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Research Papers: Hydrogen Energy

# Installation Plan of a Fuel Cell Microgrid System Optimized by Maximizing Power Generation Efficiency

[+] Author and Article Information
Shin’ya Obara

Department of Electrical and Electronic Engineering, Power Engineering Laboratory, Kitami Institute of Technology, 165 Kouen-cho, Kitami, Hokkaido 0908507, Japanobara@indigo.plala.or.jp

Itaru Tanno

Department of Mechanical Engineering, Tomakomai National College of Technology, 443 Nishikioka, Tomakomai, 0591275, Japanitaru@me.tomakomai-ct.ac.jp

J. Energy Resour. Technol 131(4), 042601 (Nov 12, 2009) (9 pages) doi:10.1115/1.4000323 History: Received May 01, 2006; Revised July 31, 2009; Published November 12, 2009; Online November 12, 2009

## Abstract

If energy-supplying microgrids can be arranged to operate with maximal efficiency, this will have a significant influence on the generation efficiency of the grid and will reduce greenhouse gas production. A means of optimizing the microgrid needs to be developed. Moreover, microgrids that use proton exchange membrane-type fuel cells (PEM-FCs) may significantly reduce the environmental impact when compared with traditional power plants. The amount of power supplied to the grid divided by the heating value of the fuel is defined as the system generation efficiency. The authors find that when a set of PEM-FCs and a natural gas reformer are connected to the microgrid in an urban area, the annual generation efficiency of the system slightly exceeds 20%. When a PEM-FC follows the electricity demand pattern of a house, it operates at a partial load most of the time, resulting in a low efficiency of the microgrid. A method of improving the generation efficiency of a fuel cell microgrid is proposed, where a supply system of power and heat with a high energy efficiency are constructed. In this paper, a method of installing two or more microgrids is proposed (known as the partition cooperation system). The grids can be connected in an urban area to maximize generation efficiency. Numerical analysis shows that the system proposed in this paper (which has an annual generation efficiency of 24.6–27.6%) has a higher generation efficiency than conventional PEM-FC systems (central generating systems have annual generation efficiencies of 20.6–24.8%).

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## Figures

Figure 1

Microgrid model (a) Interconnected microgrid model and (b) independent microgrid model

Figure 2

Introduction to microgrids. In a “partition cooperation system,” the output point of each fuel cell is decided to maximize the generation efficiency of the overall grid. (a) Stand alone system, (b) central system, (c) distributed installation method of the partition cooperation system, (d) concentrated installation method of partition cooperation system, (e) DPS fuel cell model installed in buildings with generation equipment, and (f) CPS fuel cell model installed in buildings with generation equipment.

Figure 3

Energy equipment model installed in a building (a) stand-alone system, (b) central system, (c) concentrated installation method of partition cooperation system, and (d) building model without generating equipment

Figure 4

Power output results for a test PEM-FC with a reformer. The area of the electrode, including the anode and cathode, of the fuel cell stack is 1 m2 and the reformer efficiency is 0.73. (a) Characteristics of the load ratio of the PEM-FC with a reformer, and the power generation efficiency and (b) single cell performance results.

Figure 5

Capacity of the fuel cell system

Figure 6

Power demand models (a) family household (4 persons), (b) family household (2 and 6 persons), (c) apartment (10 persons), (d) apartment (20 persons), (e) hotel, (f) Convenience store, (g) small office, (h) factory, and (i) small hospital

Figure 7

Power demand model

Figure 8

Flow chart for calculating generation efficiencies for the FC microgrid

Figure 9

Average generation efficiency of the stand-alone system

Figure 10

Power generation efficiency of the central system

Figure 11

Analysis results for the partition cooperation microgrid system using a 2 kW PEM-FC (a) January (average generation efficiency is 23%), (b) May (average generation efficiency is 22.7%), and (c) August (average generation efficiency is 20.4%)

Figure 12

Analysis result for January, using the results from August for the grid configuration (Fig. 1). A 2 kW PEM-FC is installed in each grid. Average generation efficiency is 19.9%.

Figure 13

Analysis results of the partition cooperation microgrid system using a 5 kW PEM-FC (a) January (average generation efficiency is 23.2%), (b) May (average generation efficiency is 23.7%), and (c) August (average generation efficiency is 21.6%)

Figure 14

Analysis result in January where the August grid is used (Fig. 1). A 5 kW PEM-FC is installed in each grid. Average generation efficiency is 19.2%.

Figure 15

Analysis results of the partition cooperation system (DPS) (a) January (average generation efficiency is 27.1%), (b) May (average generation efficiency is 27.8%), and (c) August (average generation efficiency is 27.6%)

Figure 16

Analysis result in January and May when using the grid routes from August (Fig. 1) (a) January (average generation efficiency is 21.1%) and (b) May (average generation efficiency is 21.3%)

Figure 17

Analysis results of the partition cooperation system (CPS) (a) January (average generation efficiency is 24.6%), (b) May (average generation efficiency is 27.8%), and (c) August (average generation efficiency is 27.6%)

Figure 18

Method and number of units installed

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