Evaluation Of Energy Balance Research Articles

Evaluation of energy balance and greenhouse gas emissions in major crops in the Ardabil plain

ABSTRACT The present study evaluated energy flow and the emission of greenhouse gases in the major crop production of the Ardabil plain, Iran, including wheat, potato, alfalfa, barley, and canola. The information required for this study was obtained using a questionnaire and face-to-face interviews with 1,078 farmers in the Ardabil plain during the crop year 2017–2018. Indices of input energy, output energy, specific energy, energy use efficiency, energy productivity, and global warming potential were calculated. The results showed that among the studied crops, the highest energy use efficiency was obtained with wheat and barley, being 5.2 and 5.14, respectively, and the lowest energy efficiency was obtained with alfalfa, rapeseed, and potato, being 4.6, 4.5, and 2.15, respectively. Potato (equivalent to 3,186.2 kg CO2/ha) and wheat (equivalent to 1,727.5 kg CO2/ha) had the largest share in the potential of global warming and greenhouse gas emissions compared to canola (equivalent to 1,326.22 kg CO2/ha), alfalfa (equivalent to 1,157.04 kg CO2/ha), and barley (equivalent to 952.39 kg CO2/ha). The production of crops with high water requirements and high chemical fertilizer consumption using old machines had a greater share in the amount of energy consumption and global warming compared to other crops.

Evaluation of Energy Balance Estimated From Total Energy Expenditure and Body Composition Changes in Junior Sumo Wrestlers: An Observational Study Over Six Months.

Background Sumo is a sport that requires wrestlers to develop their physique from childhood for athletic advantage. However, the energy expenditure and energy balance required for the growth of junior Sumo wrestlers remain unclear. This study aimed to determine the energy balance of junior Sumo wrestlers over six months usingdoubly labeled water (DLW) and bioelectrical impedance analysis (BIA). Methodology A total of 12 male Sumo wrestlers were affiliated with a local Sumo club (average age = 15 ± 1 years). The total energy expenditure (TEE) was measured using DLW, whereas body composition was evaluated using BIA. Daily physical activity was quantified using a tri-accelerometer (Active style Pro HJA-750C). Results The TEE was 4,194 ± 734 kcal/day, while daily physical activity without training was 786 ± 50 minutes. Within six months, the body weight increased by 2.0 ± 3.2 kg, fat-free mass (FFM) was augmented by 2.1 kg, while fat mass did not change significantly. The surplus energy accumulated was 5.6 ± 213 kcal/day. Conclusions The excess energy of junior Sumo wrestlers predominantly increases their FFM. To increase their physical prowess, wrestlers adhere to a lifestyle characterized by high-intensity training and attenuated daily physical activity.

Digital workflow for nearly zero-energy high-rise office building design optimization at the district scale in Mediterranean context

While the implementation of sustainable urban planning has proven to be one of the primary goals to reduce the climate change impact, the rapid adoption of nearly Zero Energy Buildings (nZEB) concept in the building sector is inevitable to reach that objective. Following this trend, this article focuses on the implementation of a parametric digital workflow to evaluate the energy performance of a nearly zero energy high-rise 23-storey office building in the climatic and urban contexts of Casablanca at the early design stage.In the scope of this study, Grasshopper-based digital workflow permits to investigate the impact of 147 parametric building designs, which are generated by varying the building's shape factor and orientation on thermal cooling and heating demand and global solar energy production. The outcomes of this holistic methodology highlight the design trade-offs between energy efficiency strategies and energy performance of building-integrated photovoltaic (bipv) and photovoltaic (pv) systems, aiming to reach optimized nZEB. Moreover, the results of the study suggest that it is possible to reach an annual load match equivalent to 29.68 %. The findings also underscore the significant role of the BIPV systems in shifting towards the goal of net zero energy, accounting for up to 64.43 % of the total solar energy output and contributing in total up to 17.62 % to the yearly self-sufficiency. In addition, the energy balance evaluation, when assessed on an hourly basis, reveals that the BIPV system significantly improves the daily load cover factor, achieving a value of 12.45 %, and increases up to 20.62 % when considering also the rooftop PV, particularly during spring season. Finally, the capacity credit factor is improved by up to 31.27 %, which is a significant share of grid connection reduction compared to the same building relying totally on the grid for its energy needs.

