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Fuel cell break through

Shinji Amaha, Kei Ogasawara, Yasuharu Kawabata, and Hisataka Yakabe, Tokyo Gas Co., Ltd.

Jeongwook Khang, Korea Gas Corporation

1. Introduction

Reducing CO2 emission is a very serious issue for energy companies to be tackled. Although

using renewable energy is the most direct and effective way for this subject, it takes so long time to

come to self-sufficient by renewable energy. Thus during the transition period to the low carbon

society, we must continue using fossil fuels. Using fossil fuels as effectively as possible is another

practical solution to reduce CO2 emission and we must consider how we make efficient use of them.

Fuel cells are expected as one of the effective methods to use fossil fuels because electricity can be

produced successfully through the electrochemical reaction of fossil fuels. While over several

decades, much effort has been paid to the research and development of them, it is not easy to

implement their technology. The past few years, however, at last several fuel cell technologies were

exploited and they are now under popularization. Various types of fuel cells, such as polymer

electrolyte, phosphoric acid, molten carbonate, and solid oxide fuel cells have been developed

intensively and commercialized in Asia, Germany and the United States.

In this report, the current status of fuel cell technologies, especially in Asia is reported.

2. Fuel cells for residential use

In Japan, residential PEFC (Polymer Electrolyte Fuel Cell) systems have been commercialized first

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① ② ③

Table 1. Comparison of the specification for three different fuel cell systems in Japan.

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in the world in 2009. Next year

residential SOFC (Solid Oxide Fuel

Cell) systems were also

commercialized. These fuel cell

systems are sold with the standard

brand name “ENEFARM”. ENEFARM

is a micro CHP (Combined Heat and

Power) system and consists of a fuel

cell unit, a hot water tank and a

backup boiler. During a power

generation, by using excess heat at

cell stacks, hot water is produced

simultaneously and stored first in the

hot water tank. Then the stored hot

water is used corresponding to the user’s demand. To avoid the running-out of the hot water,

anytime customers want to use it, the backup boiler supplies hot water and compensate the shortage.

Although ENEFARM is usually operated to follow the user’s electricity demand in each home, the

output power capacity of ENEFARM is lower than the maximum demand. Thus the shortage of the

power is compensated by commercial electricity.

Currently there are three major manufactures for ENEFARM, Panasonic Corporation, Toshiba Fuel

Cell Power Systems Corporation, and Aisin Seiki Co., Ltd. Table 1 shows the specification of

ENEFARM for each company. Panasonic and Toshiba have developed PEFC type systems and Aisin

developed an SOFC system. Although the power generation efficiency of PEFC system is lower than

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0

2000

4000

6000

8000

10000

12000

0

20000

40000

60000

80000

100000

120000

2009 2010 2011 2012 2013 2014

Su

bsid

ies (

$/u

nit)

Accu

mu

late

d U

nit N

um

be

r

Fiscal Year

Unit Number

Subsidies

Fig. 1. Increase of the ENEFARM sales and the change

of yearly subsidy to ENEFARM in Japan.

5 Fig. 2. Evolution of Panasonic and Tokyo Gas’s ENEFARM

Total efficiency（ LHV） 89% 90% 95% 95%

Installation space

(depth)

3.9 m2

(1100 mm)

2.0 m2

(900 mm)

2.0 m2

(750 mm)

1.7 m2

(750 mm)

Life time

(Start and Stop)

40000 h

4000 times

50000 h

4000 times

60000 h

4000 times

70000 h

4000 times

Price

(tax excluded) € 24,500 € 19,500 € 14,000 € 11,800

1st model

（ 2009～10）

2nd model

（ 2011～12）

3rd model

（ 2013～14）

4th model

（ 2015～）

Newest

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that of SOFC system, the heat recovery efficiency is higher than that of SOFC. Accordingly the

overall efficiency is almost the same for all the FC systems and over 90%.

Figure 1 displays the change of the yearly subsidy by Japanese government to ENEFARM sales

and the increase of the accumulated number of ENEFAEM sold in Japan. Thanks to the subsidies

the ENEFARM sales launched well and the sales number increased gradually. Although the

subsidies decreased with the reduction of the ENEFARM price, the FC business has not been

independent enough yet.

