Patent Publication Number: US-2006019149-A1

Title: Soil battery

Description:
BACKGROUND  
      There is an increasing recognition of the usefulness of sensors to monitor the condition of property and the operation of appliances. Typically, power outlets or batteries are used to provide power for sensors. In some instances, where sunlight is available, solar power may be also utilized.  
      However, each of the above listed sources of power has limitations. For example, for some sensors, no direct pathway to sunlight is available. The wiring required to connect a sensor to a power outlet may be expensive to install. Batteries often discharge after a period of time and need to be replaced. This can present a difficulty when the sensor is not readily accessible. Even when the sensor is accessible, it is often difficult to detect when a battery is discharged. The necessary monitoring of the condition of the battery can be inconvenient and therefore neglected.  
      It is desirable, therefore, to explore other potential power sources for sensors.  
     SUMMARY OF THE INVENTION  
      In accordance with embodiments of the present invention, power for a device is generated by a soil battery. The soil battery includes anode material and cathode material placed in soil.  
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a simplified block diagram showing a monitoring system in communication with various sensors powered by soil batteries in accordance with embodiments of the present invention.  
       FIG. 2  is a simplified block diagram showing soil batteries used in various applications to supply power in accordance with embodiments of the present invention. 
    
    
     DESCRIPTION OF THE EMBODIMENT  
       FIG. 1  is a simplified block diagram showing a monitoring system  10  in wireless communication with a sensor  11 , a sensor  12 , a sensor  13  and a sensor  14 . For example, sensor  11  transmits wireless transmissions, via an antenna  16 , that are received by an antenna  20  of monitoring system  10 . Sensor  12  transmits wireless transmissions, via an antenna  17 , that are received by antenna  20  of monitoring system  10 . Sensor  13  transmits wireless transmissions, via an antenna  18 , that are received by antenna  20  of monitoring system  10 . Sensor  14  transmits wireless transmissions, via an antenna  19 , that are received by antenna  20  of monitoring system  10 .  
      Sensor  11  monitors the level of liquid remaining within a storage container  36 . Sensor  11  is powered by a soil battery that includes an anode  21  and a cathode  26  placed in soil  31 .  
      For example, anode  21  is a formed of zinc metal or some other material that functions as an anode. For example, cathode  26  is formed from copper or some other material that functions as a cathode. Electrolytes within soil  31  cause soil  31  to act as an electrical chemical system. Clay minerals function as anions. Plant nutrients such as magnesium, sodium, potassium, etc., function as cations. The chemical reactions at anode  21  and cathode  26  cause a small current to travel from anode  21  through cathode  26 . Sensor  11  uses the resulting energy to perform low power monitoring and communication functions. Although the available minerals and nutrients near anode and cathode will tend to deplete, replacement electrolytes tend to diffuse in to replace the used minerals and nutrients. The soil battery tends to be most efficient in soils damp enough to allow efficient migration of electrolytes. The distance between anode  21  and cathode  26  is chosen to maximize current generation efficiency. This distance is typically around one to two feet, depending upon the soil. When anode  21  and/or cathode  26  corrode, they can be replaced. Soil amendments can be used to optimize properties of the soil.  
      Sensor  12  uses a moisture detector  37  to monitor integrity of a joint  37  within a pipe  42 . For example, pipe  42  is a water pipe used in a home or business. Sensor  12  is powered by a soil battery that includes an anode  22  and a cathode  27  placed in soil  32 .  
      For example, anode  22  is a formed of zinc metal or some other material that functions as an anode. For example, cathode  27  is formed from copper or some other material that functions as a cathode. Electrolytes within soil  32  cause soil  32  to act as an electrical chemical system. Clay minerals function as anions. Plant nutrients such as magnesium, sodium, potassium, etc., function as cations. The chemical reactions at anode  22  and cathode  27  cause a small current to travel from anode  22  through cathode  27 . Sensor  12  uses the resulting energy to perform low power monitoring and communication functions. Although the available minerals and nutrients near anode and cathode will tend to deplete, replacement electrolytes tend to diffuse in to replace the used minerals and nutrients. The soil battery tends to be most efficient in soils damp enough to allow efficient migration of electrolytes. The distance between anode  22  and cathode  27  is chosen to maximize current generation efficiency. This distance is typically around one to two feet, depending upon the soil. When anode  22  and/or cathode  27  corrode, they can be replaced.  