Development of prediction model for body weight and energy balance indicators from milk traits in lactating dairy cows based on deep neural networks

To develop a body weight (BW) prediction model using milk production traits and present a useful indicator for energy balance (EB) evaluation in dairy cows. Data were collected from 30 Holstein cows using an automatic milking system. BW prediction models were developed using multiple linear regression (MLR), local regression (LOESS), and deep neural networks (DNN). Milk production traits readily available on commercial dairy farms, such as energy-corrected milk (ECM), fat-to-protein ratio, days in milk (DIM), and parity, were used as input variables for BW prediction. The EB was evaluated as the difference between energy intake and energy demand. The DNN model showed the greatest predictive accuracy for BW compared with the LOESS and MLR models. The BW predicted using the DNN model was used to calculate the energy demand. Our results revealed that the day on which the EB status transitioned from negative to positive differed among cows. The cows were assigned to one of the three EB index groups. EB index 1 indicated that the day of EB transition was within DIM ≤ 70. The EB indexes 2 and 3 were 70 < DIM ≤ 140 and 140 < DIM ≤ 305, respectively. EB index 3 had the lowest EB, which is the slowest to transition from a negative to a positive energy balance compared with EB indexes 1 and 2. The highest ECM and feed efficiency were observed for EB index 3. The calving interval was the shortest for EB index 1. EB of individual cows during lactation can be estimated and monitored with moderately high accuracy using EB indexes.

A holistic digital workflow methodology to shifting towards net zero energy urban residential buildings in a semi-arid climate

Given the looming threats of climate change and the rapid worldwide urbanization, it is a necessity to prioritize the transition towards a carbon-free built environment. This research study provides a holistic digital methodology for parametric design of urban residential buildings with regard to the Mediterranean semi-arid climate zone of Morocco in the early design phase. The morphological parameters of the urban residential buildings, namely the buildings’ typology, the distance between buildings, the urban grid’s orientation, and the window-to-wall ratio, are evaluated in order to identify the key combinations of passive and active solar design strategies that determine the high energy performing configurations, based on the introduced Energy Performance Index (EPI), which is the ratio between solar BIPV production to maximum available installed BIPV capacity and the normalized thermal energy needs. Through an automated processing of 2187 iterations via Grasshopper, we simulate daylight autonomy, indoor thermal comfort and solar rooftop photovoltaic and building integrated photovoltaic (BIPV) energy potential. Then, we analyze the conflicting objectives of energy efficiency measures, active solar design strategies, and indoor visual comfort in the decision-making process that supports our goal of getting closer to net zero urban residential buildings. The digital workflow showed interesting trends in reaching a balanced equilibrium between performance metrics influenced by the contrasting impact of solar exposure on indoor daylight autonomy and thermal energy demand. Furthermore, the study's findings indicate that it is possible to achieve an annual load match exceeding 66,56 % while simultaneously ensuring an acceptable visual indoor comfort (sDA higher than 0.4). The findings also highlight the important role of the BIPV system in shifting towards the net zero energy goal, by contributing up to 30 % of the overall solar energy output and covering up to 20 % of the yearly self-consumption. Moreover, the energy balance evaluation on an hourly basis indicates that BIPV system notably enhances the daily load cover factor by up to 5.5 %, particularly in the case of slab SN typology, throughout the different seasons.Graphical representations of the yearly, monthly and hourly load matches and the hourly energy balance of the best performing configurations provide a thorough understanding of the potential evolution of the urban energy system over time as a result of the gradual integration of active solar electricity production.

