Energy Cogeneration Research Articles

Optimization of integrated energy system for combined cooling, heating and power supply of new energy based on energy storage

With the development of science and technology, people also pay more and more attention to the development of new energy. Although there are also many studies on integrated energy systems now, integrated energy systems containing energy storage should also be further studied. This paper proposes an optimization of integrated energy system for combined cooling, heating and power supply of new energy based on energy storage, which analyzes the gas turbine, absorption refrigerating machine, electric refrigerator, photovoltaic power generation units, wind turbine and the work characteristics of the energy storage device. In this paper, an integrated energy system optimization model of new energy cogeneration with energy storage equipment is established. An example shows that the integrated energy system with energy storage can effectively solve the independent decoupling operation relationship among cool, heat and electricity. At the same time, the proposed model can also solve the energy interaction among cool, heat and electricity. In this way, the optimal operation of the integrated energy system can be realized.

Ethanol from residual biomass of banana harvest and commercialization: A three-waste simultaneous fermentation approach and a logistic-economic assessment of the process scaling-up towards a sustainable biorefinery in Brazil

This work performs the ethanol production by a fermentation approach based on three banana residues simultaneously (banana pulp and peels, and banana pseudostem) in the realistic proportion (1:2:10) as generated at harvest and commercialization. A process model was developed using a commercial simulator to assess the energy consumption, inputs, and ethanol production, aiming to carry out a preliminary economic analysis for large-scale production in Brazil. Five scenarios for large and medium-sized plants installed in the state of Santa Catarina were created, seeking the lowest logistic cost. Two types of inoculums were chosen in the fermentations: with a monoculture of Saccharomyces cerevisiae, and with a coculture of Saccharomyces cerevisiae and Pachysolen tannophilus (ATCC32691). The highest ethanol yield (0.4 g/g), volumetric productivity (1.1 g/L h), and annual production (32.713 m3) with lower energy expenditure (138.4 GJ/m3) were obtained with fermentation by co-culture with wet pseudostem in the composed broth. Massaranduba is considered the most appropriate municipality of Santa Catarina state for the installation of a biorefinery. In an optimistic scenario, where the energy cogeneration would meet the plant's energy demand, the proposed process is economically viable, with the lowest payback time of 12.4 yr.

Techno-Economic and Environmental Assessment for Biomethane Production and Cogeneration Scenarios from OFMSW in Mexico

Mexico City is one of the largest cities in the world and therefore there is a high generation of waste, of which 44% is equivalent to the Organic Fraction of Municipal Solid Waste (OFMSW). In this work, a characterization of the household OFMSW was carried out, and two case studies were evaluated for the application of biogas production by anaerobic digestion process using OFMSW. CASE I considers obtaining biomethane, while CASE II involves energy cogeneration. An economic and environmental evaluation was carried out on different amounts of OFMSW (100–500 MT). The net present value (NPV) of this project (CASE I, NPV = − US$18,915,067/year and CASE II, NPV = − US$28,636,890/year) does not show the viability of the process, unless the support of a subsidy is considered. The value of the subsidy to find NPV = 0 is 5.64% for CASE I and 6.84% for CASE II, on the total investment at 200 MT of OFMSW. On the other hand, the WAste Reduction (WAR) analysis algorithm was used to determine the potential for environmental impact (PEI). This criterion considers the indexes of eight categories, where CASE I = 574,820 PEI/year and CASE II = 570,479 PEI/year. The in-depth research of this work helps to maintain the anaerobic digestion process in a circular economy context.Graphic Abstract

Methodological approach to the research of energy cogeneration systems operational reliability indicators

Methodological approach to the research of energy cogeneration systems operational reliability indicators

Methodological approach to the research of energy cogeneration systems operational reliability indicators

Methodological approach to the research of energy cogeneration systems operational reliability indicators

