Effects of Carbon Tax on Microgrid Combined Heat and Power Adoption

This paper describes the economically optimal adoption and operation of distributed energy resources (DER) by a hypothetical California microgrid (μGrid) consisting of a group of commercial buildings over an historical test year, 1999. The optimization is conducted using a customer adoption model developed at Berkeley Lab and implemented in the General Algebraic Modeling System. A μGrid is a semiautonomous grouping of electricity and heat loads interconnected with the existing utility grid (macrogrid) but able to island from it. The μGrid minimizes the cost of meeting its energy requirements (consisting of both electricity and heat loads) by optimizing the installation and operation of DER technologies while purchasing residual energy from the local combined natural gas and electricity utility. The available DER technologies are small-scale generators (<500?kW), such as reciprocating engines, microturbines, and fuel cells, with or without combined heat and power (CHP) equipment, such as water and space heating and/or absorption cooling. By introducing a tax on carbon emissions, it is shown that if the μGrid is allowed to install CHP-enabled DER technologies, its carbon emissions are mitigated more than without CHP, demonstrating the potential benefits of small-scale CHP technology for climate change mitigation. Reciprocating engines with heat recovery and/or absorption cooling tend to be attractive technologies for the mild southern California climate, but the carbon mitigation tends to be modest compared to purchasing utility electricity because of the predominance of relatively clean central station generation in California.     

Microgrids and Distributed Generation

Application of individual distributed generators can cause as many problems as it may solve. A better way to realize the emerging potential of distributed generation is to take a system approach which views generation and associated loads as a subsystem or a “microgrid.” The sources can operate in parallel to the grid or can operate in island, providing utility power station services. The system will disconnect from the utility during large events (e.g., faults and voltage collapses), but may also intentionally disconnect when the quality of power from the grid falls below certain standards. Utilization of waste heat from the sources will increase total efficiency, making the project more financially attractive. University of Wisconsin laboratory verification of microgrid control concepts are included.     

Economic Analysis of Thermal Energy Storage Systems

This paper describes an investigation of the economic performance of a central chiller plant with thermal energy storage (TES) operating in a hotel in California and an office building in Wisconsin for the following three conventional control strategies: chiller-priority, constant-proportion, and storage-priority control. Since all control strategies depend on properly selected design parameters, the storage and chiller capacities as the primary design parameters were varied over a wide range, and the life-cycle economic feasibility of each possible design was assessed over a 20-year economic life using the net present value method. Measured cooling and weather data for both buildings were used in annual calculations to determine annual utility cost savings on the basis of one of four artificial rate structures. Trends in the life-cycle economic performance of TES systems as a function of chiller and storage capacities were revealed, and design guidelines were developed.     

Decision Support System to Evaluate and Compare Concession Options

With the increased popularity of concession projects over the last three decades, there is a need for a decision support system (DSS) capable of evaluating and comparing several concession project investment (CPI) options in an effective and efficient manner. Hence, a novel DSS has been developed that takes into consideration both financial and nonfinancial aspects of the investment option, as well as the uncertainties commonly encountered during the feasibility stage of a project. The DSS is fully implemented as a standalone computer software package, ECCO (evaluate and compare concession options), in order to be of practical use. This paper outlines and validates ECCO’s design and structure through the demonstration of its capabilities in the evaluation and comparison of three real-life CPI case studies.     

Bid-Winning Potential Optimization for Concession Schemes with Imprecise Investment Parameters

This paper portrays the development of a concession-investment optimization model for optimizing the winning potential of a concession-bid from the prospective promoters' viewpoints by taking into account imprecise investment parameters. A financial performance measure has been developed to quantify bid-winning potential. Fuzzy set theory is embedded into a genetic algorithm to optimize bid-winning prospects of concession schemes under uncertainty. The fuzzy vertex method accomplishes propagation of uncertainty in cash flows arising from imprecision in estimation of investment parameters. Genetic algorithm solves the optimization routine. The developed model yields global near-optimal solution of bid-winning potential with contributing values of concessionary items: concession length, base price, and equity level under uncertain investment environment. A numerical example demonstrates model capabilities. The model results would help promoters devise a profitable, yet competitive, financial proposal.     

Green Buildings and Potential Electric Light Energy Savings

This paper estimates the approximate yearly electric lighting load of a “green” commercial building for a temperate climate region by studying the impact of a large curved south-facing facade with an external horizontal shading louver, a high window location, and a specular light shelf on yearly interior daylight levels, based on hourly weather data for Washington, D.C. Thus the paper determines the required electric light quantity by calculating hourly daylight illuminance levels and deriving required electric fill-in light when daylight levels are too low, determining daylight quality by calculating luminance values and luminance ratios used for office lighting criteria. It is found that electric light in lux hours per year is needed only for 16% of yearly office hours. The paper gives recommendations for window size and shape, location, light shelf geometry, ceiling and wall details, and workstation layout in order to achieve these low lighting loads.     

