A Thermoeconomic Comparison Between SOFC Hybrid Systems and the Most Worldwide Used Technologies Towards Competitive Innovative Plants

Author(s):  
A. Franzoni ◽  
L. Magistri ◽  
O. Tarnowsky ◽  
A. F. Massardo

This paper investigates options for highly efficient SOFC hybrid systems of different sizes. For this purpose different models of pressurised SOFC hybrids systems have been developed in the framework of the European Project “LARGE SOFC - Towards a Large SOFC Power Plant”. This project, coordinated by VTT Finland, counts numerous industrial partners such as Wartsila, Topsoe and Rolls-Royce FCS ltd. Starting from the RRFCS Hybrid System [1], considered as the reference case, several plant modifications have been investigated in order to improve the thermodynamic efficiency. The main options considered are (i) the integration of a recuperated micro gas turbine and (ii) the replacement of the cathodic ejector with a blower. The plant layouts are analysed in order to define the optimum solution in terms of operating parameters and thermodynamic performances. The study of a large size power plant (around 110 MWe) fed by coal and incorporated with SOFC hybrid systems is also conducted. The aim of this study is to analyse the sustainability of an Integrated Gasification Hybrid System from the thermodynamic and economic point of view in the frame of future large sized power generation. A complete thermoeconomic analysis of the most promising plants is carried out, taking into account variable and capital costs of the systems. The designed systems are compared from the thermodynamic and the thermoeconomic point of view with some of the common technologies used for distributed generation (gas turbines and reciprocating engines) and large size power generation (combined cycles and IGCC). The tool used for this analysis is WTEMP software, developed by the University of Genoa (DIMSET-TPG) [2], able to carry out a detailed thermodynamic and thermoeconomic analysis of the whole plants.

2017 ◽  
Vol 1 ◽  
pp. K4MD26 ◽  
Author(s):  
Seyfettin C. Gülen

AbstractThis article evaluates the improvement in gas turbine combined cycle power plant efficiency and output via pressure gain combustion (PGC). Ideal and real cycle calculations are provided for a rigorous assessment of PGC variants (e.g., detonation and deflagration) in a realistic power plant framework with advanced heavy-duty industrial gas turbines. It is shown that PGC is the single-most potent knob available to the designers for a quantum leap in combined cycle performance.


Author(s):  
Xinli Lu ◽  
Arnold Watson ◽  
Joe Deans

Since the first geothermal power plant was built at Larderello (Italy) in 1904, many attempts have been made to improve conversion efficiency. Among innovative technologies, using the Kalina cycle is considered as one of the most effective means of enhancing the thermodynamic performance for both high and low temperature heat source systems. Although initially used as the bottoming cycle of gas turbines and diesel engines, in the late 1980s the Kalina cycle was found to be attractive for geothermal power generation [1, 2, 3]. Different versions (KSC11, KSC12 and KSC13) were designated. Comparison between Kalina cycle and other power cycles can be found in later studies [4, 5, 6]. Here we examine KSC11, because it is specifically designed for geothermal power generation, with lower capital cost [3]. We compare this design with the existing Kawerau ORMAT binary plant in New Zealand. In addition, parametric sensitivity analysis of KCS11 has been carried out for the specific power output and net thermal efficiency by changing the temperatures of both heat source and heat sink for a given ammonia-water composition.


Author(s):  
Rolf H. Kehlhofer

In the past 15 years the combined-cycle (gas/steam turbine) power plant has come into its own in the power generation market. Today, approximately 30 000 MW of power are already installed or being built as combined-cycle units. Combined-cycle plants are therefore a proven technology, showing not only impressive thermal efficiency ratings of up to 50 percent in theory, but also proving them in practice and everyday operation (1) (2). Combined-cycle installations can be used for many purposes. They range from power plants for power generation only, to cogeneration plants for district heating or combined cycles with maximum additional firing (3). The main obstacle to further expansion of the combined cycle principle is its lack of fuel flexibility. To this day, gas turbines are still limited to gaseous or liquid fuels. This paper shows a viable way to add a cheap solid fuel, coal, to the list. The plant system in question is a 2 × 150 MW combined-cycle plant of BBC Brown Boveri with integrated coal gasification plant of British Gas/Lurgi. The main point of interest is that all the individual components of the power plant described in this paper have proven their worth commercially. It is therefore not a pilot plant but a viable commercial proposition.