POLAND'S ENERGY SECURITY IN THE CONTEXT OF EU ENVIRONMENTAL INITIATIVES

The current conditions of global development actualize the need for political actors to form a high level of energy security. It expands the state's ability to ensure the sustainability of economic development and the ability to withstand likely threats. The issue of energy security and sovereignty are key on the agenda of the EU, which seeks to implement a strategy of global leadership. The environmental modernization of the EU energy sector and each member state must comply with the main goal of «The European Green Deal», which is to reduce carbon emissions by 55% before 2030. The subject of the study is the substance and peculiarities of the formation of energy security in Poland. The aim of the study is to analyze the mechanisms of energy security of Poland in the context of EU environmental initiatives. Research methodology: systematic approach, method of analysis and comparison. The issue of energy security is recognized as key in achieving sustainable economic development in Poland. The content and basic principles of state energy security are presented in the National Security Strategy and detailed in the Energy Policy. Among the main directions of ecological modernization of the energy sector the following have been identified: efficient consumption of national energy resources; modernization of the energy sector and infrastructure; diversification of natural gas, oil, liquid fuel supplies; optimization of energy market functioning; construction of nuclear power plants; expansion of alternative energy sources; modernization of heating and co-generation energy systems; increasing energy efficiency. Polish officials have emphasized the need for a three-phase energy transition, involving a reduction in the production and use of coal, a gradual increase in the share of natural gas and the expansion of opportunities to use energy from alternative sources. The modernization of Poland's energy sector correlates with the implementation of «The European Green Deal» and other EU environmental initiatives. Energy sovereignty is secured through domestic and foreign financial assistance. The National Fund for Environmental Protection and Water Management of Poland attracts investments in environmental projects related to the development of geothermal energy and improvement of infrastructure energy efficiency. EU special funds (European Regional Development Fund/European Social Fund, Cohesion Fund, Just Transition Fund and Modernization Fund) provide funding for national or regional projects aimed at the comprehensive modernization of the Polish energy sector and the implementation of commitments to achieve climate neutrality. Poland pursues an active policy of cooperation in the energy sphere with other states – Denmark, Lithuania, Latvia, and Estonia. Projects such as "Baltic Pipe" and "The Baltic Synchronisation Project" are in the active implementation phase. The results of the study: energy security is a key factor in the sustainability of economic development of Poland, the implementation of the modernization of the national energy complex correlates with the EU environmental initiatives, which contributes to the attraction of domestic and foreign investment, as well as the resources of public diplomacy.

Optimal equipment arrangement of a total site for cogeneration of thermal and electrical energy by using exergoeconomic approach

The optimal equipment arrangement for a system for cogeneration of thermal and electrical energy for a total site is determined with exergoeconomic analysis. A steam power plant can operate concurrently in a dual-use mode producing steam and electricity. It is important to know the potential for cogeneration before designing and optimizing a central utility system in order to establish on site fuel demand targets. In the current study, two case studies with different backpressure steam turbines arrangement are considered and, if extra power generation is needed, designs with a system of condensing and gas turbines are examined. The minimum exergy destruction rate, maximum exergy efficiency, minimum total capital cost rate and minimum exergy destruction cost rate for these arrangements are investigated with exergoeconomic analysis. Finally, selected backpressure steam turbines arrangement in conjunction with the gas turbine system are introduced for finding the optimum arrangement of the cogeneration system in the total site with an exergoeconomic approach.

Biomass, grain yield, ethanol production, and energy cogeneration of sweet sorghum irrigated with domestic sewage effluent

Biomass, grain yield, ethanol production, and energy cogeneration of sweet sorghum irrigated with domestic sewage effluent

Co-optimization of multi-energy system operation, district heating/cooling network and thermal comfort management for buildings

The ongoing decarbonization of the energy sector spurs the employment of distributed generation and efficient load control approaches (demand side management). This work tackles the optimal operation of a Multi Energy System and thermal comfort management for buildings with an integrated approach. The dynamic thermal energy balance of the buildings is included in the Mixed Integer Linear Programming scheduling problem to exploit the heat capacity of buildings and increase the operational flexibility of the generators. The method is firstly applied to a single building served by different energy systems, comprising renewable energy sources, cogeneration units and heat pumps. Then, the methodology is further extended by integrating in the formulation the model of the district heating/cooling network. This method is tested in a group of 12 buildings of the Campus of University of Parma, featuring different thermal properties. By enabling a variation within ± 2 °C around the indoor temperature setpoint and by optimizing water delivery temperature, it is possible to achieve savings on operating costs over the baseline up to 80%. Results show that the load shift capability of buildings plays a major role when thermal demand mismatches renewable energy availability or low electricity price periods. Moreover, district heating network can be exploited as an additional short-term heat storage by varying water delivery temperature profile.

