Combined Heat And Power Plant Research Articles

The Effects of Phosphate Compounds on the Microstructure and Mechanical Properties of Fly Ash Geopolymer Mortars

Coal-fired power plants are a main source of energy in Poland. In the rapidly growing demand for the reduction of CO2 emission in the energy industry, the use of biomass for energy purposes has increased significantly. The combustion of biomass results in the generation of fly ash, with higher levels of CaO, K2O, P2O5, in contrast to the fly ash derived from the combustion of coal. The aim of this study was to examine the influence of phosphate compounds on fly ash-based geopolymer mortars. Geopolymers were made by mixing two types of fly ash—one from the combustion of wood biomass and the second from the combustion of coal in a heat and power station. Basic activators (NaOH and Na2SiO3) were used for the alkali activation. The maximum level of tetraphosphorus decaoxide addition was established at 5% of the total mass of the aluminosilicate precursors mass. The results showed that the phosphate oxide concentration within the specimens demonstrated a positive correlation with flexural and compressive strength across all temporal intervals (7, 28, and 56 days). The porosity, however, for samples with a 5% addition of P4O10, increased more than twofold in comparison to reference samples (from 4.26% to 9.98%).

Potential use of district heating networks and the prospects for the advancements within urban areas of Nottingham as a case study

Buildings in urban areas significantly contribute to global energy consumption, necessitating solutions to reduce energy demands and mitigate environmental impacts. This study investigates district heating networks in urban areas, using Nottingham as a case study. A literature review addresses key barriers to decarbonising building energy in the UK, focusing on: (1) Information, engagement, and behaviour, (2) Strategy, policy, and regulation, (3) Infrastructure, (4) Supply chain and skills, and (5) Distribution of costs and impacts. The study examines the network's location, current processes, energy performance, and potential future impacts. Heat mapping and energy flow assessments identify areas for energy savings, guiding system optimisation. The findings suggest that increasing the energy output from the heat station to the network can enhance performance. The analysis highlights the potential of a life cycle perspective for district heating networks, proposing a framework that considers all stages from material sourcing to system utilisation. This approach helps assess environmental impacts, including greenhouse gas emissions and resource depletion, identifying opportunities to improve resource efficiency and reduce environmental impacts. By evaluating current sustainability goals and regulatory compliance, the study provides insights into the environmental and social implications of the district heating network's operations, pinpointing areas for improvement. It emphasises the need for continuous optimisation and innovation throughout the network's life cycle. The potential of a full life cycle assessment (LCA) approach is highlighted to evaluate four main future advancements: (1) heating network with added energy storage, (2) advanced system operations through model predictive control (MPC) for demand prediction, (3) general network improvements, and (4) network expansion. Overall, this study aims to enhance the sustainability, efficiency, and resilience of district heating networks, contributing to the transition towards sustainable energy systems while ensuring environmental and economic viability over time.

НАДЕЖНОСТЬ ТРАКТОРОВ БЕЛАРУСЬ И ОРГАНИЗАЦИЯ ТЕХНИЧЕСКОГО СЕРВИСА В УСЛОВИЯХ АЗЕРБАЙДЖАНСКОЙ РЕСПУБЛИКИ

The article analyzes typical failures of Belarusian tractors by brand and component. It has been established that over the past 17 years, the production of tractors has increased by 3.28 times. Observations of more than 100 units of Belarusian tractors operating in different climatic conditions of the Republic of Azerbaijan were carried out for the effective organization of technical service, taking into account the nature of the distribution of faults. It was found that 73.2% of malfunctions occur in Belarus tractors - 892, 15.9% - in Belarus - 1221, 10.9% - in Belarus - 82.1. It has been established that 64.6% of Belarusian tractor failures occur in engines, 29.3% in transmissions, and 6.1% in hydraulic systems. Operational and technological assessment was carried out on the fields of the republic. A decrease in the efficiency of using equipment was revealed as a consequence of the fact that due to an insufficient technical service network, its efficiency decreases, costs and time to eliminate failures increase and, accordingly, the intensity and frequency of their occurrence increases. The methodology for determining the density of tractors depending on their number and area of farmland was developed to optimize the development and placement of technical service centers (TSC) for tractors in Belarus. Equipment density is characterized by the amount of equipment per 1 km2 of farmland. The average distance they travel to the central heating station depends on the density of tractors. A nomogram for determining the average moving distance of equipment to the central heating system based on the number of equipment and the density of their distribution has been developed. Thus, the effective organization of technical services in the republic helps to ensure a minimum level of prices for services with high quality.

