Impact of Thermal Storage Option for CHP Systems on the Optimal Prime Mover Size and the Need for Additional Heat Production

2012 ◽  
Author(s):  
Amanda D. Smith ◽  
Pedro J. Mago
Keyword(s):  
Carbon Dioxide Emissions ◽  
Thermal Storage ◽  
Primary Energy ◽  
Prime Mover ◽  
Commercial Building ◽  
Reference Case ◽  
Additional Heat ◽  
Chp System ◽  
Useful Heat ◽  
The Cost

Combined heat and power (CHP) or cogeneration systems provide both electricity and useful heat to a building. CHP systems can result in lower operational cost, primary energy consumption (PEC), and carbon dioxide emissions when compared to the standard alternative of purchasing electricity from the grid and supplying heat from a boiler. However, the potential for these benefits is closely linked to the relationship between the ratio of power to heat supplied by the CHP system and the ratio of power to heat demanded by the building. Therefore, the benefits of the CHP system also vary with the size of the prime mover. In the model presented in this paper, the CHP system is base-loaded, providing a constant power-to-heat ratio. The power-to-heat ratio demanded by the building depends on the location and the needs of the building, which vary throughout the day and throughout the year. At times when the CHP system does not provide the electricity needed by the building, electricity is purchased from the grid, and when the CHP system does not provide the heat needed by the building, heat is generated with a supplemental boiler. Thermal storage is an option to address the building’s load variation by storing excess heat when the building needs less heat than the heat produced by the CHP system, which can then be used later when the building needs more heat than the heat produced by the CHP system. The potential for a CHP system with thermal storage to reduce cost, PEC, and emissions is investigated, and compared with both a CHP system without thermal storage and with the standard reference case. This proposed model is evaluated for three different commercial building types in three different U.S. climate zones. The size of the power generation unit (PGU) is varied and the effect of the correspondingly smaller or larger base load on the cost, PEC, and emissions savings is analyzed. The most beneficial PGU size for a CHP system with the thermal storage option is compared with the most beneficial PGU size without the thermal storage option. The need for a supplemental boiler to provide additional heat is also examined in each case with the thermal storage option.

Evaluation of Combined Heat and Power (CHP) Systems Performance With Dual Power Generation Units

2012 ◽  
Author(s):  
Alta Knizley ◽  
Pedro J. Mago
Keyword(s):  
Power Generation ◽  
Carbon Dioxide Emissions ◽  
Operating Cost ◽  
Primary Energy ◽  
Combined Heat And Power ◽  
Department Of Energy ◽  
Environmental Benefits ◽  
Optimum Operating ◽  
Electric Load ◽  
Chp System

This paper evaluates the economic, energetic, and environmental feasibility of using two power generation units (PGUs) to operate a combined heat and power (CHP) system. A benchmark building developed by the Department of Energy for a full-service restaurant in Chicago, IL is used to analyze the proposed configuration. This location is selected since it usually provides favorable CHP system conditions in terms of cost and emissions reduction. In this investigation, one PGU is operated at base load to satisfy part of the electricity building requirements (PGU1), while the other is used to satisfy the remaining electricity requirement operating following the electric load (PGU2). The dual-PGU configuration (D-CHP) is modeled for several different scenarios in order to determine the optimum operating range for the selected benchmark building. The dual-PGU scenario is compared with the reference building using conventional technology to determine the economical, energetic, and environmental benefits of this proposed system. This condition is also compared to a CHP system operating following the electric load (FEL) and to a base-loaded CHP system, and it provides greater savings in operating cost, primary energy consumption, and carbon dioxide emissions than the optimized conditions for base loading and FEL.

Modeling of Micro-Cooling, Heating, and Power (Micro-CHP) for Residential or Small Commercial Building Applications

2006 ◽  
Author(s):  
P. J. Mago ◽  
L. M. Chamra ◽  
Alan Moran
Keyword(s):  
Electrical Power ◽  
Theoretical Models ◽  
Commercial Building ◽  
Thermally Activated ◽  
Heating And Cooling ◽  
Cooling Effects ◽  
Increasing Demand ◽  
Commercial Applications ◽  
Chp System ◽  
The Cost

The increasing demand for electrical power as well as energy for heating and cooling of residences and small commercial buildings is a growing worldwide concern. Cooling, Heating, and Power (CHP) is a promising technology for increased energy efficiency through the use of distributed electric and thermal energy delivery systems at end-user sites. Micro-cooling, heating, and power (micro-CHP) is decentralized electricity generation coupled with thermally activated components for residential and small commercial applications. Micro-CHP systems, typically designated as less than thirty kilowatts electric, can simultaneously produce heat, cooling effects, and electrical power. The number of combinations of components and parameters in a micro-CHP system are too many to be designed through experimental work alone. Therefore, theoretical models for different micro-CHP components and complete micro-CHP systems are needed to facilitate the design of these systems and to study their performance. This paper presents a model for micro-CHP systems for residential and small commercial applications. Some of the results that can be obtained using the developed model include: the cost per month of operation of using micro-CHP versus conventional technologies, the amount of fuel per month required to run micro-CHP systems, the overall efficiency of micro-CHP systems, etc. Also, this model allows to evaluate micro-CHP systems using different type of fuels such as: natural gas, propane, biofuels, etc, to determine the fuel that provides the best performance.