高产能双蓄热推钢式烧嘴加热炉的应用

介绍了加热能力为170t／h双蓄热式加热炉的工艺特点、主要设备技术性能参数以及节能措施。     

Distribution Networks with Linear and Nonlinear Loads: Cost-Based Method for Planning Dispersed Generation and Capacitor Units under Uncertainty

This paper discusses the optimal allocation of capacitors and dispersed generation units in a medium-voltage distribution system with linear and nonlinear loads. An optimization problem is formulated and solved for optimal siting and sizing, with the objective of minimizing costs sustained by the distributor for reactive power service, even containing the impact of the waveform distortions. A three-step procedure, based on genetic algorithm and decision theory, is applied to obtain a solution for the optimization problem that takes into account the unavoidable uncertainties that the dispersed generation production and the loads introduce. The numeric applications performed on an 18-bus test distribution system demonstrate of the effectiveness of the proposed procedure.     

Stochastic Model for Landfill Gas Transport and Energy Recovery

Predicting the amount of landfill gas (LFG) that will be recovered at a sanitary landfill is generally associated with a high level of uncertainty, which is primarily due to the uncertainty in the definition of the parameters that control the LFG generation rate and LFG transport. To quantify these uncertainties, a three-dimensional stochastic model for the generation and transport of LFG is proposed. Using Monte Carlo simulations, multiple realizations of key input parameters are generated. For each realization, LFG transport is simulated and then used to evaluate probabilistically the rates and efficiency of energy recovery. For demonstration, the stochastic model is applied to the Kemerburgaz landfill in Istanbul, Turkey. Uncertainty in the definition of three key parameters, namely: the LFG production rate, the waste gas permeability and the soil cover gas permeability were accounted for. Modeling results suggest that the collection system is sufficient to capture most of the generated gas, but that uncertainty in the factors controlling LFG production is the main source of uncertainty in the amount of energy that will be recovered.     

Unstructured Grid Finite-Volume Algorithm for Shallow-Water Flow and Scalar Transport with Wetting and Drying

A high-resolution, unstructured grid, finite-volume algorithm is developed for unsteady, two-dimensional, shallow-water flow and scalar transport over arbitrary topography with wetting and drying. The algorithm uses a grid of triangular cells to facilitate grid generation and localized refinement when modeling natural waterways. The algorithm uses Roe’s approximate Riemann solver to compute fluxes, a multidimensional limiter for second-order spatial accuracy, and predictor–corrector time stepping for second-order temporal accuracy. The novel aspect of the algorithm is a robust and efficient procedure to consistently track fluid volume and the free surface elevation in partially submerged cells. This leads to perfect conservation of both fluid and dissolved mass, preservation of stationarity, and near elimination of artificial concentration and dilution of scalars at stationary or moving wet/dry interfaces. Multi-dimensional slope limiters, variable reconstruction, and flux evaluation schemes are optimized in the algorithm on the basis of accuracy per computational effort.     

Airtightness Testing of Two-?and Three-Unit Buildings with a Single Fan

This paper presents a method for the field measurement of airtightness for two-?and three-unit buildings using only one fan pressurization system, commonly referred to as a blower door. The main advantage of this single-fan method is its lower equipment and labor cost as compared with multiple-fan methods. Results from consecutive tests in the individual units are used to prepare a set of simultaneous equations for airflow, allowing for the calculation of the air leakage characteristics of both the interior partitions and the exterior envelope on a unit-per-unit basis. Tests were performed on four buildings using the single-fan method and were compared with those obtained with a two-fan method. Test results indicate that the single-fan method may be of value as an inexpensive method of estimating the airtightness of two-?and three-unit residential buildings.     

Verification of Incremental Launching Construction Safety for the Ilsun Bridge, the World’s Longest and Widest Prestressed Concrete Box Girder with Corrugated Steel Web Section

The Ilsun Bridge is the world’s longest (801?m in total length) and widest (30.9?m in maximum width) prestressed concrete box girder bridge incorporating a corrugated steel web. This bridge has fourteen spans, twelve of which were erected using an incremental launching method, a method that is rarely applied in this type of bridge. To verify the construction safety of the Ilsun Bridge, this investigation focuses on the span-to-depth ratio, buckling shear stress of the corrugated steel webs, optimization of the length of the steel launching nose, detailed construction stage analysis, and the stress level endured by the corrugated steel webs during the launching process. The span-to-depth ratio of the Ilsun Bridge was found to be well-designed, using a conservative corrugated steel web design. Further, our investigation revealed that the conventional nose-deck interaction equation was not suitable for corrugated steel web bridges. As a result, a detailed construction stage analysis and measurements of this bridge was performed to examine stress levels and ensure safety during the erection process. The results revealed that there are essential design issues that should be considered when designing prestressed concrete box girder bridges with corrugated steel webs and that, when constructing them, the incremental launching method should be used.