Abstract:
A fuel cell system includes a housing partially above and below the ground containing a fuel cell beneath ground level and a fuel tank disposed above the fuel cell. The fuel cell may be accessed by raising it to above ground level with a fuel cell vertical displacement device.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     None. 
     BACKGROUND 
     Fuel cell systems convert hydrogen into electrical power while emitting only water and heat. Fuel cells based on proton exchange membranes (PEM) generally need to be humidified to conduct protons. Concurrent conduction of protons through the electrolyte and conduction of electrons through an external load is the working principle of fuel cells. 
     Because membranes in PEM fuel cells need to be humidified and because fuel cells produce water, water is always present in fuel cells. This causes problems for fuel cells operating or stored at temperatures below the freezing point of water (0° C.). A first problem is the possible freezing of water in cells, humidifiers and gas tubing, blocking the passage of gases upon start-up. A second problem is the possible damage to membranes, membrane electrode assemblies (MEA) and fuel cell humidifiers due to the formation of ice. A third problem is the suboptimal operation of fuel cell when waste heat from the fuel cell stack is insufficient to bring the latter to the optimal operating temperature. A fourth problem is the need to have fuel cell system components that are specified to operate at freezing temperatures. While strategies are currently being used to mitigate the effect of freezing temperatures on PEM fuel cells, those conditions still lead to suboptimal operation and damage to membranes. 
     High ambient temperatures can also be a problem when the cooling subsystem is unable to keep fuel cells below a temperature limit where membranes and components can operate without damage. Either a disproportionately costly and energy consuming cooling system has to be used or the fuel cell has to be shutdown above an ambient temperature limit. 
     Finally, the deployment of stationary fuel cell systems is generally limited by their high cost. While fuel cell themselves have a high cost due to membranes and catalysts, stationary fuel cell system installations also bring the cost of hydrogen storage, the cost of installing the fuel cell systems and storage on a secure base, usually comprising concrete pads and fencing, with the required civil engineering costs. 
     Some have proposed solutions to the problems described above. One current practice (as disclosed by U.S. Pat. No. 6,479,177 B1) to avoid the formation of ice after shutdown in freezing conditions by purging the fuel cell tubing and stack of water. Another solution is to provide insulation and to heat the fuel cell when it is stopped in freezing conditions (see U.S. Pat. Nos. 6,955,861 B2, 6,797,421 B2, and 6,696,192 B1 as well as Published U.S. Patent Application No. 20030087139. U.S. Pat. No. 6,905,791 B2 describes the injection of an anti-freeze compound below a certain temperature. However, these solutions have drawbacks, such as consumption of energy for heating instead of providing power to external loads. The fuel cell system also has to work in varying temperature conditions, which requires a more adaptable, and therefore more costly, thermal management system. Purging water from the system does not solve the issue of slow start-up in freezing conditions. Also, these procedures do not address the issue of cooling when operating in extremely warm conditions. 
     Thus, those of ordinary skill in the art will recognize that there is a need for an improved solution to the above problems. 
     SUMMARY 
     There is disclosed a fuel cell system including: a housing having an access opening or door; a fuel tank disposed within said housing at an upper portion thereof, said fuel tank containing a fuel; a fuel cell adapted to electrochemically produce water and electricity from the fuel and an oxidant, said fuel cell being adapted to rest on a support disposed at a bottom of a hole within which a lower portion of said housing rests; an oxidant line fluidly communicating between a source of oxidant and the fuel cell; a fuel line fluidly communicating between said fuel tank and said fuel cell; and a fuel cell vertical displacement device adapted to lower and raise the fuel cell between a lowered position where the fuel cell rests upon the support at the bottom of the hole within which the lower portion of said housing rests and a raised position where the fuel cell is accessible from outside said housing via said access opening or door. 
     There is also disclosed a method of installing the above fuel cell system. The method includes the following steps. A hole is excavated in the ground. At least lower portion of said housing is placed or formed in the hole. The fuel cell vertical displacement device is secured to said fuel cell and said housing. The fuel tank is placed within said upper portion of said housing. The fuel line is connected to said fuel tank and said fuel cell. The oxidant line is connected to said source of oxidant and said fuel cell. The fuel cell is lowered with said vertical displacement device to rest at a bottom of the hole without or without a support underneath. 
     There is also disclosed a method of maintaining the installed fuel cell system according to the above method of installation. The method includes the following the steps. The fuel line is disconnected into first and second portions, said first fuel line portion connected to said fuel tank and said second fuel line portion connected to said fuel cell. The oxidant line is disconnected into first and second portions, said first oxidant line portion being connectable to said source of oxidant and said second oxidant line portion being connected to said fuel cell. The fuel cell is raised with the fuel cell vertical displacement device to a position accessible through said door. Maintenance is performed upon the fuel cell. The fuel cell is lowered with the fuel cell vertical displacement device to the ground at the bottom of the hole. The fuel line portions are connected. The oxidant line portions are connected. 
