• Energy Research

In recent years, Poland has experienced a significant increase in the installed capacity of solar and wind power plants. Renewables are gaining increasing interest not only because of Poland’s obligations to European Union policies, but also because they are becoming cheaper. Wind and solar energy are fairly-well investigated technologies in Poland and new reports are quite frequently added to the existing research works documenting their potential and the issues related to their use. In this article, we analyze the spatial and temporal behavior of solar and wind resources based on reanalysis datasets from ERA5. This reanalysis has been selected because it has appropriate spatial and temporal resolution and fits the field measurements well. The presented analysis focuses only on the availability of energy potential/resources, so characteristics intrinsic to energy conversion (like wind turbine power curve) were not considered. The analysis considered the last 40 years (1980–2019) of available data. The Spearman coefficient of correlation was considered as a complementarity metric, and the Mann–Kendal test was used to assess the statistical significance of trends. The results revealed that: The temporal complementarity between solar and wind resources exists mostly on a seasonal scale and is almost negligible for daily and hourly observations. Moreover, solar and wind resources in joint operation exhibit a smoother availability pattern (assessed based on coefficient of variation). Further findings show that the probability of ‘resource droughts’ (periods when cumulative generation was less than arbitrary threshold) lasting one day is 11.5% for solar resources, 21.3% for wind resources and only 6.2% if both resources are considered in a joint resource evaluation. This situation strongly favors the growth of local hybrid systems, as their combined power output would exhibit lower variability and intermittency, thus decreasing storage demand and/or smoothing power system operation.

In recent years, Poland has experienced a significant increase in the installed capacity of solar and wind power plants. Renewables are gaining increasing interest not only because of Poland’s obligations to European Union policies, but also because they are becoming cheaper. Wind and solar energy are fairly-well investigated technologies in Poland and new reports are quite frequently added to the existing research works documenting their potential and the issues related to their use. In this article, we analyze the spatial and temporal behavior of solar and wind resources based on reanalysis datasets from ERA5. This reanalysis has been selected because it has appropriate spatial and temporal resolution and fits the field measurements well. The presented analysis focuses only on the availability of energy potential/resources, so characteristics intrinsic to energy conversion (like wind turbine power curve) were not considered. The analysis considered the last 40 years (1980–2019) of available data. The Spearman coefficient of correlation was considered as a complementarity metric, and the Mann–Kendal test was used to assess the statistical significance of trends. The results revealed that: The temporal complementarity between solar and wind resources exists mostly on a seasonal scale and is almost negligible for daily and hourly observations. Moreover, solar and wind resources in joint operation exhibit a smoother availability pattern (assessed based on coefficient of variation). Further findings show that the probability of ‘resource droughts’ (periods when cumulative generation was less than arbitrary threshold) lasting one day is 11.5% for solar resources, 21.3% for wind resources and only 6.2% if both resources are considered in a joint resource evaluation. This situation strongly favors the growth of local hybrid systems, as their combined power output would exhibit lower variability and intermittency, thus decreasing storage demand and/or smoothing power system operation.

This article presents research on modelling the operation of an independent electricity generation system consisting of a photovoltaic installation and energy storage in the form of electrochemical batteries (PV/BAT). The generation system was considered primarily in the context of its sizing process, i.e., the selection of the installed power of the photovoltaic installation (PV) and the rated capacity of the battery (BAT). Traditionally, the model includes a one-year analysis of the generation system based on initial (nominal) parameters without considering component performance degradation. The novelty of this research lies in the long-term simulation of the system operation, considering the degradation of its components. The sizing process was based on the numerical method. The best solution is selected on the basis of the economic criterion, while satisfying the reliability condition. The simulations were conducted using Matlab software. Using a comparative analysis, the scale of technical and economic oversizing of the system was determined by considering long-term reliability. For the assumed customer load profile, insolation profile, and battery operation in the range of 25–100% of the available capacity, providing the assumed level of reliability after accounting for degradation in the sizing process resulted in a 33.33% increase in the rated battery capacity, an 18.75% increase in the installed photovoltaic plant capacity, and a 19.5% increase in the system cost of electricity (LCOE) relative to the results of the sizing process without accounting for component performance degradation over the years of operation.

