Energy Demand Analysis Research Articles

The Influence of Verticalization on the Dynamics of the Energy Demand at Rest in Patients With Unresponsive Wakefulness Syndrome

Relevance . For the acute phase of cerebral insufficiency (ACI) analysis of energy demand at rest (REE) using indirect calorimetry method is effective to evaluate the level of hypermetabolism and selection of optimal nutritional support. In patients with chronic impairment of consciousness (CIC) the reasonability of such an approach is shown, but in this category of patients the influence of rehabilitation measures on energy demand is not taken into account. Verticalization is a routine method of prevention and treatment of immobilization syndrome in patients with ACI and its consequences today. Aim of study . To determine the effect of the verticalization procedure on the turntable on the dynamics of REE index in patients with unresponsive wakefulness syndrome (UWS). Material and methods . A prospective, comparative, non-randomized study was conducted in 136 patients in the neuro-intensive care unit of the Brain Institute Clinic. The REE index was determined using the method of indirect calorimetry without load and during verticalization in 75 patients with UWS and in 51 patients of the intensive care unit, who also underwent ACI, but were clearly conscious. Results . In patients with clear consciousness during verticalization REE increased by an average of 300 kcal (20%) from the initial values. The energy value of verticalization was about 5 kcal/kg. On the contrary, in the group of patients with UWS, the verticalization procedure practically did not increase the energy consumption, and the energy value of verticalization slightly exceeded 1 kcal/kg. Conclusion . Patients with UWS have a special metabolic status, probably due to a decrease in the functional activity of the brain. This can be confirmed using indirect calorimetry.

An Integrated Microclimate-Energy Demand Simulation Method for the Assessment of Urban Districts

Rapid urbanization and densification processes are changing microclimatic environments in cities around the world. Even though previous studies have demonstrated the impact of urban microclimate on space cooling and heating demand, modeling tools employed to support the design process largely overlook microclimatic conditions in assessing building energy performance, making use of data from weather stations often located in rural areas. This paper presents a computational approach for the quantitative analysis of building energy demand at the district scale, including interdependent factors such as local air temperature, relative humidity and wind speed, diversity in building geometry and materials. The method, which couples the microclimate model ENVI-met and the district-scale energy simulation tool City Energy Analyst, is applied to a case study in Zurich, Switzerland, in order to analyze the energy performance of the area on a hot summer day. The study contributes to advance a coupling approach between a microclimate simulation and an energy tool at the district scale. The results showed that the coupled assessment approach can deal with complex interactions between geometry, building materials and energy systems. The consideration of local microclimatic conditions led to a 5% increase in the space cooling demand on the selected day, while the simulated peak cooling load for each building was 8% higher on average. The variation in the space cooling demand was found to be mainly due to an increase in latent cooling demand. Moreover, the coupling method allowed a detailed analysis of energy demand variation at the building level showing that, when considering the local climate patterns, the space cooling demand of the individual buildings varied between -5% and +14% on the selected day. The proposed method represents a next step to reflect the mutual interactions between buildings and microclimate in urban districts and aims at supporting decision-making in the design process.

Assessment of the air streams mixing in wall-type heat recovery units for ventilation of existing and refurbishing buildings toward low energy buildings

In the cold and moderate climates the energy demand for heating of fresh ventilation air is crucial. The mechanical ventilation systems with heat recovery are used to decrease the peak power of the heating system and to save the energy. In a case of wall-type heat recovery units there is a doubt about the possibility of mixing fresh and exhausted air in the combined intake-outtake device. In this paper experimental investigations were conducted to assess their hygienic safety. The original set-up containing test chamber and the equipment for CO2 concentration measuring has been used. Visualization of airflows mixing with the usage of smoke is presented. The results show that the risk of the exhausted air return to the building is low. At the same time the ventilating efficiency of such systems is high. The analysis of the annual energy demand for the sample single-family and multi-family buildings has been conducted to present the possible energy benefits of usage such devices. Concluding, the wall-type heat recovery units should be considered as hygienic safe and helpful devices in achieving the standard of low energy buildings in a case of existing and refurbished ones.

