Repetitive operations have been extensively used in the inverter compressor refrigeration industry. The approximately periodic disturbance caused by repetitive operations must be compensated to realize stable and high-efficiency operation. In this paper, a periodic disturbance observer (PDOB) is proposed to tackle the speed fluctuation of an inverter compressor in the low-frequency range. Periodic disturbance, consisting of a fundamental wave and corresponding harmonics, can thus be estimated and compensated; in addition, sensitivity and complementary sensitivity can reach a compromise through the use of a certain parameter. Aiming at a different operation environment, an adaptive notch filter based on the Steiglitz−McBride method is employed to estimate the fundamental frequency of periodic disturbance. Finally, the feasibility of our approach is verified by MATLAB simulation, and experiments are implemented to illustrate that speed fluctuation can be more effectively attenuated by th... [more]

The radiant cooling system has a substantial energy-saving effect and can be widely applied in different kinds of low-energy buildings. This article reports the experimental study of the design strategy of the radiant cooling system in low-energy buildings from the perspective of thermal response characteristics of an indoor environment. Two types of a modular radiant cooling system, namely, the copper tube radiant cooling (CTRC) and the capillary radiant cooling (CRC) systems, were investigated. The experiments were conducted in two office rooms characterized by low energy consumption. In total, 16 cases (eight for CTRC and eight for CRC) were analyzed, covering supply water temperature with a range of 12−19 °C. The experimental results show that the supply water temperature has a more substantial effect on the temperature distribution of the envelope for CTRC, than that of CRC. The indoor air temperature stratification is acceptable in the active area of the occupant with a modular r... [more]

Many regions in Poland face the problem of air pollution. These regions include, though are not exclusive, to health resorts, an important element of the healthcare industry. Poor air quality is mainly associated with the domestic sector, which is dominated by individual solid fuel and coal boilers. One option for reducing emissions is to use alternative energy sources for heating purposes. Therefore, the paper presents an analysis into the possibility of using low enthalpy (low temperature) geothermal energy in health resort areas. The main purpose of the article is to estimate the potential of soil and water as the lower source for a heat pump. The article presents analyses of geological and hydrogeological conditions based on which the thermal parameters of the rock mass were determined, which were thermal conductivity and unit heat output for 1800 operating hours per year. The calculated values were used to perform a spatial analysis of the data and create maps of the average therm... [more]

A microgrid is a group of distributed energy resources and interconnected loads that may be operated either in isolated mode or connected mode with the main utility within electrical boundaries. Microgrids may consist of different types of renewable energy resources such as photovoltaic panels, wind turbines, fuel cells, micro turbines, and storage units. It is highly recommended to manage the dependency on these resources by implementing an energy management unit to optimize the energy exchange so that the minimum cost is achieved. In this paper, an energy management system based on the grasshopper optimization algorithm (GOA) is proposed to determine the optimal power generated by the distributed generators in the microgrid which is required to minimize the total generation cost. The proposed unit is applied to a microgrid that consists of five generating units feeding residential, commercial, and industrial loads, and results are compared to other available research in literature to... [more]

Energy consumption is of great significance to the sustainable development of the economy. Due to the spatial heterogeneity of low-carbon growth in regional economies, the relationship between energy consumption and economic growth is complicated. However, a few researches have been published about spatial spillover effects and non-linearity of energy consumption and financial development on regional economic growth in China. Based on the panel data of 30 provinces in China from 2007 to 2017, this paper analyzes the spatial spillover effects and threshold effects of energy consumption and financial development on regional economic growth by using spatial and nonlinear econometric methods. The main conclusions are as follows. Spatial econometric methods show that financial development and energy consumption are two factors of production input to promote China’s economic growth. Meanwhile, energy consumption and financial development have spillover effects on regional economic growth. Ad... [more]

This work presents a validated workflow based on an algorithm developed in Grasshopper to parametrically control the building’s shape, by maximizing the solar irradiation incident on the building envelope and minimizing the embodied emissions. The algorithm is applied to a zero-emission building concept in Nordic and Mediterranean climate zones. The algorithm enables conducting both energy and environmental assessments through Ladybug tools. The emissions embodied in materials and the solar irradiation incident on the building envelope were estimated in the early design stage. A three-steps optimization process through evolutionary solvers, such as Galapagos (one-objective) and Octopus (multi-objective), has been conducted to shape the most environmentally responsive ZEB model in both climates. The results demonstrated the replicability of the algorithm to optimize the solar irradiation by producing an increment of solar incident irradiation equal to 35% in the Mediterranean area, and... [more]