2.1 Polymer electrolyte fuel cell

Tokyo gas and Panasonic have been developing PEFC type ENEFARM. Figure 2 shows the

revolution of Panasonic and Tokyo Gas’s ENEFARM. In 2009 the first ENEFARM system was

commercialized and then, every two years, a new model was released. Along the model change, the

performance of ENEFARM was improved; the efficiency was raised, the size and price was reduced.

The price of the latest model is half the initial model.

With the model change, the sales of ENEFARM increased and this year the accumulated number

of the stock was over 50,000 systems. Tokyo Gas’s near-future target of the ENEFARM stock is

300,000 units in 2020, which is very ambitious number. To popularize ENEFARM more and more,

cost reduction, expansion of the market potential and making ENEFARM more attractive product is

indispensable. For the expansion of the market potential, a new apartment model was developed.

In Tokyo area more than 60% of the new houses are apartment houses, and the adoption of ENEFARM

to apartment houses is very important to spread the market. Thus based on the detached model, an

apartment model which is able to be installed in a small cubicle of apartment buildings was developed

as illustrated in Fig. 3. For smooth installation, the system is separated into three pieces and the

system satisfies the criteria for the apartment installation such as the earthquake resistance and the

wind resistance. Several major developers of apartment buildings have much interest in the high

performance and eco-friendly property of ENEFARM and employed them for their new buildings.

Now many systems of the apartment model have been under installment and around 1,000 units will

Fig. 3. Configuration of an apartment model installed in a cubicle; an FC unit, a Hotwater unit,

and a Backup boiler.

Backup

boiler

Hot

water

unit

Apartment model Detached model

FC

unit

Cubicle

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be operated in 2015.

2.2 Solid oxide fuel cell

Recent Activities on the Development of SOFC for residential use in Japan

An SOFC is the ultimate power-generating device that is expected to yield the highest efficiency of

power generation among any power generators using fossil fuels. In Japan a demonstrative research

project on SOFCs by New Energy and Industrial Technology Development Organization (NEDO) and

the New Energy Foundation(NEF) of Japan was carried out from 2007 to 2011[1]. In this project, 233

units of SOFC systems were installed in various sites, and a variety of operation data was collected

and evaluated. As a result, it was recognized that residential SOFC system can contribute to saving

the preliminary energy consumptions and CO2 emissions in households.

After the demonstration, JX Nippon Oil & Energy Corporation and Aisin released a residential

SOFC CHP (Combined Heat and Power generation) system in 2011 and in 2012, respectively. Flat

tubular cell-stacks manufactured by Kyocera Corporation were employed in both the unit. Kyocera’s

cell-stack is operated at 700 to 750°C with a high electrical efficiency of 46.5%(LHV) and an overall

energy efficiency of 90%[2]. Stimulated by Kyocera’s success, other ceramic manufactures started to

develop SOFC cell-stacks for residential systems. Since SOFCs can have various geometries and

designs, a number of ceramic manufacturers in Japan make use of their core competence and are

developing their original SOFC technology. Figure 5 shows major SOFC manufacturers in Japan

Fig. 4. Images of apartment buildings that employed ENEFARM.

BRANZ CITY SHINAGAWA-KATSUSHIMACompletion : July 2015 Households :356

THE PREMIER SKY SHINAGAWA-NAKANOBUCompletion : August 2015 Households :100

Fig. 5. Five major SOFC cell stack manufacturers in Japan and their cells.

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and their cell-stacks developed for residential use.

TOTO has developed tubular type cell-stacks with a thin electrolyte of lanthanum gallate to enable

low-temperature operation. NGK Spark Plug has developed planar cell-stacks whose characteristics

is the high power density. NGK Insulators is in the process of developing segmented-in-series cell-

stacks, and Murata Manufacturing is developing planar type cell-stacks prepared by single step co-

fire. Since the reliability of these cell-stacks in operations is still an unsolved issue, to tackle this

subject those manufacturers have joined the cooperative NEDO project “Fundamental study of a

method for rapidly evaluating durability of SOFCs” since fiscal 2013[3].

Recent Activities on the Development of SOFCs for residential use in the world

Overseas manufacturers are also developing their original SOFCs for residential use. Ceres

Power in UK has developed the low-cost metal supported cell operated at a lower (500 to 600°C)

temperature[4]. Solid Power in Italy has developed the anode supported cell-stacks and produced the

micro-CHP, called “EnGen™-2500”[5]. They are operating the system in the field test under the

project “Ene.field project” co-founded by the European Commission's Fuel Cells and Hydrogen Joint

Undertaking (FCH-JU).