ANALYSIS OF THE LEVEL OF IMPLEMENTATION OF PROGRAMS FOR THE EFFICIENT USE OF ENERGY AND UNCONVENTIONAL SOURCES: CASE STUDY COLOMBIA

At the First Extraordinary Meeting of the Forum of Ministers of the Environment of Latin America and the Caribbean, Johannesburg, August 2002. An initiative for sustainable development in Latin America and the Caribbean was presented. This proposes that the countries of the region should show in their energy distribution minimum participation of 10% of renewable energy sources in the Total Primary Energy Supply (OTEP). The mechanism of action of this initiative is not based on penalizing countries that their natural conditions are not favorable for energy sustainability, but on promoting greater participation of renewable energy sources. Through the analysis of the country's energy demand and energy sources and according to the initiative, the Colombian government, through its entities, organizes programs to improve its energy efficiency and the participation of renewable energy sources and technologies, not conventional. This paper shows the statistics of energy distribution and energy sources in Colombia. Based on this information, we seek to identify the deficient sectors with their problems to implement strategies at the national level that allows them to meet the proposed goals.Keywords: Efficiency, Energy, Renewable Sources, Sustainability, Total Primary Energy Supply.JEL Classifications: L78, L90, O31, Q20DOI: https://doi.org/10.32479/ijeep.9713

Thermodynamic modeling and energy analysis of a polyamine-based water-lean solvent for CO2 capture

Amine-based water-lean solvents are considered to be promising energy-saving alternatives to existing aqueous amine solvents for CO2 capture. Herein, we propose water-lean solvents comprising 3,3′-iminobis(N,N-dimethylpropylamine) (60 wt%), water (10–18 wt%), and a non-amine chemical (balance), probe the solubility of CO2 therein, and perform the energy demand analysis using an Aspen Plus®-based simulator. For CO2 solubility modeling, the e-NRTL model and Redlich-Kwong state equation were incorporated with the equilibrium reaction model proposed by previous researchers, and the Henry’s law constant of CO2 was estimated using molecular dynamics simulation as it is difficult to measure experimentally. Experimental data acquired using an equilibrium cell and 13C/1H NMR were used to regress the equilibrium reaction model. The minimum thermal energy demand under desorber pressures of 303 and 505 kPa was calculated to be as low as 1.99 and 1.95 GJ t-CO2−1, respectively, which supports the suitability of the developed WLSs for post-combustion CO2 capture.

Forecasting Solar PV Demand Split and Fuel Wood Usage Reduction in Eriti and Oke-Agunla Villages in Nigeria

The study examined solar photovoltaic demand split and fuel wood usage reduction in Eriti and Oke-Agunla villages, that were among the pilot sites for solar electrification programs in the western ecological region of Nigeria. It used questionnaire techniques to elicit information in the local dialect of the respondents, on alternative energy sources for provision of energy services from each of the household's heads, representing solar PV users, in all the 371 households that constitute about 13.4 percent of the 2,778 dwellers in the two villages, for the base year 2020. Specifically, at the rate of the observed 8 dwellers per household, data were obtained from 179 respondents, out of a total of 1,434 dwellers in Eriti village. Likewise, at the rate of the observed 7 dwellers per household, data were also obtained from 192 respondents, out of a total of 1,344 dwellers in Oke-Agunla village. Model for Analysis of Energy Demand (MADE-II) was used for the study. The study showed that the total lighting demand share for solar PV in each of the villages’ total energy demand mix in 2020 was insignificantly low at 5.1 percent share in Eriti village and 6.1 percent share in Oke-Agunla village. Contrariwise, firewood demand maintained as high as 94 and 92 percent share for Eriti and Oke-Agunla villages respectively in the total energy demand mix and by 2030, in Oke-Agunla village, 3-stones-firewood stoves demand for cooking fell drastically from 77% to 30% share, whereas improved firewood stoves demand for cooking rose astronomically from 11% share in 2020 to 45% share by 2030. Nigerian government should adopt such best policy intervention scenario for all the rural areas in the country.

Relative Effectiveness of Energy Efficiency Programs versus Market Based Climate Policies in the Chemical Industry

This paper addresses the relative effectiveness of market vs program based climate policies. We compute the carbon price resulting in an equivalent reduction in energy from programs that eliminate the efficiency gap. A reduced-form stochastic frontier energy demand analysis of plant level electricity and fuel data, from energy-intensive chemical sectors, jointly estimates the distribution of energy efficiency and underlying price elasticities. The analysis obtains a decomposition of efficiency into persistent (PE) and time-varying (TVE) components. Total inefficiency is relatively small in most sectors and price elasticities are relatively high. If all plants performed at the 90th percentile of their efficiency distribution, the reduction in energy is between 4% and 37%. A carbon price averaging around $31.51/ton CO2 would achieve reductions in energy use equivalent to all manufacturing plants making improvements to close the efficiency gap.

