the critical Strain Energy Release Rate (SERR) can be determined. Due to the axisymmetric nature of the specimen, the crack tip is not visible nor other information which would ease the analysis of the fracture process. Then, new experimental developments and experimental data reduction techniques are introduced to demonstrate the reliability of the RCAIT.

Integration of oxycombustion and microbial electrosynthesis for sustainable energy storage

Power-to-gas technology makes use of surplus electricity by its conversion and storage in the form of a gas. Currently power-to-gas schemes based on biological processes are of great interest. Microbial electrosynthesis (MES) cells are biological systems that produce biogas via microbial action and a supply of electrical energy. The OxyMES scheme proposed is a power-to-gas system that seeks to neutralize the CO2 emissions of a standard industrial process through the hybridization of oxy-fuel combustion and bioelectrochemical processes that produce CH4 (in cathode) and O2 (in anode). This oxygen is used for oxycombustion in an industrial C-fuel boiler. The energy balance analysis yielded a power-to-gas efficiency in the MES cell close to 51%, and the overall performance of the OxyMES integrated system was close to 60% for a cell with a Faradaic efficiency of 80%, CO2-to-CH4 conversion rate of 95%, and ΔVcell = 1.63 V. With the proper sizing of the CO2, O2, and biogas process tank system, it is possible to achieve 100% autonomy, free from external feedstock supplies.

Instantaneous energy balance and performance analysis during warm up period of a spark ignition engine under several thermal energy management strategies

Significant improvements can be obtained through different thermal energy management systems (TEMS) in internal combustion engines during warm up period. When the engine thermal energy management system works correctly, it ensures that the engine components are cooled exactly as needed, which is important in energy consumption and harmful exhaust emissions production. Additionally, thanks to the reduced warm up time, friction losses are reduced, after-treatment performance is increased, comfort conditions are improved in the passenger compartment, and the windshield quickly clears ice and condensation. However, the effects of the designed engine TEMSs on the energy balance during the warm up period should be well known. For this purpose, an experimental setup was established for not only the averages of the effects of different thermal strategies established as commonly done in the literature, but also the changes during the whole warm up process were analyzed. Then, three different TEMS were compared, and the effects of energy losses on each other were revealed. Results have shown that the warm up time can be reduced by 30 % with different engine TEMS, and thus, specific fuel consumption and CO emission can be reduced at different levels under several engine operating conditions. It was observed that when the engine coolant was not sent to the oil cooler heat exchanger during the warm up period, the thermostat opening time decreased from 252 s to 218 s. Moreover, it has been observed that the engine can reach steady state operating conditions approximately 10 % faster when the thermal energy is transferred from the exhaust gases, where a significant part of the fuel energy is lost, to the cooling water during the warm-up period.

Effects of a CFD-improved dimple stepped-lip piston on thermal efficiency and emissions in a medium-duty diesel engine

Diesel piston-bowl shape is a key design parameter that affects spray-wall interactions and turbulent flow development, and in turn affects the engine’s thermal efficiency and emissions. It is hypothesized that thermal efficiency can be improved by enhancing squish-region vortices as they are hypothesized to promote fuel-air mixing, leading to faster heat-release rates. However, the strength and longevity of these vortices decrease with advanced injection timings for typical stepped-lip (SL) piston geometries. Dimple stepped-lip (DSL) pistons enhance vortex formation at early injection timings. Previous engine experiments with such a bowl show 1.4% thermal efficiency gains over an SL piston. However, soot was increased dramatically [SAE 2022-01-0400]. In a previous study, a new DSL bowl was designed using non-combusting computational fluid dynamic simulations. This improved DSL bowl is predicted to promote stronger, more rotationally energetic vortices than the baseline DSL piston: it employs shallower, narrower, and steeper-curved dimples that are placed further out into the squish region. In the current experimental study, this improved bowl is tested in a medium-duty diesel engine and compared against the SL piston over an injection timing sweep at low-load and part-load operating conditions. No substantial thermal efficiency gains are achieved at the early injection timing with the improved DSL design, but soot emissions are lowered by 45% relative to the production SL piston, likely due to improved air utilization and soot oxidation. However, these benefits are lost at late injection timings, where the DSL piston renders a lower thermal efficiency than that of the SL piston. Energy balance analyses show higher wall heat transfer with the DSL piston than with the SL piston despite a 1.3% reduction in the piston surface area. Vortex enhancement may not necessarily lead to improved efficiency as more energetic squish-region vortices can lead to higher convective heat transfer losses.