Thus the developments of SOFCs for residential use are activated so much. The activities are

vigorous and will help the future expansion of SOFC markets by achieving both higher reliability and

durability as well as lower cost of the system.

3. Fuel cells for commercial and industrial use

3.1 Solid oxide fuel cell

Fuel cell systems for commercial use are expected as one of the key energy solutions for sustainable

society with the high energy savings and less environmental impact. The system also has strong

potential of a major power source in the coming Hydrogen Society.

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Fig.6. Field test of (a) a small-scale commercial SOFC cogeneration (Miura) and (b) an SOFC hybrid

cogeneration system (Mitsubishi Hitachi).

(a) (b)

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Considering the recent customers’ energy saving trend and developments of high-energy saving

technologies like LED lighting, inverter-controlled air conditioning, and building/community energy

management systems (BEMS/CEMS), the energy consumption of commercial sectors will decrease

year by year in the near future. On the other hand eventually the energy saving at each building or

community will lead to a limit. To achieve more energy savings even after applying such advanced

energy saving technologies, improvements or changes of the energy source must be quite effective.

Fuel cell technology for commercial use is one of major solutions for the improvement of customers’

energy utilization. Fuel cells also have many beneficial points for urban on-site power sources. The

high power generation efficiency with utilizing the exhaust heat, the less-NOx clean exhaust without

noise and vibration, and the easy on-site installation are advantageous compared with other

conventional power sources.

Fuel cell technologies are already put into practical use in residential and mobility sector in Japan.

Residential PEFC and SOFC cogeneration systems called ENEFARM and ENEFARM type-S, are now

increasing in the early market introduction stage. First commercial PEFC vehicle called MIRAI

(meaning future in Japanese), is also released in the mobility market. Applying these technologies

to the commercial stationary power generation system, development of fuel cell cogeneration systems

for commercial use is highly expected to be commercialized in the fiscal year 2017 (Target of Hydrogen

and Fuel Cell Roadmap 2014, Ministry of Economy, Trade, and Industry). To achieve this target,

many Japanese manufacturers are actively developing various kinds of cell-stacks and fuel cell

cogeneration systems with power output range from several kW to hundred kW.

For example, Miura Co., Ltd., one of major commercial and industrial boiler companies is now

developing a 4.2 kW SOFC cogeneration systems with Sumitomo Precision Products. Towards their

target of first commercial installation of the system in FY2017, with 48%(LHV) power generation

efficiency and 42%(LHV) heat recovery, they have been participating Japanese national SOFC

demonstration program by NEDO (New Energy and Industrial Technology Development

Organization) since 2013. Tokyo Gas is supporting their activity and supporting their system

development through the field tests in their test facilities (Fig. 6(a)). Small–size commercial SOFC

cogeneration systems are thought to be suitable for effective energy savings at restaurants, fast food

shops, and welfare facilities, etc.

Mitsubishi Hitachi Power Systems (MHPS) is also developing 250 kW Hybrid-SOFC cogeneration

systems. This system consists of efficient pressurized SOFC cell-stacks and a Micro Gas Turbine

(MGT) driven by residual reformed gas from the SOFC anode. The hybrid power generation system

with an SOFC and a MGT enables quite high power generation efficiency of 55%(LHV). Tokyo Gas

has been also supporting their development of this sophisticated system since 2012. They have been

doing field tests and demonstrated more than 4,000 hrs world-longest stable operation for the SOFC

hybrid power generation systems in 2013 (in Fig .6(b)).

Some other manufactures are also starting developments of SOFC systems for commercial use in

Japan. Most of them are aiming market introduction of their systems around FY2017 and Japanese

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major gas companies are promoting and supporting their activities toward future commercialization.

3.2 Molten carbonate fuel cell

MCFC has been commercialized in South Korea by POSCO Energy. The annual production unit

of the company in Pohang is 100 MW and the MCFC products are 100 kW, 300 kW, 2.5 MW and 8×

1.3 MW module plus 10 MW BOP. Fuel cells history in POSCO Energy is like the below table.

The 2.5 MW products consist of two of 1.25

MW module and each module has four stacks.