This article presents research on modelling the operation of an independent electricity generation system consisting of a photovoltaic installation and energy storage in the form of electrochemical batteries (PV/BAT). The generation system was considered primarily in the context of its sizing process, i.e., the selection of the installed power of the photovoltaic installation (PV) and the rated capacity of the battery (BAT). Traditionally, the model includes a one-year analysis of the generation system based on initial (nominal) parameters without considering component performance degradation. The novelty of this research lies in the long-term simulation of the system operation, considering the degradation of its components. The sizing process was based on the numerical method. The best solution is selected on the basis of the economic criterion, while satisfying the reliability condition. The simulations were conducted using Matlab software. Using a comparative analysis, the scale of technical and economic oversizing of the system was determined by considering long-term reliability. For the assumed customer load profile, insolation profile, and battery operation in the range of 25–100% of the available capacity, providing the assumed level of reliability after accounting for degradation in the sizing process resulted in a 33.33% increase in the rated battery capacity, an 18.75% increase in the installed photovoltaic plant capacity, and a 19.5% increase in the system cost of electricity (LCOE) relative to the results of the sizing process without accounting for component performance degradation over the years of operation.

Small-scale wind turbines (SWTs) have the potential to complement residential PV systems, but their feasibility is highly dependent on local wind conditions, particularly at low elevations where wind resources exhibit high spatial and temporal variability. This study evaluates SWT potential in Poland (Central Europe) using hourly wind speed measurements over six years from 269 gauging stations. A generic power curve is applied to assess wind energy generation at 173 sites with sufficient data completeness (>95 %). The economic viability of SWTs is analyzed through levelized cost of electricity (LCOE), capture price, and self-consumption, with the latter two serving as key indicators for investors exposed to dynamic (day-ahead) electricity market prices. The results reveal that only 13 sites (7.5 %) achieve a capacity factor above 10 %, a threshold comparable to PV systems. Additionally, SWTs and PV exhibit low daily complementarity, as both technologies tend to have coinciding generation peaks around midday, which limits their combined effectiveness in hybrid setups. While SWTs outperform PV systems in terms of annual power generation in selected locations, investments should be preceded by site-specific wind resource assessments, and support schemes must be carefully designed to avoid subsidies in low-potential areas. The findings suggest that without significant cost reductions or targeted policy incentives, SWTs are likely to remain a niche solution rather than a widespread alternative to PV.

Small-scale wind turbines (SWTs) have the potential to complement residential PV systems, but their feasibility is highly dependent on local wind conditions, particularly at low elevations where wind resources exhibit high spatial and temporal variability. This study evaluates SWT potential in Poland (Central Europe) using hourly wind speed measurements over six years from 269 gauging stations. A generic power curve is applied to assess wind energy generation at 173 sites with sufficient data completeness (>95 %). The economic viability of SWTs is analyzed through levelized cost of electricity (LCOE), capture price, and self-consumption, with the latter two serving as key indicators for investors exposed to dynamic (day-ahead) electricity market prices. The results reveal that only 13 sites (7.5 %) achieve a capacity factor above 10 %, a threshold comparable to PV systems. Additionally, SWTs and PV exhibit low daily complementarity, as both technologies tend to have coinciding generation peaks around midday, which limits their combined effectiveness in hybrid setups. While SWTs outperform PV systems in terms of annual power generation in selected locations, investments should be preceded by site-specific wind resource assessments, and support schemes must be carefully designed to avoid subsidies in low-potential areas. The findings suggest that without significant cost reductions or targeted policy incentives, SWTs are likely to remain a niche solution rather than a widespread alternative to PV.

