Thermoelectric modules (TEMs) are electronic devices that are transforming a heat flux into electricity (thus generating electrical power) or electricity into heat flux (thus cooling/heating). TEMs operate without having any moving parts and thus cannot worn out and do not need maintenance. A TEM air-conditioning system does not need a rotary compressor which exists in conventional air-conditioning systems. This also means that there is no environmentally hazardous refrigerant/gas involved in heating/cooling process. In the fast-growing market of Internet of Things (IoT), there is also a significant demand for small batteries; but some of those millions of sensors could be powered from heat sources (body, sun, element, etc..). A thermoelectric module (TEM) is composed of hundreds of pellets of p-type and n-type doped semiconductor materials, such as suitably doped bismuth telluride (Bi2Te3), that are connected electrically in series and thermally in parallel. Those electrically connected pellets are sandwiched between two heat conducting substrates, such that when an electrical current pass through the system, heat is pumped from one side to the other side.