MCFC Design Basis of 1.2 MW MCFC covers

650°C of operating temperature, 44-49%

electrical efficiency (LHV), 0.55 MW available

heat (to 120°C) and 0.93 MW available heat

(to 50°C).

Total stationary power generation thru

MCFC in Korea reached 149.5 MW at 25 sites

March 2015. The scale becomes larger as

the demand for RPS continues to grow.

POSCO Energy & FCE continue improving

products for 2107 targets; performance

upgrade from 320 kW stack to 370 kW,

extended life of 5 years to 7 years, cost

reduction of below $2,000 /kW and others for

customer satisfaction including reduced foot

print, automated operation and faster load ramp.

Table 2. Fuel Cells History in POSCO Energy.

2015 Cell production will be initiated in July, 2015 (100 MW/yr)

2014 MCFC/SOFC R&D Recognized & Expanded

2013 60 MW Gyounggi Green Energy in Operation

10 MW MCFC BOP Developed

2011 Production of MCFC Stack in Pohang initiated

ISO9001 Certification

2008 Production of MCFC BOP in Pohang initiated

2007 Strategic Collaboration with FCE, US

RIST/POSCO Energy initiated SOFC

Fig.7. Stationary Generation in Korea.

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Additional value proposition via technology convergence has been actively explored. Platform

products aim higher fuel utilization and secondary generation of which electrical efficiency is higher

than 60% and diversified (H2-rich) fuel & multi-purpose products. In Cascade Modules, un-reacted

fuel in the first module is further utilized in the second module resulting in increase of total fuel

utilization and electrical efficiency. Diverse configurations with more than 2 modules are possible,

however operational and control logic becomes complicate.

Process engineering has been advanced for the variety of hydrogen-rich fuel and other feedstock.

Due to the RPS and building regulations, fuel cell market for stationary generation in Korea is

steadily growing. To accommodate growing market as well as to prepare for the future non-RPS

market, the MCFC maker put an effort to develop high-efficiency hybrid products, while keep

improving current MCFC products for lower cost and longer life. Recently, large size market for IGCC

and SNG plats and/or H2-rich fuel from chemical plats emerges fast, and engineering process for fuel

Fig. 8. Classical Module and Cascade Module.

Fig. 8. ?????????????????????????????

Fig. 9. Applications for Diversified Fuel.

Note: SNG: Synthetic Natural Gas, IGFC: Integrated Gasifier Fuel Cell, ADG: Anaerobic

Digest Gas, BOG: Boil-Off Gas

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treatment are also being actively developed.

4. New technology related fuel cell

4.1 Trigeneration using SOFC

An SOFC is a very excellent distributed power generator and expected to be applied to industrial

and business use. However an issue in the adoption is how to use the excess heat because usually

heat demand is very small in such as office buildings. One of possible solutions for this problem is a

trigeneration (or co-production) concept [6-7]. The idea of the SOFC trigeneration system is that it

can produce hydrogen in addition to electricity and heat.

The configuration of an SOFC trigeneration system is shown in Fig.7. The principle of the

trigeneration is as follows. Using the excess heat of an SOFC, through steam reforming reaction,

fuel is reformed to hydrogen rich gas at an additional reformer. Then the reformate gas is refined

by a purifier, a CO shift converter and a PSA (Pressure Swing Adsorption). Instead of using the

excess heat to produce steam or hot water, it is used to produce hydrogen. The trigeneration system

can control the ratio of hydrogen production to steam or hot water freely and thus when the heat

demand is small hydrogen is generated and stored (there are several ways to store hydrogen).

Several years ago, Tokyo Gas proposed this idea and proved that it is possible to produce hydrogen

effectively by using excess heat of an SOFC system. The actual demonstration was carried out using

a 10 kW SOFC system at Tokyo Institute of Technology, and in more advanced, a PEFC system was

combined the SOFC trigeneration system. The picture of the SOFC and PEFC hybrid system is

displayed in Fig. 8. Through the demonstration it was proved that around 10% of electricity can be

additionally produced to the SOFC output by the hydrogen production. Now Tokyo Gas and

Mitsubishi Hitachi are planning to apply this system to a hydrogen refueling station and demonstrate

its validity in Tokyo Olympic.

4.2 Ultra highly efficient SOFC

Fig.7. Configuration of as SOFC and PEFC

hybrid system.

