Abstract: A method of providing electrical energy to a dewar containing a cryogenic liquid including introducing an insulated heat pipe, with a distal end and a proximal end, into a cryogenic dewar comprising an exterior surface. And providing a Seebeck module, with a cold junction and a hot junction. The distal end is in thermodynamic contact with a cryogenic fluid and the proximal is thermodynamically connected to the cold junction. The hot junction is thermodynamically connected to the exterior surface of the dewar, thereby producing an electrical flow in the Seebeck module. A level probe may be calibrated by taking a first capacitance reading with the dewar full, and a second capacitance reading when the cryogenic liquid level is within a calibration gap. The level probe is calibrated by utilizing the first capacitance reading and the second capacitance reading.