Thermoelectric generators, also known as TEGs, are devices that convert heat energy into electric energy. These generators accomplish this task by using arrays of specialised circuits known as thermoelectric modules, each of which consists of semiconductor materials -- known as p-type and n-type -- sandwiched between insulating ceramic substrates. While thermoelectric generators have several benefits, they also have their downsides.
Exploiting Unclaimed Resources
One of the greatest advantages of thermoelectric generators lies in the fact that they can derive their power from heat that would otherwise just dissipate into its surroundings. Unlike the case with a standard gasoline or diesel generator, purchasing fuel for a thermoelectric generator is unnecessary, as the generator can "steal" its fuel from any device or machine that creates and releases substantial amounts of heat. These devices can include ovens, burners and furnaces, as well as machines -- such as automobiles -- that produce heat as a by-product of creating power for other functions, such as propulsion. According to the University of the Pacific, "Thermoelectric generators help tap an unclaimed resource [heat] now considered waste."
The thermoelectric modules that make up thermoelectric generators have solid-state constructions, which make the generators highly durable. "Solid-state" refers to the fact that the modules consist entirely of solid, fixed materials and do not rely on gases or vacuums. In contrast, other modules use tube construction, wherein they pass electrical currents through glass tubes filled with gasses or containing vacuums. Unlike tube modules, solid-state thermoelectric modules are robust and are not prone to cracking or shattering -- even when faced with turbulent conditions. As the University of the Pacific notes, thermoelectric generators' durability makes them "ideal for tasks in harsh environments such as automobiles, incinerators and spacecraft."
One of the main disadvantages of thermoelectric generators, which as of 2011 has prevented their adoption on a wider scale, lies in their cost. According to the University of the Pacific, a single thermoelectric module capable of producing 14 watts of electrical power costs approximately £65.
The University of the Pacific notes that most thermoelectric generators have an average efficiency of 4 per cent, which means the generators cannot pass on 96 per cent of the energy they obtain from heat sources. According to Tufts University, a thermoelectric generator will only operate efficiently when supplying electrical current to a device that has a similar electrical resistance. For example, a 100-watt thermoelectric generator could theoretically power a 100-watt light bulb efficiently but would ultimately waste energy if attempting to power a 30-watt bulb.