Domestic Heat and Power Generation

The majority of currently active fuel cell developers are focusing on the residential and small commercial power market in the range 1 to 20 kWel. These include traditional, leading fuel cell companies and startups that sometimes originate from a university laboratory or have some other technology base. A number of these companies have substantial financial backing from leading utilities (see below).

One of the attractions of this market lies in the belief that target cost, approximately $1000 per kW, is more readily achievable than the automotive target of $50 per kW. In the past, this still did not convince the leading automotive developers to work on this application, most likely because the potential market was deemed too small for the likes of Ballard, General Motors, and other major companies.

Development targets for residential systems vary among grid-independent power generation, micro-scale CHP, and combinations of electric power generators and absorption chillers for cooling purposes.

Only two fuel cells are currently being considered for this application: the PEMFC, which is clearly leading in terms of the number of developers, and the (planar) SOFC.

8.3.1 The PAFC for Domestic Heat and Power Generation

The first domestic CHP systems were based on the phosphoric acid technology of UTC. The 12.5-kW PC-11 units were developed from 1967 onwards, and a total of 60 units were field tested under the TARGET program in 1975 in the U.S., Canada, and Japan (see Section 2.8). Figure 2.14 shows the unit, which consisted of the actual reformer and fuel cell module and a power inverter unit of almost the same size.

Despite this early, awesome achievement, currently PAFC systems are no longer considered for domestic use. Likely reasons are problems with intermittent operation and the expected cost advantages of PEMFC systems. Nevertheless, the PC-11, among a whole series of other fuel cell systems leading up to the PC25C, clearly demonstrates UTC's position as one of the most experienced developers in the fuel cell market, with an excellent record of fuel processing and systems engineering.

8.3.2 The PEMFC for Domestic Heat and Power Generation UTC Fuel Cells

UTC (South Windsor, CT), a leader in AFC technology for space applications and in PAFC technology for stationary power (compare Sections and 8.3.1), more recently recognized the importance of PEMFC technology for residential and automotive applications. With the company's background in PAFC systems development and manufacture, including the world's first residential power system, the PC-11 (see Section 8.3.1), UTC is in an excellent starting position. Moreover, UTC has developed a wide range of fuel processor technology over the past 50 years, including steam, autothermal, and partial oxidation reformers.

UTC's residential program is based on the stack shown in Fig. 8.16, which is a smaller version of UTC's Series 300 transportation stack (see Chapter 10).

Targeting the Japanese market, UTC has been working with Toshiba and, in 2000, announced the formation of a joint venture, Toshiba International Fuel Cells.

In order to develop fuel cell systems for the European market, UTC has teamed up with Buderus Heiztechnik GmbH (Germany). The European fuel cell system will produce electric power in the 3- to 5-kW range with an additional 8 to 9 kW of thermal power. Taking into account the need for substantial heating in winter, the system will also include a small gas boiler for peak demand (Buderus GmbH, 2001). Plug Power/GE Power Systems/GE MicroGen/GE Fuel Cell Systems/Vaillant

Probably the most advanced and certainly one of the most aggressive residential programs was initiated by Plug Power LLC (Latham, NY) in the second half of the 1990s. Plug Power was founded in June 1997 as a joint venture between DTE Energy, a diversified energy services company and parent of Detroit Edison (Michigan's largest electric utility), and Mechanical Technology, Inc., an early developer of fuel cells.

In 1998, GE Power Systems announced that it was going to market Plug Power's residential systems in the U.S. and founded a joint venture, GE Fuel Cell Systems, between its subsidiary GE MicroGen and Plug Power for worldwide marketing in 1999. First partners in commercialization were going to be NJR Energy Holdings (Wall, NJ) and Flint Energies (Warner Robins, GA) (HyWeb, 1999a). Commercial grid-independent HomeGen 7000 and domestic CHP systems (operating on natural gas and LPG) have been demonstrated 2001 and 2002, respectively. Prices were targeted at initially $8500, falling below $4000 by 2003 for the system.

FIGURE 8.16 The fuel cell stack in the picture is at the heart of the residential fuel cell being developed by UTC. (Photograph courtesy of UTC Fuel Cells.)

Domestic Heating System

Domestic Heating System

Buderus Sofc

Natural Gas

_ Shift- niCO-Cleanup air Converter "

Natural Gas

Bus System-

Energy Manager



_ Shift- niCO-Cleanup air Converter "


FIGURE 8.17 Process diagram of domestic co-generation system with gas boiler for peak demand. (Courtesy of Joh. Vaillant GmbH.)