Unless humanity achieves United Nations Sustainable Development Goals (SDGs) by 2030 and restores the relatively stable climate of pre-industrial CO2 levels (as early as 2140), species extinctions, starvation, drought/floods, and violence will exacerbate mass migrations. This paper presents conceptual designs and techno-economic analyses to calculate sustainable limits for growing high-protein seafood and macroalgae-for-biofuel. We review the availability of wet solid waste and outline the mass balance of carbon and plant nutrients passing through a hydrothermal liquefaction process. The paper reviews the availability of dry solid waste and dry biomass for bioenergy with CO2 capture and storage (BECCS) while generating Allam Cycle electricity. Sufficient wet-waste biomass supports quickly building hydrothermal liquefaction facilities. Macroalgae-for-biofuel technology can be developed and straightforwardly implemented on SDG-achieving high protein seafood infrastructure. The analyses i... [more]

Uncertainty of greenhouse gas (GHG) emissions was analyzed using the parametric Monte Carlo simulation (MCS) method and the non-parametric bootstrap method. There was a certain number of observations required of a dataset before GHG emissions reached an asymptotic value. Treating a coefficient (i.e., GHG emission factor) as a random variable did not alter the mean; however, it yielded higher uncertainty of GHG emissions compared to the case when treating a coefficient constant. The non-parametric bootstrap method reduces the variance of GHG. A mathematical model for estimating GHG emissions should treat the GHG emission factor as a random variable. When the estimated probability density function (PDF) of the original dataset is incorrect, the nonparametric bootstrap method, not the parametric MCS method, should be the method of choice for the uncertainty analysis of GHG emissions.

This article presents a field test of how deep renovation affects indoor climate quality. The studied apartment building was built in 1968 and is located in Finland, within the Nordic climate zone. The deep renovation included façade repair with extra insulation, new windows with trickle vents, new balcony glass and doors, and the installation of an exhaust air heat pump into the existing mechanical exhaust air ventilation. The indoor climate conditions and building envelope tightness were measured before and after the renovation. As a result of these energy renovation measures, the building envelope tightness improved by nearly 40% and the uncontrolled supply of air (draughts) decreased by approximately 24%. The overall energy consumption of the building decreased by 45%. Above all, the long testing period gives credibility to the study. The field test brought up the challenge of supplying an adequate amount of fresh air. This article highlights the fact that windows are part of a mec... [more]

Biomass from cup plant (Silphium perfoliatum L.) is considered a renewable energy source that can be converted into alternative fuel. Calorific syngas, a promising type of advanced fuel, can be produced through thermochemical biomass gasification. In this study, the suitability of cup plant biomass for gasification was assessed, including the process energy balance and environmental impacts of waste from syngas purification. Silphium perfoliatum L. was cultivated as a gasification feedstock in different conditions (irrigation, fertilization). The experiments were performed in a membrane gasifier. All obtained energy parameters were compared to the biomass yield per hectare. The toxic effects of liquid waste were assessed using tests analyzing germination/seed root elongation of Sinapsis alba. Leachates collected from condensation tanks of a gas generator were introduced to soil at the following doses: 100, 1000 and 10,000 mg kg−1 DM of soil. The usefulness of Silphium perfoliatum L. fo... [more]

This study aimed to develop a new concept for an air terminal device for a VAV (variable air volume) ventilation system that would improve overall ventilation efficiency under a varying air supply volume. In VAV systems, air volume is modified according to the thermal load in each ventilated zone. However, lowering the airflow may cause a lack of proper air distribution and lead to the degradation of hygienic conditions. To combat this phenomenon, an air terminal device with an adapting geometry to stabilize the air throw, such that it remains constant despite the changing air volume supplied through the ventilation system, was designed and studied. Simulations that were performed using the RNG k−ε model in the ANSYS Fluent application were later validated on a laboratory stand. The results of the study show that, when using the newly proposed terminal device with an adaptive geometry, it is possible to stabilize the air throw. The thermal comfort parameters such as the PMV (predicted... [more]

Global warming represents a serious challenge, which requires the adoption of renewable energy technologies worldwide. However, it can negatively affect the availability of renewable energy resources, such as wind, which are needed for electricity generation. In this context, there is an increasing need for more accurate evaluations of wind turbine power curves. A novel methodology to model the power curves of wind turbines, which combines the use of artificial neural networks (ANN) and Fuzzy logic rules, is proposed in this paper. This methodology assesses the role of environmental temperature in the power curve and the impact of temperature increases on wind energy production. The application of this methodology is illustrated with the simulation of the impact of global warming on the electricity generation of a wind farm. Due to the non-linear relationship between the power output of a turbine and its primary and derived parameters, it is shown that ANN combined with an expert syste... [more]

