Ice boxes held food and large blocks of ice that chilled the food. Ice boxes were typically made of wood, lined with tin or zinc on the inside and insulated with wood chips or sawdust. They had a pan to collect water from the melting ice, which had to be replaced daily.

When refrigerators first came on the market in the late 1800s, they transformed the way people shopped, stored food and ate. Nowadays it seems like we need an invention to help us eat all our leftovers!

Those kilowatt-hours translate to roughly 660 pounds (272 kilograms) of carbon dioxide, which is about the same amount emitted by burning 35 gallons (132 liters) of gas in your car. Newer, energy-efficient refrigerators save so much money that it's worthwhile to replace your old one.

Figuring your mileage at about 23 miles (37 kilometers) a gallon (3.8 liters), you'd have to drive some 800 miles (1,280 kilometers) to equal your refrigerator's carbon footprint. That’s more than the distance from New York City to Chicago!

Mustard and other condiments that have a high acidity typically require no refrigeration. Food that contains no preservatives or that has dairy products in it should be refrigerated. Mayonnaise is made with eggs, so it should always be chilled.

Unless you enjoy eating moldy dairy products, one week is about the longest you should leave them out of the fridge. Even though blue cheese gets moldy as part of its aging process and tastes best at room temperature, it should be refrigerated before and after serving.

If you live in a cold climate or if your power goes out in the winter, your food should be fine in the chilly outdoors. Think of it as nature's refrigerator!

While all these answers might be eco-friendly, buying smaller amounts of food would be essential. You'd have to eat everything before it spoils, so smaller quantities leave fewer leftovers to eat before they go bad.

Methods for pickling, smoking, drying, salting, canning and curing foods have been around for hundreds of years, in some cases millennia, and were the norm for preserving foods before refrigeration.

Next to your washing machine, your refrigerator uses less electricity than most other major appliances. Start by turning off your air conditioner if you want to really save money and be more eco-conscious.

Without a refrigerator, you probably will buy less food during your shopping trips, but the smaller portions you buy often use more packaging materials than larger portions of the same thing.

When you unplug your fridge, you have to be ready to eat leftovers very quickly before they spoil -- or throw away your money when you throw away food.

A small freezer uses nearly a third of the energy that a good quality refrigerator uses. So is it really worth it to do without the fridge?

The more food you keep in your refrigerator, the less time it takes to cool down after you open and close the door.

Cleaning your refrigerator coils once a year should be enough to make sure they work well and don't waste too much energy.

Older refrigerators often waste energy by letting cool air leak out around the door. Check the rubber seal of yours to make sure it closes tightly all around.

British scientists are trying to revitalize a refrigerator invented by Einstein and his colleague. Amazingly, it has no moving parts, runs on pressurized gas and consumes no electricity at all!

Researchers in the U.S. are working on a refrigerator design that runs on a biodiesel- and solar-powered generator and uses a thermoelectric coolant.

Freon is poisonous, so other coolants are preferable. An older fridge that leaks Freon could be hazardous.

In America, the Energy Star rating indicates the efficiency of your appliance; the higher the rating, the more efficient the appliance. Doing your research on what type and size of refrigerator you actually need helps too.