Experimental and Aspen Plus modeling research on bio-char and syngas co-production by gasification of biomass waste: the products and reaction energy balance evaluation

Experimental and Aspen Plus modeling research on bio-char and syngas co-production by gasification of biomass waste: the products and reaction energy balance evaluation

Ammonia Recovery from Livestock Manure Digestate through an Air-Bubble Stripping Reactor: Evaluation of Performance and Energy Balance

The recovery of livestock manure, rich in nutrients, as fertilizer in agriculture, could pose the risk of an excessive load of nitrogen on the soil. Ammonia stripping is one of the available technologies for reducing the amount of nitrogen in the digestate obtained by the anaerobic digestion of manure. The study investigated the performance and energy consumption of a full-scale ammonia-stripping plant, equipped with a bubble reactor and working without the use of any alkaline reagent under semi-batch conditions. Stripping tests were conducted on the liquid fraction of the digestate, studying the current and optimized operative conditions of the plant. The main variables influencing the process were pH, temperature, airflow, and feed characteristics. In the experimental tests, the pH spontaneously increased to 10, without dosing basifying agents. Higher temperatures favoured the stripping process, the higher tested value being 68 °C. The airflow was kept equal to 15 Nm3 h−1 m−3digestate in the pre-stripping and to 60 Nm3 h−1 m−3digestate in the stripping reactors, during all tests. The energy requirement was completely satisfied by the CHP (combined heat and power) unit fed with the biogas produced by manure digestion. Results showed anaerobic digestion coupled with stripping to be a suitable solution for removing up to 81% of the ammonium with neither external energy input nor reagent dosage.

Modeling and optimization of natural gas distribution networks for new supplier projects

• NG distribution networks involving suppliers with unspecified streams. • Cost minimization and specification assurance for the consumer market. • Real case study involving all the alternatives for receiving NG for distribution. • Feasibility and flexibility of applying the model in different configurations. • Reduction in the total cost of distribution of 22.65%. The opening of the market and the possibility of the participation of several suppliers in Natural Gas (NG) distribution networks has raised the level of complexity associated with the quality control of the final stream to be made available to the consumer market. There are suppliers that offer lower prices but supply a lower quality of fuel which can contribute to an out-of-spec final stream (after mixing the different suppliers). On the other hand, it is not always economically viable to build Processing Units and acquire analytical equipment for gas quality control. In general, simulations in natural gas distribution networks focus on the evaluation of physical criteria and energy balance. This work presents a dynamic optimization model, validated by real case studies, for the monitoring and quality control of a natural gas stream mixing process that involves several suppliers providing varying quality levels (including out of specification streams) and prices. The results show the feasibility of executing projects for new suppliers, as well as supplying natural gas to customers who use it as a raw material and who establish more restrictive specification limits than those established by the regulatory agency. Comparing with the conventional operating strategy, the results obtained by the proposed optimization model show a reduction in the cost of distribution equal to 13.5% and 22.6% in the two case studies analyzed, respectively.

Effect of temperature on sandstone acidizing using non-Newtonian fluids

Rock formation is subjected to acid stimulation to increase oil reservoirs productivity. Acidizing of sandstone rocks is a common method to remove damage and recover the oil flow to the wellbore. A matrix acid stimulation will always require additives depending on mud acid (HF/HCl) components, which cause non-Newtonian fluid behavior. In this study, the 3-D mathematical model of sandstone matrix acidizing in radial flow has been presented by a modified two-parameter model to consider non-Newtonian fluids and temperature effects. To this end, the Carreau-Yasuda equation has been employed to predict dissolution patterns created by non-Newtonian reactive fluids in sandstone formations. Meanwhile, the energy equation has been solved in the porous media to estimate the temperature in each time step, which affects the dissolution patterns in matrix acidizing. Three main phenomena are involved in dissolution patterns: surface reaction, diffusion and convection. Acidizing simulation indicates the acid-rock reaction constant in the formation network is temperature sensitive, and increases exponentially by increasing the reservoir temperature. In this work, the effects of various heterogeneity magnitude and porosity in the porous media, injection rate, reaction rate constant, power-law index (n) and temperature are considered by the various presented dissolution patterns of sandstone acidizing. The results show that, to reach a certain penetration length, the pore volume (PV) of injected acid decreases sharply with reservoir temperature, but after the critical temperature, it decreases slowly. The model discretized the Darcy, mass and energy balance equations by finite difference method and pore evaluation by Karman-Cozney correlations, and then employed the Tri-Diagonal matrix algorithm (TDMA) method to achieve the solution of the model and analysis of dissolution patterns in various acidizing regimes and rheological properties. All mathematical estimations including Darcy correlations, mass and energy balance and pore evaluation have been solved in FORTRAN program by parallel processing to accelerate 3-D calculations.

