Abstract:
An electrically isolated fuel cell powered server is disclosed. The present invention discloses: a server; an electrical module located within the server; a fuel cell, located within the server, for generating electrical power; and an electrical bus, located within the server, coupling the electrical power generated by the fuel cell to the electrical module. The method of the present invention discloses: generating electrical power for a server with a fuel cell located in the server; transmitting the electrical power from the fuel cell over an electrical bus, located in the server, to an electrical module, also located in the server; and adjusting the electrical power generated by the fuel cell in response to electrical power consumed by the electrical module.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates generally to systems and methods for powering servers, and more particularly to an electrically isolated fuel cell powered server.  
           [0003]    2. Discussion of Background Art  
           [0004]    Modern service and utility based computing is increasingly driving enterprises toward consolidating large numbers of electrical servers, such as blade servers, and their supporting devices into massive data centers. A data center is generally defined as a room, or in some cases, an entire building or buildings, that houses numerous printed circuit (PC) board electronic systems arranged in a number of racks. Such centers, of perhaps fifty-thousand nodes or more, require that such servers be efficiently networked, powered, and cooled.  
           [0005]    Typically such equipment is physically located within a large number of racks. Multiple racks are arranged into a row. The standard rack may be defined according to dimensions set by the Electronics Industry Association (EIA) for an enclosure: 78 in. (2 meters) wide, 24 in. (0.61 meter) wide and 30 in. (0.76 meter) deep.  
           [0006]    Standard racks can be configured to house a number of PC boards, ranging from about forty (40) boards, with future configuration of racks being designed to accommodate up to eighty (80) boards. Within these racks are also network cables and power cables. FIGS. 1A through 1D each show an example of what such equipment racks can look like. FIG. 1A is a pictorial diagram of electrical cabling within a first equipment rack. FIG. 1B is a pictorial diagram of electrical cabling within a second equipment rack. FIG. 1C is a pictorial diagram of electrical cabling within a third equipment rack. And, FIG. 1D is a pictorial diagram of electrical cabling within a fourth equipment rack.  
           [0007]    The PC boards typically include a number of components, e.g., processors, micro-controllers, high-speed video cards, memories, and semi-conductor devices, that dissipate relatively significant amounts of heat during the operation. For example, a typical PC board with multiple microprocessors may dissipate as much as 250 W of power. Consequently, a rack containing 40 PC boards of this type may dissipate approximately 10 KW of power.  
           [0008]    Generally, the power used to remove heat generated by the components on each PC board is equal to about 10 percent of the power used for their operation. However, the power required to remove the heat dissipated by the same components configured into a multiple racks in a data center is generally greater and can be equal to about 50 percent of the power used for their operation. The difference in required power for dissipating the various heat loads between racks and data centers can be attributed to the additional thermodynamic work needed in the data center to cool the air. For example, racks typically use fans to move cooling air across the heat dissipating components for cooling. Data centers in turn often implement reverse power cycles to cool heated return air from the racks. This additional work associated with moving the cooling air through the data center and cooling equipment, consumes large amounts of energy and makes cooling large data centers difficult.  
           [0009]    In practice, conventional data centers are cooled using one or more Computer Room Air Conditioning units, or CRACs. The typical compressor unit in the CRAC is powered using a minimum of about thirty (30) percent of the power required to sufficiently cool the data centers. The other components, e.g., condensers, air movers (fans), etc., typically require an additional twenty (20) percent of the required cooling capacity.  
           [0010]    As an example, a high density data center with 100 racks, each rack having a maximum power dissipation of 10 KW, generally requires 1 MW of cooling capacity. Consequently, air conditioning units having the capacity to remove 1 MW of heat generally require a minimum of 300 KW to drive the input compressor power and additional power to drive the air moving devices (e.g., fans and blowers).  
           [0011]    Quite clear from these Figures, technicians, who install and service these cable intensive racks, are presented with a substantial amount of work each time such electrical servers are installed, removed, or serviced. With such wiring complexity, not only do such tasks require a significant amount of time, to wade through all of the wires and cables, but there is also a substantial chance that errors will be made during reinstallation, especially if more than one server unit is serviced at a time. Such excessive cabling also impedes equipment inspection and substantially impedes the flow of cooling air within the equipment rack, leading to device hot-spots and thus premature equipment failure.  
           [0012]    Another problem with conventional systems is that each equipment rack&#39;s power needs can vary substantially, depending upon: how many servers or other devices are located in the rack; whether such devices are in a standby mode or are being fully utilized; and the variations in rack cabling losses. While central high-voltage/current power sources located elsewhere in the data center can provide the necessary power, the aforementioned power consumptions variations often result in greater overall data center transmission line losses, and more power-line transients and spikes, especially as various rack equipment goes on-line and off-line. Due to such concerns, power-line conditioning and switching equipment is typically added to each rack, resulting in even greater losses and heat generation.  
