Terms Of Capital Costs Research Articles

Closed-Loop Distribution Network by a Midvoltage Flexible HTS DC System

A scheme of closed-loop distribution network by a midvoltage flexible high-temperature superconducting (HTS) dc system is proposed and analyzed. This midvoltage (10-kV) scheme is compared, in terms of capital costs, with that of the closed-loop distribution network by a high-voltage (110-kV) flexible conventional dc system. Based on the HTS cables that are made of the first-generation Bi2223 tapes with a length of 2.5 km, the total investment cost of the 10-kV flexible superconducting dc system with a power capacity of 42 MVA is estimated about 1% lower than that of the 110-kV flexible conventional dc system with the same power capacity, owing to the substantial cost reduction of the voltage-source converter stations with the reduced voltage level. According to the “N - 1” principle of distribution networks, with the interconnecting flexible HTS dc system of 42 MVA, the total power to supply loads of the connected substations can be increased by the same power capacity of the interconnecting system. The simulation results of a three-phase short-circuit fault reveal that the voltage recovery time of the critical loads in the closed-loop distribution network can be reduced to less than 0.1 s, which is much faster than that in open-loop distribution networks.

Optioneering analysis for connecting Dogger Bank offshore wind farms to the GB electricity network

This paper outlines possibilities for connecting 2.4 GW of power from two separate wind farms at Dogger Bank in the North Sea to the GB transmission system in Great Britain. Three options based on HVDC with Voltage Source Converters (VSC HVDC) are investigated: two separate point-to-point connections, a four-terminal multi-terminal network and a four-terminal network with the addition of an AC auxiliary cable between the two wind farms. Each option is investigated in terms of investment cost, controllability and reliability against expected fault scenarios. The paper concludes that a VSC-HVDC point-to-point connection is the cheapest option in terms of capital cost and has the additional advantage that it uses technology that is commercially available. However, while multi-terminal connections are more expensive to build it is found that they can offer significant advantages over point to point systems in terms of security of supply and so could offer better value for money overall. A multi-terminal option with an auxiliary AC connection between wind farms is found to be lower cost than a full multi-terminal DC grid option although the latter network would offer ability to operate at greater connection distances between substations.

A holistic examination of the load rating design of longwall shields after more than half a century of mechanised longwall mining

It is a commonly asked question: how big should the longwall shields be? The answer is a key aspect of a longwall mining feasibility study when the consequences of inadequately rated shields are considered. This paper addresses this question based on the measured nature of the loading environment in which shields are required to operate, the various geological and geometrical controls of that environment and the various links between their load rating, a range of other relevant shield design factors and the loss event they are required to prevent a major roof collapse on the longwall face. The paper concludes that despite the tremendous advances that have been made in shield design and load rating over the past 50years, the same drivers that caused longwall miners of the past to seek improved roof control on the longwall face via the use of ever-higher rated shields, are still as relevant today. However at the current time, the limits of the largest available longwall shields have yet to be tested, therefore industry focus for the foreseeable future should possibly be in achieving the maximum level of roof control on the face via their optimum operational use rather than considering further shield rating increases and incurring the inevitable downsides in terms of capital cost and shield weight.

Investigation of Guided-Particle Transport for Noninvasive Healing of Damaged Piping Systems by Use of Electro-Magneto-Mechanical Methods