     The above system and methods may include one or more of the following aspects.
         the fuel is hydrogen, said fuel tank is a compressed hydrogen tank, said oxidant is air, and said oxidant line fluidly communicates between said fuel cell and an atmosphere adjacent said housing.   the cell system further includes thermal insulation disposed above said fuel cell and/or between said fuel cell and said lower portion of said housing.   the fuel cell system further includes:
           a coolant reservoir in heat exchange with said fuel cell; and   said fuel line includes a heat exchanger extending through an interior of said reservoir, said fuel line heat exchanger being adapted to exchange heat between said fuel flowing therethrough and coolant contained within said reservoir.   
           the fuel cell system further includes:
           a coolant reservoir in heat exchange with said fuel cell; and   said oxidant line includes a heat exchanger extending through an interior of said reservoir, said oxidant line heat exchanger being adapted to exchange heat between said oxidant flowing therethrough and coolant contained within said reservoir.   
           the fuel cell system further includes:
           a coolant reservoir in heat exchange with said fuel cell;   said fuel line includes a heat exchanger extending through an interior of said reservoir, said fuel line heat exchanger being adapted to exchange heat between said fuel flowing therethrough and coolant contained within said reservoir; and   said oxidant line includes a heat exchanger extending through an interior of said reservoir, said oxidant line heat exchanger being adapted to exchange heat between said oxidant flowing therethrough and coolant contained within said reservoir.   
           the fuel cell is disposed at a height below a frost line of the ground adjacent the hole.   the method, wherein:
           said fuel cell system further comprises a reservoir in heat exchange with said fuel cell; and   said fuel line includes a heat exchanger extending through an interior of said reservoir, said fuel line heat exchanger being adapted to exchange heat between said fuel flowing therethrough and coolant contained within said reservoir.   
           the method, wherein:
           said fuel cell system further comprises a reservoir in heat exchange with said fuel cell; and   said oxidant line includes a heat exchanger extending through an interior of said reservoir, said oxidant line heat exchanger being adapted to exchange heat between said oxidant flowing therethrough and coolant contained within said reservoir.   
           the method, wherein:
           said fuel cell system further comprises a reservoir in heat exchange with said fuel cell;   said fuel line includes a heat exchanger extending through an interior of said reservoir, said fuel line heat exchanger being adapted to exchange heat between said fuel flowing therethrough and coolant contained within said reservoir; and   said oxidant line includes a heat exchanger extending through an interior of said reservoir, said oxidant line heat exchanger being adapted to exchange heat between said oxidant flowing therethrough and coolant contained within said reservoir.   
               

    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a further understanding of the nature and objects of the present invention, reference should be made to the following detailed description, taken in conjunction with the accompanying drawings, in which like elements are given the same or analogous reference numbers and wherein: 
         FIG. 1  is a cross-sectional schematic with (portions of the housing not shown) of an embodiment of the inventive system with the fuel cell stack in the lowered position 
         FIG. 2  is a cross-sectional schematic of the embodiment of  FIG. 1  with the fuel cell stack in the raised position. 
     
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     As best shown in  FIGS. 1-2 , an interior of the fuel cell system may be accessed by opening door  1 . Optionally, the door  1  may be removed from housing  77 . During operation, hydrogen from compressed hydrogen cylinder  25  flows through hydrogen conduit  22 , while air flows into air intake  9 . The portion of the housing  77  adjacent the air intake  9  may be louvered downwardly and the portion of the housing  77  adjacent exhaust line  5  may be louvered upwardly in order to separate the flow of air flowing into air intake  9  from the flow of excess air and hydrogen being exhausted from exhaust line  5 . Additionally or alternatively, each of the air intake  9  and exhaust line  5  may be disposed on different sides of the housing. 
     While the combination of air intake  9 , hydrogen conduit  22 , exhaust line  5 , cooling lines  98 , and cable  85  in practice separately extend from the fuel cell stack  45  and fuel cell auxiliary components  49 , for ease of illustrating a two-dimensional, elevation view schematic, they are illustrated as line  29 ′ above quick connections  33  and as line  29 ″ below connections  33 . Thus, in actuality air intake  9 , hydrogen conduit  22 , exhaust line  5 , cooling lines  98 , and cable  85  are separate from one another. 
     The hydrogen and air flow through hydrogen conduit  21  and air intake  9  through respective heat exchangers (not shown) disposed within coolant reservoir  46  and thenceforth to fuel cell stack  45 . In this manner, the temperatures of the hydrogen and air are moderated, thereby helping the fuel cell stack  45  to achieve a more optimal operating temperature. 
