USA NO You should never exceed the rated wattage for a fixture. If, however, you mean to say a CFL with a rated lumen output EQUAL TO a 100 watt lamp, in which case the CFL wattage is about 17, the answer is yes you can. Light output is measured in lumens. The power consumed by the lamp is measured in watts. CFLs are attractive right now because they give just as much light (lumens) for much less power (watts). And it is the power - rated in watts, that you pay for. Your meter reads the amount of watts you use, not the lumens. So, the less watts used, the better.
Again, NEVER exceed the rated wattage of a light fixture.