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tutorials:energy_harvesting [2026/02/23 16:40] – [References and Further Reading] ibchadmintutorials:energy_harvesting [2026/02/24 18:57] (current) – [Energy Harvesting] ibchadmin
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-====== Energy Harvesting ======+====== Energy Harvesting Overview ======
  
 By forgoing batteries, intermittent devices are required to get their energy from external energy harvesters.  Some of the most common options are listed below, as well as additional considerations that affect design decisions and performance. By forgoing batteries, intermittent devices are required to get their energy from external energy harvesters.  Some of the most common options are listed below, as well as additional considerations that affect design decisions and performance.
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 Since capacitors can hold only a fraction of the power a battery can, harvester behavior heavily dictates overall design considerations and the intended deployment can often place strict requirements on what harvesting methods are available.  However, some general challenges and considerations apply regardless of harvester type: Since capacitors can hold only a fraction of the power a battery can, harvester behavior heavily dictates overall design considerations and the intended deployment can often place strict requirements on what harvesting methods are available.  However, some general challenges and considerations apply regardless of harvester type:
  
-  * **Limited availability**: energy availability is frequently transient, and any intermittent design should be prepared to handle loss of power gracefully.+  * **Limited availability**: energy availability is frequently transient, and any intermittent design should be prepared to [[tutorials:checkpointing_overview|handle loss of power gracefully]].
   * **Overall efficiency**: most methods of harvesting have limits on the amount of energy they can practically harvest, even when it is otherwise plentiful.  This can be due to various factors, such as being optimized for certain frequencies or the size of the device itself limiting how large or complex a given harvester can feasibly be.  Even under optimal conditions, overall power generation can be low (down to the microwatt level for the smallest devices), heavily limiting device operation and making optimal use of what power is available critical.   * **Overall efficiency**: most methods of harvesting have limits on the amount of energy they can practically harvest, even when it is otherwise plentiful.  This can be due to various factors, such as being optimized for certain frequencies or the size of the device itself limiting how large or complex a given harvester can feasibly be.  Even under optimal conditions, overall power generation can be low (down to the microwatt level for the smallest devices), heavily limiting device operation and making optimal use of what power is available critical.
   * **Event tracking vs. available energy**: a device tracking irregular, unpredictable events may not have the necessary energy to detect them when they occur.  Devices should adapt an energy harvesting method that allows them to capture as many events as possible, or failing that try and ensure that a device has sufficient reserve power to detect an event even when available ambient energy is low.   * **Event tracking vs. available energy**: a device tracking irregular, unpredictable events may not have the necessary energy to detect them when they occur.  Devices should adapt an energy harvesting method that allows them to capture as many events as possible, or failing that try and ensure that a device has sufficient reserve power to detect an event even when available ambient energy is low.
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 While able to harvest energy from across the frequency spectrum, there are notable limitations.  First, energy density is low compared to solar/photovoltaic harvesting.  Second, an antenna’s physical design will determine the optimal frequency range it can harvest, losing efficiency the further a signal falls outside of the optimal band (and while multiple antennas can overcome this issue to an extent, this incurs an increase in device size and complexity which may be impractical).  Third, while it is possible for an antenna to pull double duty as for both communications and energy harvesting, this can have negative impacts on reception. While able to harvest energy from across the frequency spectrum, there are notable limitations.  First, energy density is low compared to solar/photovoltaic harvesting.  Second, an antenna’s physical design will determine the optimal frequency range it can harvest, losing efficiency the further a signal falls outside of the optimal band (and while multiple antennas can overcome this issue to an extent, this incurs an increase in device size and complexity which may be impractical).  Third, while it is possible for an antenna to pull double duty as for both communications and energy harvesting, this can have negative impacts on reception.
  
-Examples +**Examples** 
-WISP (https://sites.google.com/uw.edu/wisp-wiki/home?authuser=0) + 
-Moo (https://web.cs.umass.edu/publication/docs/2011/UM-CS-2011-020.pdf)+  * [[https://sites.google.com/uw.edu/wisp-wiki/|WISP]] 
 +  * [[https://web.cs.umass.edu/publication/docs/2011/UM-CS-2011-020.pdf|Moo]]
 ==== Power Transmission ==== ==== Power Transmission ====
  
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 A subset of photovoltaic/RF energy harvesting, a base station is used to transmit power (e.g. through targeted light/lasers at a solar panel or higher-power signal for RF devices) to batteryless devices in the vicinity: in a controlled environment this can minimize the inherent unpredictability of harvested power.  In practice, there is an upper bound to how much power can be supplied in this fashion outside of a research environment, as regulations usually limit light/laser intensity and radio transmission strength. A subset of photovoltaic/RF energy harvesting, a base station is used to transmit power (e.g. through targeted light/lasers at a solar panel or higher-power signal for RF devices) to batteryless devices in the vicinity: in a controlled environment this can minimize the inherent unpredictability of harvested power.  In practice, there is an upper bound to how much power can be supplied in this fashion outside of a research environment, as regulations usually limit light/laser intensity and radio transmission strength.
  
