Need an engineer to calculate wattage and batteries needed

I need to calculate the wattage needed (and the batteries needed) for a mini heating system that uses an etched heater (Kapton Polyimide heaters) for the heat element, and uses batteries for the power. The heating element will be placed between two pieces of 26 gauge stainless steel, which is .0178" in thickness for each piece of steel. Each piece of stainless steel is smooth surface (non-brushes). Each piece of steel is 6" in length, and 1" in width. The distance from the battery compartment to the start of the heating element is approximately 2.75". And last, the desired temperate of the surfaces is a minimum of 100 degrees Fahrenheit, and 120 degrees F maximum. There will be a dial to control the temperature from the minimum temperature up to the maximum temperature. I need to know the wattage necessary, and the number/type of batteries needed to operate this (preferably AAA, but am flexible).