Summary Virtually all engineering applications involve the use of piping, conduits, and channels. In the petroleum industry, piping systems are extensively used in upstream and downstream processes. These piping systems often carry fluids that are corrosive, which leads to wear, cavitation, and cracking. The replacement of damaged piping systems can be quite expensive, both in terms of capital costs and in operational downtime. This motivates the present research on noninvasive healing of cracked piping systems. In this investigation, we propose to develop computational models for characterizing noninvasive repair strategies involving electromagnetically guided particles. The objective is to heal industrial-piping systems noninvasively, from the exterior of the system, during operation, resulting in no downtime and minimal relative cost. The particle accumulation at a target location is controlled by external electromagnetic/mechanical means. There are two primary effects that play a role for guiding the particles to the solid-fluid-interface/wall: mechanical shear caused by the fluid flow, and an electrical or magnetic force. In this work we develop and study a relationship that characterizes contributions of both, and ascertain how this relationship scales with characteristic physical parameters. Characteristic nondimensional parameters that describe system behavior are derived, and their role in design is illustrated. A detailed, fully 3D discrete-element-simulation framework is presented, and illustrated by use of a model problem of magnetically guided particles. The detailed particle behavior is considered to be regulated by three effects: the field strength, the mass-flow rate, and the wall interactions.

Bioethanol recovery and purification using extractive dividing-wall column and pressure swing adsorption: An economic comparison after heat integration and optimization

Extractive dividing-wall column (E-DWC) is a promising alternative to current bioethanol recovery and purification processes, garnering interest from the research community. In this study, E-DWC and pressure swing adsorption (PSA) processes for bioethanol recovery/purification are studied on a consistent basis, and an economic evaluation of both processes is made after heat integration and optimization. For this, realistic feed stream of 10wt% ethanol, 89.9wt% water and 0.1wt% carbon dioxide is considered, and both processes are simulated in Aspen HYSYS v8.2. PSA process involves distillation for removing most of water, before dehydration by PSA. Results indicate that, while E-DWC process has advantages over PSA process in terms of capital cost and thermal energy demand, PSA process still has 33% lower cost of manufacture per unit product than E-DWC process, mostly because of solvent loss. This shows that it is not sufficient to consider only energy requirement in assessing the feasibility of a promising technology; rather, an overall economic evaluation under realistic conditions should be performed. In addition, this work has investigated economies of scale and identified the optimal production capacity of PSA process for bioethanol recovery/purification.

WaterNetGen Helps C-Town

Abstract The methodology proposed to solve the C-Town water distribution network problem (BBLAWN) comprises two optimization models: a least cost design model to identify the pipes to be replaced and size them; and an optimal operation model to define the pump controls and the PRV settings. Both models are solved by linking a hydraulic simulation model (WaterNetGen, a pressure driven EPANET extension) with a simulated annealing algorithm. This methodology, supported by some additional engineering expertise, provided a set of good solutions in terms of capital cost, and a good commitment with the environmental and financial damage caused by water losses.

An analytical approach for estimating optimal multi-layer network cost, exploiting the flexible-grid optical technology

In this paper we provide analytical insights for dimensioning a multi-layer network and in particular the virtual optical transport network topology exported to the packet client layer according to cost and power consumption. A new approach is described, approximating optimum routing, that can be effectively used to provide an estimation of network cost and reference architectures in network implementations. Results using this estimation approach are compared with those obtained using other estimation approaches regarding bandwidth allocation and network costs. We found that the approximated routing calculations, applied on a virtual network topology, do not significantly penalize the accuracy of the results. This approach can be extended to analyze the impact of new a optical networking technique, flexible-grid wavelength division multiplexing (WDM), providing some insights regarding scenarios in which migration from fixed-grid WDM systems to flexible-grid WDM systems would be advantageous in terms of capital cost and power consumption.

Problems of Rural Electrification in Bayelsa State

Rural electrification scheme is aimed at promoting the welfare of the rural community and improve the economic status of the people. The presence of the National Electric Power Authority (NEPA) is rarely felt, that the supply of power to Bayelsa from the grid is less than 10 percent. The Kolo creek gas turbine is only available to only two local communities in the state. The paper therefore is aimed at presenting these problems by studying the problems facing the present scheme in terms of capital cost, the dispersed settlement, the load profile and transport system. It was seen that the coastal environment and the fairly big rivers coupled with the high capital cost are major impediments to successful electrification of the state. It was seen that it cost sever time more than an equivalent scheme in the upload areas. With the abundant oil and gas resources and the renewable energies (solar and wind), off grid electrification project could be the solution to the electrification scheme if properly harnessed.