     The temperature moderation of the air and hydrogen flows is especially important when the air temperature above ground level  61  is below the freezing point of water. Under these conditions, the cold hydrogen and air (less than 0° C.) are heated by indirect heat exchange with the coolant contained within the interior of the reservoir  46  to help prevent freezing of moisture within the fuel cell stack  45 . Because the reservoir  46  is located underground, passive heat exchange between the ground  10  and the walls of the reservoir  46  via support  57  helps maintain a reservoir  46  interior temperature above the freezing point of water. Preferably, the reservoir  46  is disposed beneath the frost line  65 . 
     The compressed hydrogen cylinder  25  may be filled via line  21  at an access (not shown) through upper housing  77 . This access is preferably placed at a height not accessible by a person outside the housing  77  without the aid of a tool or support in order to deter tampering with the compressed hydrogen cylinder  25 . 
     The support  57  isolates the fuel cell stack  45  from contaminants and insects. While the support  57  may be made of any material, preferably it is made of a heat conducting material such as metal. However, cement may be used. 
     The fuel cell auxiliary components  49  includes the typical equipment associated with a fuel cell such as electronics, a battery, an external humidifier, and an air blower or compressor for pressurizing the air feed. 
     The upper housing  77  is preferably made of a rigid metal such as steel or aluminum and may be secured to a lower housing  73  (preferably of concrete) with bolts  81 . 
     Freezing of moisture within the fuel cell stack  45  is further prevented by isolating the fuel cell stack  45  and associated fuel cell auxiliary components  49  from the air and from the frozen ground  10  above the frost line  65 . This is accomplished with thermal insulating blocks  69  disposed above and around the fuel cell stack  45  and fuel cell auxiliary components  49 . The frost line  65  is the lowest depth at which soil freezes during the year. This depth depends on the location, soil characteristics and snow cover, and varies from a few centimeters in temperate climates to over a meter in many regions of Canada with cold winters. Provided that the thermal insulating blocks  69  provide insulation at least equal to the surrounding soil and given that the lower housing  73  will be in thermal contact with the non-frozen ground  10  below the frost line  65 , the fuel cell system will not be exposed to freezing. Additionally, each of the hydrogen conduit  21 , air intake  9 , exhaust line  9 , coolant line  98  and/or connections  33  may be thermally insulated. Furthermore, weather-stripping may be provided between adjacent surfaces of the thermal insulating blocks  69  and the upper housing  77 . 
     Excess air, unreacted hydrogen, and moisture resulting from reaction of the hydrogen and air are vented from the fuel cell stack  45  via an exhaust line  5 . In the case where moisture tends to condense in air and/or exhaust line  5 , a basin may be disposed beneath the fuel cell stack  45  to collect the liquid water. The liquid water is discharged into drain  20 . 
     When the temperature above ground level  61  is not below freezing such that freezing of moisture within the fuel cell stack  45  is not an issue, excess heat may become a concern. Even if the temperature above ground level  61  is below freezing, running the fuel cell stack  45  for a sufficiently long period of time may also result in excessive heat. In these cases, excess heat may be removed from the fuel cell stack  45  with a cooling circuit utilizing a temperature probe, thermostat, coolant line  98 , radiator  97 , and fan  96 . A temperature probe is typically placed within or adjacent to the fuel cell stack  45  or within the coolant fluid just as it exits the fuel cell stack  45 . When the temperature rises to a sufficiently high level, the thermostat opens up the cooling circuit such that the coolant fluid circulates through radiator  97  via coolant line  98 . The fan  96  helps achieve greater heat exchange between the coolant and ambient air at radiator  97 . Of course, the coolant reservoir  46  fluidly communicates with, and acts as a buffer vessel for, the cooling circuit. 
     Because the reservoir  46  is in heat exchange with the non-frozen ground  10  below the frost line  61  through support  57 , the temperature of the coolant fluid is moderated in comparison to the relatively frigid air above ground. So when excess heat is not a concern, the coolant from coolant reservoir  46  may still optionally be circulated through fuel cell stack  45 . This helps to avoid freezing of moisture within the fuel cell stack  45 . 
     As best illustrated in  FIG. 2 , easier access to the fuel cell stack  45 , coolant reservoir  46 , and fuel cell auxiliary components  49  may be achieved as follows. First, the upper portions of each of the air intake  9 , hydrogen conduit  21 , exhaust line  5 , and coolant line  98  (depicted as line  29 ′) are disconnected from the corresponding lower portions (depicted as line  29 ″) at connections  33 . One of ordinary skill in the art will recognize that several different types of connections  33  may be used in practice of the invention, such as quick disconnect or conventional valves. 
