In Spain the company Cidete Ingenieros SL of Vilanova, Barcelona in Spain, offers both Seebeck electricity generating and Peltier cooling thermoelectric devices. The energy harvesting versions employ two stage structure. The company advises the, "In order to generate current from a hot source, establish a temperature difference of at least 70C between the faces of the thermoelectric device. A source at 100C or more can generate five watts of electricity". For more see http://cidete.org/.
