Small Stationary Power Units

Fuel cell-based power plants that have an output of up to 10 kW are under vigorous development as well, and they find ever wider practical uses. Table 24.3 shows the number of such plants produced every year from 2001 to 2010. Approximately half of the units produced in 2006 had a power of about 1 kW, and the other half had an output of 1.5-10 kW, the numbers being distributed evenly over this time interval. The overwhelming number (more than 50%) of these plants were produced and set up in Japan, with the United States taking the second place. Most of the low-power units were built with polymer electrolyte fuel cells. The fraction of solid oxide fuel cells has decreased gradually. 

The range of applications of small power plants is very large. They are designed primarily for the needs of communities for a combined supply of electric power and heat (hot water and heating) to individual structures of different sizes individual cottages, administrative and office buildings, hospitals. At present, the cost of these units, as a rule, is not competitive (it should be no higher than 1500/kW). Therefore, a part of the costs is supported by municipal or federal authorities. 

Another important area of application is the use of small power units as backup power in situations of sudden loss of grid power because of natural or technical problems. Such backup units are extremely important to those consumers who cannot tolerate power interruptions. This is the case for various stationary telecommunications installations (for instance, receivers, transmitters, relay stations, signal amplifiers). Ofher users who can use unifs of fhis fype are surgery wards in hospitals, computer units in traffic control, financial insfifufions, and emergency lighting systems in public 

TABLE 243. Annual Number of Small Fuel Cell Units Installed 

The Japanese company Ebara Ballard, a subsidiary of the well-known Canadian company Ballard, is the most important maker of PEMFCs. They developed a 1-kW power plant for combined heat and power production. It is remarkable that this unit is designed to be operated for a period of 10 years, in accord with requirements set by the Japanese government. A similar unit also designed for an operating time of 10 years was developed by the Japanese company Fuji Electric. TTiese units cost 12,000 to 16,000 (Adamson, 2006). 

Numerous examples of small fuel cell-based power units produced and used for domestic applications could be cited. Thus, the Vaillant Group, which has production facilities in a number of European countries, has developed a combined heat and power unit (CHP unit) designed for an electric power output of 4.6 kW and a heat output of 11 kW. Such units were installed in several countries (Germany, the Netherlands, Spain, Portugal). The European Commission has supported 30% of the full project costs, estimated at 8.6 billion [Kommu-nalwirtschaft, No. 2, p. 107 (2004)]. 

Other users who can use units of this type are the surgery wards in hospitals, the computer units in traffic control and financial institutions, and the systems of emergency lighting in public spaces. Uninterruptible power is needed here to prevent loss of lives, severe accidents, or loss of valuable data that sometimes may not be recoverable. 

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As stated earlier, fuel processing technology from large chemical installations has been successfully transferred to small compact fuel cell units to convert pipeline natural gas, the fuel of choice for small stationary power generators. The technology for converting natural gas is described later in this section. 

At present, apart from the United States, polymer electrolyte membrane fuel cells and power plants on their basis are developed in many other countries including China, France, Germany, South Korea, and the United Kingdom, and so on. The major part of the power plants delivered in 2006 (about 60%) was for power supply to portable equipment. The second place (about 26%) was taken by small stationary power plants for uninterruptible power supply. 

Today, most large fiiel-cell-based plants are produced and set up in the United States, following active government support. A similar tendency can be seen in South Korea. In Japan, where many large fuel cell-based power plants had been built and operated in earlier years, attention is focused, at present, on the development of small stationary power plants and on power units for electric vehicles. 

An integrated fuel processing system for different fuels for mobile and small-scale stationary power units up to a range of 5 kWe was developed by the IMM [44]. A complete fuel processor for 5 kW (Figure 23.5) was set up for use of isooctane as fuel. 

In previous sections it was shown that for technical and economic reasons the number of high-power stationary power units based on fuel cells is relatively limited tens for large units and hundreds (up to thousands) for smaller ones. At the same time, there are very large market demands (hundred of thousands) for low-power and small power units for portable devices. During future decades a considerable increase in market demand for medium-power units for electric vehicles and other mobile applications (e.g., mobile fuel cells) can be anticipated. 

PAFC systems are commercially available from the ONSI Corporation as 200-kW stationary power sources operating on natural gas. The stack cross sec tion is 1 m- (10.8 ft"). It is about 2.5 m (8.2 ft) tall and rated for a 40,000-h life. It is cooled with water/steam in a closed loop with secondary heat exchangers. The photograph of a unit is shown in Fig. 27-66. These systems are intended for on-site power and heat generation for hospitals, hotels, and small businesses. Another apphcation, however, is as dispersed 5- to 10-MW power plants in metropolitan areas. Such units would be located at elec tric utihty distribution centers, bypassing the high-voltage transmission system. The market entiy price of the system is 3000/kW. As production volumes increase, the price is projec ted to dechne to 1000 to 1500/kW. 

In Japan, being completely dependant on fossil fuels imports, a long tradition exists in developing stationary and mobile fuel cell applications. Programs funded by the NEDO and METI departments have already resulted in hundreds of small scale micro Combined Heat and Power Units as well as fuel cell vehicles running in road demonstrations [4]. 

Ballard, a company known for developing fuel cells for vehicles, also is developing small stationary fuel cell systems for backup power generation as well as CHP. The AirGen is the world s first portable backup power generator specifically designed for indoor use. The 1 kW unit can provide power for up to 15 h off of one compressed hydrogen... 

From the mid-1990s, there arose anew wave in fuel cell applications, that is, the automotive application and closely related applications of small stationary. It began with PEFC. Even so, SOFC has also received the impacts of new applications. This leads to two important efforts on SOFC developments (1) severer requirements for mechanical stability in automotive applications [22] and (2) smaller stationary application. The former has come from the new application proposed by BMW, Delphi, and Renault to utilize SOFC systems as auxiliary power unit in combustion engine cars. Since BMW and Delphi have cooperated with National Laboratories in their own countries, materials development has been made to improve mechanical instability. Development of simulation technique also helps to improve the stack technologies. The latter case of the small stationary systems gave rise to a big impact in Japan, Australia, Switzerland, and UK where the SOFC cogeneration systems have attracted strong attention. 

SOFC technology, on the other hand, offers interesting options to improve the effectiveness of CHP units. The reasons are many the prospects for high efficiency, low emissions, low noise, scalability, reliabihty, and, finally, potentially low cost. However, the main attractiveness in CHP is the high system efficiency even for small units and at part load operation [14]. Among the most interesting applications are stationary distributed power generation (incl. CHP), small residential combined heat and power units (micro CHP), various transport apphcations (auxiliary power units, APU), and medium-sized portable systems up to 5 kWei-... 

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