Assessment of CHP System Performance With Commercial Building Benchmark Models in Different U.S. Climate Zones

2009 ◽  
Author(s):  
Heejin Cho ◽  
Rogelio Luck ◽  
Pedro J. Mago ◽  
Louay M. Chamra
Keyword(s):  
Carbon Dioxide ◽  
Carbon Dioxide Emissions ◽  
Carbon Dioxide Emission ◽  
Primary Energy ◽  
Department Of Energy ◽  
Commercial Building ◽  
Climate Zones ◽  
Climate Conditions ◽  
The Impact ◽  
The U.S

Combined Cooling, Heating, and Power (CHP) systems have been widely recognized as an alternative for electric and thermal energy generation because of their outstanding energy efficiency, reduced environmental emissions, and relative independence from centralized power grids. The performance of CHP systems depends on the type of buildings and climate conditions. Recently the U.S. Department of Energy (DOE) has developed a set of standard benchmark building models. According to the DOE [1], these models cover approximately 70% of the commercial building energy use. This paper evaluates and discusses the simulations of the performance of CHP systems for several commercial building benchmark models in 16 locations representing the U.S. climate zones described in the DOE report. The evaluation has been carried out using an optimal energy dispatch algorithm. The performance index for the optimization process is varied in order to investigate the impact of optimizing operational cost, primary energy consumption, and carbon dioxide emission. The results of this simulation can be used as a guideline to end-users when deciding on energy alternatives for their buildings or by policy makers deciding on regulations for cost, primary energy, or carbon dioxide emissions.

FEASIBILITY OF COMBINED HEAT AND POWER SYSTEM IN THE CENTRAL BUSINESS DISTRICT OF SHANGHAI

2009 ◽  
Vol 33 (1) ◽  
pp. 39-50
Author(s):  
Ji Xuan ◽  
Weijun Gao
Keyword(s):  
Energy Savings ◽  
Municipal Government ◽  
Central Business District ◽  
Primary Energy ◽  
Combined Heat And Power ◽  
Energy Structure ◽  
Chp System ◽  
The One ◽  
Business District ◽  
The Cost

As one of the most developed and energy intensive cities in China, the Shanghai’s municipal government tries to make Shanghai one of the leading cities of energy conservation in China. Expanding the use of combined heat and power (CHP) system is the one of the main ways to optimize Shanghai’s energy structure and to protect its environment. This paper aims to analyze the feasibility of introducing CHP in the central business district, in Shanghai, to determine the energy savings, environmental impact and economic efficiency. Three types of energy supply systems are considered: electricity-only system, 2 CHP systems with electric tracking and thermal tracking. Relative to the conventional electricity-only system, the CHP systems are capable of reducing the primary energy consumption by approximately 24% and 4%, CO2 emission by 38% and 11%, respectively. For CHP, although the initial costs are often substantially higher than a conventional system, it is expected to dramatically reduce the cost of running. The result shows if introducing CHP, it only takes approximately 5 years can return the initial investment, in each case. This implies that the introduction of CHP can achieve high profitability.

Effect of the Power Generation Unit Operation on the Energy, Economical, and Environmental Performance of CCHP Systems for a Small Commercial Building

2009 ◽  
Author(s):  
Anna K. Hueffed ◽  
Pedro J. Mago ◽  
Louay M. Chamra
Keyword(s):  
Power Generation ◽  
Environmental Performance ◽  
Carbon Dioxide Emissions ◽  
Waste Heat ◽  
Combustion Engine ◽  
Primary Energy ◽  
Hot Water ◽  
Commercial Building ◽  
Power Generation Unit ◽  
Generation Unit

Combined cooling, heating, and power (CCHP) systems generate electricity at or near the place of consumption and utilize the accompanying waste heat to satisfy the building’s thermal demand. CCHP systems have often been cited as advantageous alternatives to traditional methods of power generation and one of the critical components affecting their performance is the power generation unit (PGU). This investigation examines the effect of the PGU on the energy, economical, and environmental performance of CCHP systems. Different size PGUs are simulated under the following operational strategies: follow the building’s electric load, follow the building’s thermal load, and operate at constant load. An internal combustion engine is used as the PGU in the CCHP system to meet hourly electric, cooling, heating, and hot water loads of a typical office building for a year. Annual operational cost, primary energy consumption (PEC), and carbon dioxide emissions (CDE) are found for two cities and compared to a conventional building. Finally, a simple optimization is performed to determine the best engine load for each hour during the simulation. Among the results, the smallest engine generally yielded the lowest costs and lowest PEC; but, no such trend was found with regards to CDE.

