NOVELTY - A method for providing electric power in a well comprises applying a temperature gradient of the well across at least a pair of thermocouples of one or more thermoelectric devices (100) having an electric power output terminal.    USE - For generating electrical power for recharging battery packs used to power downhole electrical systems, system electronics, and other downhole devices or tools, or to power the same systems in its own right.    ADVANTAGE - Use of the thermoelectric device increases the life span of battery packs, resulting in less operational downtime. The thermoelectric device can supply high levels of electrical power over long periods of time for e.g. electronic sensors used to permanently monitor downhole parameters such as pressure and temperature data, etc. and to detect specialized and conventional subterranean formations The thermoelectric device is also relatively unaffected by hostile downhole environments which also reduce battery life.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for an apparatus comprising a tubing string (34) for conveying a fluid flow heat source from a subterranean formation and a thermoelectric device (100) having two thermocouples, the first of which is thermally coupled to the tubing string and the second of which is thermally coupled with a heat sink source of the well.    An INDEPENDENT CLAIM is also included for an apparatus for extending a life span of a downhole battery pack (202) which comprises the thermoelectric device and a battery recharge circuit having an input terminal and an output terminal, the input terminal being connected to the electric power terminal of the thermoelectric device and the output terminal being electrically coupled to a downhole electronic device.    An INDEPENDENT CLAIM is included for a method of generating electric power downhole in a well where a first surface of a thermoelectric device is coupled to a heat source and a second thermoelectric device surface having two terminals is connected to a heat sink source, so that a temperature differential between the heat source and heat sink temperatures causes the thermoelectric device to generate a voltage potential between the terminals of the thermoelectric device.    DESCRIPTION OF DRAWING(S) - The drawing shows a thermoelectric downhole power generator.    well casing (17)    tubing string (34)    inner bore of tubing string (35)    thermoelectric device (100)    battery pack (202)    frictional heat generating devices (400)    orifice (402)    passage portion (404)    diffuser (generating frictional energy) (406)    passage portion (408)