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Osaka Gas and Kyocera Announce Development of a 700-W Class Solid Oxide Fuel Cell (SOFC) Cogeneration System for Household Use

The world's smallest cogeneration system for household use that can be installed in a small urban residence

January 25, 2007
(This document was translated from the Japanese press release.)

Osaka Gas Co., Ltd.
Kyocera Corporation


Osaka Gas Co., Ltd. (President: Hirofumi Shibano) and Kyocera Corporation (President: Makoto Kawamura) have developed a solid oxide fuel cell (SOFC*1) cogeneration system for household use that can be installed in a small urban residence through modification of the rated output from the conventional 1 kW to 700 W. Both companies have positioned this system as being easy to install and as having superior power generating efficiency. The device is a prototype of the unit to be released on the market in fiscal 2008. The companies are working toward practical use.

The companies installed an SOFC cogeneration system with output of 1 kW in a joint research home in the Next 21 experimental housing complex owned by Osaka Gas and conducted the first trial operation in a residential house in Japan. Demonstrations have shown that the power generation efficiency, the primary energy reduction and CO2 emission reduction are at a high level.*2

Since the SOFC cogeneration system has a high proportion of power generation efficiency in total efficiency, it offers environmental and economical advantages in household use where there is comparatively small thermal demand. The system was also downsized to improve ease of installation so that more people can use the cogeneration system at home. The hot-water supply and heating unit using exhaust heat was co-developed by Osaka Gas and Chofu Seisakusho Co., Ltd. (President: Yasuo Kawakami).


The main features of this system
1.Significant downsizing of the power generation unit
(1) Thinner cell and smaller cell stack
The unit was made much smaller through the development of new ultra-thin cells with a thickness of 2 mm instead of the previous 3 mm and a reduction in the cell stack (cell aggregate) structure from the conventional 200 cells to 126 cells.

(2) Simpler power generation unit structure
The power generation unit structure has been simplified by integrating the air induction part that supplies air to the generation module (a metal container with a built-in cell stack and device to transform fuel) into the generation module cabinet. As a result, the volume of the power generation unit was reduced by approximately 50% compared to that of the 1 kW class unit.

2. Thin hot-water supply and heating unit using exhaust heat
Through optimum sizing of the hot water storage tank and modification of the donkey boiler's layout, a hot-water supply and heating unit using exhaust heat was developed that was just 330 mm thick to maximize ease of installation in a small urban residence. These developments made the power generation unit and the hot-water supply and heating unit using exhaust heat the smallest cogeneration system for household use in the world in terms of installation area and volume.

3. Power generation efficiency of 45% (AC generator output efficiency*2, LHV*3) and exhaust heat recovery efficiency of 30% or more in the 700-W class
The rated output was reduced from 1 kW to 700 W to reduce the size of the unit for greater ease of installation and to bring more economical and environmental advantages to the customers. In the performance evaluation, this new model exhibited a power generation efficiency of 45% or more and exhaust heat recovery efficiency of 30% or more, which exceed each of the original targets.

To promote this eco-friendly cogeneration system for household use, both companies will work on the development of technologies to improve reliability and reduce costs through field tests and application for SOFC experimental studies planned by the Ministry of Economy, Trade and Industry from fiscal 2007, and aim to launch products in the market in fiscal 2008.


*1 Solid Oxide Fuel Cell

*2 Osaka Gas and Kyocera Press release as of May 16, 2006
"Osaka Gas and Kyocera Announce the Results of the First Domestic Trial Operations of Solid Oxide Fuel Cell (SOFC) Cogeneration System for Household Use"

*3 Power generation efficiency at AC 100V available to customers. Power generation efficiency that subtracts the loss of the inverter to convert a direct current generated by fuel cells into an alternating current, and other supplementary mobile power.

*4 Abbreviation of Lower Heating Value. This is the quantity of heat generated after subtracting the condensation of latent heat of evaporation generated by the burning of fuel from the volume of fuel for heat generation.


Power generation unit (left) and hot-water supply and heating unit using exhaust heat (right)

Power generation unit (left) and hot-water supply and heating unit using exhaust heat (right)

2 mm-cell (the new cell, left) and 3 mm-cell (the old cell, right)
2 mm-cell (the new cell, left) and 3 mm-cell (the old cell, right)

Specifications of SOFC cogeneration system
[Power generation unit]
Manufacturer Kyocera Corporation
Form of installation Outdoor floor type
Outer dimension D 350 mm x H 950 mm x W 540mm
Weight 91.5 kg
Gas in use Town gas 13A
Output of power generation Rate 700 W
Minimum 100 W or less
Power generation efficiency rate Rate 45% (LHV)
Exhaust heat recovery quantity Rate 470 W
Exhaust heat recovery efficiency Rate 30% (LHV)
Exhaust heat recovery temperature Rate 75 degrees Celsius
Operation method Continuous/load following operation


[Hot-water supply and heating unit using exhaust heat]
Manufacturer Chofu Seisakusho Co., Ltd.
Form of installation Outdoor floor type
Outer dimension D 330 mm x H 1700 mm x W 750 mm
Weight 105 kg
Capacity of hot water storage tank 70 L
Gas in use Town gas 13A
Hot water supply Capability 41.9 kW (No. 24)
Re-warming Capability 10 kW (8600 kcal/h)
Heater Capability High temperature: 14 kW (12000 kcal/h)
Low temperature: 7 kW (6000 kcal/h)



(Reference)

[Lineup of cogeneration systems for household use]
  Rated Power Generation
(Power generation efficiency*)
Rated Heat Generation
(Exhaust heat recovery efficiency*)
Ratio of Heat Generation to
Power Generation
Engine-type cogeneration system: ECOWILL 1.0 kW
(22.5%)
2.8 kW
(63%)
2.8
Target specifications for the PEFC cogeneration system 0.7 kW – 1.0 kW
(35%)
0.90 kW - 1.29 kW
(45%)
1.29
Target specifications for the SOFC cogeneration system 0.7 kW
(45%)
0.47 kW
(30%)
0.66
*LHV basis