By the end of 2001, Plug Power was planning to bring between 125 and 150 5-kW systems onto the market, followed by 300 to 600 units in 2002 (HyWeb, 2001b). Primary customers for these systems are Long Island Power Authority (57 systems delivered by October 31) and subisidiaries of General Electric and DTE Energy (sole distributor in Michigan, Illinois, Ohio, and Indiana). Forty-four units were also delivered to the New York State Research and Development Authority by October 31, 2001. In the same year, Plug Power received CSA certification for its products.

Outside the U.S., Plug Power, GE Fuel Cell Systems, and Joh. Vaillant GmbH u. Co (Remscheid, Germany), a privately owned heating system developer, are targeting the European market for domestic CHP systems. The systems will include a condensing natural gas boiler for peak load (HyWeb, 1999b). The process diagram is shown in Fig. 8.17. Sales were expected to start in 2003, with target sales of 100,000 units per year in 2010.

The current Plug Power 7000 system is believed to be based on Plug Power's stack technology and natural gas reformer technology developed by Gastec (acquired by Plug Power in February 2000; now Plug Power Holland). Earlier reformer tests included Johnson Matthey's HotSpot® reformer, in 1997, for which the company was awarded the Italgas prize in 1999.

In 1997, Plug Power also demonstrated electric power generation from a gasoline-powered reformer. In 2000, Plug Power signed three important agreements, with Advanced Energy Systems for inverter technology, with Celanese (formerly Hoechst/Aventis/Axiva) (see Chapter 4) to develop a high-temperature membrane electrode unit, and with Engelhard Corporation to develop and supply advanced catalysts to increase the overall performance and efficiency of Plug Power's fuel processor.

Despite having to reschedule some of its commercialization programs, the Plug Power group is one of the most promising developers, certainly in the United States. Ballard Generation Systems (BGS)

In January 2001, BGS signed an agreement with Tokyo Gas, Ebara Ballard, and Ebara Corporation for joint development of a natural gas reformer as part of a 1-kW domestic CHP system for the Japanese market. Ballard plans to build a demonstrator before introducing a commercial product (Ballard, 2001b).

On a larger power scale, Ballard Generation Systems completed the construction and commenced in-house testing of a 10-kW natural-gas-fueled engineering prototype stationary fuel cell power generator. The 10-kW unit is being designed for backup, light industrial, and standby applications for telecom and other value-added applications, where Ballard sees a significant market potential for standby fuel-cell-powered products in this size range (Ballard, 2001c). Unfortunately, nothing has been made known about the design of the overall system and the type of reformer employed. BGS started rather late to show a serious interest in this kind of application but, with its PEMFC and reformer technology base, Ballard is certainly one of the most serious developers. Teledyne Energy Systems/Energy Partners

Teledyne Energy Systems (Hunt Valley, MD), a subsidiary of Teledyne Technology, Inc. (Los Angeles), merged in July 2001 with Energy Partners (Florida) (HyWeb, 2001b). Energy Partners has been developing fuel cell technology since 1990, with prototype systems ranging up to 10 kWel. Technology owned by Energy Partners includes stack technology based on molded graphite composite plates as well as self-humidifying fuel cells.

In September 2001, Teledyne Technology announced that Teledyne Energy Systems had completed operational tests of its prototype 3-kW natural-gas-fueled stationary fuel cell power system, comprising the necessary fuel processing, fuel cell, and control systems required for independent operation.

As eventual markets for commercial products, Teledyne named uninterruptible and backup power generating capabilities for telecommunications, premium residences, and remote premium power applications.

In the past, Energy Partners was also involved in the Genesis Zero Emission Transporter, an electric, zero-emission concept vehicle, and the Gator, a fuel-cell-powered utility vehicle completed in 1996. The Gator was powered by a hydrogen/air 10-kW PEM fuel cell and was developed in a collaborative effort by Energy Partners, Inc., and Deere & Company as a test platform.

Based in Belleville, NJ, H-Power Corp. was founded in 1989 with a focus on PEMFC technology for portable, automotive, and residential fuel cell applications. In 2001, H Power announced it was working with Energy Co-Opportunity (ECO) to market a residential fuel cell system in California. Altair Energy has been appointed as a non-exclusive distributor for the Southern California market (H Power, 2001). H Power has further facilities in Monroe, NC, for production and in Montreal. Nuvera Fuel Cells/Epyx (Arthur D. Little)/De Nora/ETek/RWE Plus

Nuvera (Cambridge, MA, and Milano, Italy) was formed in 2000 from Epyx, a subsidiary of Arthur D. Little specializing in fuel processor technology, and De Nora Fuel Cells, part of De Nora (Milano, Italy).

