According to the EPA, or Environmental Protection Agency, an old refridgerator can cost around $150 to run. If you have an old refridgerator plugged in just because you don't want to throw it away you may want to reassess whether or not you need it. Appliances account for nearly 20% of your annual utility costs. If you have an old appliance you can see immediate savings on your bills by replacing it with a newer energy efficient model.
Be sure to recycle your old appliances!