Reduction of Primary Energy Consumption Through Distributed Thermal Storage in Buildings Connected With a District Heating Network

2014 ◽  
Author(s):  
Giorgia Baccino ◽  
Sara Cosentino ◽  
Elisa Guelpa ◽  
Adriano Sciacovelli ◽  
Vittorio Verda
Keyword(s):  
Energy Consumption ◽  
Thermal Load ◽  
Waste Heat ◽  
Distributed Storage ◽  
Fluid Dynamic ◽  
District Heating ◽  
Thermal Storage ◽  
Primary Energy ◽  
Operating Conditions ◽  
Primary Energy Consumption

One of the possible options for increasing the primary energy efficiency in district heating networks (DHNs) consists in flattening the thermal load diagram of the plants. This can be obtained through thermal storage. Storage generally allows one to increase the percentage of heat produced through CHP plants, waste heat or renewable systems. In this work, a numerical approach to analyze possible effects of distributed storage on the primary energy consumption is presented. This is based on the availability of detailed information about the thermal substations that connect the users to the DHN and a thermo-fluid dynamic model of the network. First, the analysis of a user of the district heating network is proposed in order to show the operating conditions of the heat exchanger in the thermal substation. Then the model of the network is presented and an application is proposed. This application allows us to discuss how the thermal request of a user modifies along the network because of the heat capacity of the network itself and mixing with the mass flow rates at different temperatures. Therefore, the thermal load that the plants should fulfill is different than the simple summation of the thermal request of the users. This tool allows one to link the thermal thermal request of the users to the thermal load of the plant and thus to the global primary energy consumption. It can be then applied to the evaluation of possible variation of thermal request profile of the users.

Optimization of the Thermal Request Profiles of Buildings Connected With a Large District Heating Network

2016 ◽  
Author(s):  
Vittorio Verda ◽  
Elisa Guelpa ◽  
Giulia Barbero ◽  
Francesco Brundu ◽  
Andrea Acquaviva ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Waste Heat ◽  
Central Area ◽  
District Heating ◽  
Thermal Storage ◽  
Primary Energy ◽  
Physical Models ◽  
Primary Energy Consumption ◽  
Peak Shaving ◽  
Start Up

Thermal storage is very important in modern district heating networks in order to increase the share of waste heat and heat produced through renewable sources and cogeneration. The role of thermal storage is even more important in the case of Mediterranean areas, where climate and user behavior cause high peak requests in the morning. Nevertheless the installation of large storage volumes is not always feasible, especially in dense urban areas, therefore alternative options are investigated. One of these options is virtual storage. This consists in proposing changes to the thermal request profiles of some of the connected buildings, in order to obtain a peak shaving, which is an effect similar to that obtained using storage. To perform such approach there are two crucial elements: 1) an advanced ICT solution able provide real time information about the thermal request of the buildings and the thermodynamic conditions at the thermal substations; 2) a detailed thermo fluid-dynamic model of the district heating network able to simulate the temperature evolution along the network as the function of time. Using physical models it is possible to examine the effects, obtained by modifying the thermal request of users, on the total load of the thermal plants feeding the network. In particular, the model is applied to the analysis of changes in the start-up time of the buildings as well as possible pauses during the day. The start-up strategy should not produce significant effects on the building temperatures, so that acceptable comfort standard can be guaranteed. This is checked using a compact model of the buildings which parameters are obtained through data measured at the thermal substations. These changes in the request profiles usually involve a larger heat request. Nevertheless, peak shaving is accompanied by a reduction in heat generation of boilers and an increase in the thermal production of efficient systems, such as cogeneration units. This results in a significant reduction in the primary energy consumption. The goal of the analysis is to find the optimal start-up strategy in order to minimize the primary energy consumption at the thermal plants. An application to the Turin district heating network, which is the largest network in Italy, is presented. In particular, a subnetwork connecting the main transport network to about 100 buildings located in the central area of the town is considered. The analysis if performed in selected days where the optimization was conducted the day before on the basis of weather forecasts and then applied to the network. Despite the changes in the request profiles could be applied only to a limited number of buildings, the analysis show that the peak request can be reduced. Simulations performed considering the application of changes to a larger number of buildings show that reduction in the primary energy consumptions of the order of 1.25% can be obtained.