The paper analyzes the main issues of power market development for clean energy production within the broader framework of ensuring the country’s energy security. In addition, special attention is paid to the technologies aimed at reducing emissions of toxic substances and greenhouse gases by the fossil-fired power plants. Even though the future electricity markets would most likely depend on the high shares of renewable energy sources (RES) in the electricity system, energy efficiency such as the one based on the near-zero emission technologies might also play a crucial role in the transition to the carbon-free energy future. In particular, there are the oxy-fuel combustion technologies that might help to reduce the proportion of unburned fuel and increase the efficiency of the power plant while reducing the emissions of flue gases. Our paper focuses on the role and the place of the near-zero emission technologies in the production of clean energy. We applied economic and mathematical... [more]

The economic development of the EU’s countries depends on stable and permanent access to various energy sources. The integration of European energy markets is a long-term process. Each member country has a different energy balance, energy resources and electricity generation technologies. Therefore, comparing Member States with one another is a complex task. The article deals with organizing the set of objects in multidimensional spaces of variables from the point of view of a certain characteristics that cannot be measured in a simple way, i.e., the relative level of the development of energy markets. The following diagnostic variables were adopted for the analysis: consumption of electric energy generated from renewables per capita (TWH/person), hard coal consumption (million tons/person), greenhouse gas emissions per capita, available for final consumption gigawatt-hour per person, final energy consumption thousand tons of oil equivalent (TOE) per person, petroleum available for fin... [more]

Anaerobic digestate supernatant can be used as a nutrient source for microalgae cultivation, thus integrating phytoremediation processes with high value products storage in microalgae biomass. Microalgae are able to use nitrogen and phosphorous from digestate, but high nutrient concentration can cause growth inhibition. In this study, two microalgae strains (C. vulgaris and S. obliquus) were cultivated on the anaerobic co-digestion supernatant (obtained from the organic fraction of municipal solid waste (OFMSW) and waste activated sludge (WAS)) in a preliminary Petri plate screening at different dilutions (1:10 and 1:5) using a synthetic medium (ISO) and tap water (TW). Direct Nile red screening was applied on colonies to preliminarily identify hydrophobic compound storage and then a batch test was performed (without air insufflation). Results show that C. vulgaris was able to grow on digestate supernatant 1:5 diluted, while Nile red screening allowed the preliminary detection of hydro... [more]

Future power systems will be based on the more active role of distribution system and its cooperation with transmission system. The main issue, which will appear in the network, is the congestion. Congestion management will become one of the crucial elements of power system operation since Distributed Energy Resources (DERs) will be playing a more important role in power systems. Moreover, the evolution also changed the character of the systems to be more dynamic—the need for precise description of power flow and shares of particular nodes in line flows will emerge. This paper presents the potential solution to the congestion management problem by using the active role of the distribution system, which may dismantle the congestions by offering flexibility services. The tools which will be indispensable in this process will be Power Flow Tracing (PFT) methods. The main goal of this paper is to present modification of PFT method and its possible applications. The correctness of the Modif... [more]

Improving the eco-efficiency of food systems is one of the major global challenges faced by the modern world. Short food supply chains (SFSCs) are commonly regarded to be less harmful to the environment, among various reasons, due to their organizational distribution and thus the shortened physical distance between primary producers and final consumers. In this paper, we empirically test this hypothesis, by assessing and comparing the environmental impacts of short and long food supply chains. Based on the Life Cycle Assessment (LCA) approach, we calculate eco-efficiency indicators for nine types of food distribution chains. The analysis is performed on a sample of 428 short and long food supply chains from six European countries. Our results indicate that, on average, long food supply chains may generate less negative environmental impacts than short chains (in terms of fossil fuel energy consumption, pollution, and GHG emissions) per kg of a given product. The values of eco-efficienc... [more]

In the construction industry, it is the material production phase and the use phase of buildings’ life cycles that represent the greatest environmental burden. The presented research focused on wood constructions during their use phase. The primary objective of the research was to determine the amount of CO2 produced during the operation of specific wood constructions in connection with the energy demand for their heating. A correlation analysis of selected parameters revealed a statistically significant correlation between heating medium type and energy demand for heating (p = −0.5773) and between heating medium type and amount of CO2 produced (p = 0.4796). A more detailed analysis showed that, in terms of the average energy demand for heating, the column constructions were the most efficient among the compared construction systems, regardless of the energy standard. Similar findings were obtained for annual CO2 production in connection with the average energy demand for heating. The... [more]

This paper evaluates the link between economic growth, renewable energy, tourism arrivals, trade openness, and carbon dioxide emissions in the European Union (EU-28). As an econometric strategy, the research uses panel data. In the first step, we apply the unit root test, and the results demonstrated that the variables used in this study are integrated I (1) in the first difference. In the second step, we apply the Pedroni cointegration test, and Kao Residual cointegration test, and we observe that the variables are cointegrated in the long run. The panel fully modified least squares (FMOLS), panel dynamic least squares (DOLS), and generalized moments system (GMM-System) estimator are considered in this research. The econometric results proved that trade openness and renewable energy decreased climate change and environmental degradation. The empirical study also found a positive effect of economic growth on carbon dioxide emissions. Moreover, tourism arrivals are negatively correlated... [more]