      Sensor  13  uses a moisture detector  38  to monitor moisture within soil  33 . Sensor  13  is powered by a soil battery that includes an anode  23  and a cathode  28  placed in soil  33 .  
      For example, anode  23  is a formed of zinc metal or some other material that functions as an anode. For example, cathode  28  is formed from copper or some other material that functions as a cathode. Electrolytes within soil  33  cause soil  33  to act as an electrical chemical system. Clay minerals function as anions. Plant nutrients such as magnesium, sodium, potassium, etc., function as cations. The chemical reactions at anode  23  and cathode  28  cause a small current to travel from anode  23  through cathode  28 . Sensor  13  uses the resulting energy to perform low power monitoring and communication functions. Although the available minerals and nutrients near anode and cathode will tend to deplete, replacement electrolytes tend to diffuse in to replace the used minerals and nutrients. The soil battery tends to be most efficient in soils damp enough to allow efficient migration of electrolytes. The distance between anode  23  and cathode  28  is chosen to maximize current generation efficiency. This distance is typically around one to two feet, depending upon the soil. When anode  23  and/or cathode  28  corrode, they can be replaced.  
      Sensor  14  uses a thermometer  39  to monitor temperature of soil  34 . Sensor  14  is powered by a soil battery that includes an anode  24  and a cathode  29  placed in soil  34 .  
      For example, anode  24  is a formed of zinc metal or some other material that functions as an anode. For example, cathode  29  is formed from copper or some other material that functions as a cathode. Electrolytes within soil  34  cause soil  34  to act as an electrical chemical system. Clay minerals function as anions. Plant nutrients such as magnesium, sodium, potassium, etc., function as cations. The chemical reactions at anode  24  and cathode  29  cause a small current to travel from anode  24  through cathode  29 . Sensor  14  uses the resulting energy to perform low power monitoring and communication functions. Although the available minerals and nutrients near anode and cathode will tend to deplete, replacement electrolytes tend to diffuse in to replace the used minerals and nutrients. The soil battery tends to be most efficient in soils damp enough to allow efficient migration of electrolytes. The distance between anode  24  and cathode  29  is chosen to maximize current generation efficiency. This distance is typically around one to two feet, depending upon the soil. When anode  24  and/or cathode  29  corrode, they can be replaced.  
      In addition to powering sensors, soil batteries can be used with any device that does not require greater power or current than can be supplied by a soil battery.  
      For example,  FIG. 2  shows a controller  51  that is powered by a soil battery implemented by placing an anode  61  and a cathode  71  into soil  81 . Controller  51  controls an actuator  53 . Actuator  53  is powered by a soil battery implemented by placing an anode  63  and a cathode  73  into soil  83 . For example, communication between controller  51  and actuator  53  is performed by a wire link, a wireless link or an optical link.  
      Controller  51  communicates with a repeater  52 . Repeater  52  is powered by a soil battery implemented by placing an anode  62  and a cathode  72  into soil  82 . For example, communication between controller  51  and repeater  52  is performed by a wire link, a wireless link or an optical link.  
      Repeater  52  communicates with a router  54 . Router  54  is powered by a soil battery implemented by placing an anode  64  and a cathode  74  into soil  84 . For example, communication between repeater  52  and router  54  is performed by a wire link, a wireless link or an optical link.  
      Repeater  52  communicates with a computer  55 . Computer  55  is powered by a soil battery implemented by placing an anode  65  and a cathode  75  into soil  85 . For example, communication between repeater  52  and computer  55  is performed by a wire link, a wireless link or an optical link.  
      Computer  55  controls a remote display  56 . Remote display  56  is powered by a soil battery implemented by placing an anode  66  and a cathode  76  into soil  86 . For example, communication between remote display  56  and computer  55  is performed by a wire link, a wireless link or an optical link.  
      The foregoing discussion discloses and describes merely exemplary methods and embodiments of the present invention. As will be understood by those familiar with the art, the invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. Accordingly, the disclosure of the present invention is intended to be illustrative, but not limiting, of the scope of the invention, which is set forth in the following claims.