Economic evaluation and optimization of a photovoltaic–fuel cell–batteries hybrid system for use in the Brazilian Amazon

Energy Policy ◽  
2010 ◽  
Vol 38 (11) ◽  
pp. 6713-6723 ◽  
Author(s):  
Sergio B. Silva ◽  
Marco A.G. de Oliveira ◽  
Mauro M. Severino
Author(s):  
Mehdi Mehrpooya ◽  
Parimah Bahramian ◽  
Fathollah Pourfayaz ◽  
Hadi Katooli ◽  
Mostafa Delpisheh

Abstract The production of liquefied natural gas (LNG) is a high energy-consuming process. The study of ways to reduce energy consumption and consequently to reduce operational costs is imperative. Toward this purpose, this study proposes a hybrid system adopting a mixed refrigerant for the liquefaction of natural gas that is precooled with an ammonia/water absorption refrigeration (AR) cycle utilizing the exhaust heat of a molten carbonate fuel cell, 700°C and 2.74 bar, coupled with a gas turbine and a bottoming Brayton super-critical carbon dioxide cycle. The inauguration of the ammonia/water AR cycle to the LNG process increases the cooling load of the cycle by 10%, providing a 28.3-MW cooling load duty while having a 0.45 coefficient of performance. Employing the hybrid system reduces energy consumption, attaining 85% overall thermal efficiency, 53% electrical efficiency and 35% fuel cell efficiency. The hybrid system produces 6300 kg.mol.h−1 of LNG and 146.55 MW of electrical power. Thereafter, exergy and sensitivity analyses are implemented and, accordingly, the fuel cell had an 83% share of the exergy destruction and the whole system obtained a 95% exergy efficiency.


Author(s):  
D. P. Bakalis ◽  
A. G. Stamatis

A hybrid system based on an existing recuperated microturbine and a pre-commercially available high temperature tubular solid oxide fuel cell is modeled in order to study its performance. Individual models are developed for the microturbine and fuel cell generator and merged into a single one in order to set up the hybrid system. The model utilizes performance maps for the compressor and turbine components for the part load operation. The full and partial load exergetic performance is studied and the amounts of exergy destruction and efficiency of each hybrid system component are presented, in order to evaluate the irreversibilities and thermodynamic inefficiencies. Moreover, the effects of various performance parameters such as fuel cell stack temperature and fuel utilization factor are investigated. Based on the available results, suggestions are given in order to reduce the overall system irreversibility. Finally, the environmental impact of the hybrid system operation is evaluated.


2009 ◽  
Author(s):  
W. J. Sembler ◽  
S. Kumar

The reduction of shipboard airborne emissions has been receiving increased attention due to the desire to improve air quality and reduce the generation of greenhouse gases. The use of a fuel cell could represent an environmentally friendly way for a ship to generate in-port electrical power that would eliminate the need to operate diesel-driven generators or use shore power. This paper includes a brief description of the various types of fuel cells in use today, together with a review of the history of fuel cells in marine applications. In addition, the results of a feasibility study conducted to evaluate the use of a fuel-cell hybrid system to produce shipboard electrical power are presented.


Author(s):  
Ji Ho Ahn ◽  
Tong Seop Kim

Owing to the increasing consumption of fossil fuels and emission of greenhouse gases, interests in highly efficient and low carbon emitting power systems are growing fast. Several research groups have been suggesting advanced systems based on fuel cells and have also been applying carbon capture and storage technology to satisfy the demand for clean energy. In this study, the performance of a hybrid system, which is a combination of a molten carbonate fuel cell (MCFC) with oxy-combustion carbon capture and an indirectly fired micro gas turbine (MGT) was predicted. A 2.5MW MCFC system that is used in commercial applications was used as the reference system so that the results of the study could be applicable to practical situations. The ambient pressure type hybrid system was modeled by referring to the design parameters of an MGT that is currently being developed. A semi-closed type design characterized by flow recirculation was adopted for this hybrid system. A part of the recirculating gas is converted into liquefied carbon dioxide and captured for storage at the carbon separation unit. Almost 100% carbon dioxide capture is possible with this system. In these systems, the output power of the fuel cell is larger than in the normal hybrid system without carbon capture because the partial pressure of carbon dioxide increases. The increased cell power partially compensates for the power loss due to the carbon capture and MGT power reduction. The dependence of net system efficiency of the oxy-hybrid on compressor pressure ratio is marginal, especially beyond an optimal value.


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