Table 5.

Advantages and disadvantages of generators based on the passive mechanism.

Generator type	Pros	Cons
IR generators	•Production of high electric potential difference around room temperature [26,28] •Continuous and continuous power generation [28]	•Low energy conversion efficiency [28] •Lack of high efficiency in hot environments (temperature above 33 $°C$) [26,28] •Complex and expensive structure [28]
Electrokinetic	•Ability to produce high electric potential difference [30] •Flexibility [47]	•The need for a pressure difference along narrow carbon channels to produce an electric potential difference [48] •Dependence of the produced electric potential difference on the fluid movement speed in the cavities of the porous carbon structure [48]
Pyroelectric	•High relative energy conversion efficiency [36] •Long life and high durability [36] •Suitable for working in adverse weather [36]	•Dependence of potential difference and produced electric current on temperature fluctuation rate [15,33] •The need for a high-frequency temperature fluctuation rate [49]
Ionic thermoelectric	•Production of high electric potential difference [50] •High thermal resistance in the structure [50] •High flexibility [50]	•Transient output electric current [51] •High structural and electrical resistance [50] •Low thermoelectric properties in some ionic conductors used in the structure of these generators, such as electrolyte solutions and ionic liquids [50] •It is complicated and expensive to make these generators with ion gels [50]
Thermoelectric	•Continuous electric current generation [50] •Low electrical resistance [50] •Ability to integrate with other generators [5,13,52] •Scalability [4] •The simplicity of the structure [38] •High stability and durability [38] •Suitable for working in adverse weather [3]	•Decrease in temperature difference between hot and cold plates due to low thermal resistance [50] •The fragility of some conventional thermoelectric materials [36]