           [0013]    Reliance on central power systems also subjects the racks to data center wide power failure conditions, which can result in disruptions in service and loss of data. While some equipment racks may have a battery backup, such batteries are designed to preserve data and permit graceful server shutdown upon experiencing a power loss. The batteries are not designed or sized for permitting equipment within the rack to continue operating at full power though.  
           [0014]    Each equipment rack&#39;s cooling needs can also vary substantially depending upon how many servers or other devices are located in the rack, and whether such devices are in a standby mode, or being fully utilized. Central air conditioning units located elsewhere in the data center provide the necessary cooling air, however, due to the physical processes of ducting the cooling air throughout the data center, a significant amount of energy is wasted just transmitting the cooling air from the central location to the equipment in the racks. Cabling and wires internal to the rack and under the data center floors blocks much of the cooling air, resulting in various hot-spots that can lead to premature equipment failure.  
           [0015]    One way of reducing energy wasted by ducting cooling air from a central source to equipment within the racks is to directly cool various rack components using liquid cooling. Such systems include surrounding equipment with liquid cooled “cold-plates.” Such cold-plates may alternatively be mounted inside the equipment proximate to specific heat generating components. However, while such liquid cooling systems provide greater control and targeting of coolant to where it is needed most, such liquid systems also create a safety and reliability problem when interspersed with a rack&#39;s electrical cabling. Accidental spills, condensation, and/or leaky connections can easily damage or short-out various electrical equipment within the rack, resulting not only in degradation of the data center&#39;s level of service, but also a potentially very expensive repair bill.  
           [0016]    In response to the concerns discussed above, what is needed is a system and method for powering servers that overcomes the problems of the prior art.  
         SUMMARY OF THE INVENTION  
         [0017]    The present invention is an electrically isolated fuel cell powered server. The present invention includes: a server; an electrical module located within the server; a fuel cell, located within the server, for generating electrical power; and an electrical bus, located within the server, coupling the electrical power generated by the fuel cell to the electrical module.  
           [0018]    The method of the present invention includes: generating electrical power for a server with a fuel cell located in the server; transmitting the electrical power from the fuel cell over an electrical bus, located in the server, to an electrical module, also located in the server; and adjusting the electrical power generated by the fuel cell in response to electrical power consumed by the electrical module.  
           [0019]    These and other aspects of the invention will be recognized by those skilled in the art upon review of the detailed description, drawings, and claims set forth below.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]    [0020]FIG. 1A is a pictorial diagram of electrical cabling within a first equipment rack;  
         [0021]    [0021]FIG. 1B is a pictorial diagram of electrical cabling within a second equipment rack;  
         [0022]    [0022]FIG. 1C is a pictorial diagram of electrical cabling within a third equipment rack;  
         [0023]    [0023]FIG. 1D is a pictorial diagram of electrical cabling within a fourth equipment rack;  
         [0024]    [0024]FIG. 2 is a block diagram of one embodiment of an electrically isolated fuel cell powered server; and  
         [0025]    [0025]FIG. 3 is a flowchart of one embodiment of a method for controlling an electrically isolated fuel cell powered server.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0026]    The present invention in one embodiment uses fuel cell technology to reduce or eliminate reliance on a central power source by instantiating a fuel cell within a sealed server. The present invention significantly reduces or eliminates intra-rack power cabling, thereby permitting the rack to be more efficiently cooled, more easily serviced, and avoiding the problem of mixing rack fluids with rack electrical cabling. Fuel cell liquids, such as methanol, can also be used to help cool the server directly. All of these capabilities make the present invention particularly advantageous over the prior art.  
         [0027]    [0027]FIG. 2 is a block diagram of one embodiment  200  of an electrically isolated fuel cell powered device  202 . FIG. 3 is a flowchart of one embodiment of a method  300  for controlling the electrically isolated fuel cell powered device  202 . The device  202  and method  300  are herein described together in just one of many possible embodiments.  
         [0028]    The fuel cell device  202  refers generally to any type of electrical device. More specifically, and preferably, the fuel cell device  202  is a fuel cell server. The fuel cell device/server  202 , in the one embodiment discussed herein, is presumed to be located within an equipment rack (not shown) which itself is located within a data center (also not shown) of a predetermined size. The data center includes a variety of centralized resources, and stores. Those skilled in the art however will know that the fuel cell device/server  202  could alternatively be located in a variety of other environments. The fuel cell device/server  202  is also preferably a sealed unit which is electrically isolated from other external equipment.  