SOFC

Reformer

Natural Gas

SOFC system

Shift Convertor

Compressor

PSA H2 storage tank

Exhaust

Cooling

H2 Refiner

Pure H2

PEFC system

Reformate

Pure H2

Power

Pre-reformer

Reformate

Heat

Power

Off-gas

SOFC

PEFC

,SOFC (4.5kW×2)

Radiator

Combustor

H2 cylinder

PSA

Controller

Hotwater tankPEFC (0.8 kW)

Fig.8. Outline of the demonstrated SOFC and

PEFC hybrid system.

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In usual SOFCs have the highest power efficiency among fuel cells. However enhancing the

efficiency of small scale SOFC systems higher than up-to-date large scale combined cycle thermal

power plants can make them more competitive and is beneficial to develop and expand gas business

markets. For example, major business and industrial customers in Japan have more power demands

than thermal ones, and have potential to achieve greater environmental and economical benefits by

using power generator with higher efficiency.

One effective way to increase power generating efficiency of SOFC systems is, for example,

combining an SOFC with a turbine in large-scale systems. However the operation of the combined

system is complicated and difficult, and moreover this system cannot be adopted to smaller one.

Tokyo Gas is making a different approach to increase the efficiency of SOFC systems. The main

principle is refining the fuel exhaust gas from the cell part and reusing the refreshed gas as a fuel

again. To realize this concept multiple cell-stacks configuration is employed. The point is that, by

removing carbon dioxide (CO2) and water in the exhaust fuel from the first SOFC stack, the unreacted

fuel can be concentrated so as to be reused effectively as a fuel for the second stack (see Fig. 9).

Thereby the fuel utilization for the overall system is improved greatly, which in turn improves power

generating efficiency. This method is applicable in principle not only to large scale but also to

medium and small scale systems.

The R&D activities of Tokyo Gas include manufacturing a hot module for proving the concept. As

schematically shown in Fig. 10, three SOFC stacks were incorporated in the hot module together with

fuel refining equipment filled with CO2 absorbing agent, and also a water condensation unit at outer

vicinal of the module. Since this unit is too small to be thermally sustainable, the insufficiency of

the heat is assisted by an external heater. Although the thermal dissipation was compensated by

the heater, this demonstration unit showed very excellent performance. The maximum fuel

utilization reached 92.0% attaining power efficiency of 77.8% (DC, LHV) at the rated output power of

1.4 kW. More efforts will be made in order to eventually demonstrate high-efficiency power

generation by actual systems.

Fig. 9. Schematic diagram of an SOFC concept with high fuel utilization

Hot exhaust gas

Off air

SOFC

Off air

Fuel reproduction technology

Anode

Cathode

SOFC

Anode

Cathode

SOFC2

Anode

Cathode

SOFC

Anode

Cathode

SOFC1

Combustor

Heat exchanger

Exhaust gas

Vaporizer

Steamreformer

Water

Methane

Air

Blower

Mixer

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Furthermore, recently Tokyo Gas and

Kyushu University collaboratively presented

an innovative concept for the critically high

power efficiency of an SOFC system

supposing a multi stage stack configuration

with a proton-conducting solid electrolyte [8].

The calculated maximum efficiency was 85%

(DC, LHV) and 76% (net AC, LHV).

References

[1] K. Horiuchi, ECS Trans. 57(1), 3 (2013).

[2]

http://global.kyocera.com/news/2012/0305_woec.html.

[3] H. Yokokawa, ECS Trans. 68 (1), 1827-1836 (2015).

[4] R. Leah, A. Bone, M. Lankin, A. Selcuk, M. Rahman, A. Clare, L. Rees, S. Phillip, S. Mukerjee

and M. Selby, ECS Trans. 68 (1), 95-107 (2015).

[5] M. Bertoldia, O. Buchelib, and A. V. Ravagnia, ECS Trans, 68 (1), 117-123 (2015).

[6] Hisataka Yakabe, Hideki Yoshida and Shinji AMaha, ECS Trans, 25 (2), 301-312 (2009).

[7] Hideki Yoshida, Shinji Amaha and Hiataka Yakabe, ASME-IMECE 8, 577-585 (2008).

[8] Scientific Reports 5, Article number: 12640 (2015), doi:10.1038/srep12640.

Fig. 10. Schematic diagram of the configuration of

a hot module for high efficiency power generation

test.

Heat exchanger

CO2 absorber

SOFC stacks

Vaporizer / Reformer