Author(s):  
Tagir R. Nigmatulin ◽  
Vladimir E. Mikhailov

Russian power generation, oil and gas businesses are rapidly growing. Installation of new industrial gas turbines is booming to fulfill the demand from economic growth. Russia is a unique country from the annual temperature variation point of view. Some regions may reach up to 100C. One of the biggest challenges for world producers of gas turbines in Russia is the ability to operate products at power plants during cold winters, when ambient temperature might be −60C for a couple of weeks in a row. The reliability and availability of the equipment during the cold season is very critical. Design of inlet systems and filter houses for the Russian market, specifically for northern regions, has a lot of specifics and engineering challenges. Joint Stock Company CKTI is the biggest Russian supplier of air intake systems for industrial gas turbines and axial-flow compressors. In 1969 this enterprise designed and installed the first inlet for the power plant Dagskaya GRES (State Regional Electric Power Plant) with the first 100MW gas-turbine which was designed and manufactured by LMZ. Since the late 1960s CKTI has designed and manufactured inlet systems for the world market and been the main supplier for the Russian market. During the last two years CKTI has designed inlet systems for a broad variety of gas turbine engines ranging from 24MW up to 110MW turbines which are used for power generation and as a mechanical drive for the oil and gas industry. CKTI inlet systems with filtering devices or houses are successfully used in different climate zones including the world’s coldest city Yakutsk and hot Nigeria. CKTI has established CTQs (Critical to quality) and requirements for industrial gas turbine inlet systems which will be installed in Russia in different climate zones for all types of energy installations. The last NPI project of the inlet system, including a nonstandard layout, was done for a small gas-turbine engine which is installed on a railway cart. This arrangement is designed to clean railway lines with the exhaust jet in a quarry during the winter. The design of the inlet system with efficient multistage compressor extraction for deicing, dust and snow resistance has an interesting solution. The detailed description of challenges, weather requirements, calculations, losses, and design methodologies to qualify the system for tough requirements, are described in the paper.


Author(s):  
Sung Ho Park ◽  
Young Duk Lee ◽  
Sang Gyu Kang ◽  
Kook Young Ahn

Fuel cell systems are currently regarded as a promising type of energy conversion system. Various types of fuel cell have been developed and investigated worldwide for portable, automotive, and stationary applications. In particular, in the case of large-scale stationary applications, the high-temperature fuel cells known as the molten carbonate fuel cell (MCFC) and the solid oxide fuel cell (SOFC) have been used as a power source due to their higher efficiency compared to low-temperature fuel cells. Because SOFCs have many advantages, including a high power density, low corrosion, and operability without a metal catalyst, many efforts to develop a SOFC hybrid system have been undertaken. SOFC hybrid systems with a gas turbine or engine show improved system efficiency through their utilization of waste heat and unreacted fuel. Especially, the internal combustion engine has the advantage of robustness, easy maintenance, and a low cost compared to gas turbines, this type is more adaptable for use in a hybrid system with a SOFC. However, the engine should be operated stably at a high air fuel ratio because the SOFC anode exhaust gas has a low fuel concentration. The homogeneous charge compression ignition (HCCI) engine has both the advantages of SI and CI engines. Moreover, the lean burn characteristics of the HCCI engine make it a strong candidate for SOFC hybrid systems. The objective of this work is to develop a novel cycle composed of a SOFC and a HCCI engine. In order to optimize the SOFC-HCCI hybrid system, a system analysis is conducted here using the commercial software Aspen Plus®. The SOFC model is validated with experimental data. The engine model is developed based on an empirical equation that considers the ignition delay time. The performance of the hybrid system is compared with that of a SOFC stand-alone system to confirm the optimization of the system. This study will be useful for the development of a new type of hybrid system which uses a fuel cell and an optimized system.


Author(s):  
J. Parente ◽  
A. Traverso ◽  
A. F. Massardo

Part A of this paper demonstrated that the HAT cycle, when applied to small-size gas turbines, can significantly enhance the efficiency and specific work of simple and recuperated cycles without the drastic changes to plant layout necessary in medium- and large-size plants. In this part B a complete thermoeconomic analysis is performed for microturbines operating in a Humid Air cycle. The capital cost and internal rate of return for both new machines and existing microturbines working in an mHAT-optimised cycle are presented and analysed. Three different scenarios are considered. The first scenario reflects a distributed electrical power generation application where cogeneration is not taken into account. Instead, the other two scenarios deal with CHP civil applications for different heat demands. The thermoeconomic results of the integrated mHAT cycle, based on a preliminary design of the saturator, demonstrate that microturbine performance can be greatly enhanced, while specific capital costs, in some cases, can be reduced up to 14%, without significant increase in layout complexity. Moreover, thanks to its operational flexibility (able to operate in dry and wet cycles), the mHAT is financially attractive for distributed power and heat generation (micro-cogeneration), particularly when heat demand is commutated in short period.


2016 ◽  
Vol 11 (2) ◽  
pp. 260-265
Author(s):  
P. Balmér

Economic data from 40 years of operation of three regional wastewater treatment companies have been compiled and analysed. The transport systems consist mainly of gravity flow tunnels with lengths of 55–120 km. In spite of the heavy initial investments <20% of the cumulative total costs can be allocated to the transport systems. The treatment plants all remove 90% or more of the influent Biological Oxygen Demand (BOD) and phosphorus and 65–80% of the nitrogen. The wastewater treatment is responsible for about 90% of the cumulative operation costs while the transport system is responsible for 20–40% of the cumulative capital costs. Over time the cost of the transport systems has decreased considerably and is after 40 years of operation only 4–13% of the total costs. Although the main benefit of the regional solutions has been the transfer of wastewater from sensitive inland streams and lakes, the data presented give strong evidence that the regional solutions also has been advantageous from an economic point of view.