A control strategy considering buildings’ thermal characteristics to mitigate heat supply-demand mismatches in district heating systems

In district heating systems (DHS), periodic heat supply-demand mismatches (HSDM) exacerbate issues such as thermal imbalance and hydraulic instability. To mitigate these issues, this paper proposes a supply water temperature correction strategy for heating stations that considers building's thermal characteristics. Firstly, buildings are classified into energy-saving levels based on comprehensive thermal characteristic Bc and heat load index. Secondly, simulation models are developed for buildings with different thermal characteristics, and response of indoor temperature to supply-demand mismatch rates was analyzed. Then, after determining the regulation sequence and supply water temperature of heating stations, a balanced control strategy is formulated for HSDM conditions. Finally, the proposed strategy was applied to a practical combined heat and power system (CHPS) in severe cold regions. The results showed that the studied heating stations were classified into 4 types. After regulation of both insufficient and excessive heating conditions, the indoor temperature guarantee rate increased by over 20 %; the ranges of thermal imbalance degree and hydraulic imbalance degree were reduced by more than 0.09 and 0.22, respectively; the SD of supply water pressure and supply-return pressure difference were reduced by over 0.17 and 0.11, respectively. The strategy provides a reference for global balanced control of DHS under similar HSDM conditions.

Booster heat pump with drop-in zeotropic mixtures applied in ultra-low temperature district heating system

The pursuit of sustainable district heating solutions has driven a growing interest in ultra-low temperature district heating (ULTDH) systems, where booster heat pumps (BHPs) play a pivotal role despite challenges posed by their efficiency limitations under large temperature glide conditions. This paper investigates the potential of drop-in R-1234yf/R-32 zeotropic mixtures in BHPs compared to a baseline R-134a system, within the context of a ULTDH framework. This study focused on the viability of the mixtures of R-1234yf/R-32 with the composition ratio of 80 %/20 % and 90 %/10 %. The investigation reveals disparities in compressor efficiency and heat exchanger pressure drop at the component level. Device-level analysis unveils increased COP for R-1234yf/R-32 mixtures, alongside with maximum second-law efficiencies reaching 0.32. A remarkable enhancement in heating capacity up to 58 % was found. System-level analysis demonstrated exergetic efficiencies and identified preferable district heating temperatures. Exergetic efficiencies of 0.47, 0.55, and 0.59 were achieved for domestic hot water preparation at district heating supply temperatures of 30 °C, 35 °C, and 40 °C, with a subsequent shift in optimal district heating temperatures as central heating station efficiency decreased. Temperature profile analysis underscored challenges stemming from excessive subcooling, highlighting the need for configuration refinements.

Strategies for decarbonizing European district heating: Evaluation of their effectiveness in Sweden, France, Germany, and Poland

