The costs of deploying the fuel cells over a 10 to 20 year period were compared to the present total cost of energy for single homeowners. [...] The electrical efficiency of the fuel cell is then obtained by dividing the amount of energy obtained from a cubic meter of hydrogen by the amount theoretically available. [...] Despite these apparent differences, the operating principle of the fuel cell does not differ from that of the hydrogen fuel cell described above and it is still the reaction of hydrogen and oxygen from which the energy is derived. [...] In order to calculate the amount of diesel fuel required, the same fuel cell efficiency was assumed as for the natural gas fuel cell, 55%. [...] Therefore the amount of electricity retrieved from the diesel fuel is equal to 55% of the amount of energy available.