scholarly journals Experimental and Numerical Study of a Microcogeneration Stirling Unit under On–Off Cycling Operation

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 801
Author(s):  
Gianluca Valenti ◽  
Aldo Bischi ◽  
Stefano Campanari ◽  
Paolo Silva ◽  
Antonino Ravidà ◽  
...  
Keyword(s):  
Numerical Study ◽  
Thermal Storage ◽  
Primary Energy ◽  
Operational Cost ◽  
Cogeneration Plant ◽  
Economic Optimization ◽  
Viable Option ◽  
Heating Value ◽  
Energy Flows

Stirling units are a viable option for micro-cogeneration applications, but they operate often with multiple daily startups and shutdowns due to the variability of load profiles. This work focused on the experimental and numerical study of a small-size commercial Stirling unit when subjected to cycling operations. First, experimental data about energy flows and emissions were collected during on–off operations. Second, these data were utilized to tune an in-house code for the economic optimization of cogeneration plant scheduling. Lastly, the tuned code was applied to a case study of a residential flat in Northern Italy during a typical winter day to investigate the optimal scheduling of the Stirling unit equipped with a thermal storage tank of diverse sizes. Experimentally, the Stirling unit showed an integrated electric efficiency of 8.9% (8.0%) and thermal efficiency of 91.0% (82.2%), referred to as the fuel lower and, between parenthesis, higher heating value during the on–off cycling test, while emissions showed peaks in NOx and CO up to 100 ppm but shorter than a minute. Numerically, predictions indicated that considering the on–off effects, the optimized operating strategy led to a great reduction of daily startups, with a number lower than 10 per day due to an optimal thermal storage size of 4 kWh. Ultimately, the primary energy saving was 12% and the daily operational cost was 2.9 €/day.

scholarly journals Uncertainty Cost Functions in Climate-Dependent Controllable Loads in Commercial Environments

Energies ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2885
Author(s):  
Daniel Losada ◽  
Ameena Al-Sumaiti ◽  
Sergio Rivera
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Simulation Method ◽  
Electricity Sector ◽  
Cost Functions ◽  
Density Estimator ◽  
Monte Carlo Simulation Method ◽  
Commercial Building ◽  
Complementary Method ◽  
The Cost

This article presents the development, simulation and validation of the uncertainty cost functions for a commercial building with climate-dependent controllable loads, located in Florida, USA. For its development, statistical data on the energy consumption of the building in 2016 were used, along with the deployment of kernel density estimator to characterize its probabilistic behavior. For validation of the uncertainty cost functions, the Monte-Carlo simulation method was used to make comparisons between the analytical results and the results obtained by the method. The cost functions found differential errors of less than 1%, compared to the Monte-Carlo simulation method. With this, there is an analytical approach to the uncertainty costs of the building that can be used in the development of optimal energy dispatches, as well as a complementary method for the probabilistic characterization of the stochastic behavior of agents in the electricity sector.

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.

Distributed control strategies for high-penetration commercial-building-scale thermal storage

PES T&D 2012 ◽  
2012 ◽  
Author(s):  
Andrea Mammoli ◽  
C. Birk Jones ◽  
Hans Barsun ◽  
David Dreisigmeyer ◽  
Gary Goddard ◽  
...  
Keyword(s):  
Distributed Control ◽  
Control Strategies ◽  
Thermal Storage ◽  
Commercial Building ◽  
High Penetration

A Methodology to Conduct a Combined Heating and Power System Assessment and Feasibility Study for Industrial Manufacturing Facilities

2011 ◽  
Author(s):  
Chad Wheeley ◽  
Pedro J. Mago
Keyword(s):  
Economic Analysis ◽  
Feasibility Study ◽  
Prime Mover ◽  
Viable Option ◽  
Industrial Manufacturing ◽  
System Assessment ◽  
Manufacturing Facilities ◽  
Economic Analyses ◽  
Chp System ◽  
Topping Cycle

This paper considers combined heat and power (CHP) systems based on topping cycles only, in which electricity is generated by a prime mover and heat is then recovered from the exhaust and utilized to offset all or a portion of the facility’s process and/or space heating requirements.. The objective of this paper is to develop a methodology to perform a topping cycle CHP assessment and feasibility study for industrial manufacturing facilities. In order to determine the best and most viable option for the facility in question, the proposed methodology can be used to size different systems which utilize diverse technologies and fuel sources, perform an economic analysis of each proposed option, and then compare the benefits and setbacks of each type of CHP system considered. The calculations performed in the economic analysis will then provide a broad insight as to which proposed system will show the best payback if installed. Examples are presented in this paper that describe in detail the application of this methodology, from equipment selection and sizing through economic analyses and proposed system comparisons, which is recommended for use in order to determine the most economically feasible CHP system for an industrial manufacturing facility.

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