Decarbonizing the EU's district heating is crucial for meeting climate goals and securing a sustainable energy future. Currently, district heating suffers from inefficiency, high operating temperatures, significant distribution losses, and reliance on fossil fuels. Literature highlights strategies for reducing emissions, including integrating low-carbon heat sources, lowering supply temperatures, and employing efficient technologies like heat pumps and combined heat and power (CHP). However, the individual effectiveness of these strategies in reducing emissions within existing networks remains unassessed. This study addresses the gap by applying a comprehensive model that evaluates energy and emissions across the district heating supply chain, coupled with a derivative-based sensitivity analysis. We apply this methodology to the national-level district heating systems of Sweden, France, Germany, and Poland. Results indicate that the impact of decarbonization strategies on district heating emissions varies significantly by the system's characteristics, i.e., the energy mix in power and district heating supply and the presence of CHP plants. Primarily, incorporating more low-carbon heat sources emerges as the most effective method for emission reduction across nearly all examined countries. A 1 % increase in the share of low-carbon heat sources can potentially cut emissions by 0.8–1.3 kg CO2e per GJ of heat. In countries like Sweden and France, where the power generation already relies heavily on low-carbon resources, technologies which convert electricity to heat—such as heat pumps and electric boilers—rank as the second most effective approach. In contrast, for countries like Germany and Poland, with their moderate to low use of low-carbon power, reducing distribution losses and decreasing heat demand prove more effective, with emission reductions ranging between 0.8-1.3 and 0.7–1.2 kg CO2e per GJ in these countries, respectively. Additionally, cutting down power generation in fossil fuel-based CHP plants significantly reduces emissions in these regions. While green hydrogen and carbon capture and storage (CCS) also contribute to emission reductions, a 1 % increase in green hydrogen's share might decrease emissions by just 0.3–0.5 kg CO2e per GJ of heat, highlighting their lower effectiveness compared to the aforementioned strategies. These insights hold value for both district heating operators and for technology suppliers seeking decarbonization pathways. This is also true for policymakers focused on climate change mitigation, guiding the distribution of subsidies and R&D investments.

Research on Intelligent Heating for Urban Systems Based on Digital Twin

Abstract This article focuses on the intelligent heating platform driven by digital twins, analyzing the overall framework of the system according to the sensor layer, application layer, and network layer, and building an information service platform for intelligent heating networks. The data of the entire heating system, including heat sources, primary networks, heating stations, secondary networks, and heat users, is remotely collected, analyzed, and diagnosed. Subsequently, statistical analysis is conducted on the energy consumption of each heat source and heating station, achieving data sharing and data mining among various business systems. This article conducts research on several key technologies for optimizing decision-making methods of heating system operation scheduling based on simulation models and develops software systems to support the intelligent upgrading of heating systems. The results show that intelligent heating system based on digital twins can better meet the balance between supply and demand in urban heating systems, and optimize the overall operating costs and environmental benefits of the system under multiple constraints.

Production of biobased polyethylene terephthalate and its precursors for diversification in the global sugarcane industry

The technical and economic viability of producing fully bio-based polyethylene terephthalate (PET) or its monomers was investigated. First generation (1 G) biorefineries, utilizing A-molasses, and combined first and second generation (1G2G) biorefineries, utilizing molasses and sugarcane bagasse and brown leaves, were considered. Simulations were developed for self-sufficient biorefineries, where the energy demands were met by utilizing the existing sugar mill boiler, accompanied by a new medium-pressure boiler and biogas generator. 1G2G scenarios required the replacement of the sugar mill boiler with a new, high-efficiency combined heat and power (CHP) plant, where electricity and useful heat were generated from a portion of 2 G biomass and other residues. 1 G PET was unprofitable at a minimum selling price (MSP) of $2946.t−1. 1 G production of Ethylene ($1847.t−1), monoethylene glycol (MEG) ($1648.t−1), 5-Hydroxymethylfurfural (HMF) ($1576.t−1) and iso-butanol (iButOH) ($1292.t−1) were more economically viable than PET, terephthalic acid (TPA) ($2689.t−1) and p-xylene (PX) ($2983.t−1), due to less complex processing and lower energy demands. 1G2G biorefineries were less profitable than 1 G equivalents, due to the cost of pretreatment and new CHP plants. The most profitable scenario was 1 G iButOH, with an MSP 19.0 % lower than its market price. New technologies to produce p-xylene and TPA from biomass in fewer steps, such as Virent Inc.’s Bioforming® technology, could potentially improve the economic viability of PET in the future.

