Last updated Sunday July 15, 2012: Updated January 25, 2015
The Energy Use of Home Cooking
Not only does it cost less to cook your own meals, from a total food production cycle, it takes less energy as well. Home made food does not have to travel nearly as far as foods processed in a factory somewhere across the country or even across the world.
Store Bought Food: Raw ingredients are shipped to a factory. That factory uses energy to run machines that process the food. Preservatives are also added to make the food last longer so it can survive the long journey before it makes it to your table. Additionally, higher temperatures used in processing lowers the nutritional value of the food. The food is then put into a package made from materials of paper, metal or plastic. Those materials also take energy and natural resources to be manufactured and transported to this factory.
The end food product is then shipped to a warehouse for storage until it can be sent to a distributor who then ships it to the grocery store where we as consumers buy it and transport it home. After we open the store bought food, the packaging material is thrown away or recycled.
The food is eaten as-is or minimally processed according to a recipe. Store bought food requires little energy from the home consumer but the over-all energy required to produce this food, including packing materials and transportation is very high.
Home Stored and Home Cooked Food: Raw ingredients are bought in bulk from a distributor at a low cost and with minimal packaging materials. This food has minimal or no preservatives because it is still in a natural (or minimally processed) form that maintains long shelf life (beans, whole grains, sugar, honey and salt).
The bulk food is stored as-is or transferred into re-usable bins or buckets and then stored. When ready, a smaller portion of the bulk ingredients are processed according to a recipe and eaten.
The home-cooked food has almost no preservatives and is higher in nutrition since the ingredients are in a more natural form. More preparation time and slightly more energy is required of the end consumer to process it before it is eaten.
The over-all energy required to produce the home-cooked food is very low since it does not require nearly as much packing materials or transportation.
What does it cost to process food at home?
Here is a list of the energy costs associated with processing foods at home in various kitchen appliances: (assuming 10 cents per KWh of electricity).
Small Crock Pot (3 qt) 160 Watts on High (6 hours = 0.96KWh or 10 cents in electricity).
Large Crock Pot (7 qt) 325 Watts High, 248 Watts Low, 78 W warming (6-hours on high = 1.95KWh (or 20 cents in electricity).
Whisper Mill Wheat Grinder 700 Watts under load, 460 watts no load Average of 5 watt-hours of electricity per cup of flour (less than 1/200th of a cent to grind 1 cup of whole-wheat flour).
Waffle Iron (4 waffles) 1100 Watts, 0.04KWh per x4 waffle (1/10th of a cent per waffle).
Toaster (2 and 4 slice) 700 watts for 2 slices, 1400 watts for 4 slices. 17 watt-hours (1/6th of a cent) to make 2 pieces of toast.
Toaster Oven 1244 watts (1/3rd of a cent for 2 pieces of toast).
Microwave Oven 1544 watts (only 33% efficient). (1/2 cent for 2 minutes of cook-time).
Electric Range (40-49% efficient) 800 watts (small burner) 2100 watts largest burner. (20 minutes of cook time = 2.6 cents small burner and 7 cents for large burner). Costs will be lower if burner is not on high and cycling on/off.
Electric Oven 5700 watts (cycles on/off according to temperature), 2700 watts mid cycle. At 350 °F averages out to be ~2000 watts continuous. (1 hour of cook time costs 20 cents).
Electric Oven Cleaning 5.3 kWh per cleaning cycle. Costs about $0.53 in electricity.
Electric Griddle 1300 watts (cycles on/off according to temperature).
Kitchen Aid 185 watts. Less than 1/6 cent per meal.
Garbage Disposal 185 watts while running. (1 cent per month)
Dish Washer 1300 watts while running (650 watts with no heating element running). (10-30 cents per wash).
Refrigerator (Energy Star) Side-by-side 60 watts overall average, (185 watts when running, 950 watts while de-icing). (13 cents per day).
Cooking in the winter will decrease your home heating costs, while cooking in the summer will increase your home air conditioning usage.
In Utah, the operating cost of a gas appliance is 2-4 times less than an electric one but I have yet to find a gas powered blender ;)
Kitchen appliance operating costs (regardless of being gas or electric) are so low in comparison to say the operating cost of driving a gas car, it almost isn't worth arguing over which is better.