The objective of the present study is to show a comprehensive assessment of the wind resource dynamics along the Spanish coastal environment of the Iberian Peninsula. After studying the historical resources (reported at 100 m height) for the 20-year period from 1999 to 2018 by analyzing the ERA5 time series of wind speed data, the 10 locations with highest historical wind resources are considered. For these, the study of the future dynamics for the 30-year period from 2021 to 2050 under the climate change scenario RCP 4.5 is carried out. After further selection, mean and maximum values, as well as the seasonal and monthly variability of the wind power density, are obtained for six locations along the Spanish coasts. Furthermore, a performance and economic dynamics assessment is presented for four different wind turbine technologies with rated capacities ranging between 3 and 9.5 MW. A further comparison with other locations in the Baltic Sea and the Black Sea is presented to provide a... [more]

Many embedded systems are implemented for healthcare, and smart homes and spaces. These devices are generally designed for elderly care, for monitoring, surveillance, and collection information. As embedded systems are ubiquitous and pervasive in a smart home, office, or space, different layout affects not only reduce the implementation cost but also the power density of electromagnetic waves. This study aimed to develop a multiple-embedded-system optimization layout to consume less electromagnetic wave power density and gain better communication strength. For smart offices, we analyzed the layout topology of n-shaped and n-shaped with door layout categories. On the basis of the location of each embedded system in a communication center via an n-shaped layout, we investigated the electromagnetic wave effect to the local, direct, and semidirect effects. Indirect and subindirect effects were also studied in the n-shaped layout with a door. In addition, we derived a set of formulas from t... [more]

Urbanization and climate change are requiring cities to find novel pathways to a sustainable future, and therefore the urban context may accelerate the conversion to a circular economy. In this sense, climate change is a considerable threat to the environment, affecting both human and natural systems, and in this context individuals have a very important role. Therefore, the paper aims to investigate, on the one hand, what determines people to undertake specific actions in fighting climate change and, on the other hand, what determines some people to engage in adopting multiple actions exhibiting extra mitigation behaviour compared to others, paving the way to an urban circular economy. In order to do that, multilevel logistic regression analysis using hierarchical data (individuals grouped in counties), reflecting group variability and group-level characteristics effects on outcomes at individual level has been applied. Special attention was given to modernisation thesis validation, s... [more]

PV temperature significantly affects the module’s power output and final system yield, and its accurate prediction can serve the forecasting of PV power output, smart grid operations, online PV diagnostics and dynamic predictive management of Building Integrated Photovoltaic (BIPV) systems. This paper presents a dynamic PV temperature prediction model based on transient Energy Balance Equations, incorporating theoretical expressions for all heat transfer processes, natural convection, forced convection, conduction and radiation exchanges between both module sides and the environment. The algorithmic approach predicts PV temperature at the centre of the cell, the back and the front glass cover with fast convergence and serves the PV power output prediction. The simulation model is robust, predicting PV temperature with high accuracy at any environmental conditions, PV inclination, orientation, wind speed and direction, and mounting configurations, free-standing and BIPV. These, alongsid... [more]

The common use of electric lighting in interiors has led to the need to search for user- and environmentally-friendly solutions. In this research, the impact of the luminaires and room parameters on the selected parameters of general lighting in interiors was assessed. To achieve the objective of this work, a computer simulation and statistical analysis of results were conducted. The illuminance uniformity on work plane, ceiling and wall relative illuminances, utilance, and normalized power density of lighting installations for 432 situations were analyzed in detail. The scenarios were varied in terms of room size, reflectance, lighting class, luminaire downward luminous intensity distribution, and layout. The lighting class was a factor having the highest impact on ceiling and wall illumination, utilance, and power. It was also shown that the impact of lighting class on ceiling illumination, utilance and power, was different in interiors of various sizes. The impact of reflectances an... [more]

The article offers a systematic approach to the method of developing mathematical models of a chemical-technological system (CTS) in conditions of deficit and fuzziness of initial information using available data of various types. Based on the results of research and processing of the collected quantitative and qualitative information, mathematical models of the reactor are constructed. Formalized and obtained mathematical statements of the control problem for choosing effective modes of operation of technological systems are based on mathematical modeling. Based on the obtained expert information, linguistic variables were described and a database of rules describing the operation of the input parameters of the reactor unit of the catalytic cracking unit was obtained.