Previously, De Nora had already acquired ETek, a small volume supplier of PEM fuel cell components such as catalysts and electrodes.

Nuvera is collaborating with SET (Sustainable Energy Technologies, Ltd.) on the power conditioning for a fuel cell power system that will be targeted at the North American residential-scale market.

In Europe, Nuvera also formed a joint venture with utility RWE Plus AG (Essen, Germany) to develop and distribute fuel cell systems in Europe powered by natural gas or propane, ranging up to 50 kW. The announcement of this cooperation in May 2001 follows earlier RWE plans to carry out field trials with Vaillant/Plug Power, which now have been abandoned.

It is believed that Nuvera's residential technology is based on the Epyx reformer and De Nora's fuel cell. Commercial prototypes were expected for 2001, with field trials starting towards the middle of 2002 and commercial sales in 2004 (Nuvera, 2001). IdaTech/North West Power Systems

IdaTech Fuel Cells (Bend, OR; formerly North West Power Systems) is largely owned by IdaCorp. IdaTech has targeted fuel cell applications requiring less than 10 kW of electric power, in particular 3 kW methanol-powered residential fuel cell systems (see Fig. 8.18). In addition to methanol, the unique

FIGURE 8.18 IdaTech FCS 5000™ methanol-powered 5 kW residenial power system. (Courtesy of IdaTech, LLC.)

IdaTech fuel processor has demonstrated operation on a wide range of feedstocks including ethanol, methane, propane, kerosene, diesel, and biodiesel. The fuel processor combines three functions — steam reforming, heat generation, and hydrogen purification — into a single, compact device.

The alcohol version has a single supply for a premixed alcohol/water feedstock whereas the hydrocarbon version has two supplies, one for water and one for the hydrocarbon feedstock. Since the purification process is driven by a pressure gradient, the steam reforming reactions are conducted at elevated pressure — typically between 50 and 250 psig (approximately 3.5 and 18 bara). For liquid feedstocks, the electrical power required for pumping the feedstock into the fuel processor is <50 W. Gaseous feedstocks (natural gas and propane) require about 250 W of electrical power. If combustion air is provided by a dedicated blower, the parasitic power requirement is <200 W.

After the steam reforming process, the reformate enters a palladium membrane purification chamber. The hydrogen is further purified in a catalytic methanation bed and sent to the fuel cell (see Chapter 5). The diverted molecules, including CO and CO2, are sent back into the combustion chamber, where they fuel the steam reforming process.

For all fuels tested, IdaTech reports product hydrogen with less than 1 ppm CO and 5 ppm CO2 and essentially free of all trace impurities (see Table 8.5). Also, the hydrogen composition is unaffected by load changes of the reformer.

In 1999, IdaTech started a first series of field trials in Bend with Methanex, the world's leader in methanol production and sales, and Statoil, the Norwegian national oil and gas company and leading methanol producer in Europe. Under this project, a number of homes were supplied with grid-independent power from IdaTech's residential power units. Following these trials, Bonneville Power Administra-

TABLE 8.5 Composition by Analysis of the Product Hydrogen from IdaTech Fuel Processors Operating on Methanol and Methane


CO (ppm)

CO2 (ppm)

CH4 (ppm)

H2 (%/rate)





99.95/29-31 SLMa





99.97/40 SLM

a SLM: Standard liters per minute.

Note: Minimum detectable limits for all gases other than hydrogen are 1 ppm; H2 obtained by difference.

a SLM: Standard liters per minute.

Note: Minimum detectable limits for all gases other than hydrogen are 1 ppm; H2 obtained by difference.

FIGURE 8.19 General Motors' 5.3-kW residential power system. (Photograph courtesy of General Motors.)

tion (Portland, OR) ordered 110 systems for further field trials (DWV, 1999). IdaTech also delivered a 3-kW system to the leading French utility EdF in 2001.

PEMFC stacks from four different manufacturers have been operated on hydrogen produced by the IdaTech fuel processor. It is currently not clear, however, which stack technology Ida Tech is using in its residential systems.

