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Vehicles with hybrid drive systems, are increasingly more often being equipped with solutions that increase the drive systems efficiency. One of such solutions is to use an increased supply voltage for electric motors of such vehicles. The battery voltage is increased several times in the inverter system in order to increase the electrical power supplied to the electric motor. This article presents possible uses of such voltage amplification (called boost) in urban traffic conditions. The tests used the latest models of vehicles with hybrid drive systems equipped with the same drive units: Lexus NX 300h and Toyota RAV4 Hybrid. The study analyses the conditions of starting such a system and the characteristics of its operation. It has been shown that the amplification of the voltage powering the electrical machinery in both vehicles occurs at high torque values. The maximum voltage amplification–almost threefold (up to 650 V) allows a two-fold increase in the torque of the drive system.

Abstract Natural gas is an important source of energy in the global economy, hence understanding the drivers of its prices is of significant interest for economic agents. This paper investigates the role of structural shocks for the dynamics of the U.S. natural gas market within the Bayesian Structural Vector Autoregression framework applied by Baumeister and Hamilton (2019a, AER), to the crude oil market. This approach provides clear intuition for the identification strategy and allows us to correctly estimate the short-term price elasticity of natural gas supply and demand. Our results indicate that the former is low, whereas the latter is higher than the average estimate in the literature. We also show that market specific demand shocks explain a dominant fraction of natural gas prices variability, while the contribution of supply, aggregate economic activity and inventory shocks is important only during specific market events such as the recent outbreak of the COVID-19 pandemic. Finally, we illustrate how changes in supply in the era of shale gas revolution contributed to the dynamics of natural gas prices.

Reducing energy consumption, increasing energy efficiency technologies and solutions, decreasing emissions are very effective tools towards EU environmental policy. The constant demand for domestic hot water (DHW) throughout the year creates great benefits for drain water heat recovery (DWHR) systems in hotels, which is the most promising and significant feature of energy saving potential for the hotel sector in Poland. This paper determines the feasibility of heat recovery in a typical hotel in Poland. The energy analysis was carried out for the installed DWHR system (from washbasins and showers) at the hotel building. To evaluate the energy saving potentiality, daily, monthly and yearly calculation results were performed for an exemplary hotel in Poland. Two types of heat exchangers were adopted for further calculations: vertical (System 1) and horizontal (System 2), this intention aimed to find the most efficient type and relevant solution of energy saving and reduction of CO2 emissions in the analysed hotel. The analysis and calculations were repeated to enhance the saving potentiality of the proposed DWHR systems for various parameters like constant and variable temperature of supply cold water, daily hot water consumption profiles, the efficiency of heat recovery, reduction of annual carbon dioxide emission (CDE), facility standard of operating procedure, the impact of hotel size, etc. The obtained results of the conducted calculations ensure a significant potential of energy savings by implementing the proposed DWHR systems in analysed hotel, which allow to save energy demand and to reduce CO2 emission by 27.3% and improve the efficiency of the DHW preparation system.

The European Union is currently in the process of transformation toward a circular economy model in which different areas of activity should be integrated for more efficient management of raw materials and waste. The wastewater sector has a great potential in this regard and therefore is an important element of the transformation process to the circular economy model. The targets of the circular economy policy framework such as resource recovery are tightly connected with the wastewater treatment processes and sewage sludge management. With this in view, the present study aims to review existing indicators on resource recovery that can enable efficient monitoring of the sustainable and circular solutions implemented in the wastewater sector. Within the reviewed indicators, most of them were focused on technological aspects of resource recovery processes such as nutrient removal efficiency, sewage sludge processing methods and environmental aspects as the pollutant share in the sewage sludge or its ashes. Moreover, other wide-scope indicators such as the wastewater service coverage or the production of bio-based fertilizers and hydrochar within the wastewater sector were analyzed. The results were used for the development of recommendations for improving the resources recovery monitoring framework in the wastewater sector and a proposal of a circularity indicator for a wastewater treatment plant highlighting new challenges for further researches and wastewater professionals.