District Heating Network Modelling for the Analysis of Low-Exergy Sources

2017 ◽  
Author(s):  
Vittorio Verda ◽  
Elisa Guelpa
Keyword(s):  
Power Plants ◽  
Waste Heat ◽  
Fluid Dynamic ◽  
Renewable Energy Sources ◽  
Variable Mass ◽  
District Heating ◽  
Conservation Equation ◽  
Operating Conditions ◽  
Heat Sources ◽  
District Heating System

One of the main advantages of district heating system technology is the possibility of integrating multiple heat sources for domestic heating. In particular, it is often possible exploit low-exergy sources, such as waste heat recovered from industry or from renewable energy sources, that are often affected by time variation of the temperature. A very convenient and useful opportunity for predicting and analyzing district heating network behavior is modelling. Modelling allows to quantify opportunities related to changes in DH (district heating) network design or management, before real implementation. Therefore an important point is the creation of models able to simulate network, also very large and linked to many power plants, working at variable heat production conditions (i.e. variable mass flow rates and temperatures). The goal of this work is to propose a novel approach which combines exergy analysis with a DH network model for evaluating the best DH operating conditions. A thermo-fluid dynamic model based on conservation equation has been adapted for the discussed aims and applied to a network involving different low-exergy heat sources with variable temperatures. An evaluation of the implementation of these sources is provided for the Turin district heating network, which is the largest network in Italy.

Pumping Cost Minimization in an Existing District Heating Network

2013 ◽  
Author(s):  
Adriano Sciacovelli ◽  
Elisa Guelpa ◽  
Vittorio Verda
Keyword(s):  
Control Strategy ◽  
Urban Areas ◽  
Cost Minimization ◽  
Fluid Dynamic ◽  
District Heating ◽  
Primary Energy ◽  
Operating Conditions ◽  
Waste To Energy ◽  
District Heating System ◽  
Partial Load

District heating is expected to significantly contribute to the reduction of primary energy needs for heating in urban areas. This result is obtained through use of such as CHP systems, residual heat from industries or waste-to-energy plants, as well as the integration of renewable energies. The pumping system plays a crucial role and may significantly affect its performances. In this paper a large district heating system is considered. Various operating conditions corresponding with partial load operation are analyzed through a thermo-fluid dynamic model of the network. For each condition, the optimal set point of the various pumps is obtained. The set of optimal operating conditions is finally used to obtain a control strategy for the network. Results show that with respect to conventional control strategy significant reductions in primary energy consumption can be achieved.

Waste Heat Recovery in Data Centers Using Sorption Systems

2012 ◽  
Vol 4 (2) ◽  
Author(s):  
Adrienne B. Little ◽  
Srinivas Garimella
Keyword(s):  
Energy Consumption ◽  
Data Center ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Data Centers ◽  
Waste Heat ◽  
District Heating ◽  
Integrated Approach ◽  
The United States ◽  
Primary Energy

Of the total electricity consumption by the United States in 2006, more than 1% was used on data centers alone; a value that continues to rise rapidly. Of the total amount of electricity a data center consumes, about 30% is used to cool server equipment. The present study conceptualizes and analyzes a novel paradigm consisting of integrated power, cooling, and waste heat recovery and upgrade systems that considerably lower the energy footprint of data centers. Thus, on-site power generation equipment is used to supply primary electricity needs of the data center. The microturbine-derived waste heat is recovered to run an absorption chiller that supplies the entire cooling load of the data center, essentially providing the requisite cooling without any additional expenditure of primary energy. Furthermore, the remaining waste heat rejected by the data center is boosted to a higher temperature with a heat transformer, with the upgraded thermal stream serving as an additional output of the data center with negligible additional electrical power input. Such upgraded heat can be used for district heating applications in neighboring residential or commercial buildings, or as process heat for commercial end uses such as laundries, hospitals, and restaurants, depending on the location of the data center. With such a system, the primary energy usage of the data center as a whole can be reduced by up to 23% while still addressing the high-flux cooling loads, in addition to providing a new income stream through the sales of upgraded thermal energy. Given the large and fast-escalating energy consumption patterns of data centers, this novel, integrated approach to electricity and cooling supply, and waste heat recovery and upgrade will substantially reduce primary energy consumption for this important end use worldwide.

Thermal Storage Systems for District Heating Networks

2010 ◽  
Author(s):  
Vittorio Verda ◽  
Francesco Colella
Keyword(s):  
Electricity Market ◽  
Thermal Load ◽  
Storage Systems ◽  
Fluid Dynamic ◽  
District Heating ◽  
Heating System ◽  
Maximum Load ◽  
Operating Conditions ◽  
District Heating System ◽  
The Impact