Author(s):  
Frank Sander ◽  
Roland Span

A drastic reduction of greenhouse gas emissions can only be achieved if CO2 capture will be introduced to fossil fueled power plants. Since CO2 capture lowers the efficiency of the overall power cycle tremendously, technologies have to be developed which reduce the loss in efficiency as much as possible. Due to the resources of fossil fuels, coal will still play an important role in future power generation processes. Especially, the emerging and developing countries such as India and China are already using an enormous amount of coal for power production. In this work, an IGCC process with an integrated H2-selective membrane has been investigated to substitute the CO2 capture unit by such a membrane reactor. Hydrogen-selective membranes have been studied intensively in combination with power generation processes [22, 23]. Palladium has been considered as membrane material in the present study. Due to its catalytic surface, high hydrogen permeability, and infinite hydrogen selectivity palladium and Pd-based alloys show a high potential for hydrogen separation [24, 25, 26]. The investigation has shown that the advantage of the H2-selective membrane reactor, it uses nitrogen as sweep gas on the permeate side of the membrane reactor, cannot defeat the existing drawbacks of the process layout: small mass flow rate through the gas turbine (and consequently through the HRSG) and higher energy requirements for oxygen production and CO2 compression, respectively. The net efficiency of the investigated IGCC process with integrated hydrogen-selective membrane reactor and capture of CO2 is compared with other IGCC concepts — with and without CO2 capture. The net efficiency of the overall process is 34.30%, which is about 3%-points lower compared to an IGCC process with chemical absorption and cryogenic ASU. Moreover, in comparison with an IGCC process with integrated OTM reactor and CO2 capture the efficiency is 1.7 percentage points lower than that of the process option with the lowest efficiency. Although no cost evaluation has been carried out, it can be assumed that hydrogen-selective membrane reactor would increase the capital cost of the overall IGCC process. The results indicate that the IGCC process with integrated hydrogen-selective membrane reactor and CO2 capture is less attractive from the thermodynamic point of view but also from a thermo-economic point of view.


2014 ◽  
Vol 493 ◽  
pp. 56-61
Author(s):  
Reza Adiprana ◽  
Danu Sito Purnomo ◽  
Iwan Setiono

UNIT-1 KAMOJANG geothermal power plant marked the new era of renewable energy in Indonesia. With its built capacity of 30 MWe, it constantly supply electricity to Java-Bali grid for more than 30 years now.Over those period, Unit-1 has given its best performance with highest achievement on Capacity Factor (CF) and Equivalent Availability Factor (EAF).High performance geothermal power plant involves the integration not only from the point of view of power generation, but also the optimation of geothermal potention in the area. Kamojang geothermal field, which is considered as one among five steam dominated reservoir in the world produces 200 MWe of the electricity nowadays. In order to maintain this production rate, some technical consideration must be made.Towards sustainable power generation of geothermal power, some assessment has been made to turbine, generator and cooling tower to ensure its current condition. Basically what it called remaining life assessment gives a rough picture of how long the equipment will run through in its operational condition.Based on those assessment, additional 20.900 hours is given to the turbine with the existing operating conditions. On the other hand, cooling tower infrastucture test and simulation delivers operation period for another 25 years.


Author(s):  
Michael Welch ◽  
Andrew Pym

Increasing grid penetration of intermittent renewable power from wind and solar is creating challenges for the power industry. There are times when generation from these intermittent sources needs to be constrained due to power transmission capacity limits, and times when fossil fuel power plant are required to rapidly compensate for large power fluctuations, for example clouds pass over a solar field or the wind stops blowing. There have been many proposals, and some actual projects, to store surplus power from intermittent renewable power in some form or other for later use: Batteries, Compressed Air Energy Storage (CAES), Liquid Air Energy Storage (LAES), heat storage and Hydrogen being the main alternatives considered. These technologies will allow power generation during low periods of wind and solar power, using separate discrete power generation plant with specifically designed generator sets. But these systems are time-limited so at some point, if intermittent renewable power generation does not return to its previous high levels, fossil fuel power generation, usually from a large centralized power plant, will be required to ensure security of supplies. The overall complexity of such a solution to ensure secure power supplies leads to high capital costs, power transmission issues and potentially increased carbon emissions to atmosphere from the need to keep fossil fuel plant operating at low loads to ensure rapid response. One possible solution is to combine intermittent renewables and energy storage technologies with fast responding, flexible natural gas-fired gas turbines to create a reliable, secure, low carbon, decentralized power plant. This paper considers some hybrid power plant designs that could combine storage technologies and gas turbines in a single location to maximize clean energy production and reduce CO2 emissions while still providing secure supplies, but with the flexibility that today’s grid operators require.


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