• Energy Research
• Closed Access close
• Restricted close
• 13. Climate action close
• 11. Sustainability close
• 6. Clean water close
• PL close

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.

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.

Information about decadal to millennial variability of El Nino Southern Oscillation (ENSO) is fundamental for the assessment of ENSO responses to natural and anthropogenic forcings. Despite a growing number of ENSO reconstructions, the overall picture of Holocene ENSO variability is inconsistent. Here, we revisit the iconic Holocene ENSO sediment record of Lake Pallcacocha, Ecuador (Rodbell et al., 1999). We asked: (i) How coherent are the records of clastic layers (flood layers) in the sediments of Lake Pallcacocha and adjacent Lake Fondococha? (ii) What are the synoptic-scale atmospheric conditions that lead to intense precipitation and, potentially, to alluvial activity promoting the deposition of clastic layers in these lakes? (iii) Is intense precipitation in this area associated with El Nino, or not? We analyzed clastic layers in Late-Holocene sediments from multiple cores in Lakes Pallcacocha and Fondococha from Cajas National Park, southern Ecuadorian Andes. Additionally, we investigated precipitation data from 13 nearby meteorological stations to test if intense precipitation (percentiles P0.95, P0.99, P0.995) is predominantly related to El Nino conditions or not (based on 15 different ENSO indices). Our results show that the absolute flood frequencies (clastic layers per 100 years) differ substantially from lake to lake. This indicates that the frequency of clastic layers reflects different sensitivities (thresholds of precipitation) of the catchments to alluvial activity. 210Pb ages suggest that neither the 1982/83 nor the 1997/98 very strong El Ninos produced clastic layers comparable to those found in the late Holocene. Daily precipitation records from meteorological stations close to Lake Pallcacocha including a high-altitude station from the western slope of the Andes did not show unusually high precipitation during the super El Nino 2015/16. We further find that intense precipitation in this area occurs at roughly equal probability under El Nino, La Nina and neutral conditions. Although the spectral properties of the late Holocene clastic layers in Lake Pallcacocha fall into the typical ENSO frequency band, we do not find evidence in the recent sediments and the meteorological data that would support a diagnostic link between alluvial activity in Lake Pallcacocha and strong El Nino events. Our data do not support the idea that the (late) Holocene flood record of Lake Pallcacocha is a conclusive paleo-El Nino record

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 Invasion of mud filtrate from the borehole into the surrounding formation can significantly alter the response of logging tools. In this paper the neutron tool response was calculated for a gas-bearing rock crossed by the borehole. The invaded zone is characterized by variable fluid and gas saturation and is defined by a specific hyperbolic function. The saturation function is based on the characteristics of Polish Carpathian Foredeep Miocene formations reached in gas-bearing rocks. The whole system including neutron tool equipped with Am-Be neutron source and a set of neutron detectors, borehole, invaded zone, and virgin zone, was numerically modeled and used as the input to the Monte-Carlo neutron transport code. The response of each detector was calculated for different combinations of porosity and saturation of invaded zone and virgin zone.

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.

Abstract Heat pumps (HP) represent an attractive option as a heat source, since they utilise “free” ambient heat. However, as they need to be driven by electric energy, their ecological efficiency depends not only on their performance, but also on the energy mix used for electricity generation. Effectiveness of HP can be improved by applying renewable energy sources (RES) providing electricity to drive the system. In order to properly assess such a system, it should be evaluated within a global balance boundary reaching the level of primary resources. The authors propose the use of thermo-ecological cost (TEC) indices for exergo-ecological assessment. TEC is defined as cumulative consumption of non-renewable exergy connected with the fabrication of a particular product. TEC also includes additional consumption of non-renewable natural resources which results from the necessity of compensating environmental losses caused by rejection of harmful substances to the environment. Within the paper, a HP system has been analysed from the ecological point of view. The system consists of a heat pump driven by electricity, and photovoltaic panels or wind turbines as a basic source of electricity. The balance of electricity demand for HP is complemented by electricity from grid. To evaluate this system, real environmental data on solar radiation, wind and ambient temperature deciding on heat demand have been taken into account. The authors present the ecological benefits resulting from supporting heat pumps by electricity generated in RES. It has been demonstrated by comparing results obtained within local and global balance boundaries, that the second approach should be consequently applied when systems based on a mix of renewable and non-renewable energy are analysed, since the first approach may lead to misleading conclusions.

The aim of this research is to find out suitable material for insulator and their flashover performance to withstand the high pollution degree in different environmental conditions. The experimental investigation was carried out on various insulating material like porcelain, glass, and rubber to find out the artificial effluence to examine alternate current flashover potentials. The result shows that the polluted flashover voltage is affected by equivalent salt deposit density and non soluble deposit density, the authorities of which are autonomous of each one on another. The correction formulae of the flashover voltage of various insulators at various salt deposit density and non soluble deposit density levels have pointed out by means of the flashover voltages examination. Also the dissimilarity existing between the flashover voltages of various types of polluted insulators. From this we are able to conclude which insulating material withstands the pollution degree better amongst the above three.