Amine Modeling for CO2 Capture: Internals Selection

Traditionally, trays have been the mass-transfer device of choice in amine absorption units. However, the need to process large volumes of flue gas to capture CO2 and the resultant high costs of multiple trains of large trayed columns have prompted process licensors and vendors to investigate alternative mass-transfer devices. These alternatives include third-generation random packings and structured packings. Nevertheless, clear-cut guidelines for selection of packings for amine units are lacking. This paper provides well-defined guidelines and a consistent framework for the choice of mass-transfer devices for amine absorbers and regenerators. This work emphasizes the role played by the flow parameter, a measure of column liquid loading and pressure, in the type of packing selected. In addition, this paper demonstrates the significant economic advantage of packings over trays in terms of capital costs (CAPEX) and operating costs (OPEX).

Direct-drive permanent magnet generators for high-power wind turbines: benefits and limiting factors

Wind turbines are getting larger. Their rated power capacities are moving from the 3 MW range to 6 MW and beyond. As a result, their size and mass, which grow rapidly with power capacity, is becoming a problem in terms of capital cost, logistics and assembly. Moreover, there is a move to offshore installations. Offshore wind turbines demand higher reliability, encouraging wind turbine manufacturers to integrate into their new designs inherently more reliable direct-drive permanent magnet synchronous generators. However, today's high-power direct-drive generators are massive units that will need to become smaller to minimise costs. Here, the authors review the technological and economic benefits and limitations of direct-drive permanent magnet synchronous generators (DD-PMSGs). The authors examine the benefits and the physical and economic limitations of DD-PMSGs and consider their appropriateness as a key piece in the overall wind turbine system design. The authors look at why these generators are so big and propose a change that can lead to a more compact, more economical wind turbine nacelle.

A cryogen-based peak-shaving technology: systematic approach and techno-economic analysis

A peak-shaving technology is recently proposed, which integrates peak-electricity generation, cryogenic energy storage and CO2 capture. In such a technology, off-peak electricity is used to produce liquid nitrogen and oxygen in an air separation and liquefaction unit. At peak hours, natural gas (or alternative gases, e.g. from gasification of coal) is burned by oxygen from the air separation unit (oxy-fuel combustion) to generate electricity. CO2 produced is captured in the form of dry ice. Liquid nitrogen produced in the air separation plant not only serves as an energy storage medium but also supplies the low-grade cold energy for CO2 separation. In addition, waste heat from the tail gas can be used to superheat nitrogen in the expansion process to further increase the system efficiency. This article reports a systematic approach, with an aim to provide technical information for the system design. Three potential blending gases (helium, oxygen and CO2) are considered not only for assessing thermodynamic performance but also for techno-economic analysis. The peak-shaving systems are also compared with natural gas combined cycle and an oxynatural gas combined cycle in terms of capital cost and peak electricity production cost. Copyright (c) 2011 John Wiley & Sons, Ltd.

Statistical Simulation to Estimate Uncertain Behavioral Parameters of Hybrid Energy-Economy Models

In energy-economy modeling, new hybrid models attempt to combine the technological explicitness of bottom-up models with the macroeconomic feedbacks and statistically estimated behavioral parameters of top-down models. However, statistical estimation of behavioral parameters (portraying firm and household technology choices) with such models is challenged by the number of uncertain variables and the lack of historical data on technologies in terms of capital costs, operating costs, and market shares. Multiple combinations of parameter values might equally explain past technology choices. This paper reports on the application of a Bayesian statistical simulation approach for estimating the most likely values for these key behavioral parameters in order to best explain past technology choices and then simulate policies to influence future technology choices. The method included (1) data collection of key technology market shares, capital costs, and operating costs over the past; (2) backcasting a hybrid energy-economy model over a historical time period; and (3) the application of Markov chain Monte Carlo statistical simulation using the Metropolis–Hastings algorithm as a tool for estimating distributions for key parameters in the model. The results provide a means of indicating the uncertainty bounds around key behavioral parameters when generating forecasts of the effect of certain policies. However, the results also indicate that this approach may have limited applicability, given that future available technologies may differ substantially from past technologies and that it is difficult to separate the effects of parameter uncertainty from model structure uncertainty.