Techno-economic analysis of AMP/PZ solvent for CO2 capture in a biomass CHP plant: towards net negative emissions

Compared to conventional monoethanolamine (MEA), alternative solvents are expected to substantially contribute to reduce the energy demand of post-combustion CO2 capture from flue gases. This study presents a comprehensive techno-economic analysis of a 27 wt% 2-amino-2-methyl-1-propanol (AMP) + 13 wt% piperazine (PZ) aqueous solution for CO2 capture, compared to a 30 wt% MEA solution. The study addresses the retrofit of a carbon capture unit to a biomass-fired combined heat and power (CHP) plant, effectively making it a bioenergy with a carbon capture and storage (BECCS) system. The treated flue gas has a flow rate of 23 tons/hour (t/h) with 11.54 vol% CO2 and a 90% capture rate is aimed for. Aspen Plus V14 was employed for process simulations. Initially, binary interaction parameters for AMP/PZ, AMP/H2O, and PZ/H2O are regressed using vapor-liquid equilibrium (VLE) data, which were retrieved from literature along with reaction kinetics. Validation of parameters from available experimental literature yields an average absolute relative deviation (AARD) of only 5.9%. Afterwards, a process simulation model is developed and validated against experimental data from a reference pilot plant, using a similar AMP/PZ blend, resulting in 5% AARD. Next, a sensitivity analysis optimizes operating conditions, including solvent rate, absorber/stripper packing heights, and stripper pressure, based on regeneration energy impact. Optimized results, compared to MEA, reveal that AMP/PZ reduces the energy consumption from 3.61 to 2.86 GJ/tCO2. The retrofitting of the capture unit onto the selected CHP plant is examined through the development of a dedicated model. Two control strategies are compared to address energy unavailability for supplying the capture unit. The analysis spans 4 months, selected to account for seasonal variations. At nominal capacity, CO2 emissions, rendered negative by biomass combustion and CO2 capture, reach a maximum of −3.4 tCO2/h compared to 0.36 tCO2/h before retrofitting. Depending on the control strategy and CHP plant operating point, the Specific Primary Energy Consumption for CO2 Avoided (SPECCA) ranges from 4.91 MJ/kgCO2 to 1.76 MJ/kgCO2. Finally, an economic comparison based on systematic methodology reveals a 7.87% reduction in capture cost favoring the AMP/PZ blend. Together, these findings highlight AMP/PZ as a highly favorable alternative solvent.

RECONSTRUCTION OF HEATING SYSTEMS IN RESIDENTIAL BUILDINGS WHILE MAINTAINING EXISTING HEAT SOURCES

The purpose of the article is to substantiate the need for real reconstruction of single-pipe vertical centralized heating systems, which are operated in most multi-story residential buildings in Ukraine, into apartment horizontal systems. The paper presents the main design shortcomings of heating systems in residential buildings built in the second half of the 20th century. The feasibility of using horizontal apartment systems is substantiated. For the first time, the heating system was reconstructed during the heating season without displacing residents and without stopping the existing heating system. A technical solution is proposed for supplying heat to apartments from an existing individual heating station with an elevator without its reconstruction. The article presents the results of a number of studies aimed at improving the heating system and determining the indicators of its economic and energy efficiency. Installation work can be carried out selectively in any number of apartments, and "old" and "new" heating systems can operate in parallel. The methodology for the reconstruction of heating systems presented in this paper can be used in the process of post-war restoration of the destroyed infrastructure of the housing stock of Ukraine. Modernizing in-building systems while maintaining the existing heat source is much cheaper than decentralizing heat supply by installing independent heating systems with a gas boiler in each apartment. The main conclusions of the article include that the reconstruction of existing heating systems is an objective necessity, without which the subscriber's influence on his heat consumption is impossible. The modernization described in this article is dictated by all the regulatory deadlines for major repairs of heating systems, which in most cases are more than twice as long.

