Optimal Design and Control Strategies for Novel Combined Heat and Power (CHP) Fuel Cell Systems: Part I of II—Datum Design Conditions and Approach

Author(s):  
Whitney G. Colella

Energy network optimization (ENO) models identify new strategies for designing, installing, and controlling stationary combined heat and power (CHP) fuel cell systems (FCSs) with the goals of 1) minimizing electricity and heating costs for building owners and 2) reducing emissions of the primary greenhouse gas (GHG) — carbon dioxide (CO2). A goal of this work is to employ relatively inexpensive simulation studies to discover more financially and environmentally effective approaches for installing CHP FCSs. ENO models quantify the impact of different choices made by power generation operators, FCS manufacturers, building owners, and governments with respect to two primary goals — energy cost savings for building owners and CO2 emission reductions. These types of models are crucial for identifying cost and CO2 optima for particular installations. Optimal strategies change with varying economic and environmental conditions, FCS performance, the characteristics of building demand for electricity and heat, and many other factors. ENO models evaluate both “business-as-usual” and novel FCS operating strategies. For the scenarios examined here, relative to a base case of no FCSs installed, model results indicate that novel strategies could reduce building energy costs by 25% and CO2 emissions by 80%. Part I of II articles discusses model assumptions and methodology. Part II of II articles illustrates model results for a university campus town and generalizes these results for diverse communities.

Author(s):  
Whitney G. Colella ◽  
Stephen H. Schneider ◽  
Daniel M. Kammen ◽  
Aditya Jhunjhunwala ◽  
Nigel Teo

Stationary combined heat and power (CHP) fuel cell systems (FCSs) can provide electricity and heat for buildings, and can reduce greenhouse gas (GHG) emissions significantly if they are configured with an appropriate installation and operating strategy. The Maximizing Emission Reductions and Economic Savings Simulator (MERESS) is an optimization tool that was developed to allow users to evaluate avant-garde strategies for installing and operating CHP FCSs in buildings. These strategies include networking, load following, and the use of variable heat-to-power ratios, all of which commercial industry has typically overlooked. A primary goal of the MERESS model is to use relatively inexpensive simulation studies to identify more financially and environmentally effective ways to design and install FCSs. It incorporates the pivotal choices that FCS manufacturers, building owners, emission regulators, competing generators, and policy makers make, and empowers them to evaluate the effect of their choices directly. MERESS directly evaluates trade-offs among three key goals: GHG reductions, energy cost savings for building owners, and high sales revenue for FCS manufacturers. MERESS allows users to evaluate these design trade-offs and to identify the optimal control strategies and building load curves for installation based on either 1) maximum GHG emission reductions or 2) maximum cost savings to building owners. Part I of II articles discusses the motivation and key assumptions behind MERESS model development. Part II of II articles discusses run results from MERESS for a California town and makes recommendations for further FCS installments (Colella 2008 (a)).


Author(s):  
Whitney G. Colella ◽  
Stephen H. Schneider ◽  
Daniel M. Kammen ◽  
Aditya Jhunjhunwala ◽  
Nigel Teo

Stationary combined heat and power (CHP) fuel cell systems (FCSs) can provide electricity and heat for buildings and can reduce greenhouse gas (GHG) emissions significantly if they are configured with an appropriate installation and operating strategy. The maximizing emission reduction and economic saving simulator (MERESS) is an optimization tool that was developed to evaluate novel strategies for installing and operating CHP FCSs in buildings. These novel strategies include networking, load following, and the use of variable heat-to-power ratios, all of which industry typically has not implemented. A primary goal of models like MERESS is to use relatively inexpensive simulation studies to identify more financially and environmentally effective ways to design and install FCSs. Models like MERESS can incorporate the pivotal choices that FCS manufacturers, building owners, emission regulators, competing generators, and policy makers make, and empower them to evaluate the effect of their choices directly. MERESS directly evaluates trade-offs among three key goals: GHG reductions, energy cost savings for building owners, and high sales revenue for FCS manufacturers. MERESS allows one to evaluate these design trade-offs and to identify the optimal control strategies and building load curves for installation based on either (1) maximum GHG emission reductions or (2) maximum cost savings to building owners. Part I discusses the motivation and key assumptions behind MERESS model development. Part II discusses run results from MERESS for a California town and makes recommendations for further FCS installments (Colella , 2011, “Optimizing the Design and Deployment of Stationary Combined Heat and Power Fuel Cell Systems for Minimum Costs and Emissions—Part II: Model Results,” ASME J. Fuel Cell Sci. Technol., 8(2), p. 021002).