El mundo está experimentando una rápida transformación energética dominada por las crecientes capacidades de las fuentes de energía renovables, como la energía eólica y solar. La naturaleza variable intrínseca de tales fuentes de energía renovables requiere soluciones de almacenamiento de energía asequibles. Este documento propone el uso de ascensores y apartamentos vacíos en edificios altos para almacenar energía. Lift Energy Storage Technology (LEST) es una solución de almacenamiento basada en la gravedad. La energía se almacena levantando contenedores de arena húmeda u otros materiales de alta densidad, transportados de forma remota dentro y fuera del elevador con dispositivos de remolque autónomos. El sistema requiere espacios vacíos en la parte superior e inferior del edificio. Se puede utilizar un ascensor existente para transportar los contenedores desde los apartamentos inferiores a los apartamentos superiores para almacenar energía y desde los apartamentos superiores a los apartamentos inferiores para generar electricidad. El coste de la capacidad de almacenamiento instalada se estima entre 21 y 128 USD/kWh, dependiendo de la altura del edificio. LEST es particularmente interesante para proporcionar servicios auxiliares descentralizados y de almacenamiento de energía con ciclos de almacenamiento de energía diarios a semanales. El potencial global de la tecnología se centra en las grandes ciudades con edificios de gran altura y se estima en alrededor de 30 a 300 GWh. Le monde subit une transformation énergétique rapide dominée par des capacités croissantes de sources d'énergie renouvelables, telles que l'énergie éolienne et solaire. La nature variable intrinsèque de ces sources d'énergie renouvelables nécessite des solutions de stockage d'énergie abordables. Ce document propose d'utiliser des ascenseurs et des appartements vides dans les grands bâtiments pour stocker l'énergie. Lift Energy Storage Technology (LEST) est une solution de stockage gravitationnelle. L'énergie est stockée en soulevant des conteneurs de sable mouillé ou d'autres matériaux à haute densité, transportés à distance dans et hors de l'ascenseur avec des dispositifs de remorque autonomes. Le système nécessite des espaces vides en haut et en bas du bâtiment. Un ascenseur existant peut être utilisé pour transporter les conteneurs des appartements inférieurs aux appartements supérieurs pour stocker l'énergie et des appartements supérieurs aux appartements inférieurs pour générer de l'électricité. Le coût de la capacité de stockage installée est estimé à 21 à 128 USD/kWh, en fonction de la hauteur du bâtiment. LEST est particulièrement intéressant pour fournir des services auxiliaires et de stockage d'énergie décentralisés avec des cycles de stockage d'énergie quotidiens à hebdomadaires. Le potentiel mondial de la technologie est axé sur les grandes villes avec des immeubles de grande hauteur et est estimé à environ 30 à 300 GWh. The world is undergoing a rapid energy transformation dominated by growing capacities of renewable energy sources, such as wind and solar power. The intrinsic variable nature of such renewable energy sources calls for affordable energy storage solutions. This paper proposes using lifts and empty apartments in tall buildings to store energy. Lift Energy Storage Technology (LEST) is a gravitational-based storage solution. Energy is stored by lifting wet sand containers or other high-density materials, transported remotely in and out of the lift with autonomous trailer devices. The system requires empty spaces on the top and bottom of the building. An existing lift can be used to transport the containers from the lower apartments to the upper apartments to store energy and from the upper apartments to the lower apartments to generate electricity. The installed storage capacity cost is estimated at 21 to 128 USD/kWh, depending on the height of the building. LEST is particularly interesting for providing decentralized ancillary and energy storage services with daily to weekly energy storage cycles. The global potential for the technology is focused on large cities with high-rise buildings and is estimated to be around 30 to 300 GWh. يشهد العالم تحولًا سريعًا في مجال الطاقة تهيمن عليه القدرات المتزايدة لمصادر الطاقة المتجددة، مثل طاقة الرياح والطاقة الشمسية. وتدعو الطبيعة المتغيرة الجوهرية لمصادر الطاقة المتجددة هذه إلى إيجاد حلول لتخزين الطاقة بأسعار معقولة. تقترح هذه الورقة استخدام المصاعد والشقق الفارغة في المباني الشاهقة لتخزين الطاقة. تقنية تخزين طاقة الرفع (LEST) هي حل تخزين قائم على الجاذبية. يتم تخزين الطاقة عن طريق رفع حاويات الرمال الرطبة أو غيرها من المواد عالية الكثافة، ويتم نقلها عن بعد داخل وخارج المصعد باستخدام أجهزة مقطورة مستقلة. يتطلب النظام مساحات فارغة في الجزء العلوي والسفلي من المبنى. يمكن استخدام مصعد موجود لنقل الحاويات من الشقق السفلية إلى الشقق العلوية لتخزين الطاقة ومن الشقق العلوية إلى الشقق السفلية لتوليد الكهرباء. تقدر تكلفة السعة التخزينية المركبة من 21 إلى 128 دولارًا أمريكيًا/كيلو واط في الساعة، اعتمادًا على ارتفاع المبنى. لئلا تكون مثيرة للاهتمام بشكل خاص لتوفير خدمات تخزين الطاقة اللامركزية مع دورات تخزين الطاقة اليومية إلى الأسبوعية. تركز الإمكانات العالمية للتكنولوجيا على المدن الكبيرة ذات المباني الشاهقة وتقدر بحوالي 30 إلى 300 جيجاوات في الساعة.