Study of the differences in collection scope of raw materials of biomass CHP plants caused by regional factors

Combined heat and power (CHP) plants fueled by biomass can collect and utilize waste straw resources in a productive way. This paper considers the impact of regional factors on biomass energy potential and the energy needs of the population, so as to study the differences in construction of biomass CHP plants and the collection scope of raw materials, and proposes evaluating suitability for biomass energy development based on scope of resource collection. Taking five counties in China as its study areas, this paper assesses biomass energy potential. A topology system of biomass CHP plants has been reasonably established in different counties through ArcGIS, the required installed capacity has been calculated according to the number of persons served by such plants. Finally, the collection length and corresponding value range of raw materials of CHP plants along roads has been obtained based on biomass energy potential and energy demand. The result shows that the differences in area, straw yield and biomass fuelization rate depending on regions have a great impact on biomass energy potential, while the residue-to-product ratio of straw and biomass calorific value have less of an impact. When the biomass energy per capita of a region reaches 9.75GJ/person, it is suitable for biomass energy development. The installed capacity in the biomass CHP plant system of each study area is mostly within the scope of 3–59 MW, and the collection length of corresponding biomass resources of such plants along roads is mostly within the scope of 5.09–25.23 km.

A flexible and deep peak shaving scheme for combined heat and power plant under full operating conditions

Improving the flexible and deep peak shaving capacity of combined heat and power (CHP) plant under full operating conditions to facilitate renewable energy consumption is the main choice of novel power system. Accordingly, a dry/wet state automatic conversion control scheme fuses the precise mechanism structure, reinforcement learning and multi-objective model predictive control (MPC) algorithms is designed to promote the deep peak shaving ability of CHP plant in this paper. Firstly, the detailed mechanism models of once-through boiler at dry and wet state are presented by analyzing the dynamic characteristics of steam-water flow. Secondly, the large-scale unknown parameters in mechanism models are identified via the Takagi-Sugeno fuzzy modeling, reinforcement learning algorithms and actual dry/wet state conversion data. Thanks to the proposed hybrid modeling strategy, the high-precision boiler-steam unit models at dry and wet state are rapid obtained. Then, to meet different peak shaving demands, the multi-objective MPC algorithm is respectively constructed under dry and wet state with the comprehensive consideration of operational constraints, load tracking error, algorithm stability, power generation cost, CO2 and NOx emission costs. Aiming at maximizing the peak shaving efficiency and flexible operation ability of plant, a dry/wet automatic control scheme combined the designed multi-objective MPC algorithms and identified dry/wet state models is proposed. Finally, the load variation rate of 5 % and 2 % RCM/min is respectively achieved in the dry/wet state conversion tests on a 350 MW CHP plant based on the proposed control scheme. Thus, the rapid and thorough dry/wet state conversion performance of once-through boiler has successfully improved the operational flexibility of CHP plant under full operating conditions.

Cost-benefit analysis and comparison of grid-stabilizing energy flexibility options and their applications in relation to the German energy system

With an increasing share of renewable energies, flexibility is becoming an important factor to ensure the German electricity grid stability. Therefore, decision-makers have to deal with the implementation of the necessary transformations and adaptions. To provide an indication, a cost–benefit analysis and comparison of grid-stabilizing energy flexibility options and their applications for a current and an outlook scenario is conducted. In the results, due to its low costs, the flexibilization of existing CHP (combined heat and power generation) plants stands out as a particularly attractive option. Similarly, the flexibilization of existing wind turbines and photovoltaic systems, as well as the flexibilization of small heat pumps, appear to be highly attractive in the outlook (integration is enabled by pooling). Furthermore, in the future, large-scale batteries and PEM (Polymer electrolyte membrane) electrolysis as well as controlled charging (pooling) will become increasingly beneficial for the energy system. The overall worst performing flexibility option is power-to-methane, which requires additional effort from the system in both scenarios. In general, the research showed that even for similar flexibility options, the resulting systemic benefit highly depends on the specific flexibility application. Nonetheless, the results give an indication towards important sources of flexibility and further research priorities.