Pollutant Removal and Energy Recovery from Swine Wastewater Using Anaerobic Membrane Bioreactor: A Comparative Study with Up-Flow Anaerobic Sludge Blanket

Due to its high content of organics and nutrients, swine wastewater has become one of the main environment pollution sources. Exploring high-efficient technologies for swine wastewater treatment is urgent and becoming a hot topic in the recent years. The present study introduces anaerobic membrane bioreactor (AnMBR) for efficient treatment of swine wastewater, compared with up-flow anaerobic sludge blanket (UASB) as a traditional system. Pollutant removal performance, methanogenic properties, and microbial community structures were investigated in both reactors. Results showed that by intercepting particulate organics, AnMBR achieved stable and much higher chemical oxygen demand (COD) removal rate (approximately 90%) than UASB (around 60%). Due to higher methanogenic activity of anaerobic sludge, methane yield of AnMBR (0.23 L/g-COD) was higher than that of UASB. Microbial community structure analysis showed enrichment of functional bacteria that can remove refractory organic matter in the AnMBR, which promoted the organics conversion processes. In addition, obvious accumulation of acetotrophic and hydrotrophic methanogens in AnMBR system was recorded, which could broaden the organic matter degradation pathways and the methanogenesis processes, ensuring a higher methane yield. Through energy balance analysis, results concluded that the net energy recovery efficiency of AnMBR was higher than that of UASB system, indicating that applying AnMBR for livestock wastewater treatment could not only efficiently remove pollutants, but also significantly enhance the energy recovery.

Energy efficiency for wine companies: Regional sustainability initiatives in the Guadalupe valley from a transdisciplinary perspective

Energy efficiency is an aspect highly related to the sustainability and competitiveness in the medium and long term of any company. This paper describes the theoretical and technical generalities of some case studies related to wine-producing companies located in the Guadalupe Valley, Mexico, which began the implementation of an energy management system based on ISO 50001 to optimize the use of energy and minimize the carbon footprint of its products (wine). The framework for these Capstone Projects and the multi-year energy balance analysis using Sankey diagrams are presented to determine the Energy Performance Indicators and Significant Energy Uses. In addition, considering the experiences gained in these projects, a transdisciplinary analysis is carried out to strengthen the sustainable life cycle of the wine based on resource efficiency as the main element from a circular economy approach.

Determining Optimal Temperature Combination for Effective Pretreatment and Anaerobic Digestion of Corn Stalk.

Temperature is one of the important factors affecting both chemical pretreatment and anaerobic digestion (AD) process of corn stalk (CS). In this work, the combined ways between pretreatment temperature (40 °C and 60 °C) and AD temperature (35 °C and 55 °C) were selected to investigate the AD performance for sodium hydroxide (NaOH) pretreated CS. Three organic loading rates (OLRs) of 1.6, 1.8 and 2.0 g·L−1·d−1 were studied within 255 days using continuously stirred tank reactors (CSTR). The results revealed that biogas yields of CS after pretreated were higher than that of untreated groups by 36.79–55.93% and 11.49–32.35%, respectively. When the temperature of NaOH pretreatment changed from 40 °C to 60 °C, there was no significant difference in enhancing the methane yields during the three OLRs. The mesophilic AD (MAD) of CS pretreated with 2% NaOH under 40 °C and 60 °C conditions produced 275 and 280 mL·gvs−1 methane yield at OLR of 1.6 g·L−1·d−1. However, as the OLR increased, the methane yield of CS under thermophilic AD (TAD) condition was further higher than under MAD condition. Furthermore, from the perspectives of energy balance and economic analysis, AD of 40 °C-treated CS recovered more energy and TAD is less expensive. Therefore, temperature of 40 °C was considered as an appropriate for pretreatment whether in mesophilic or thermophilic AD system. On the other hand, TAD was chosen as the optimal AD temperatures for higher OLRs.