         [0029]    The fuel cell device/server  202  in the one embodiment of the present invention, shown in FIG. 2, includes a fuel cell  204 , a memory module  206 , a processor module  208 , a communications module  210 , an internal fuel cell manager  212 , and a thermally conductive external surface  214  (shown with diagonal lines). Those skilled in the art will recognize that the number of modules and other internal components in the fuel cell device  202  may be varied depending upon how the present invention is implemented.  
         [0030]    The fuel cell  204  is preferably a Direct Methanol Fuel Cell (DMFC), although those skilled in the art recognize which other fuel cells may work as well. The fuel cell  204  includes a hydrogen circuit and an oxidizer circuit separated by a semi-permeable catalytic membrane. It is the interaction between the hydrogen and the oxidizer across the membrane which produces current flow and thus electrical power from the fuel cell  204 . On the hydrogen circuit side of the membrane, a mixture of methanol and water enter into the fuel cell  204 , while a mixture of methanol, water, and carbon dioxide exit. On the oxidizer circuit side of the membrane, an oxidizer, such as oxygen enters the fuel cell  204 , while a mixture of oxygen, water, and nitrogen exit. The gasses exiting the oxidizer circuit are typically vented to the air, while the water is mixed back in with the water and methanol exiting the hydrogen circuit side of the membrane. Thus the fuel cell  204  typically requires at least two fluid ports, an input port for receiving the incoming methanol/water mixture and an output port for exhausting the outgoing methanol, carbon dioxide, and water mixture. During normal operation, the incoming fluid mixture is preferably very cold so that the methanol can be used to cool equipment within the rack  202 . However, an added benefit of cold methanol is that the methanol&#39;s volatility is reduced.  
         [0031]    The fuel cell  204  itself generates heat during its operation, and thus is preferably ensconced by the thermally conductive external surface  214 , permitting said heat to be conducted to a cold plate or other cooling device. The memory module  206  and processor module  208  support internal device/server operations.  
         [0032]    An electrical bus  216  internally routes electrical power generated by the fuel cell  204  to the other modules  206 ,  208  and  210  as well as to the internal fuel cell manager  212 . A battery  217  is preferably connected between the fuel cell  204  and the electrical bus  216 . The battery  217  helps provide a steady regulated voltage on the electrical bus  216  since the fuel cell&#39;s  204  output voltage is not easy to regulate. The internal fuel cell manager  212  preferably monitors the battery&#39;s  217  voltage as well as the battery&#39;s  217  charge rate from the fuel cell  204  and discharge rate from the electrical bus  216 .  
         [0033]    The communications module  210  is connected to a communications bus  218  routes data between the fuel cell device/server  202  and any external device, such as an external equipment rack fuel cell manager (not shown). Preferably the communications bus  218  is a fiber optic cable, so as to keep the fuel cell device/server  202  electrically isolated, and thus not be as affected by any fluid leaks external to the fuel cell device/server  202 . However, the communications bus  220  could also be of another type.  
         [0034]    A fluids bus  220 , external to the fuel cell device  202 , routes incoming and outgoing fluids to the fuel cell  204  from the data center&#39;s centralized fluid stores and repositories. Since the fuel cell  204  as discussed herein preferably is a methanol based fuel cell, the fluids bus  220  routes fluids to an methanol inlet conduit  224  and a methanol outlet conduit  226 . The inlet conduit  224  and the output conduit  226  are preferably coupled to the fluid bus  220  using leak-resistant no-drip connectors.  
         [0035]    A valve (not shown), which is external to the fuel cell device/server  202 , controls the flow of methanol through the inlet conduit  224 , in response to commands from the rack fuel cell manager. The valve has a range of adjustments from fully-open to fully-closed.  
         [0036]    Since, the fuel cell  204  needs methanol in order to produce electricity, the more methanol available to the fuel cell  204 , the more electricity the fuel cell  204  can produce, whereas, the less methanol made available to the fuel cell  204 , the less electricity the fuel cell  204  can produce. By varying the amount of methanol supplied to the fuel cell  204  input port, the valve controls how much electricity the fuel cell  204  can produce, and functions similar to a conventional electrical power switch. Unlike electrical power switches, however, the valve does not consume electrical power and generate significant heat. Those skilled in the art will recognize that other embodiments of the present invention may use different fuel cell technology, which require a different, but functionally equivalent, fluid bus  220 .  