El mundo está experimentando una rápida transformación energética dominada por las crecientes capacidades de las fuentes de energía renovables, como la energía eólica y solar. La naturaleza variable intrínseca de tales fuentes de energía renovables requiere soluciones de almacenamiento de energía asequibles. Este documento propone el uso de ascensores y apartamentos vacíos en edificios altos para almacenar energía. Lift Energy Storage Technology (LEST) es una solución de almacenamiento basada en la gravedad. La energía se almacena levantando contenedores de arena húmeda u otros materiales de alta densidad, transportados de forma remota dentro y fuera del elevador con dispositivos de remolque autónomos. El sistema requiere espacios vacíos en la parte superior e inferior del edificio. Se puede utilizar un ascensor existente para transportar los contenedores desde los apartamentos inferiores a los apartamentos superiores para almacenar energía y desde los apartamentos superiores a los apartamentos inferiores para generar electricidad. El coste de la capacidad de almacenamiento instalada se estima entre 21 y 128 USD/kWh, dependiendo de la altura del edificio. LEST es particularmente interesante para proporcionar servicios auxiliares descentralizados y de almacenamiento de energía con ciclos de almacenamiento de energía diarios a semanales. El potencial global de la tecnología se centra en las grandes ciudades con edificios de gran altura y se estima en alrededor de 30 a 300 GWh. Le monde subit une transformation énergétique rapide dominée par des capacités croissantes de sources d'énergie renouvelables, telles que l'énergie éolienne et solaire. La nature variable intrinsèque de ces sources d'énergie renouvelables nécessite des solutions de stockage d'énergie abordables. Ce document propose d'utiliser des ascenseurs et des appartements vides dans les grands bâtiments pour stocker l'énergie. Lift Energy Storage Technology (LEST) est une solution de stockage gravitationnelle. L'énergie est stockée en soulevant des conteneurs de sable mouillé ou d'autres matériaux à haute densité, transportés à distance dans et hors de l'ascenseur avec des dispositifs de remorque autonomes. Le système nécessite des espaces vides en haut et en bas du bâtiment. Un ascenseur existant peut être utilisé pour transporter les conteneurs des appartements inférieurs aux appartements supérieurs pour stocker l'énergie et des appartements supérieurs aux appartements inférieurs pour générer de l'électricité. Le coût de la capacité de stockage installée est estimé à 21 à 128 USD/kWh, en fonction de la hauteur du bâtiment. LEST est particulièrement intéressant pour fournir des services auxiliaires et de stockage d'énergie décentralisés avec des cycles de stockage d'énergie quotidiens à hebdomadaires. Le potentiel mondial de la technologie est axé sur les grandes villes avec des immeubles de grande hauteur et est estimé à environ 30 à 300 GWh. The world is undergoing a rapid energy transformation dominated by growing capacities of renewable energy sources, such as wind and solar power. The intrinsic variable nature of such renewable energy sources calls for affordable energy storage solutions. This paper proposes using lifts and empty apartments in tall buildings to store energy. Lift Energy Storage Technology (LEST) is a gravitational-based storage solution. Energy is stored by lifting wet sand containers or other high-density materials, transported remotely in and out of the lift with autonomous trailer devices. The system requires empty spaces on the top and bottom of the building. An existing lift can be used to transport the containers from the lower apartments to the upper apartments to store energy and from the upper apartments to the lower apartments to generate electricity. The installed storage capacity cost is estimated at 21 to 128 USD/kWh, depending on the height of the building. LEST is particularly interesting for providing decentralized ancillary and energy storage services with daily to weekly energy storage cycles. The global potential for the technology is focused on large cities with high-rise buildings and is estimated to be around 30 to 300 GWh. يشهد العالم تحولًا سريعًا في مجال الطاقة تهيمن عليه القدرات المتزايدة لمصادر الطاقة المتجددة، مثل طاقة الرياح والطاقة الشمسية. وتدعو الطبيعة المتغيرة الجوهرية لمصادر الطاقة المتجددة هذه إلى إيجاد حلول لتخزين الطاقة بأسعار معقولة. تقترح هذه الورقة استخدام المصاعد والشقق الفارغة في المباني الشاهقة لتخزين الطاقة. تقنية تخزين طاقة الرفع (LEST) هي حل تخزين قائم على الجاذبية. يتم تخزين الطاقة عن طريق رفع حاويات الرمال الرطبة أو غيرها من المواد عالية الكثافة، ويتم نقلها عن بعد داخل وخارج المصعد باستخدام أجهزة مقطورة مستقلة. يتطلب النظام مساحات فارغة في الجزء العلوي والسفلي من المبنى. يمكن استخدام مصعد موجود لنقل الحاويات من الشقق السفلية إلى الشقق العلوية لتخزين الطاقة ومن الشقق العلوية إلى الشقق السفلية لتوليد الكهرباء. تقدر تكلفة السعة التخزينية المركبة من 21 إلى 128 دولارًا أمريكيًا/كيلو واط في الساعة، اعتمادًا على ارتفاع المبنى. لئلا تكون مثيرة للاهتمام بشكل خاص لتوفير خدمات تخزين الطاقة اللامركزية مع دورات تخزين الطاقة اليومية إلى الأسبوعية. تركز الإمكانات العالمية للتكنولوجيا على المدن الكبيرة ذات المباني الشاهقة وتقدر بحوالي 30 إلى 300 جيجاوات في الساعة.