570 Regional Cortical Thinning in Subjects at Genetic High Risk of Psychosis with High Genetic Loading

Climate change is leading to concerning fluctuations in weather patterns mainly due to anthropogenic activities such as deforestation and burning of fossil fuels, which are and will affect different sectors such as food chains, wildlife, and human life. CO2 capture and conversion or CO2 capture and utilization can be seen as a method to mitigate the current dangerous CO2 level in the Earth’s atmosphere by capturing the carbon emissions and converting them into more valuable and environmentally beneficial products. Here we report on the itemized cost estimation, in terms of capital cost and operating cost of nanomaterials used in CO2 capture and conversion technologies.

CO2 reduction potential of coal-to-liquids (CTL) process: Effect of gasification technology

Abstract Coal-to-liquids (CTL) is a process of producing synthetic transportation fuels from coal. The process involves gasification of coal to produce synthesis gas which is then catalytically converted to liquid fuels in a Fischer-Tropsch (FT) reactor. A major concern of CTL plants is their emissions of carbon dioxide (CO2) produced as part of the process. A significant fraction of the plant-level CO2 is produced in the gasification process, which needs to be separated before the syngas is fed into the FT reactor. In this paper, CTL processes using two different coal-feeding methods–slurry and dry–are studied for their effect on the performance, emissions and cost of a CTL plant. The slurry-fed and dry-fed systems are modeled based on the commercially available GE and Shell gasifier designs, respectively. Effect of implementing CCS or carbon constraints that impose a price or cost on CO2 emissions is also studied. The potential of the co-production configuration to reduce the overall CO2 emissions by displacing conventional pulverized coal power plants is also investigated. It was found that the process using a dry-feed Shell gasification is more efficient, emits less CO2 and has lower capital and product costs compared to a CTL plant using a slurry-feed GE gasifier. For both the cases, the costs of liquid product from both liquids-only and co-production plants are comparable to the crude oil prices seen in the past 2–3 years. Though co-production plants are much costlier than liquids-only configurations in terms of capital cost, because of the high electricity revenues, the cost of liquid product is lower than that of the liquids-only case, at market prices of electricity. Co-production is also much more efficient than the separate production of liquids and power and, the difference in efficiency increases with the addition of CCS.

Fouling behaviour for different module formats in membrane filtration applications for surface water treatment

Design of a membrane filtration plant requires a careful selection of flux. A low flux will make the plant expensive in terms of capital cost (capex), since the membrane area requirement will increase. A high flux will lead to high operating costs (opex), since fouling rates increase exponentially with flux, and necessitate the use of high driving pressures and frequent chemical cleaning. The design therefore reflects a compromise between capex and opex. Membrane filtration applications in water treatment use one of three formats, either pressure driven (PD) or submerged, with inside or outside feed configurations. The different formats have different advantages and disadvantages, with all three concepts competitive in most applications. This paper looks at fouling behaviour for two of the module formats, namely PD inside feed and submerged. The data suggest that at a given flux, fouling rates are similar for the same type of feed using either format, though the optimum design flux will vary due to differences in module characteristics. The paper then introduces a method for monitoring plant performance, and quantifying the stability of operation based on two simple indices, evaluated from permeability measurements. The method can be applied to any membrane filtration plant.