Author(s):  
Whitney G. Colella

We evaluate innovative design, installation, and control strategies for generating combined cooling, heating, and electric power (CCHP) with fuel cell systems (FCS). The addition of an absorptive cooling cycle allows unrecovered FCS heat to be converted into cooling power, such as for air-conditioning. For example, unrecovered low temperature (80–160°C) heat can be used to drive absorption chillers to create a chilled water stream to cool building spaces. Compared with separate devices that individually generate electricity, heat, and cooling power, such CCHP FCS can reduce feedstock fuel consumption and the resulting greenhouse gas emissions (GHG) by at least 30%. We develop economic and environmental models that optimize the installed capacity of CCHP FCS to minimize either global carbon dioxide (CO2) emissions or global energy costs. Our models evaluate innovative engineering design, installation, and control strategies not commonly pursued by industry, and identify strategies most beneficial for reducing CO2 emissions or costs. Our models minimize costs for building owners consuming cooling power, electricity, and heat by changing the installed capacity of the FCS and by changing FCS operating strategies. Our models optimize for a particular location, climatic region, building load curve set, FCS type, and competitive environment. Our models evaluate the benefits and drawbacks of pursuing more innovative FCS operating strategies; these include 1) connecting FCS to distribution networks for cooling power, heat, and electricity; 2) implementing a variable heat-to-power ratio, to intentionally produce additional heat to meet higher heat demands; 3) designing in the ability to tune the quantity of cooling power from the absorption chiller compared with the amount of recoverable heat from the FCS; and 4) employing the ability to load-follow demand for cooling, heat, or electricity. We base our datum design conditions on measured data describing generator performance in-use, and on measured data describing real-time electricity, heating, and cooling demand over time. A unique feature of our data sets is that the space cooling demand is directly measured and distinguishable from electricity demand (unlike as with standard air conditioning systems). We report results for optimal installed capacities and optimal FCS operating strategies. We generalize these results so that they are applicable to a wide-range of environments throughout the world.


2017 ◽  
Vol 359 ◽  
pp. 119-133 ◽  
Author(s):  
Etienne Dijoux ◽  
Nadia Yousfi Steiner ◽  
Michel Benne ◽  
Marie-Cécile Péra ◽  
Brigitte Grondin Pérez

2016 ◽  
Vol 41 (19) ◽  
pp. 8286-8295 ◽  
Author(s):  
Kyungmun Kang ◽  
Haneul Yoo ◽  
Donghee Han ◽  
Ahrae Jo ◽  
Junhee Lee ◽  
...  

Author(s):  
Jenny E. Hu ◽  
Joshua B. Pearlman ◽  
Atul Bhargav ◽  
Gregory S. Jackson

Recent advances in anode electrocatalysts for low-temperature PEM fuel cells are increasing tolerance for CO in the H2-rich anode stream. This study explores the impact of current day and future advances in CO-tolerant electrocatalysts on the system efficiency of low-temperature Nafion-based PEM fuel cell systems operating in conjunction with a hydrocarbon autothermal reformer and a preferential CO oxidation (PROx) reactor for CO clean-up. This study explores the effects of incomplete H2 cleanup by preferential oxidation reactors for partial CO removal, in combination with reformate-tolerant stacks. Empirical fuel cell performance models were based upon voltage-current characteristic from single-cell MEA tests at varying CO concentrations with new alloy reformate-tolerant electrocatalysts tested in conjunction with this study. A system-level model for a 5 kW maximum liquid-fueled system has been used to study the trade-offs between the improved performance with decreased CO concentration and the increased penalties from the air supply to the PROx reactor and associated reduction in H2 partial pressures to the anode. As CO tolerance is increased over current state-of-the-art Pt alloy catalysts system efficiencies improve due to higher fuel cell voltages. Furthermore, increasing CO tolerance of anode electrocatalysts allows for increased reformer efficiency by reducing PROx CO conversion requirements.


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