SOLAR PHOTOVOLTAICS CONTRIBUTION TO ENERGY MIX IN SELECTED NIGERIAN ESTATES

This paper assessed the share of Solar Photovoltaics (PV) in the energy mix for various energy services in Nigerian residential estate. Model for Analysis of Energy Demand (MADE-II) was used to analyze the primary and other secondary data obtained for the study. The results showed that the current contribution of solar PV in energy demand split for the estates was still low, with a total share of 8.8%, 6.7% and 4.4% in Ijapo, Alagbaka and Sunshine Housing Estate despite various government interventions. Its usage level constituted an insignificant share of 27.9%, 57.3%, 18.3%, 0%, 0%, 0%, 0%, and 16.8% for the total lighting, computing/internet, entertainment, process heat, cooking, refrigeration, water pumping and ventilation services requirement respectively in Ijapo Housing Estate, 26.5%, 70.6%, 13.7%, 0%, 0%, 0%, 0%, and 16.5% in Alagbaka Housing Estate, and 24.0%, 50%, 14.1%, 0%, 0%, 0%, 0%, and 1.8% in Sunshine Housing Estate. The study concluded that utilization of solar PV as an energy source for energy service ensure access to affordable, reliable, sustainable and modern energy for all. The research recommended that government support for solar PV intervention should be further encouraged.

Downscaling NLDAS-2 daily maximum air temperatures using MODIS land surface temperatures.

We have developed and applied a relatively simple disaggregation scheme that uses spatial patterns of Land Surface Temperature (LST) from MODIS warm-season composites to improve the spatial characterization of daily maximum and minimum air temperatures. This down-scaling model produces qualitatively reasonable 1 km daily maximum and minimum air temperature estimates that reflect urban and coastal features. In a 5-city validation, the model was shown to provide improved daily maximum air temperature estimates in the three coastal cities, compared to 12 km NLDAS-2 (North American Land Data Assimilation System). Down-scaled maximum temperature estimates for the other two (non-coastal) cities were marginally worse than the original NLDAS-2 temperatures. For daily minimum temperatures, the scheme produces spatial fields that qualitatively capture geographic features, but quantitative validation shows the down-scaling model performance to be very similar to the original NLDAS-2 minimum temperatures. Thus, we limit the discussion in this paper to daily maximum temperatures. Overall, errors in the down-scaled maximum air temperatures are comparable to errors in down-scaled LST obtained in previous studies. The advantage of this approach is that it produces estimates of daily maximum air temperatures, which is more relevant than LST in applications such as public health. The resulting 1 km daily maximum air temperatures have great potential utility for applications such as public health, energy demand, and surface energy balance analyses. The method may not perform as well in conditions of strong temperature advection. Application of the model also may be problematic in areas having extreme changes in elevation.

GIS-based Heat Demand Modelling for Tourist Accommodation. A Case Study in the State of Salzburg

Spatial energy planning plays a key role in energy transition. Geo-information systems (GIS) make an important contribution in this context: spatially differentiated modelling, representation, and analysis of energy demands in the building sector are the basis for well-founded strategic energy planning. This paper presents a GIS-based method to model the heat demand for tourist accommodation in the federal state of Salzburg. The paper includes the development, description, implementation and validation of the heat demand modelling based on a bottom-up approach. The discussion reflects on possible improvements to the approach.

Combining Machine Learning with Visual Analytics for Explainable Forecasting of Energy Demand in Prosumer Scenarios

Abstract This paper presents the design and a prototypical implementation of a tool for short-term energy demand forecasting in prosumer scenarios in local energy systems. The prototype combines explainable machine learning and visual analytics to facilitate the forecasting and analysis of energy demand and supply in a way usable for small utilities not used to complex analytical approaches. It applies a kNN (k-Nearest Neighbour) algorithm to forecast energy demand and supply and presents the results in an interactive visual dashboard that allows the user to analyze different forecast alternatives, to understand how they relate to the input parameters and identify consumption and production patterns. Initial assessment of the forecasting accuracy (MAPE 5.77%) on a limited dataset and the feedback from target users support the feasibility of the proposed approach.

