I don't know if a technical manual for TOS or TNG states this, but is there any reference to how much energy is consumed in transporting a person (I expect this would vary from person to person, so base it on an average human being)?
The TNG Technical Manual would suggest that the power requirement to successfully convert a human into a matter-stream is between 32-37 mega-electronvolts (MeV).
This, however is directly contradicted in Voy: "Eye of the Needle", where Kim needs to boosts transporter power to 37 megajoules (MJ) in order to get the transporter to work correctly. This works out to just over 2.5 MeV.
This disparity seems to be an outright error by the writers.
KIM: Phase transition coils.
(It still won't solidify.)
TORRES: Ramp the coils to thirty seven megajoules.
KIM: Thirty seven megajoules.
The manual also mention that the emergency transporters (and older transporter models) use a great deal less power in their operation but doesn't name a precise figure.
Another take would be to calculate the energy change before and after the entire process. Assume the Enterprise is in low Earth orbit (100 km), beaming a human of 100 kg (a bit overweight but makes the maths easier) to the equator. g is 10 m/s2 (actually about 9.8 on the surface and 9.5 in orbit). GPE=mgh gives an energy change of 108 J, or 100 MJ - pretty similar to the Voyager episode quoted.
But that's not all. At the equator, the human will have a speed of 464 m/s, but in orbit their speed was 7,859 m/s. Even orbiting in the same direction, they'll have to change their speed by over 7000 m/s; using E=(1/2)mv2 gives us about 2.5x109 J, or 2.5 GJ.
Transportation takes roughly 5 seconds, so P=E/t gives an average power of 500 MW, or half a gigawatt - the power of a small city. Maybe 1.21 jigowatts isn't so far off!
Interestingly, it takes about 500 seconds to get to orbit via conventional rocket. The energy change per kilogram is the same, so P=E/t = 5 MW - the power of a small town.
All of this is based on a conservation of energy argument, giving a lower limit. In practice operating the machine (whether transporter or rocket) increases this energy and power.