Fire Models as a Tool for Evaluation of Energy Balance in Burning Space Relating to Building Structures

Fire is defined as an extremely hazardous event, causing a threat to life and health of persons, but also damage to the economic sphere. It has been shown many times that fire can occur anywhere and at any time. In order to minimize the risk of fire manifestations, it is necessary to understand its course. In technical practice, computational models are used to determine the partial manifestations of fire, such as fire spread rate, smoke generation rate in the burning area, formation of toxic burning products, flame height, and others. One of the important characteristics is also the energy balance in the burning area relating to the character of burning material, access of oxygen necessary for exothermic reaction of burning, and reaction of the installed safety devices. In this paper we will point out the fire safety of the building. The FDS (Fire Dynamics Simulator) model is recently used in practice, and its advantage is the possibility to model fire even in large and atypical spaces. The contribution of this paper is the practical application of fire safety of construction using the FDS Model, to reduce the cost of fire safety for the structure being constructed. Attention was paid to evaluating how the heat energy that is released during a fire can be influenced by the installed stable fire-extinguishing equipment, taking into consideration the fire resistance of the building structures.

Anaerobic Co-digestion of Rice Straw and Pig Manure Pretreated With a Cellulolytic Microflora: Methane Yield Evaluation and Kinetics Analysis.

Agricultural wastes, such as rice straw (RS) and pig manure (PM), cause serious environmental pollution due to the non-existence of effective disposal methods. Urgent investigations are needed to explore how such wastes can be transformed into resources. In this study, we comprehensively assessed methane yield and kinetics of RS and PM anaerobic co-digestion, with or without pretreatment of a previously developed cellulolytic microflora, under conditions of their maximum organic loading rate. The anaerobic co-digestion results revealed that the cumulative methane production of RS and PM after bio-pretreatment was 342.35 ml (g-VS)−1, which is 45% higher than that of the control group [236.03 ml·(g-VS)−1]. Moreover, the kinetic analysis showed the first-order kinetic, while the modified Gompertz models revealed higher fitting properties (R2 ≥ 0.966). After bio-pretreatment, the hydrolytic constant, maximum accumulative methane production, and maximum methane production rates of RS and PM reached 0.46 day−1, 350.79 ml·(g-VS)−1, and 45.36 ml·(g-VS)−1·day−1, respectively, which were 77, 45.1, and 84.3% higher than those without pretreatment. Also, we found that the lag phase and effective methane production time after bio-pretreatment decreased from 2.43 to 1.79 days and 10.7 to 8.92 days, respectively. Upon energy balance evaluation, we reported a net energy output of 5133.02 kWh·ton−1 after bio-pretreatment. Findings from this present study demonstrated that bio-pretreatment of RS and PM mixtures with cellulolytic microflora could greatly enhance methane production and anaerobic digestion efficiency.

食品廃棄物を対象とした省エネルギー型小規模メタン発酵施設の物質・エネルギー収支の評価

食品廃棄物を対象とした省エネルギー型小規模メタン発酵施設の物質・エネルギー収支の評価

The Enhancement of Energy Efficiency in a Wastewater Treatment Plant through Sustainable Biogas Use: Case Study from Poland