     Next, cable  13  is drawn across pulley  17  via access  14  through housing  77 . The ease of pulling cable  13  may be enhanced by providing a counterweight at an end thereof. Also, one of ordinary skill in the art will recognize that pulley  17  and brute force are not essential to practice of the invention. Rather, any one of a number of commercially available motorized drives may be used to raise and lower the stack  45 , reservoir  46 , and auxiliary components  49  via cable  13 . 
     Once a suitable height is gained, the cable  13  may be secured. The fuel cell stack  45  and auxiliary components  49  may then be accessed and rolled onto the ground via wheels  53 . After maintenance is performed, the fuel cell stack  45 , auxiliary components  49  and/or reservoir  46  are rolled back into position and cable  13  slowly released. In order to prevent unauthorized access to the interior of the housing, the door  1  may be locked. 
     The fuel cell stack  45  and fuel cell auxiliary components  49  are connected to a load via cable  85 . The load may be any device consuming electricity such as, for example, a light-producing device, an antenna, or other communication device. Additionally, the fuel cell stack  45  and fuel cell auxiliary components  49  may be connected to an electricity generating device, such as a windmill or solar panel, in order to supplement the electrical production during periods of high demand or low production. 
     One or ordinary skill in the art will recognize that the invention may be utilized with fuel cell systems consuming reactants other than hydrogen and air. Thus, in one embodiment the fuel cell stack  45  may consume oxygen instead of air. In this case, a compressed oxygen cylinder may be included in an upper portion of the fuel cell system within upper housing  77  above ground and be connected to air intake  9 . In another embodiment, the fuel cell stack  45  may consume a fuel other than hydrogen, in which case a suitable container for the non-hydrogen fuel may be used instead of compressed hydrogen cylinder  25 . The hydrogen conduits can otherwise be used for handling the non-hydrogen fuel. 
     The fuel cell system may be installed according to the following steps. First, a hole is excavated from the ground  10 , preferably to a depth below the frost line  65 . Concrete may be poured into a mold within the hole to form the lower housing  73 . Alternatively, a lower housing  73  made of pre-formed concrete may be placed within the hole. Preferably, the ground  10  is compacted before and/or after pouring the concrete or placing the base  73  in the hole. 
     Next, the upper housing  77  may be secured to the lower housing  73  with bolts  81  or any other fastening device. In one aspect of the invention, and in order to provide extra rigidity and stability, the outer circumference formed by the side walls of the upper housing  77  is smaller than that of the lower housing  73  and/or the thickness of the side walls of the upper housing  77  is also less than that of the lower housing  73 . However, it should be understood that the invention may be practiced with an upper housing  77  having an outer circumference larger than that of, or the same as, the lower housing. The pulley  17  is then secured to housing  77  and the cable  13  strung over it. The fuel cell stack  45  is secured to fuel cell auxiliary components  49  and reservoir  46 . One end of the cable  13  is then secured to either the housing  77  or some other rigid support and the other end secured to the fuel cell stack  45 /auxiliary components  49 /reservoir  46 . Thermal insulating blocks  69  are then placed along an interior wall of lower housing  73  and atop the stack  45 /auxiliary components  49 . The thus-secured stack  45 /auxiliary components  49 /reservoir  46  are then lowered in snug-fitting fashion within enclosing thermal insulating bocks  69  disposed along the interior wall of the base  73 . Finally, the upper portions of each of the air intake  9 , hydrogen conduit  21 , exhaust line  5 , coolant line  98  (depicted as line  29 ′) may be connected at connections  33  to the corresponding lower portions (depicted as line  29 ″) and the door  1  lowered and locked. 
     The present invention and/or various aspects of the present invention provide several advantages. First, exposure of freeze-sensitive fuel cell components may be inhibited or eliminated. Second, the fuel cell system may be protected from extremely warm conditions. Third, the footprint of a stationary fuel cell system and its fuel storage may be reduced. Fourth, the cost of installing a fuel cell system and its fuel storage (especially civil engineering costs) may be reduced and nearly eliminated. Fifth, the need for fencing requirements or other unauthorized access restriction may be eliminated when the housing  77  materials and construction are sufficiently resistant to tampering. This last advantage may be accomplished at a reasonable cost with a cylindrical aluminum or steel housing structure similar to those used for utilities such as highway lamp posts. 
     Preferred processes and apparatus for practicing the present invention have been described. It will be understood and readily apparent to the skilled artisan that many changes and modifications may be made to the above-described embodiments without departing from the spirit and the scope of the present invention. The foregoing is illustrative only and that other embodiments of the integrated processes and apparatus may be employed without departing from the true scope of the invention defined in the following claims.