Analysis of Heat Demand and Thermal Comfort in Naturally Ventilated Single-Family Houses of Various Constructions

Abstract The aim of the paper was a comparative analysis of energy demand for heating and human thermal comfort of a model single-family house with natural ventilation in various construction technologies (wood and brick), located in the Polish temperate climate. The frequency, as well as, the window opening area in the building have been optimized taking into account two objective functions: heating demand and number of thermal discomfort hours. The analyses were based on thermal simulations using the EnergyPlus program on the nine-zone model of the selected house. Each building construction case was calculated for two variants of external partitions insulation. The thermal model, separately for each zone, contained hourly internal heat gain schedules. All simulations were carried out with a 15-minute step for the full calendar year. Analyzes have shown that the heating demand for a building made in wooden technology is higher than a building in brick technology. The wooden building has a greater number of thermal discomfort hours. Increasing the insulation properties of the house increases the number of hours of discomfort.

Sustainable Energy Planning for Nepal in the Federal Structure

This paper examined the energy planning in each province, sustainable technology policy interventions in the energy demand and social cost benefit analysis in energy sector for Nepal in the federal structure over the period 2017-2050 using LEAP-IBC modeling framework. Four scenarios were developed, reference, Low economy, accelerated economy and sustainable scenario, former three are based on socioeconomic assumption and later is technology intervention case. In reference scenario, energy consumption will increase by 3 folds from 544 PJ to 1645 PJ during 2017-2050, whereas in sustainable scenario the value expected to increase to 866 PJ by 2050. In the base year 2017, emission is 69 million metrictons of Co2 equivalents whereas per capita emission is 2.36 metric tons. In the reference scenario the carbon emission increases to 178 million Metric tons of CO2 equivalent in 2050 whereas per capita carbon emission increases to the 4.06metric ton in the year 2050. In sustainable scenario the carbon emission increases to 21.95 million Metric tons of CO2 equivalent in 2030 whereas per capita carbon emission reduces to the 0.64 metric ton in the year 2030 due to the technological policy intervention. The calculated NPV shows that SED scenario is most economically viable with NPV value 7899 million NRS. In sustainable policy scenario efficient as well as new and improved technologies has been considered as a result of which substantial amount of reduction in energy intensities and per capita final energy consumption is achieved. In reference scenario per capita energy consumption 18GJ is increase to 40 GJ and in sustainable scenario is expected to 19GJ by 2050.

Sizing of district heating systems based on smart meter data: Quantifying the aggregated domestic energy demand and demand diversity in the UK

The sizing of district energy systems involves a trade-off between reliability and continuity of service, and avoidance of capital and running costs associated with oversizing. Finding the most appropriate sizing requires a thorough understanding of energy demand. However, empirical data necessary to support such an understanding is scarce, and district energy systems are typically oversized. This study uses smart meter data from the largest field trial to analyse residential energy consumption in the UK. It presents graphically the seasonal and daily variations in energy consumption patterns, the weather dependence of energy loads, and peak hourly demand during particularly cold weather conditions. It also explores the diversity effect in residential energy consumption and computes the after diversity maximum demand at different levels of aggregations. Results show that, peak hourly gas consumption was nearly seven times higher than electricity consumption during the cold spells, while diversity reduced gas and electricity maximum demand per dwelling up to 33% and 47%, respectively. This empirical quantitative analysis of energy demand and diversity can support improved design and operation of district energy, and in particular, enable reduced capital and running costs, and an improved understanding of economies of scale for district heating networks.

Adapting futures scenarios to study UK household energy demand

Greenhouse gas emissions originating from the built environment play a significant role towards climate change. Carefully planning the future of the building sector is key to mitigating these emissions. Addressing this problem by using a predictive approach may miss possible futures that cannot be anticipated. Using explorative scenarios to perform futures analysis helps widen the range of futures taken into account, which minimises this risk. Tools that use scenarios to help study the resilience of sustainable solutions for the UK urban environment are already available. However, they do not facilitate in-depth analysis of future household energy demand. This paper considers how one such tool, ‘Designing Resilient Cities’ (DRC), could be modified appropriately. It includes (a) a series of indicators representing factors affecting the energy demand in dwellings and (b) their characteristics for each scenario to complement the narratives in DRC. As a case study to validate these additions, the resilience of a recommendation to decrease domestic electricity consumption is evaluated.