-Examples +**Examples** 
-Phaser (https://mobilex.cs.columbia.edu/phaser/)+ 
 +  * [[https://mobilex.cs.columbia.edu/phaser/|Phaser]]
 ==== Thermoelectric ==== ==== Thermoelectric ====
  
-Thermoelectric generators utilize the Seebeck effect: temperature differences in a conductive material will produce a potential difference (and therefore voltage) between the hot and cold areas of the material.  Doping can be further used to enhance the effect and efficiency of the material itself, and the lack of moving parts can make for a more durable energy harvesting method than some alternatives.+Thermoelectric generators utilize the [[https://en.wikipedia.org/wiki/Thermoelectric_effect|Seebeck effect]]: temperature differences in a conductive material will produce a potential difference (and therefore voltage) between the hot and cold areas of the material.  Doping can be further used to enhance the effect and efficiency of the material itself, and the lack of moving parts can make for a more durable energy harvesting method than some alternatives.
  
 Thermoelectric generators suffer from relatively low efficiency (and power generation) that is heavily environmentally dependent, as efficiency of the generator increases with the difference between the temperatures of the “hot” and “cold” areas (and vice versa).  Thermoelectrics are also dependent on some way to create or maintain a temperature differential, typically through a heat exchanger: often, the size of the heat exchanger dwarfs the thermoelectric portion itself, to the point that allowable exchanger size will dictate the thermoelectric rather than the other way around. Thermoelectric generators suffer from relatively low efficiency (and power generation) that is heavily environmentally dependent, as efficiency of the generator increases with the difference between the temperatures of the “hot” and “cold” areas (and vice versa).  Thermoelectrics are also dependent on some way to create or maintain a temperature differential, typically through a heat exchanger: often, the size of the heat exchanger dwarfs the thermoelectric portion itself, to the point that allowable exchanger size will dictate the thermoelectric rather than the other way around.
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 As a result, thermoelectric generators are most useful in situations that are both tolerant of low power and can reliably count on a temperature differential from the environment or their use case to improve efficiency (such as a wearable device powered by body heat). As a result, thermoelectric generators are most useful in situations that are both tolerant of low power and can reliably count on a temperature differential from the environment or their use case to improve efficiency (such as a wearable device powered by body heat).
  
-Examples +**Examples** 
-REPUBLIC (https://dl.acm.org/doi/10.1145/3384419.3430722)+ 
 +  * [[https://dl.acm.org/doi/10.1145/3384419.3430722|REPUBLIC]]
 ==== Kinetic ==== ==== Kinetic ====
  
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 Electromagnetic energy harvesters utilize the fact that changes in a magnetic field acting on a coil will produce current, and by extension power.  The exact design varies, but a common implementation is a free-moving magnet in a tube surrounded (or adjacent) to one or more sets of coils: movements or vibrations cause the magnet to move, which in turn produces changes in the magnetic fields on the coils that can be harvested for power.  Pendulum generators operate on similar principles, but instead produce magnetic fluctuations using magnets attached to a pendulum instead. Electromagnetic energy harvesters utilize the fact that changes in a magnetic field acting on a coil will produce current, and by extension power.  The exact design varies, but a common implementation is a free-moving magnet in a tube surrounded (or adjacent) to one or more sets of coils: movements or vibrations cause the magnet to move, which in turn produces changes in the magnetic fields on the coils that can be harvested for power.  Pendulum generators operate on similar principles, but instead produce magnetic fluctuations using magnets attached to a pendulum instead.
- 
-Examples 
  
 === Piezoelectric === === Piezoelectric ===
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 Similar to RF harvesters, piezoelectric generators have an optimal frequency at which they most optimally convert input force to energy, which should be taken into account when implementing a design. Similar to RF harvesters, piezoelectric generators have an optimal frequency at which they most optimally convert input force to energy, which should be taken into account when implementing a design.
  