Abstract The structure of modern energy systems has evolved based on the assumption that it is the demand side which is variable, whilst the supply side must adjust to forecasted (or unforecasted) changes. But the increasing role of variable renewable energy sources (VRES) has led to a situation in which the supply side is also becoming more and more unpredictable. To date, various approaches have been proposed to overcome this impediment. This paper aims to combine mixed integer modeling with an Artificial Neural Networks (ANN) forecasting method in order to predict the volume of energy flow between a local balancing area which is using PV–WT–PSH and the national power system (NPS). Calculations has been performed based on the hourly time series of wind speed, irradiation and energy demand. The results indicate that both probabilistic and ANN models generate comparably accurate forecasts; however, the opportunity for improvement in the former appears to be significantly greater. The mean prediction error (for a one hour ahead forecasts) for the best model was 0.15 MW h, which amounts to less than 0.2% of a mean hourly energy demand of the considered energy consumer. The proposed approach has huge potential to reduce the impact of VRES on the NPS operation as well as can be used to facilitate the process of their integration and increase their share in covering energy demand.

Abstract The structure of modern energy systems has evolved based on the assumption that it is the demand side which is variable, whilst the supply side must adjust to forecasted (or unforecasted) changes. But the increasing role of variable renewable energy sources (VRES) has led to a situation in which the supply side is also becoming more and more unpredictable. To date, various approaches have been proposed to overcome this impediment. This paper aims to combine mixed integer modeling with an Artificial Neural Networks (ANN) forecasting method in order to predict the volume of energy flow between a local balancing area which is using PV–WT–PSH and the national power system (NPS). Calculations has been performed based on the hourly time series of wind speed, irradiation and energy demand. The results indicate that both probabilistic and ANN models generate comparably accurate forecasts; however, the opportunity for improvement in the former appears to be significantly greater. The mean prediction error (for a one hour ahead forecasts) for the best model was 0.15 MW h, which amounts to less than 0.2% of a mean hourly energy demand of the considered energy consumer. The proposed approach has huge potential to reduce the impact of VRES on the NPS operation as well as can be used to facilitate the process of their integration and increase their share in covering energy demand.