         [0037]    The internal fuel cell manager  212  is preferably a computer operated device which monitors and manages the fuel cell  204  and the fluid stream supplied via the fluid bus  220 , according to the method  300  of FIG. 3. When the fuel cell  204  is first turned on, the internal fuel cell manager  212 , in step  302 , activates electrical heaters, powered by the internal battery, to warm the cold methanol entering the fuel cell  204  input port. Pre-heating the incoming methanol permits the fuel cell  204  to reach its normal operating efficiency level more quickly. Since the fuel cells themselves also generate heat during operation, such heat can be used to continue pre-heating the incoming methanol, so that the electrical heaters may be turned off.  
         [0038]    In step  304 , the internal fuel cell manager  212  determines the fuel cell device/server&#39;s  202  current configuration. The fuel cell device/server&#39;s  202  configuration refers to a number of power consuming modules and other components within the fuel cell device  202  and their individual power needs. The internal fuel cell manager  212  also calculates its own power consumption needs. In step  306 , the internal fuel cell manager  212  transmits the device/server&#39;s  202  configuration to the external rack fuel cell manager (not shown) in the equipment rack which controls fluid bus  220  flow throughout the rack. In step  308 , the external equipment rack fuel cell manager anticipates the device/server&#39;s  202  power needs and adjusts the valve accordingly, using the current configuration information.  
         [0039]    In step  310 , the internal fuel cell manager  212  monitors and records the fuel cell&#39;s  204  current power production. In step  312 , the internal fuel cell manager  212  monitors and records the electrical bus  216  voltage and the power consumed by the modules  206 ,  208 ,  210  and other devices within the fuel cell device/server  202 . If the electrical bus  216  voltage drops below a predetermined voltage a predetermined number of times over a predetermined time period, the internal fuel cell manager  212 , in step  314 , transmits a message over the communication bus  218  to the external equipment rack fuel cell manager, requesting that the rack fuel cell manager command the valve (not shown) to further open, thus permitting more methanol to flow to the fuel cell  204 . Similarly, if the electrical bus  216  voltage rises above a predetermined voltage a predetermined number of times over a predetermined time period, the internal fuel cell manager  212 , in step  316 , transmits a message, over the communication bus  218  to the external equipment rack fuel cell manager, requesting that the rack fuel cell manager command the valve (not shown) to further close, thus restricting methanol flow to the fuel cell  204 . Preferably the electrical bus  216  voltage is monitored at or near the battery  217  connected between the fuel cell  204  and the electrical bus  216 . The battery is needed since the fuel cell&#39;s  204  output voltage is not easy to directly regulate.  
         [0040]    In step  318 , device/server  202  power consumption is analyzed by the internal fuel cell manager  212  to determine if there are any relatively predictable power consumption patterns. In step  320 , the internal fuel cell manager  212  transmits a message, over the communication bus  218  to the external equipment rack fuel cell manager, requesting that the rack fuel cell manager command the valve to a new open/closed position in anticipation of the predicted power consumption pattern. Power consumption anticipation is preferred since fuel cells do not instantaneously vary their power output with changes in methanol flow.  
         [0041]    If the fuel cell&#39;s  204  temperature rises above a predetermined thermal limit a predetermined number of times over a predetermined time period, the internal fuel cell manager  212 , in step  322 , transmits a message over the communication bus  218  to the external equipment rack fuel cell manager, requesting that the rack fuel cell manager command the valve to further close, or close completely, thus cooling the fuel cell  204 .  
         [0042]    While, as mentioned above, any type of fuel cell can power the fuel cell device/server  202 , methanol fuel cells present certain further opportunities to cool the fuel cell device/server  202  as well. Methanol tends to be very volatile at room temperature, and can easily ignite or evaporate. Cooling the methanol, pumped to the fuel cell device  202 , significantly reduces such volatility. However, methanol fuel cells also operate most efficiently when their incoming methanol stream is warmed/heated to a predetermined temperature. Such preferred engineering guides present an opportunity to both cool the fuel cell device  202  and pre-heat the methanol for the fuel cell  204  simultaneously. Thus in step  324 , methanol transmitted on the fluid bus  220  is cooled to a predetermined temperature. Either as the methanol passes through the fluid bus  220 , or is routed somewhere internal to the fuel cell device/server  202  itself, the cold methanol is pre-heated using waste heat, in step  326 . Any pre-heating of the methanol preferably occurs after the methanol is used for cooling so that ability of the methanol to cool the rack equipment is maximized. Thus, within the present invention, power production and cooling are symbiotically combined, thereby further simplifying the rack&#39;s construction and ease of maintenance and operation.  
         [0043]    While one or more embodiments of the present invention have been described, those skilled in the art will recognize that various modifications may be made. Variations upon and modifications to these embodiments are provided by the present invention, which is limited only by the following claims.