The improvement of energy efficiency ensuring high nutrients removal is a great concern for many wastewater treatment plants (WWTPs). The energy balance of a WWTP can be improved through the application of highly efficient digestion or its intensification, e.g., through the introduction of the co-substrates with relatively high energy potential to the sewage sludge (SS). In the present study, the overview of the energetic aspect of the Polish WWTPs was presented. The evaluation of energy consumption at individual stages of wastewater treatment along with the possibilities of its increasing was performed. Additionally, the influence of co-digestion process implementation on the energy efficiency of a selected WWTP in Poland was investigated. The evaluation was carried out for a WWTP located in Iława. Both energetic and treatment efficiency were analyzed. The energy balance evaluation of this WWTP was also performed. The obtained results indicated that the WWTP in Iława produced on average 2.54 GWh per year (7.63 GWh of electricity in total) as a result of the co-digestion of sewage sludge with poultry processing waste. A single cubic meter of co-substrates fed to the digesters yielded an average of 25.6 ± 4.3 Nm3 of biogas (between 18.3 and 32.2 Nm3/m3). This enabled covering the energy demand of the plant to a very high degree, ranging from 93.0% to 99.8% (98.2% on average). Importantly, in the presence of the co-substrate, the removal efficiency of organic compounds was enhanced from 64% (mono-digestion) to 69–70%.

An energy balance evaluation in lithium-ion battery module under high temperature operation

Lithium-ion battery systems are becoming a major component in numerous applications. The thermal behaviour of cells should be monitored for many reasons. In this paper, the investigation of the energy balance for lithium-ion battery system is described. The electrothermal model allows to describe heat generation and heat dissipation processes in all components of a battery pack (BP). Moreover, this model can be easily adapted for bigger, modular battery systems, since the primitive in the proposed model is a single cell. A method to determine the energy balance through experimental investigations and to validate the model is also proposed. Four types of BPs with sixteen cylindrical 18650 lithium-ion cells were tested. The influence of both busbar material and the presence of heatsinks on the BP thermal conditions was investigated. The results show that the heat accumulated in cells can be decreased by 20% and the cell temperature lowered by 8 °C if additional elements are used in a BP.

Evaluation of Energy Balance in Tropical and Temperate Crossbred Dairy Cows at Post-Partum Transition Stage: A Case Study

Objective of the present study was to assess the energy balance of tropical (Sahiwal x Jersey) and temperate (Friesian x Jersey) crossbred dairy cows in Sri Lanka using serum metabolic profile. The study consisted of tropical and temperate crossbred dairy cows which were at post-partum transition stage, and were from two medium-scale farms in low country dry zone, and mid country intermediate zone, respectively. Each cow was bled (0800 hours) on the day of data collection and serum metabolic profile was assessed. Milk production, body weight and body condition score (BCS) of cows were recorded whereas, dry matter, crude protein and metabolizable energy contents of the mixed rations fed to cows in both farms were analysed. Results revealed that, serum non-esterified fatty acids (NEFA), urea and calcium contents were significantly (P

Carbohydrate intake and ketosis in self-sufficient multi-stage ultramarathon runners

ABSTRACTUltra-endurance athletes accumulate an energy deficit throughout their events and those competing in self-sufficient multi-stage races are particularly vulnerable due to load carriage considerations. Whilst urinary ketones have previously been noted in ultra-endurance exercise and attributed to insufficient carbohydrate (CHO) availability, not all studies have reported concomitant CHO intake. Our aim was to determine changes in blood glucose and β-hydroxybutyrate concentrations over five days (240 km) of a self-sufficient multi-stage ultramarathon in combination with quantification of energy and macronutrient intakes, estimated energy expenditure and evaluation of energy balance. Thirteen runners (8 male, 5 female, mean age 40 ± 8 years) participated in the study. Glucose and β-hydroxybutyrate were measured every day immediately post-running, and food diaries completed daily. CHO intakes of 301 ± 106 g·day−1 (4.3 ± 1.8 g·kg−1·day−1) were not sufficient to avoid ketosis (5-day mean β-hydroxybutyrate: 1.1 ± 0.6 mmol.L−1). Furthermore, ketosis was not attenuated even when CHO intake was high (9 g·kg−1·day−1). This suggests that competing in a state of ketosis may be inevitable during multi-stage events where load reduction is prioritised over energy provisions. Attenuating negative impacts associated with such a metabolic shift in athletes unaccustomed to CHO and energy restriction requires further exploration.