-Examples +**Examples** 
-REPUBLIC (https://dl.acm.org/doi/10.1145/3384419.3430722)+ 
 +  * [[https://dl.acm.org/doi/10.1145/3384419.3430722|REPUBLIC]]
 ==== Microbial Fuel Cells ==== ==== Microbial Fuel Cells ====
  
-Microbial fuel cells are designed around the behaviors of exoelectrogenic bacteria, which release electrons as part of their own biological processes.  MFCs are designed to harvest the electrons released by these bacteria, converting it to power in the process.  The exact medium can vary depending on deployment, but soil-based batteries are the most “common” type of design.+Microbial fuel cells are designed around the behaviors of [[https://en.wikipedia.org/wiki/Exoelectrogen|exoelectrogenic bacteria]], which release electrons as part of their own biological processes.  MFCs are designed to harvest the electrons released by these bacteria, converting it to power in the process.  The exact medium can vary depending on deployment, but soil-based batteries are the most “common” type of design.
  
 While promising as a renewable, environmentally-friendly power source, there are several issues that have stymied deployment outside of a research environment.  Maintaining sufficient microbial activity is a major issue: without some way to replenish nutrients or bacteria, an MFC ultimately acts more as a battery than as an energy harvester.  Power output is also low (usually in the microwatts range) relative to harvester size, and soil MFCs are heavily affected by soil moisture, with power output dropping when soil is dry. While promising as a renewable, environmentally-friendly power source, there are several issues that have stymied deployment outside of a research environment.  Maintaining sufficient microbial activity is a major issue: without some way to replenish nutrients or bacteria, an MFC ultimately acts more as a battery than as an energy harvester.  Power output is also low (usually in the microwatts range) relative to harvester size, and soil MFCs are heavily affected by soil moisture, with power output dropping when soil is dry.
  
-Examples +**Examples** 
-Soil-Powered Computing (https://dl.acm.org/doi/10.1145/3631410) + 
-Real World Behavior+  * [[https://dl.acm.org/doi/10.1145/3631410|Soil-Powered Computing]] 
 ===== Making Harvested Energy Useful ===== ===== Making Harvested Energy Useful =====
  
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-[[https://www.sciencedirect.com/science/article/pii/S1364032115012629|Energy harvesting in wireless sensor networks: A comprehensive review]] +  * [[https://www.sciencedirect.com/science/article/pii/S1364032115012629|Energy harvesting in wireless sensor networks: A comprehensive review]] 
- +  * [[https://www.sciencedirect.com/science/article/pii/S0360544219302993|Efficiency in RF energy harvesting systems: A comprehensive review]] 
-[[https://www.sciencedirect.com/science/article/pii/S0360544219302993|Efficiency in RF energy harvesting systems: A comprehensive review]] +  * [[https://thermoelectrics.matsci.northwestern.edu/publications/pdf/TEEnergyHarvestingBookChapter.pdf|Thermoelectric Energy Harvesting]] 
- +  * [[https://www.sciencedirect.com/science/article/pii/S2211285524009479|Piezoelectric energy harvesting and ultra-low-power management circuits for medical devices]] 
-[[https://thermoelectrics.matsci.northwestern.edu/publications/pdf/TEEnergyHarvestingBookChapter.pdf|Thermoelectric Energy Harvesting]] +  * [[https://www.sciencedirect.com/science/article/pii/S2352431617300482|On the efficiency of piezoelectric energy harvesters]] 
- +  * [[https://dl.acm.org/doi/pdf/10.1145/3631410|Soil-Powered Computing: The Engineer's Guide to Practical Soil Microbial Fuel Cell Design]] 
-[[https://www.sciencedirect.com/science/article/pii/S2211285524009479|Piezoelectric energy harvesting and ultra-low-power management circuits for medical devices]] +  * [[https://patpannuto.com/pubs/marcano2021einkbiobattery.pdf|Soil Power? Can Microbial Fuel Cells Power Non-Trivial Sensors?]]
- +
-[[https://www.sciencedirect.com/science/article/pii/S2352431617300482|On the efficiency of piezoelectric energy harvesters]] +
- +
-[[https://dl.acm.org/doi/pdf/10.1145/3631410|Soil-Powered Computing: The Engineer's Guide to Practical Soil Microbial Fuel Cell Design]] +
- +
-[[https://patpannuto.com/pubs/marcano2021einkbiobattery.pdf|Soil Power? Can Microbial Fuel Cells Power Non-Trivial Sensors?]] +
  
tutorials/energy_harvesting.1771864829.txt.gz · Last modified: 2026/02/23 16:40 by ibchadmin
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