Microwave plasma torch operating at a low pressure for material processing

Most operations involving the use of a microwave plasma torch are carried out at atmospheric pressure as an open system. A microwave plasma torch operated in a closed and isolated environment may provide an opportunity for the mass production of chemically active radicals for various chemical and biological processes. This study presents a microwave plasma torch operating at a low pressure in an isolated chamber. A microwave torch operating at a low pressure may be economical in terms of capital costs, maintenance costs, and operational costs compared to other plasma devices used in material processing operations. The properties of the torch plasma at a low pressure were investigated. It is found that the plasma profile at a low pressure is asymmetric with higher density on the incoming side of the microwaves. This behavior of the torch inhibits high-power operation of the microwave plasma torch at a low pressure. However, the asymmetry of the plasma profile disappears under a high gas flow rate. It was also found that a microwave plasma torch used at a low pressure can efficiently produce an abundance of chemical radicals.

Recirculating gravel filters: high-performance treatment at low cost for two small communities

Wastewater from small communities often has a greater environmental impact than conventional on-site treatment systems can mitigate, yet the flow rate is too low to achieve economies of scale with municipal treatment processes. As a result, the cost of wastewater treatment is often beyond the financial means of the community, in terms of capital costs and annual operational costs. The recirculating gravel filter (RGF) is an attached-growth treatment process for wastewater from small communities. In the RGF process, pre-settled wastewater is recirculated through a gravel filter bed, while a biofilm on the filter media oxidizes the organic matter and ammonia. Effluent from the RGF process has equivalent or lower concentrations of BOD5, TSS and ammonia nitrogen as effluent from other wastewater treatment processes typically employed in small communities. Two small communities in Washington State, USA, have selected the RGF process for wastewater treatment, due to low operational costs, simplicity of equipment, and high effluent quality. For the two communities, the RGF wastewater treatment facilities were estimated to have somewhat lower construction costs and significantly lower annual operational costs than the alternatives evaluated. Low annual operational expenses are important for wastewater system sustainability in small communities.

Case study: the performance and design outline of a buffering stormwater drainage system for a low‐lying area

AbstractPerformance evaluation and safety assessment of a buffering stormwater drainage system (BSDS) for a low‐lying area are discussed in this paper. Unlike a conventional pump drainage system, the BSDS, which drains stormwater runoff of a low‐lying area to a nearby channel system through underground conduits with gravity, and then buffering peak flows with the storage capacity of a channel system, will discharge stormwater to rivers outside the low‐lying area with pumps or flood gates if necessary. This kind of drainage system is considered to be environment friendly and economic both in terms of capital cost and operating & maintenance expenses. To investigate the design parameters and evaluate the performance and safety of BSDS, a hydraulic model coupling the conduit systems and a channel system was developed in this paper, and a case‐study approach based on field investigation and simulation test was used. Moreover, the design requirements for safety of BSDS were drawn through a simulation test.

Immersion frying for the thermal drying of sewage sludge: An economic assessment

This paper presents an economic study of a novel thermal fry-drying technology which transforms sewage sludge and recycled cooking oil (RCO) into a solid fuel. The process is shown to have significant potential advantage in terms of capital costs (by factors of several times) and comparable operating costs. Three potential variants of the process have been simulated and costed in terms of both capital and operating requirements for a commercial scale of operation. The differences are in the energy recovery systems, which include a simple condensation of the evaporated water and two different heat pump configurations. Simple condensation provides the simplest process, but the energy efficiency gain of an open heat pump offset this, making it economically somewhat more attractive. In terms of operating costs, current sludge dryers are dominated by maintenance and energy requirements, while for fry-drying these are comparatively small. Fry-drying running costs are dominated by provision of makeup waste oil. Cost reduction could focus on cheaper waste oil, e.g. from grease trap waste.

Using e‐commerce to deliver high productivity

E‐commerce is either a major opportunity or a significant business threat. The cost of entry is low in terms of capital costs but high in terms of effort and opportunity cost. It can significantly lower the cost of trading but using it for this purpose is sub‐optimal; it allows restructuring of the supply chain, of business processes and of the nature of the business itself. Its effective deployment requires an understanding of the way in which the company operates now and of a vision of the way it could operate in the future. E‐commerce offers the technology to make, and can act as a catalyst for, this change.