Evaluation of energy balance and greenhouse gas emissions in rice cultivation in Guilan province, northern Iran

The agricultural sector as a supplier of nutritional needs is becoming increasingly dependent on energy consumption. The present study was carried out to investigate the effect of paddy farm level of mechanization on the energy balance and greenhouse gas emissions as well as their effect on rice cultivation in Guilan province, Iran. The survey contains a strategy for assessing sustainable development in the agricultural sector and protecting the environment. To this end, the indicators of energy efficiency and the amount of greenhouse gas emissions from inputs were analyzed. The data used in this study were gathered from questionnaires during the crop years of 2013–2014. Data were grouped based on the level of mechanization. According to the results of the two groups, there was a significant difference in terms of energy input consumption, and direct, renewable, and non-renewable energies, and greenhouse gas (GHG) emissions. Net energy in high and low mechanization levels of 19,340.55 and 20,237.18 MJ ha−1 was calculated for the crop season, respectively. The share of indirect energy in both groups was approximately 80%. The renewable and non-renewable energy usages based on input were 35 and 65% in high mechanization level. Similarly, for low mechanization level, these ratios were 37 and 63%. In the high mechanization level, 44% of total greenhouse gas emissions were from diesel, 31% from nitrogen, and 13.5% from machinery. Also, in the low mechanization group, 40% of the total greenhouse gas emissions were due to nitrogen fertilization, 35.5% of diesel consumption and 11% of machinery. It should be noted that in both groups, agricultural pesticides account for less than 10% of greenhouse gas emissions. Carbon efficiencies, being the ratio of yield’s carbon content to carbon emissions, were estimated to be 10.67 and 12.85 in high and low mechanization levels, respectively. Therefore, it is implied that the low mechanization level group is more eco-friendly. The results of the Cobb–Douglas model in the low mechanization level showed that the impact of the energy input of irrigation water was positive, while that of the energy inputs of diesel fuel, chemical fertilizers, labor, and pesticides was negative.

Energy balance evaluation and optimization of photovoltaic systems for zero energy residential buildings in different climate zones of China

Abstract The application of a photovoltaic (PV) system for zero energy buildings is crucial to balance energy consumption. This paper investigated the potential of PV systems for buildings in different climate zones of China. The tilt angle, orientation, plot ratio, PV conversion efficiency and location were selected to study their influences on electricity production. The performance of the PV system was analyzed based on a residential building, and employed RETScreen in combination with TRNSYS. The results indicate that southwest China is the best place to develop zero energy buildings. Low-rise residential buildings can realize zero energy in China when the PV conversion efficiency is higher than 20%. However, an energy balance only occurs in the southwest when the PV conversion efficiency is 10%. For different building heights, with a high conversion efficiency (20%), the energy consumptions rates are less than 15 kW h/m2a all over China. In the southeast, the effect of the building shape on energy generation can be ignored due to the high solar elevation angle in the summer. Although the optimal tilt angle varies for different cities, the energy deviations are less than 10% when tilt angle is within 10° of the optimal angle. This study proposed a formula to evaluate the potential of a building PV system. The maximum difference between the simulated and calculated results is approximately 10%, which is reasonable and acceptable. This paper provides some references for the application of PV systems in zero energy buildings.

Method for accurate measurement of infrared emissivity for opaque low-reflectance materials.

Accurate determination of infrared (IR) emissivity is important for non-contact temperature measurement and for energy balance evaluation in systems that exchange radiation. A method for accurate measurement is proposed based on active modulation of the background radiation. The hemispherical directional reflectance is measured as a proxy for directional emissivity using an IR camera and an integrating sphere, while the background radiation is modulated using an IR emitter and a mechanical shutter. Measurement of the apparent temperature observed by the camera under two different illumination conditions allows the extraction of reflectance and emissivity. The accuracy of the measurement and its sensitivity to surface properties are analyzed, showing uncertainty values as low as 0.004 in some cases. Example measurements of natural and artificial surfaces are presented.

Evaluation of Negative Energy Balance in Dairy Cows in Qom Province, and its Relationship with Periparturient Diseases

Evaluation of Negative Energy Balance in Dairy Cows in Qom Province, and its Relationship with Periparturient Diseases