Economic Dispatch of CHP Units through District Heating Network’s Demand-Side Management

Optimisation of heat and electrical load distribution, where the objective function is the maximum efficiency of the CHP unit for a given load range, can be done considering the limitations of electrical power and the heat load. Simulating a real CHP unit with a district heating network shows that demand-side management can improve the overall economic efficiency of the CHP plant and increase the unit’s operating range in the electricity spot market. Economic dispatch makes it possible to determine a reasonable additional increase in the electric power of the CHP unit, and to optimise the supply temperature and mass flow of the district heating network. The results obtained and the analysis performed indicate that the proposed methodology provides logical results and can be used to calculate the efficiency indicators of the cogeneration of electrical and thermal energy. The problem of optimising the operating mode of the CHP unit was solved, which allows us to determine the optimal additional increase in the unit’s electrical load at a given heat load of consumers, which on average increases the CHP unit’s efficiency up to an additional 1.5%.

Biomass direct gasification for electricity generation and natural gas replacement in the lime kilns of the pulp and paper industry: A techno-economic analysis

This study shows a comparative techno-economic analysis of the integration of biomass gasification for generation of producer gas to be used in electricity production and to replace natural gas in the lime kilns of the pulp and paper industry. Three study cases with alternative configurations of the energy system integrating biomass gasification were analysed, including or not the co-generation of electricity and thermal energy, namely: i) Case I, for generation of electricity from residual forest biomass (RFB) in an integrated gasification combined cycle system, ii) Case II, generation of producer gas by RFB gasification for replacement of natural gas in the burners of a lime kiln, and iii) Case III, as an integration of Cases I and II for combined production of electricity and heat. Residual forest biomass from eucalyptus logging activities for feedstock processing for the pulp and paper industry was considered as fuel for direct (air) gasification in bubbling fluidized bed. The analysis made is supported on review reports, namely, the evaluation of the existing literature on investment projects in biomass power plants, and on experimental investigation for determining the composition of the producer gas from gasification of the selected feedstock. An economic model was developed that combines the net present value, internal rate of return and payback period. The main results of the energy system analysis show that the net electricity generation is between 72 and 83 GWh/year, while the production of CaO in the lime kiln supported by combustion of producer gas, is 82.12 kt/year, and a global energy efficiency between 21.70 and 34.17 % is achieved for the analysed configurations of the energy system. The results of the economic analysis show a positive NPV, an IRR greater than the discount rate and a PBP less than the useful life of the plant. The sensitivity analysis shows quite favorable investment projections given the low probability that the NPV will reach negative values and compromise the economic viability of the project.

Using the sun to co-generate electricity and freshwater

Using the sun to co-generate electricity and freshwater

Thermodynamic evaluation and optimization of a cogeneration energy system integrated with steam network

Cogeneration energy systems are one of the most promising clean, efficient technologies for satisfying industrial energy needs. In this study, a cogeneration system consisting of a solid oxide fuel cell, a gasification unit, a gas turbine cycle, and a steam network module is proposed. This topping system is integrated with a steam network that provides steam for different utilities by recovering steam. Also, biomass –as renewable energy– is used to address the problems of fossil fuels, such as scarcity of resources and environmental issues. The system is evaluated from an energy perspective to ascertain the feasibility of the system. Based on the results, the efficiency attained from this system is 54.35%. An optimization study based on a genetic algorithm is performed to find the best conditions, which indicates an efficiency improvement to 65.06%. Moreover, a parametric study on different steam network pressure levels is taken place, which shows the importance of the VHP header on system performance.

