Apparatus for electrode heating of earth for recovery of subsurface volatiles and semi-volatiles

An apparatus for electrically heating an in situ subsurface formation having a volume and a thickness, to remove volatile and semi-volatile hazardous waste material therefrom over a processing time, comprising:

• at least n electrodes of substantially equal length each having substantially the same input resistance, and placed in a subsurface formation substantially equidistantly, wherein n is greater than the product of the volume of the formation of cubic meters, multiplied by the input resistance of an electrode in ohms, multiplied by the constant 75 kilowatt hours, divided by 20 and further divided by the processing time in hours, the effective number of electrodes within the formation being sufficient to mitigate the evaporation of water near the electrodes and increase the temperature at a mid-point between adjacent electrodes,
• electrical energy supply means for supplying electrical energy of opposite polarity to at least two of said electrodes,
• means for passing a gas into said subsurface formation,
• means for collecting gas, and
• means for removing hazardous vapors from said collected gas.