Changing energy cultures? Household energy use before and after a building energy efficiency retrofit

Government- and community-initiated energy retrofits of existing residential buildings abound across Europe. This paper argues that retrofitting initiatives need to extend their current emphasis on technical-material changes to include an equally strong focus on researching and potentially changing the energy-related expectations, aspirations and actual activities of those who inhabit and use these buildings. The concept of energy cultures serves as a useful heuristic to structure the analysis of household energy demand and internal environment. Covering three key elements of energy culture – 1) material conditions that relate directly to domestic energy use, 2) householders’ attitudes, perceptions and norms concerning the use of energy and 3) observable everyday practices that use energy –, and their interactions, we examine data from 20 households in a social housing estate in Ireland collected before and after retrofitting. Overall, the results highlight the urgent need for an integrated approach to energy retrofitting that combines technology-aided changes in material conditions with a parallel re-shaping of householders’ views and practices to achieve real and lasting reductions in energy use. The latter seems particularly pressing given both the persistence of many energy-intensive domestic activities and the possible emergence of rebound effects that have the potential to cancel out at least some of the savings made through retrofitting.

Energy solutions for producing shale oil: Characteristics of energy demand and economic analysis of energy supply options

Increasing energy demands and oil price volatility have made oil shale attracted more and more attention. However, the shale oil recovery requires huge thermal energy and brings serious environmental problems, such as air pollution. In this paper, to reduce fossil fuel consumption, solar energy, a renewable energy, is introduced. The heat demand and the production yield of the shale oil recovery are obtained through the transients models developed in this paper. Then, three possible energy supply options for the shale oil recovery, i.e. natural gas, the solar thermal energy and the combination of these two, are analyzed and optimized in terms of the net present value and the return on investment over lifetime. The results show that for the shale oil recovery, Option 3, solar energy and gas boiler back up, is the optimal one, which has a return on investment value of 3.12 and can generate $ 72.4 M net present value more return than the Option 1, which uses natural gas only in the project lifetime.

Modeling and energy demand analysis of a scalable green hydrogen production system

Models based on too many parameters are complex and burdensome, difficult to be adopted as a tool for sizing these technologies, especially when the goal is not the improvement of electrochemical technology, but the study of the overall energy flows.The novelty of this work is to model an electrolysis hydrogen production process, with analysis and prevision of its electrical and thermal energy expenditure, focusing on the energy flows of the whole system. The paper additionally includes investigation on auxiliary power consumption and on thermal capacity and resistance as functions of the stack power. The electrolysis production phase is modeled, with a zero-dimensional, multi-physics and dynamic approach, both with alkaline and polymer membrane electrolyzers.Models are validated with experimental data, showing a good match with a root-mean-square percentage error under 0.10. Results are scaled-up for 180 kg/day of hydrogen, performing a comparison with both technologies.

Energy efficiency improvement in hospital buildings, based on the example of a selected type of hospital facility in Poland

Energy demand in hospitals is of highly diverse nature: heat energy, cool energy and electricity. A guarantee of energy supply is required to ensure continuity of medical procedures. Taking care of the lowest possible costs of hospital operations, special attention should be paid to energy efficiency of the installations used in the hospital buildings. The paper presents an analysis of energy demand for heating, cooling, ventilation and lighting in an example hospital in Poland. The selected object was considered a reference as it was built according to a repetitive construction plan, according to which several dozen other hospitals were built in Poland. On the basis of data from 2013-2017, a summary of heat, cold and electricity demand for the hospital in its current technical condition was prepared. Concepts of technical and economic modernization of systems using energy in the analysed facility were proposed, assuming different ranges of changes for individual installations in the hospital. After the analysis of various modernization options, a project was proposed combining the use of heat pumps, photovoltaic installations and generation of heat and cooling in trigeneration, all of which allowed to reduce the costs of operation of the hospital energy systems by about 31%.

2050 年の低炭素社会実現に向けたアジア・世界のエネルギー需給見通しに関する分析

2050 年の低炭素社会実現に向けたアジア・世界のエネルギー需給見通しに関する分析