The many-objective optimal design of renewable energy cogeneration system

To alleviate the issues of climate warming and fossil resources depletion, this paper proposes a wind-photovoltaic-thermal energy storage-electric heater cogeneration system, which adopts the structure of concentrated solar power plant but replaces the expensive collector field and tower with wind and photovoltaic farms and electric heater that converts the excess electricity as thermal energy source. The cogeneration system can effectively regulate the fluctuating wind and photovoltaic output to satisfy electricity load by electric heater based on resistive heating of molten salt, two-tank molten salt thermal energy storage and power block based on steam Rankine cycle, and supply heat load directly from the molten salt heat transfer fluid and heat exchanger. This paper considers minimizing levelized cost of energy, loss of power and heat supply probability, energy reduction rate and lifecycle equivalent CO2 emissions as optimized objectives, and investigates the many-objective (having four or more objectives) capacity optimization problem by Nondominated Sorting Genetic Algorithm-Ⅲ coupled with Principal Component Analysis and Technique for order preference by similarity to ideal solution. Moreover, residual analysis is applied to consider the uncertainty of wind power prediction. The detailed optimization process and performance comparison of many-objective algorithms, the all-year energy flow and seasonal output characteristics analysis of the optimal-compromise solution are presented. Finally, the proposed cogeneration system is compared to the power-only system with the same installed capacity and equivalent load demand, and the comparison results show that the proposed cogeneration system performs better in all evaluation metrics. Therefore, the proposed renewable energy cogeneration system is feasible and cost-effective for practical applications.

Increase in the irrigated area of sugarcane and its potential in the bioenergetic generation of Brazil

Sugarcane has alarge capacity for producing electricity using completely clean technology from a renewable source, contributing to environmental preservation. This study aimed to evaluate the increase in biomass resulting from the implementation of irrigation in Brazilian sugarcane plantations, estimate the potential for cogeneration, and calculate how much it will be possible to increase the Brazilian energy cogenerated with sugarcane bagasse and the impact on the Brazilian energy matrix. The increase in irrigation in the rainfed areas of Brazilian sugarcane plantations has substantial potential in increasing biomass for energy cogeneration. Considering an increase of 15% in the sugarcane plantation yields in rainfed areas achieved by the increase in irrigation, it leadsto a potential increase of 96.39 million tons of sugarcane and 26.80 million tons biomass produced. In the energy matrix, the potential impact is 1.42 GWh of cogenerated energy, which corresponds to a 12.47% increase in cogeneration in the sugar-energy sector and a 0.85% increase in Brazil's energy matrix. The expansion of the sugarcane irrigated area contributes to the increase in the production of bagasse and bioenergetic generation in Brazil.

Energy Cane x Sugarcane Microregion Interaction in the State of Pernambuco: Sugarcane for Production of Bioenergy and Renewable Fuels

Assessing the differential behavior of a group of genotypes in various environments is fundamentally important in any breeding program. As sugarcane is the most important crop in the state of Pernambuco, it is of great relevance to study its performance in different cultivation sites to assist in the recommendation of new cultivars that increase the productivity of the cane fields. In view of the new demand from the sugar-energy sector for cultivars with high energy potential, this work aimed to select and recommend new genotypes with high fiber and sucrose percentage in the sugarcane microregions of the state of Pernambuco. The methodologies used to classify genotypes for adaptability and stability were as follows: simple linear regression, the modified centroid method, additive main effects, multiplicative interaction analysis, and linear mixed models. Genotypes with higher productivity and specific adaptability to the tested microregions were identified. The methodologies applied were efficient and complementary in recommending genotypes with favorable prospects for increasing sugar productivity, cogeneration of electric energy and the production of renewable fuels. Genotypes 6, 7, 9, 14, 16, and 18 stand out in terms of the productivity of sugar and fiber, with high potential to be released as commercial cultivars.

Thermodynamic assessment and optimization of the influences of the steam-assisted turbocharging and organic Rankine cycle on the overall performance of a diesel engine-based cogeneration integrated with a reverse osmosis desalination unit

Waste heat recovery (WHR) of internal combustion engines (ICEs) is a subject of study for researchers concerned with energy conservation. For this purpose, various bottoming cycles, along with the influences of Steam-Assisted Turbocharger (SAT) on diesel engines' performances, have sufficiently been investigated. In this paper, a cogeneration system powered by a steam-assisted turbocharged marine Diesel engine and an organic Rankine cycle (ORC) is thermodynamically evaluated. Seawater is desalinated by a Reverse-Osmosis (RO) module to provide freshwater for heating units and engine's cooling jacket. Exergy analysis reveals that the condenser, the RO module, the heat exchanger 1, and the oil cooler are the devices with the lowest exergy efficiencies. Furthermore, the genetic algorithm is used to optimize the system parameters and determine the best combination of the proposed system. Results indicate that the combination of SAT with other components can negatively affect the cogeneration system's overall efficiency. On the optimal state, the system exhibits cogeneration energy and exergy efficiencies of 82.82% and 54.10%, respectively, being 2.18 and 1.54 times higher than the sole engine. The optimized system offers a net electrical power of 668 kW and a heating capacity of 646.3 kW through supplying process steam and domestic hot water (DHW).