HiFi-Gas: Hierarchical Federated Learning Incentive Mechanism Enhanced Gas Usage Estimation

Gas usage estimation plays a critical role in various aspects of the power generation and delivery business, including budgeting, resource planning, and environmental preservation. Federated Learning (FL) has demonstrated its potential in enhancing the accuracy and reliability of gas usage estimation by enabling distributedly owned data to be leveraged, while ensuring privacy and confidentiality. However, to effectively motivate stakeholders to contribute their high-quality local data and computational resources for this purpose, incentive mechanism design is key. In this paper, we report our experience designing and deploying the Hierarchical FL Incentive mechanism for Gas usage estimation (HiFi-Gas) system. It is designed to cater to the unique structure of gas companies and their affiliated heating stations. HiFi-Gas provides effective incentivization in a hierarchical federated learning framework that consists of a horizontal federated learning (HFL) component for effective collaboration among gas companies and multiple vertical federated learning (VFL) components for the gas company and its affiliated heating stations. To motivate active participation and ensure fairness among gas companies and heating stations, we incorporate a multi-dimensional contribution-aware reward distribution function that considers both data quality and model contributions. Since its deployment in the ENN Group in December 2022, HiFi-Gas has successfully provided incentives for gas companies and heating stations to actively participate in FL training, resulting in more than 12% higher average gas usage estimation accuracy and substantial gas procurement cost savings. This implementation marks the first successful deployment of a hierarchical FL incentive approach in the energy industry.

Performance evaluation and operation optimization of a combined heat and power plant integrated with molten salt heat storage system

Combined heat and power is an effective way to enhance the energy efficiency of thermal power plants. The solar and wind power are intermittent, and dispatchable power sources are critical to balance the supply and demand sides. To facilitate the high penetration of renewable energy, combined heat and power (CHP) plants should provide more and more peak shaving services for the power grid. The thermal energy can be stored in and released from the molten salt heat storage system (MSHSS). The integration of MSHSS can enlarge the adjustable range of the power load of CHP plants, so it is a potential way to enhance the operational flexibility of CHP plants supplying industrial steam and power. In this study, the MSHSS integrated within CHP plants are proposed, which store a part of sensible heat energy carried by extraction steam before supplying to industrial users. The heat storage capacity dominates the flexibility enhancement, and indicators to evaluate energy performances of the proposed system are defined. Moreover, models for the operation optimization of CHP plants integrated with the MSHSS are developed, and a case study of a 350 MW CHP unit is conducted. When the reheat steam is extracted to supply to industrial steam, the maximum and minimum adjustable power loads can be increased and decreased by 17.13 and 12.01 MW, respectively with the integration of the MSHSS. Moreover, during the peak, flat, valley time of reference day, the heat supply coal consumption rates are 73.94, 74.19 and 81.03 kg t−1,respectively. With the operation scheduling of CHP plant integrated with MSHSS, the MSHSS with reheat steam as heat source show the lowest coal consumption rate as 1553.79 ton/day.

Productivity of two Brassica oilseed crops in a Mediterranean environment and assessment of the qualitative characteristics of raw materials for bioenergy purposes

Rapeseed (Brassica napus var. oleifera D.C.) and Ethiopian mustard (Brassica carinata A. Braun) are promising industrial crops for cultivation in the Southern Mediterranean area due to profitable yields under semi-arid conditions. The exploitation of raw materials produced by these crops is very convenient for farmers to produce bioenergy directly on-farm and permits them to create a short agri-energy supply chain. The purpose of this study was to determine their yield performance under rainfed conditions and make an economic assessment of a combined heat and power plant (CHP) system operating on pure vegetable oil (PVO). Tests were conducted in Sicily (Italy) from 2012 to 2014. Seed and crop residue yields were detected. The analysis of seed, defatted seed meal and crop residue, and the chemical-physical aspects of PVO were carried out according to conventional protocols. A pilot CHP system was used for cogenerating electricity and heat. In general, rapeseed had the highest seed (2.27 t ha−1) and oil (1.11 t ha−1) yields. The average oil content ranged from 44.88 % (Ethiopian mustard) to 45.73 % dry matter (rapeseed). Ethiopian mustard performed better than rapeseed in terms of aboveground biomass yield (5.49 t ha−1), in both years. The two crops showed different fatty acid profiles of the oil mainly due to diverse content of erucic and oleic acids. The CHP system had an average consumption of 14.41 kg PVO h−1. These results confirm that the productivity of the species can be appreciable in the Southern Mediterranean area and indicate the use of raw materials of these crops as crucial to the development a sustainable short agri-energy supply chain.