Abstract The article analyses to what extent ‘negative net CO2 emissions’ from decarbonised biogas-to-electricity can contribute to solving Poland’s carbon capture and sequestration dilemmas. From the criteria-based evaluation of low-carbon power technologies it is found, that biogas-to-electricity is among technologies having increasing production potential in Poland. Therefore, in future biogas will be able to contribute to solving Poland’s CCS dilemmas, because it offers carbon-neutral electricity. Moreover, by applying CCS into biogas-to-electricity the ‘negative net CO2 emissions’ can be achieved. The article examines three biogas-to-electricity technologies involving CO2 capture, i.e. biogas-to-biomethane, biogas-to-CHP and biogas-to-electricity via the ORFC cycle. It is emphasised that the ORFC cycle offers low-cost CO2 separation from a CO2–H2 mixture, low O2-intensity, and the opportunities for advanced mass and energy integration of involved processes. Besides, energy conversion calculations show that the ORFC cycle can offer comparable cycle efficiency with air- and oxy-combustion combined cycles. In regard to the design of biogas-based energy systems it is recommended to include (i) distributed production of biogas in order to avoid costs of long-distance transportation of high-moisture content biomass and (ii) centralised large-scale decarbonised biogas-to-electricity power plants since costs of pipeline transportation of gases are low but large-scale plants could benefit from increased energy and CCS efficiencies.

Abstract A conceptual model of BIM-based design and refurbishment, based on pre-built indicators and allowing the assessment of the building energy demand and eco-building parameters, is presented. The new approach presented in this model creates a knowledge-based decision-making environment for refurbishment strategies and quality control, in this way creating the preconditions to bridge the gap between expected and actual energy performance. The model with integration of new BIM-based optimization subsystems enables energy management and optimization processes. For a comprehensive evaluation of refurbishment measures, it is suggested to include energy efficiency, eco-efficiency, and economic parameters.

The article demonstrates the features and applicability of the πESA platform designed for optimization of the Poland's power sector considering air pollution and health effects. πESA is comprised of: a bottom-up energy-economic model TIMES-PL, an air quality modelling system Polyphemus and a module for assessment of environmental and health impacts MAEH. It has been designed as a web application employing computational resources of the ZEUS cluster of the PL-Grid infrastructure. The results show, that the impact of carbon prices on the fuel and technological power generation structure is much stronger as compared to impact of fuel prices. Future PM emissions from the centralized power and heat generation sector do not differ much irrespective of energy scenario considered. For analysed cases, the statistical life expectancy in Poland due to long-term exposure to PM2.5 air pollution is reduced on average by approx. 183 days. That gives over 12 million years lost for all cohorts included in the analysis. An optimization platform has been developed for the power sector in Poland.It allows for assessment of health impact of energy scenarios.Carbon prices have strong impact on fuel and technology transitions.Future PM emissions from power sector are comparable in all scenarios considered.

Water and energy conservation are indispensable commitments to achieve the sustainable development of the iron and steel industry. Hereby, this study established an evaluation framework to model the water and energy consumption in the iron and steel industry. This framework quantitatively assessed the energy and water saving with adoption of conventional and emerging technologies. Thirty mainstream technologies, among which 21 focused on energy saving and the remaining 9 focused on water saving, were selected for analysis. Five scenarios were developed to examine systematic water- and energy-saving potentials, including benchmark (BM) scenario, constrained product (CP) scenario, business as usual (BAU) scenario, and benefit/cost-driven (BD) scenario and strengthened policy (SP) scenario. The results show that the energy-saving potentials of BAU, BD and SP scenarios are 1.75 PJ, 1.21 PJ and 1.65 PJ, respectively. The water-saving potentials of BAU, BD and SP scenarios are 4.83 billion m3, 5.71 billion m3 and 9.15 billion m3, respectively. The specific energy consumption and water consumption decreased to 15.01-15.59 GJ/t and 54.13-58.77 m3/t, respectively. This study suggested to implement encouraging policies in prompt popularity rate of technologies, and promote energy-saving and water-saving technologies to achieve sustainable development of iron and steel industry.

Abstract Under conditions of low funding for the production of “green energy” in Poland, it became necessary to search for other – cheaper sources of biomass and the development of more efficient technologies. The maize straw is waste material arising in the production of grain. Therefore currently has no wider application and the cost of acquisition is several times lower than in case of maize silage. This paper presents the results of research on biogas efficiency of the maize straw silage, the dynamics of the fermentation process and the decomposition time of biomass under the meso- and thermophilic conditions. Moreover, the exploitation costs of a biogas plant working on this substrate and maize silage have been compared. It has been proved that thermophilic fermentation is significantly shorter (17%) than mesophilic and permits to increase biogas production (8.6%) and methane content (9.3%). In turn, mesophilic fermentation has more stable pH changes in comparison with the thermophilic technology. However, it is related to inhibition of the propionic acid, which can be of great importance in case of continuous fermentation. On the basis of energetic calculations it was shown that the substitution of the maize silage with the maize straw silage allows for nearly three-fold costs reduction and thus increase of the biogas plant profitability.