Solar Hybrid System Component Study in Low Concentrated Sunlight

The solar energy is increasingly used as a renewable energy source. Raising the efficiency of energy conversion from solar to useful energy (electric and thermal) represents an important research direction in the renewable energy domain. Using hybrid systems for electric and thermal energy cogeneration can be a solution. In this study, a hybrid system (HS) is designed, manufactured, implemented, and experimentally tested under concentrated sunlight with a concentration ratio of 25 suns, obtained using a Fresnel lens as a sunlight concentrator. The HS comprises of four concentrated photovoltaic cells (CPVs), four thermoelectric generators (TEGs), and a solar thermal collector (STC). The HS is studied in three configurations of the exposed surface: only the CPV active area, the CPV active area with ceramic support, and the CPV active area with ceramic support covered with graphite sheet. Results reveal that the efficiency of each system component is affected by the exposed surface. If the efficiencies of the CPVs decrease from 32.3% to 30.8% from the first configuration to the last one, the efficiencies of TEGs and STC increase from 0.12% to 0.44 and from 26.3% to 52.0%, respectively. Increasing the concentration ratio from 25 to 33 suns, the power of the CPVs increases with almost 31%, but the efficiency decreases slightly, instead the efficiencies of the TEGs and STC increase.

Phase equilibria modeling of biorefinery-related systems: a systematic review

Abstract The search for sustainable ideas has gained prominence in recent decades at all levels of society since it has become imperative an economic, social, and environmental development in an integrated manner. In this context, biorefineries are currently present as the technology that best covers all these parameters, as they add the benefits of waste reuse, energy cogeneration, and fossil fuel substitution. Thus, the study of the various applicable biological matrices and exploring the technical capabilities of these processes become highly attractive. Thermodynamic modeling acts in this scenario as a fundamental tool for phase behavior predictions in process modeling, design, and optimization. Thus, this work aimed to systematize, using the PRISMA statement for systematic reviews, the information published between 2010 and 2020 on phase equilibria modeling in systems related to biorefineries to organize what is already known about the subject. As a result, 236 papers were categorized in terms of the year, country, type of phase equilibria, and thermodynamic model used. Also, the phase behavior predictions of different thermodynamic models under the same process conditions were qualitatively compared, establishing PC-SAFT as the model that best represents the great diversity of interest systems for biorefineries in a wide range of conditions.

Тенденції розвитку систем централізованого теплопостачання України

We considered trends in the development of district heating systems (DHS) in Europe and Ukraine. It was established that DHS are widely used and make a significant contribution to the heat supply of European countries. In the European Union as a whole, the share of DHS is 13%, and there are plans to increase it to 50% in 2050 with a wide use of cogeneration and renewable sources of energy, including environmental energy with using heat pumps. Ukraine is one of the countries with a high level of DHS, but, at present, there are negative trends to reducing their contribution to the total heat supply for heating and hot water supply – from 65.2% in 2014 to 52% in 2017. In several cities, DHS ceased to function at all. The main equipment of the DHS of Ukraine is physically worn out and technologically obsolete and needs to be renewed by means of wide reconstruction, modernization, and technological re-equipment. We determined factors and the level of their influence on the demand in thermal energy of DHS. It was established that the factors reducing demand have a much greater potential. We created forecasts of demand for thermal energy, fuel balance, and the structure of DHS generation by 2050. It is shown that the demand for thermal energy from DHS will decrease and reach about 35 million Gcal in 2050. To ensure the low-carbon development of Ukraine in the structure of thermal energy generation in DHS, the use of coal-fired CHPs and boilers, as well as boilers on petroleum products will be significantly reduced. The share of natural gas in the fuel balance of DHS of Ukraine will also decrease, but it will be the main fuel for the period of technological transformation of generating capacities under conditions of the low-carbon development of Ukraine. The use of technologies for the production of thermal energy from biomass, waste, environment, and electricity will gradually increase, and in 2050, using these sources will produce about 23.8 million Gcal, which is more than 60% of the total thermal energy of DHS. Keywords: district heating systems, thermal energy, factors of influence, demand, fuel balance, generation structure