A robust optimization approach for resiliency improvement in power distribution system

AbstractThe occurrence of natural disasters has led to an alarming increase in power interruptions, with severe impacts. Compounding this problem is the uncertain nature of data, which presents significant challenges in enhancing the resiliency of power distribution systems following such events. To tackle these issues, this paper introduces a robust optimization approach for improving the resiliency of power distribution systems. The approach encompasses crew teams for switching actions as part of the restoration process, along with demand response programs and mobile generators (MGs). By simultaneously leveraging these elements and considering the uncertainty associated with electrical load and electrical price, the resiliency of the system is enhanced. The objective function is tri‐level, comprising minimum, maximum, and minimum functions. At the first level, the approach minimizes the cost of commitment of combined heat and power plants (CHPs) by taking into account the location of MGs and the reconfiguration structure in power distribution systems. The second level aims to identify the worst‐case scenario for the uncertainty variables. Finally, the third level focuses on minimizing the total operation cost under the worst‐case scenario using demand response programs. The proposed algorithm is implemented on an IEEE 33‐bus test distribution system, with four different cases investigated.

Biophotonic Combined Energy System (BCES)

A comprehensive outline of a new approach in closed loop processing for energy utilisation and biomass genera tion using micro algae for electricity, heat and chemicals is presented - the Biophotonic Combined Energy System (BCES). The basic idea proposes that life-cycle management is an es sential strategy in research and business. In terms of the BCES a carbon cycle driven by solar radiation via the photosystems of the Chlorophyceae species Scenedesmus rubescens serves as the core process from which valuable materials are extracted. The resi dues serve as the substrate for biogas generation which is used to run a Combined Heat and Power Plant (CHP) equipped with a gas motor and an exhaust gas carbon dioxide and heat recovery system. The electricity generated is fed into the public grid and the thermal energy is used to make the right temperature for the micro algae suspension. The carbon dioxide from biogas combus tion is injected into the algae suspension thereby closing the elementary loop within the system.

Turning toward a smart region by implementing a hybrid power system

Distributed generation (DG) especially energy acquired from renewable energy sources (RES) plays a significant role in modern power sector due to high carbon emissions around the globe. Its emerging potential is feasible by implementing microgrids as they are beneficial for networks in terms of increasing flexibility and stability, providing frequency and voltage support, power factor compensation etc. This makes the investment into microgrid incorporating RESs attractive, while at the same time reducing overall investment in the grid. Higher cost and stochastic nature of intermittent RES are complications for the implementation and operation of such solutions. This paper will analyse economic feasibility of hybrid power system (HPS) implementation consisting of a wind generator (WG), a photovoltaic system (PVS), gas combined heat and power plant (CHP) and storage batteries. Each of the elements is optimized according to power demand and RES’s potential. Technical analysis of the grid integration, parallel operation of the system and the grid is analysed with an example of a real medium-voltage distribution network operating in Bosnia and Herzegovina by using quasi-dynamic load flow simulation of one-week time-period. Finally, different operating mechanisms and strategies will be proposed, following the minimal power form the grid premise to satisfy maximum usability of RES’s potential. It is shown that implementing such HPS would be beneficial in terms of both economy and, ecology, as well as in reducing energy losses. Besides, it will reduce power supplying costs and energy losses, as well as and secure better exploitation and utilization of natural renewable energy sources. These technologies positively affect power network by decreasing the risk of network-components overloading, better exploiting the power-generation facilities based on renewable resources and positively impacting voltage profiles. Similar places, situated on remote locations, may use this analysis as an example to follow, to reduce their costs of electricity, acquire more reliable and sustainable power supply, and embrace green future.

Current state and approaches to automation of central heating stations at industrial enterprises

The paper examines the problems of forming technical requirements for the automation of central heating points of fuel and energy complex enterprises. The main technological schemes that are subject to automation are considered, the basic requirements for the installation of technical automation equipment are shown, the basic requirements are identified based on modern concepts for constructing automated control systems, and the main adjustable and controlled parameters of the central heating station for the main application in State Unitary Enterprise “Fuel and Energy Complex” are clarified.