District Heating is an efficient way to provide heat to residential, tertiary and industrial users. Heat is often produced by CPH plants, usually designed to provide the base thermal load (40–50% if the maximum load) while the rest is provided by boilers. This choice is made on the basis of economic criteria, in fact the investment cost of a CHP plant is much higher than the cost of boiler, thus its use is convenient when it operates for a large number of hours. The use of storage tanks would permit to increase the annual operating hours of CHP: heat can be produced when the request is low (for instance during the night), stored and then used when the request is high. The use of boilers results partially reduced, thus the thermal load diagram is flattered. Depending on the type of CHP plant this may also affect the electricity generation. All these considerations are crucial in the free electricity market. In this paper, the use of storage systems connected to the district heating systems, is examined. A thermo fluid dynamic model of the tanks is considered in order to calculate the amount of energy actually provided, taking the real operating conditions into account. These considerations are applied to the Turin district heating system, in order to determine the impact of storage systems on the primary energy consumption required to supply heat to the users over the entire heating season.

scholarly journals The Impact of Parallel Energy Consumption on the District Heating Networks

2019 ◽  
Vol 23 (1) ◽  
pp. 1-13 ◽  
Author(s):  
Eduard Latosov ◽  
Anna Volkova ◽  
Andres Siirde ◽  
Martin Thalfeldt ◽  
Jarek Kurnitski
Keyword(s):  
Energy Consumption ◽  
Negative Impact ◽  
Electric Energy ◽  
District Heating ◽  
Cost Savings ◽  
Primary Energy ◽  
Primary Energy Consumption ◽  
Capital Costs ◽  
Electric Energy Consumption ◽  
The Impact

Abstract The aim of this study is to evaluate and compare the impacts of heat recovery ventilation (HRV) and exhaust air heat pump (EAHP)-based solutions used in renovated buildings, which make it possible to reach performance class C in district heating (DH) area CO2 emissions, primary energy consumption and total energy costs for consumers. Evaluation is based on the methodology presented in the previous research paper [1]. Calculation results show that the use of EAHP has a negative impact on DH sustainability (heat losses in the DH network, DH heat price, reduced consumption of DH heat) and CO2 emissions related to energy delivery (heat and electricity) to consumers in the DH area. Positive aspects of the EAHP use include the fact that almost the same primary energy consumption level can be achieved with lesser (up to 7 %) annual costs (annual capital costs, DH heat costs and electricity costs) and lower initial investments (about 10 %). At the same time, every renovated building with EAHP will experience a negative impact on heat prices. In DH areas where almost all buildings are renovated with EAHP, cost savings are not as evident compared to buildings with HRV in DH areas where the use of parallel consumption solutions (EAHP) is minimized. It is reasonable to promote these renovation packages and solutions that benefit the building’s primary energy reduction, and also do not increase electric energy consumption (additional electric power generators are needed) and do not damage DH networks.

Saving Primary Energy Consumption Through Exergy Analysis of Combine Distillation and Power Plant

2012 ◽  
Vol 9 (2) ◽  
pp. 65
Author(s):  
Alhassan Salami Tijani ◽  
Nazri Mohammed ◽  
Werner Witt
Keyword(s):  
Energy Consumption ◽  
Power Plant ◽  
Heat Pump ◽  
Heat Recovery ◽  
Energy Savings ◽  
Primary Energy ◽  
Heat Pumps ◽  
Saturated Steam ◽  
Distillation Unit ◽  
Primary Energy Consumption

Industrial heat pumps are heat-recovery systems that allow the temperature ofwaste-heat stream to be increased to a higher, more efficient temperature. Consequently, heat pumps can improve energy efficiency in industrial processes as well as energy savings when conventional passive-heat recovery is not possible. In this paper, possible ways of saving energy in the chemical industry are considered, the objective is to reduce the primary energy (such as coal) consumption of power plant. Particularly the thermodynamic analyses ofintegrating backpressure turbine ofa power plant with distillation units have been considered. Some practical examples such as conventional distillation unit and heat pump are used as a means of reducing primary energy consumption with tangible indications of energy savings. The heat pump distillation is operated via electrical power from the power plant. The exergy efficiency ofthe primary fuel is calculated for different operating range ofthe heat pump distillation. This is then compared with a conventional distillation unit that depends on saturated steam from a power plant as the source of energy. The results obtained show that heat pump distillation is an economic way to save energy if the temperaturedifference between the overhead and the bottom is small. Based on the result, the energy saved by the application of a heat pump distillation is improved compared to conventional distillation unit.

scholarly journals Decarbonization of Residential Building Energy Supply: Impact of Cogeneration System Performance on Energy, Environment, and Economics

Energies ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2538
Author(s):  
Praveen K. Cheekatamarla
Keyword(s):  
Carbon Dioxide ◽  
Power Generation ◽  
Energy Consumption ◽  
Carbon Footprint ◽  
Residential Buildings ◽  
Building Energy ◽  
Primary Energy ◽  
Primary Energy Consumption ◽  
Cogeneration System ◽  
The Impact

