Sorry to rain on your parade, Calvin but that is one of the most common myths out there.
Running on 240 does have advantages, but saving money on your bill is not one of them. The electric company charges by kwh, as measured coming through your meter. How you deliver that electricity from your meter to your device does not matter. 240 can be more efficient in that regard but it doesn't use less electricity.
You can run more devices (or more powerful ones) with a single circuit on 240 than you can on 120 (duh) but the kwh running through the meter will not change.
If what you suggest were true (that electricity use can be cut in half, simply by running on 240), wouldn't everything run on 240?