It should also be noted that, so far, no load following has been attempted for IdaTech's reformer (IdaTech, 2002). The economics of palladium-membrane-based systems are not clear, neither is lifetime (see Chapter 5) so far. But, particularly for methanol operation, these systems have a number of very attractive features. General Motors

In September 2001, General Motors surprisingly presented a residential 5.3-kW power system based on its automotive technology. The system is shown in Fig. 8.19. GM is confident that the system could be in the marketplace in large numbers by 2005. Clearly, GM has more experience with reforming liquid hydrocarbons rather than natural gas. This may open up an opportunity for capturing part of the residential market in regions where only fuel oil is available. It is unlikely that GM wants to distribute the system itself, but cooperation with utilities or heating system developers has not yet been announced (as of January 2002) (General Motors, 2001). Other Developers of PEMFC Residential Systems

Although it is believed that the leading developers have been mentioned, the list of developers, especially PEMFC-based system developers, is long. It also includes DAIS-Analytic (formed by a merger between DAIS and Analytic Power, Boston; previously cooperating in Europe with HGC, Hamburg) and Avista Laboratories (Spokane, WA).

Dais has become known for proprietary low-cost hydrocarbon-based membrane materials (of limited lifetime). Avista is developing a unique, low-power-density, modular fuel cell plant with the option of replacing modules under load ("Hot Swap"). Nothing is known about the status of reformer technology or the cost of the low power density concept.

8.3.3 The SOFC for Domestic Heat and Power Generation

SOFC- and PEMFC-based systems are competing for the domestic CHP market, and it is currently not clear which of the two systems offers the greater benefits to the end user and can be manufactured by more cost-effective automated processes.

FIGURE 8.20 Sulzer Hexis' prototype of a high-temperature SOFC residential co-generation system delivering 1 kW of electric power. (Photograph courtesy of Sulzer Hexis.) Sulzer Hexis

Sulzer Hexis (Winterthur, Switzerland) is the leading developer of residential fuel cell systems based on planar SOFC technology (compare Section 8.1.3). Working with a range of mainly German utilities, the company has successfully carried out a series of field trials of its system operating on natural gas8 and rated at 1 kW electric power (and approximately 30% electric efficiency). The system is shown in Fig. 8.20.

Sulzer Hexis acknowledges having gained valuable insights from these trials regarding cyclic oxidation/ reduction of the fuel cell anode, alternative fuel processors (catalytic partial oxidation as opposed to steam reforming, which requires a supply of pure water) and general customer requirements (Batawi et al., 2001).

Meanwhile, Sulzer Hexis has started developing its commercial product with continuously increasing automation of the production process, leading to market entry in 2004. Automation steps include robotic screen printing with integrated weight control and, in the future, infrared-based layer quality control (Batawi et al., 2001). Global Thermoelectric

Global Thermoelectric Inc. (Calgary, Alberta, Canada), launched its fuel cell division in 1997. The SOFC program is based on the development and commercialization of planar SOFC technology acquired from Forschungszentrum Jülich (see Section 8.1.3).

In July 2000, Global forged a strategic alliance with Enbridge, Inc. (Toronto), Canada's largest natural gas distributor, and in May 2001 Global announced delivery of a prototype system for residential energy to Enbridge. The prototype is powered by natural gas and has an electric power rating of 2.3 kW. During the evaluation period, the use of heat will also be investigated.

Targeting the U.S. propane market, Global announced a strategic partnership with Suburban Propane L.P. (Whippany, NJ) for development and commercialization of propane-powered units to customers in remote locations (HyWeb, 2001c).

Field trials, also for emergency power supplies and small commercial use, are envisaged for 2002 (HyWeb, 2001d).

8 Alternative fuels such as diesel, heating oil, or gasified wood have also been tested. Fuel Cell Technologies

Fuel Cell Technologies, based in Kingston (Ontario, Canada), is developing 5- to 15-kW residential power systems. The company wants to produce demonstration units by the middle of 2002, working with Kinetrics (for power handling and integration) and Siemens-Westinghouse (tubular stack supply) (Fuel Cell Technologies, 2002).

The fact that Fuel Cell Technologies wants to base its domestic CHP systems on SWPC's tubular fuel cell technology is remarkable. When the original 1500-mm tubes are used, a 5-kW unit will require approximately 50 tubes. Apart from cost consequences (see the discussion in Section 8.1.3), 50 cells will only give a small overall voltage, making power conditioning rather complicated.

However, Fuel Cell Technologies' further collaboration with InDec (Fuel Cell Technologies, 2002) may indicate that tubular technology could be superseded by planar stacks at a later stage. Other Developers

Other SOFC developers include the planar fuel cell developers mentioned in Section 8.3.1. Most of these companies or institutes are still at the research and development stage or target primarily other applications, most notably auxiliary power units (APUs) for cars. These will be discussed in Section 9.2.3.

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