Electrical and thermal loads of residential buildings present a unique opportunity for onsite power generation, and concomitant thermal energy generation, storage, and utilization, to decrease primary energy consumption and carbon dioxide intensity. This approach also improves resiliency and ability to address peak load burden effectively. Demand response programs and grid-interactive buildings are also essential to meet the energy needs of the 21st century while addressing climate impact. Given the significance of the scale of building energy consumption, this study investigates how cogeneration systems influence the primary energy consumption and carbon footprint in residential buildings. The impact of onsite power generation capacity, its electrical and thermal efficiency, and its cost, on total primary energy consumption, equivalent carbon dioxide emissions, operating expenditure, and, most importantly, thermal and electrical energy balance, is presented. The conditions at which a cogeneration approach loses its advantage as an energy efficient residential resource are identified as a function of electrical grid’s carbon footprint and primary energy efficiency. Compared to a heat pump heating system with a coefficient of performance (COP) of three, a 0.5 kW cogeneration system with 40% electrical efficiency is shown to lose its environmental benefit if the electrical grid’s carbon dioxide intensity falls below 0.4 kg CO2 per kWh electricity.

scholarly journals Assessment Methodology for Efficiency, CO2-Emissions and Primary Energy Consumption for Refrigeration Technologies in the Industry

2018 ◽  
Vol 882 ◽  
pp. 215-220
Author(s):  
Matthias Koppmann ◽  
Raphael Lechner ◽  
Tom Goßner ◽  
Markus Brautsch
Keyword(s):  
Energy Consumption ◽  
Energy Efficient ◽  
Air Conditioning ◽  
Primary Energy ◽  
Primary Energy Consumption ◽  
Assessment Methodology ◽  
Alternative Technologies ◽  
Overall Efficiency ◽  
Chp System ◽  
The Individual

Process cooling and air conditioning are becoming increasingly important in the industry. Refrigeration is still mostly accomplished with compression chillers, although alternative technologies are available on the market that can be more efficient for specific applications. Within the scope of the project “EffiCool” a technology toolbox is currently being developed, which is intended to assist industrials users in selecting energy efficient and eco-friendly cooling solutions. In order to assess different refrigeration options a consistent methodology was developed. The refrigeration technologies are assessed regarding their efficiency, CO2-emissions and primary energy consumption. For CCHP systems an exergetic allocation method was implemented. Two scenarios with A) a compression chiller and B) an absorption chiller coupled to a natural gas CHP system were calculated exemplarily, showing a greater overall efficiency for the CCHP system, although the individual COP of the chiller is considerably lower.

Performance analysis of a combined cooling, heating, and power system driven by a waste biomass fired Stirling engine

2010 ◽  
Vol 225 (2) ◽  
pp. 420-428 ◽  
Author(s):  
J Harrod ◽  
P J Mago
Keyword(s):  
Energy Consumption ◽  
Natural Gas ◽  
Wood Chip ◽  
Primary Energy ◽  
Stirling Engine ◽  
Primary Energy Consumption ◽  
Operational Cost ◽  
Excess Production ◽  
Prime Movers ◽  
Combined Cooling

Due to the soaring costs and demand of energy in recent years, combined cooling, heating, and power (CCHP) systems have arisen as an alternative to conventional power generation based on their potential to provide reductions in cost, primary energy consumption, and emissions. However, the application of these systems is commonly limited to internal combustion engine prime movers that use natural gas as the primary fuel source. Investigation of more efficient prime movers and renewable fuel applications is an integral part of improving CCHP technology. Therefore, the objective of this study is to analyse the performance of a CCHP system driven by a biomass fired Stirling engine. The study is carried out by considering an hour-by-hour CCHP simulation for a small office building located in Atlanta, Georgia. The hourly thermal and electrical demands for the building were obtained using the EnergyPlus software. Results for burning waste wood chip biomass are compared to results obtained burning natural gas to illustrate the effects of fuel choice and prime mover power output on the overall CCHP system performance. Based on the specified utility rates and including excess production buyback, the results suggest that fuel prices of less than $23/MWh must be maintained for savings in cost compared to the conventional case. In addition, the performance of the CCHP system using the Stirling engine is compared with the conventional system performance. This comparison is based on operational cost and primary energy consumption. When electricity can be sold back to the grid, results indicate that a wood chip fired system yields a potential cost savings of up to 50 per cent and a 20 per cent increase in primary energy consumption as compared with the conventional system. On the other hand, a natural gas fired system is shown to be ineffective for cost and primary energy consumption savings with increases of up to 85 per cent and 24 per cent compared to the conventional case, respectively. The variations in the operational cost and primary energy consumption are also shown to be sensitive to the electricity excess production and buyback rate.

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